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Written by: M.M. a/k/a DatBtrue
Copyright 2008 by M.M. a/k/a DatBtrue
All rights reserved.
No part of this article may be reproduced in any form without the written permission of the copyright owner.
great read on peptides from another board
ARTICLES:
Basic Guide: CJC-1295
Basic Guide: Growth Hormone Secretagogues
Growth Hormone Administration vs. CJC-1295/GHRP-6
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Restoring Growth Hormone
"It has been argued that the age-dependent decline in sex steroid, Growth Hormone, and IGF-I production is nature’s way of protecting us from cancer and heart disease, but a far more likely scenario is that once we reach our reproductive capacity, nature begins programming us for death."- Roy G. Smith, Ph.D. Director, Huffington Center on Aging; Professor, Department of Molecular & Cellular Biology; former Vice President for Basic Research at Merck Research Laboratories, Merck & Co
Such programming begins as the second decade of life draws to a close, the negative consequences of which become more noticeable with each passing year.
We begin to experience a steady decline in immune function. (1,2) Our bodies increase production of glucocorticoids (catabolic hormones) and cytokines (inflammatory) which negatively impact metabolism, bone density, strength, exercise tolerance, cognitive function, and mood. (3,4–8)
The hormones of sex, dehydroepiandrosterone (DHEA), Growth Hormone (GH), and Insulin-like Growth Factor (IGF-1) are positively correlated with the health and well-being of the body in general and the specific functioning of metabolism, the cardiovascular system, the musculature skeletal system, cognitive function & the immune system. However these hormonal levels naturally decline as we age and as a consequence those systems necessary to maintain optimal health decline as well. (1-4,9)
"Hence, if we wish to maintain quality of life during aging we must oppose nature." - Roy G. Smith, Ph.D.
A progressive decline in lean body mass, atrophy of its component organs & reduction in their function and increased deposition of adipose tissue mass characteristic of the aging human body result partially from the body's diminished secretion of growth hormone. (10-13) These negative changes resulting from growth hormone deficiency have been shown to be reversible by replacement doses of growth hormone. (14-21)
Growth Hormone is a vital anabolic hormone whose positive stimulatory effects on protein synthesis (particularly in the liver, muscle, bone, cartlidge, spleen, kidney, skin, thymus, and red blood cells) and on lipolysis (the breakdown of fat stored in fat cells) contributes greatly to growth, repair & well-being. (10)
Growth Hormone (GH) secretion is primarily regulated by the release of two peptides, Growth Hormone-Releasing Hormone (GHRH) and Somatostatin. The hypothalamus region of the brain releases these hormones in response to signals from the central nervous system. GHRH once released makes its way to the receptors on the somatotrope cells of the pituitary gland of the brain where it stimulates Growth Hormone release.
Somatostatin once released makes its way to the receptors on the somatotrope cells of the pituitary gland of the brain where it inhibits Growth Hormone release. (15)
The primary physiological action of somatostatin is to inhibit synthesis and release of GH. (16-19) The primary physiological action of Growth Hormone-Releasing Hormone (GHRH) is to stimulate synthesis and release of GH.
The end product of this cascade, Growth Hormone (GH) once secreted exerts its effect in the body as a whole both directly and indirectly through its initiation of Insulin-like Growth Factor (IGF-1) synthesis in the liver. IGF-1 in turn exerts its effect in the body and its rise in turn begins to inhibit any further GH release.
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Growth Hormone (GH) is released periodically within the body in a controlled pulsating fashion. This periodic pattern plays an important role in transmitting the GH "growth, repair & well-being" message to tissue. A review of several studies involving GH replacement in GH-deficient animals reveals the biological significance of episodic secretion. These studies conclude that GH released in a pulsatile pattern is far more efficient in improving mammalian growth and repair than the method of GH administration by constant infusion.
In males GH pulses occur approximately every three (3) hours, a frequency that appears across most mammals. The secretion bursts are preceded and followed by almost undetectable levels of plasma GH.
In females however GH pulses occur more frequently and the base level of plasma GH remains higher than males who have fewer GH pulses but the amplitude of which are more pronounced.
GH pulse amplitudes are increased during slow wave sleep such that particularly in males, most GH secretion occurs at night. (22)
Growth Hormone secretion is highest during the growing years of youth and early adulthood. In humans the secretion rate starts to noticeably decrease during the third decade of life and strongly decreases during the fourth decade of life. As we age the daytime secretory pulses diminish first, while the sleep associated GH pulse persists and diminishes gradually.
Nudging Nature
Growth Hormone levels may be increased either by exogenically administering Growth Hormone or by administering Growth Hormone-Releasing Hormone which then endogenically stimulates the somatrope cells of the pituitary to secrete additional Growth Hormone. The primary advantage of GHRH is that GH ends up being released in physiological conformance to the body’s natural biorhythm. This biorhythm is pulsatile.
Studies have concluded that endogenous Growth Hormone Releasing Hormone (GHRH) is the principal regulator of pulsatile GH secretion in humans and that continuous GHRH infusion augments pulsatile GH release. Whereas exogenic administration of GH raises overall GH levels but has no effect on amplifying the pulses.
People of all ages naturally continue to possess the ability to secrete GH from stores within the pituitary. Most studies are in agreement on this point. One study in particular examined the effects of administration of GHRH & a Growth Hormone Releasing Peptide on all adult age groups from those in their 20's to those above 75 years of age. They observed substantial increases in GH release as a direct result of administration of GHRH & GHRP-6. This prompted them to conclude, "...that the lack of side-effects & safety of the protocol and the discovered lack of age-related decline in the 'GHRH-GHRP-6-mediated' GH release opens the possibility of using it as a therapeutical tool to revert some deleterious manifestations of aging in man." (23)
Long-lasting GHRH analog CJC-1295
While the studies have demonstrated repeatedly that administration of GHRH does increase GH secretion and amplifies the release pulse there does remain a significant drawback. GHRH has a very short half life, measured in minutes with a fairly short clearance rate measured in hours. (24) While this is a sufficient amount of time to exert a positive effect on GH secretion, particularly if GHRH is administered multiple times a day, the result is less than optimal. (25,26)
It is for this reason that longer-lasting analogs of GHRH were researched and developed. (28) The most effective of which is CJC-1295.
Exposure of native GHRH to blood plasma results in rapid degradation. CJC-1295, a synthetic human GHRH analog avoids rapid degradation by possessing the ability to selectively and covalently bind to endogenous albumin after subcutaneous administration. Albumin possesses a half-life of 19 days in humans and so modified GHRH bound to albumin greatly extends its half-life and duration of action. (27)
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In a recent (2006) study "Prolonged Stimulation of Growth Hormone (GH) and Insulin-Like Growth Factor I Secretion by CJC-1295, a Long-Acting Analog of GH-Releasing Hormone, in Healthy Adults", Sam L. Teichman, et al. Journal of Clinical Endocrinology & Metabolism 91(3):799-805, CJC-1295 was found to result in "sustained, dose-dependent increases in GH and IGF-I levels in healthy adults and was safe and relatively well tolerated, particularly at doses of 30mcg/kg or 60 mcg/kg."
It has been demonstrated repeatedly in various studies that GHRH is effective at instigating GH release and longer acting analogs do increase the overall effectiveness. So it is no surprise that the results of this CJC-1295 study comport with what has been previously demonstrated.
What was unknown was what effect persistent elevation of GH by a long-lasting GHRH analog would have on the pulsatility of release. This was explored in a follow up study, "Pulsatile Secretion of Growth Hormone (GH) Persists during Continuous Stimulation by CJC-1295, a Long- Acting GH-Releasing Hormone Analog", Madalina Ionescu, et al. The Journal of Clinical Endocrinology & Metabolism 91(12):4792-4797.
That study found that pulsatility was not interfered with and was in fact preserved in all subjects both immediately after administration and continuing 7 days post-administration.
This is obviously a very beneficial characteristic to preserve. In fact episodic release appears to be imperative to growth and repair of tissue in mammals.
The study further found that while growth hormone secretion was increased by almost fifty percent there was no increase in pulse amplitude or frequency. All of the increase came from a substantial elevation of trough levels with preserved pulsatility.
One further note of interest is that study participants were all of young age with lower lean body masses which may indicate that GHRH in the form of CJC-1295 is an effective avenue for growth hormone release for those of young age.
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The results of the study charted above show that administration of single doses of CJC-1295 resulted in a 2 to10-fold increase in mean serum GH levels in all dosing groups, which was dose incremental and persisted for up to 7 days. Similarly, a dose-related increase in mean serum IGF-I levels was observed at all dose levels, ranging from 1.5- to 3-fold and persisting for up to 14 days. (29)
The results from a toxicology study wherein 50mcg/kg of CJC-1295 was administered subcutaneously to monkeys for a period of six months found no ill effects and no indication of presence of neutralizing antibodies. They concluded that the Drug Affinity Complex (DAC) a technology that enables covalent binding (conjugation) of a drug to albumin produced no evidence of immunogenic or immunotoxic effects in monkeys. (30)
In summary, although the added Drug Affinity Complex adds complexity and increases the expense of CJC-1295 peptide synthesis, it does add tremendously to both the dosing convenience and the biological activity of GHRH without any identifiable adverse toxicity.
References:
1 - Hadden JW, Malec PH, Coto J, Hadden EM 1992 Thymic involution in aging. Prospects for correction. Ann NY Acad Sci 673: 231–239
2 - Mackall CL, Gress RE 1997 Thymic aging and T-cell regeneration. Immunol Rev 160:91–102
3 - Ershler WB, Keller ET 2000 Age-associated increased interleukin-6 gene expression, late-life diseases, and frailty. Annu Rev Med 51:245–270
4 - van Eekelen JA, Rots NY, Sutanto W, de Kloet ER 1992 The effect of aging on stress responsiveness and central corticosteroid receptors in the brown Norway rat. Neurobiol Aging 13:159–170
5 - Martignoni E, Costa A, Sinforiani E, Liuzzi A, Chiodini P, MauriM, Bono G, Nappi G 1992 The brain as a target for adrenocortical steroids: cognitive implications. Psychoneuroendocrinology 17: 343–354
6 - Liu J, Mori A 1999 Stress, aging, and brain oxidative damage. Neurochem Res 24:1479–1497
7 - Sapolsky R, Armanini M, Packan D, TombaughG1987 Stress and glucocorticoids in aging. Endocrinol Metab Clin North Am 16:965– 980
8 - Heffelfinger AK, Newcomer JW 2001 Glucocorticoid effects on memory function over the human life span. Dev Psychopathol 13:491–513
9 - Murialdo G, Barreca A, Nobili F, Rollero A, Timossi G, Gianelli MV, Copello F, Rodriguez G, Polleri A 2001 Relationships between cortisol, dehydroepiandrosterone sulphate and insulin-like growth factor-I system in dementia. J Endocrinol Invest 24:139–146
10 - Rudman D. Growth hormone, body composition, and aging. J Am Geriatr Soc 1985; 33:800-7.
11 - Meites J. Neuroendocrine biomarkers of aging in the rat. Exp Gerontol 1988; 23:349-58.
12 - Finkelstein JW, Boyar RM, Roffwarg HP, Kream J, Hellman L. Age-related change in the twenty-four-hour spontaneous secretion of growth hormone. J Clin Endocrinol Metab 1972; 35:665-70.
13 - Rudman D, Kutner MH, Rogers CM, Lubin MF, Fleming GA, Bain RP. Impaired growth hormone secretion in the adult population: relation to age and adiposity. J Clin Invest 1981; 67:1361-9.
14 - van Buul-Offers S, Van den Brande JL. The growth of different organs of normal and dwarfed Snell mice, before and during growth hormone therapy. Acta Endocrinol 1981; 96:46-58.
15 - Parra A, Argote RM, Garcia G, Cervantes C, Alatorre S, Perez-Pasten E. Body composition in hypopituitary dwarfs before and during human growth hormone therapy. Metabolism 1979; 28:851-7.
16 - van der Werff ten Bosch JJ, Bot A. Effects of human pituitary growth hormone on body composition. Neth J Med 1987; 30:220-7.
17 - Crist DM, Peake GT, Mackinnon LT, Sibbitt WL Jr, Kraner JC. Exogenous growth hormone treatment alters body composition and increases natural killer cell activity in women with impaired endogenous growth hormone secretion. Metabolism 1987; 36:1115-7.
18 - Jorgensen JOL, Pedersen SA, Thuesen L, et al Beneficial effects of growth hormone treatment in GH-deficient adults. Lancet 1989; 1:1221-5.
19 - Crist DM, Peake GT, Egan PA, Waters DL. Body composition response to exogenous GH during training in highly conditioned adults. J Appl Physiol 1988; 65:579-84.
20 - Salomon F, Cuneo RC, Hesp R, Sonksen PH. The effects of treatment with recombinant human growth hormone on body composition and metabolism in adults with growth hormone deficiency. N Engl J Med 1989; 321:1797- 803.
21 - Jones AJS, O’Connor JV. Chemical characterization of methionyl human growth hormone. In: Hormone drugs: proceedings of the FDA–USP Workshop on Drug and Reference Standards for Insulins, Somatropins, and Thyroid- axis Hormones, Bethesda, Maryland, May 19–21, 1982.
22 - Holl RW, Hartman ML, Veldhuis JD, et al. Thirty-second sampling of plasma growth hormone in man: correlation with sleep stages. J Clin Endocrinol Metab 1991;72:854–61.
23 - Micic D, et al. Preserved Growth Hormone (GH) Secretion in Aged and Very Old Subjects after Testing with the Combined Stimulus GH-Releasing Hormone plus GH-Releasing Hexapeptide-6. J Clin Endocrinol Metab. 1998 Jul;83(7):2569-72
24 - Frohman LA, Downs TR, Williams TC, Heimer EP, Pan YCE, and Felix AM. Rapid enzymatic degradation of growth hormone-releasing hormone by plasma in vitro and in vivo to a biologically inactive, N-terminally cleaved product. J Clin Invest 78: 906–913, 1986.
25 - Iordanova VK, Wen SY, Moreau IA, Smith SY, Frohman LA, and Castaigne JP. Every other day subcutaneous administration of CJC-1295, a drug affinity complex (DAC)-growth hormone releasing factor (GRF) analogue, increases body weight and bone mineral content in dogs (Abstract). 87th Annual Meeting of The Endocrine Society, 2005, p. P1–78.
26 - Jette L, Leger R, Thibaudeau K, Benquet C, Robitaille M, Pellerin I, Paradis V, van Wyk P, Pham K, and Bridon DP. Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-lasting GRF analog. Endocrinology 146: 3052–3058, 2005.
27 - Peters JRT. All About Albumin. Biochemistry, Genetics and Medical Applications. San Diego, CA: Academic, 1996.
28 - Hoffman, Andrew R., et al. Efficacy of a Long-Acting Growth Hormone (GH) Preparation in Patients with Adult GH Deficiency. J Clin Endocrinol Metab 90(12):6431–6440
29 - Teichman SL, Neale A, Lawrence B, Cagnon C, Castaigne JP, and Frohman LA. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab 91: 799–805, 2006.
30 – Wen, S. et al. Immunogenicity AND Immunotoxicity Assessments of Two Drug Affinity Complexe Compounds in Cynomogus Monkeys. Toxicologist, Report 170, 2005.
Written by: M.M. a/k/a DatBtrue
Copyright 2008 by M.M. a/k/a DatBtrue
All rights reserved.
No part of this article may be reproduced in any form without the written permission of the copyright owner.
__________________
Growth Hormone Secretagogues
In the 1980's three classes of compounds where studied to determine their effect on growth hormone release. These three compounds were:
Growth Hormone Releasing Hormone (natural hormone)
Growth Hormone Releasing Peptides (synthetic molecules often termed "GH-Secretagogues")
Opiates (Dermorphin & Benzomorphan)
Individually each class of compound when administered in laboratory rats was found to induce growth hormone release. However when they were all combined growth hormone release dramatically increased.
Growth Hormone Releasing Hormone (GHRH) + Growth Hormone Releasing Peptide (GHRP) was found to induce a large synergistic secretion of growth hormone (GH).
However when the Opiate was combined with GHRH & GHRP the synergy was huge amounting to a release of GH more than double that achieved by the GHRH/GHRP combo alone.
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When all three classes of compounds were examined it was discovered that each compound released GH by a mechanism different and distinct from that of the others. Furthermore it was found that these three modes of action accomplished growth hormone release in ways complementing and not interfering with each other.
Unfortunately opiates have several drawbacks. Not withstanding their illegality chronic use is both toxic and addicting with undesirable alterations in normal physiology.
Fortunately we are left with two tools with which we can maximize a synergistic release of growth hormone. These tools have no toxicity and promote desirable alterations in normal physiology.
Growth Hormone Releasing Hormone (GHRH) in the form of its long-lasting analog (CJC-1295) was discussed in the previous article. It is therefore left to this article to discuss Growth Hormone Releasing Peptides (GHRPs) and the human studies that demonstrate synergy between these two compounds (GHRP + GHRH).
NOTE: The information presented in this section was drawn generally from Refs: 1-11
Growth Hormone Releasing Peptides (GHRPs) - A Quick Look
What are they?
Growth Hormone Releasing Peptides (GHRPs) are synthetic forms of the natural hormone Ghrelin. These simple short-chained amino acid peptide strings possess most of the positive characteristics of Ghrelin (such as effecting GH secretion) and few of the negative properties (such as Ghrelin's lipogenic behavior (i.e. conversion of glucose to fatty acids)).
GHRPs belong to a broader class of compounds all of which share the common trait of being able to bind to the Growth Hormone Secretagogue Receptor (GHS-R) and effect GH release. These compounds include the synthetic peptides (GHRP-6, GHRP-1, GHRP-2, Hexarelin, Ipamorelin) and smaller synthetic non-peptide molecular compounds such as MK-0677 as well as the natural ligand Ghrelin. This broad class which includes all of the above but not Growth Hormone Releasing Hormone (GHRH) is termed Growth Hormone Secretagogues (GHSs).
These Growth Hormone Secretagogues (GHSs) exert their effect on increasing GH output in multiple ways.
First they INDIRECTLY increase growth hormone (GH) secretion by inducing Growth Hormone Releasing Hormone (GHRH) release from the hypothalamus in the brain. GHRH once released makes its way to the Growth Hormone Releasing Hormone Receptors (GHRH-R) in cells within the pituitary (a gland just below the brain) where it binds and exerts its direct influence in signaling GH release.
Second these GHS also make there way to those same pituitary cells where they themselves bind to a Growth Hormone Secretagogue Receptor (GHS-R) and exert a DIRECT influence in signaling GH release. This signaling uses a different mode of action distinct from that of GHRH. As a consequence both bound GHRH & bound GHS can exert their positive influence concurrently resulting in synergistic growth hormone (GH) release.
Third they INDIRECTLY increase GH secretion by reducing release of Somatostatin (the GH inhibiting hormone) from the hypothalamus and DIRECTLY by reducing the magnitude of Somatostatin's inhibiting action once it binds to its receptor on the pituitary cells.
In essence Growth Hormone Secretagogues (GHS) turn up the positive signal to release GHRH, turn down the negative signal to release the inhibiting hormone Somatostatin, speak directly to the growth hormone releasing pituitary cells themselves to encourage them to release GH and speak directly to the growth hormone releasing pituitary cells themselves to encourage them to ignore Somatostatin's message to stop releasing GH.
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Oral GHS
Based on the effectiveness of GHRPs smaller non-peptide molecules were created in an effort to mimic the GH releasing effects of GHRPs with the desire to develop a compound with high oral bioavailability. As a result MK-0677 was eventually created as a non-peptide compound with sustained GH release and higher oral bioavailability. Unfortunately desensitization was found to occur fairly rapidly. In addition the dose for the orally administered MK-0677 is measured in several milligrams while the effective dose for the injectable GHRPs is measured in micrograms making GHRPs more cost effective. Research is ongoing on non-peptide GHSs, particularly with Ipamorelin derivatives so perhaps an oral GHS devoid of desensitization will eventually be developed.
My own thought is that these molecular compounds appear to be small enough to be used in a transdermal formula. Also it would be nice to have these orally/transdermally active compounds available to use on a limited basis perhaps making usage when traveling convenient.
NOTE: The information presented in this section was drawn generally from Ref: 12
Growth Hormone Releasing Peptides - A Longer Look
What are they?
In 1980 the first highly potent GH-Releasing peptide was developed and named GHRP-6. This peptide was found to illicit a strong GH release response and so became the first member of a class of growth hormone releasing peptides more broadly called GH secretagogues. Structurally GHRP-6 is composed of the amino acids L-Histidine, D-Tryptophan, L-Alanine, L-Tryptophan, D-Phenylalanine and L-Lysine. The "L" form of an amino acid is the naturally occurring form and often in the nomenclature the "L" is dropped. The "D" form does not occur in nature and is the isomeric form (i.e. mirror image) of the naturally occurring "L" form.
GHRP-6 is composed of both natural and isomeric forms of those aforementioned six amino acids. Its structure is represented as:
His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
Investigators subsequently modified the structure of GHRP-6 and identified more potent peptides. For example, activity was enhanced by replacing D-Trp with D-2-(2-napthyl)alanine and His with D-Alanine to create GHRP-2 whose structure is represented as:
D-Ala-D-2 Nal-Ala-Trp-D-Phe-Lys-NH2
In 1982, after a long search the natural hormone "Growth Hormone Releasing Hormone" (GHRH) was finally isolated and identified. As a result the interest in Growth Hormone Secretagogues (at that point limited to the three peptides) faded. Eventually researchers discovered that those GH-Releasing Peptides (specifically GHRP-6 & GHRP-2) followed a mode of action which bound them to and was mediated through receptors different from those for GHRH. In addition researches discovered that these GH-Releasing Peptides acted synergistically with the natural hormone Growth Hormone Releasing Hormone (GHRH) in vivo (in both laboratory animals & humans) to produce large releases of Growth Hormone.
Taken together these two discoveries made it clear that GHRPs were not simply surrogates of GHRH. GHRP-6 and its analogues were artificial activators of a separate newly discovered receptor termed the "Growth Hormone Secretagogue Receptor" (GHS-R). Eventually the natural hormone Ghrelin was discovered as the endogenous ligand that binds to the GHS-R. Together the natural hormone Ghrelin, and all the synthetic compounds (both peptides & smaller molecules) such as GHRP-6 were termed "Growth Hormone Secretagogues" (GHSs).
This nomenclature continues in the literature to this day however increasingly new terminology is used. For instance the "Ghrelin Receptor" is synonymous with "GHS-R" and "Ghrelin mimetics" are synonymous with all the synthetic compounds that are capable of binding to the GHS-R. This paper uses the more established nomenclature throughout.
NOTE: The information presented in this section was drawn generally from Refs: All of the Bower's studies
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Pituitary Actions of GHSs
All GHSs act directly on the pituitary. They do so by binding to and activating their specific receptor (GHS-R). Once this occurs GH secretion is commanded to rise. GHRH does the same thing. It acts directly on the pituitary and binds to and activates its specific receptor (GHRH-R). Once this occurs GH secretion is commanded to rise.
However GHSs and GHRH operate through a different "mode of action" or intracellular signaling system within the cell that eventually activates GH secretion. These modes of action are contrasted as follows.
GHRH when it binds to its receptor (GHRH-R) on the cellular membrane of a somatotrope cell activates the cAMP–PKA (cAMP-dependent protein kinase) pathway (in essence a secondary messenger), and by a poorly understood mechanism causes a persistent rise in intracellular Calcium (Ca2+) ions by opening Ca2+ channels (simply ports on the cell membrane that open and close to either permit or deny entry) on the cellular membrane and letting into the cell Ca2+ from the outside. The rise in calcium concentration within the cell signals in conjunction with other signaling processes the instruction to the somatotrope cell to release Growth Hormone.
It should be noted that Somatostatin (the GH inhibiting hormone) once bound to its receptor brings about a decrease in GH in part by inhibiting cAMP formation. As a consequence of limiting this messenger the signaling cascade is weakened resulting in less Calcium (Ca2+) ions entering the cell and thus inhibition of GH release.
GHSs however do not rely on cAMP as a messenger. GHSs once bound to their respective receptor initiate a process that leads to an inhibition of Potassium (K+) ion channels. This action results in a sustained depolarization of the cellular membrane. The result is identical to that affected by GHRH, namely the Calcium ion level rises via voltage-activated channels leading to the signal to secrete GH. But the mode of action relies on the use of depolarization of the cellular membrane and inhibiting Potassium ion channels rather then GHRH's cAMP-mediated opening of Calcium ion channels.
In addition to allowing Ca2+ into the cell, GHSs may also cause a rise in intracellular Ca2+ by redistribution from internal stores of Ca2+ within the cell. This process is mediated by the generation of inositol trisphosphate whose main functions are to mobilize Ca2+ from storage organelles and to regulate cell proliferation.
This brief description is an over simplification. The important point is that GHRH and GHS act through their own receptors and distinct intermediate pathways.
This is not the only difference. Although the image herein depicts one pituitary somatotrope with both types of receptors activated (GHRH-R & GHS-R) this may not give a completely accurate picture. GHRH and GHS appear to act on different somatotrope subpopulations. GHRP has been shown to increase the number of somatotropes releasing GH, without altering the amount of hormone released by each individual cell. On the other hand, GHRH stimulates both the number of cells secreting GH and the amount of GH secreted per cell.
From these limited discoveries we can begin to understand how GHRH and GHSs compliment each other's GH releasing actions rather then duplicate one another.
It should be noted that Somatostatin (the GH inhibiting hormone) has been shown primarily to decrease the number of cells secreting GH without affecting the amount of GH secreted per cell.
To sum up in very general terms GHS increases, while Somatostatin decreases, the number of active GH secreting somatotropes, probably because these two factors act by depolarizing and hyperpolarizing cells, respectively (i.e. GHSs turns the cell into a Calcium ion sponge & Somatostatin turns the cell into a squeegee, squeezing out and repelling Calcium ions).
On the other hand GHRH does both, but acts primarily by stimulating the amount of secreted GH within the active somatotropes.
NOTE: The information presented in this section was drawn generally from Refs: 13-17
Hypothalamic Actions of GHS
In vitro (in a laboratory dish) the amount of GH release from GHRH and GHSs is additive. GHSs cause a rise of 2...GHRH causes a rise of 1...put them together and the GH rise is merely the sum 3.
But something different happens when you put these two compounds into living breathing mammals. In vivo (in body) the GH rise that occurs from the combination of GHRH and GHSs is more then the sum of their individual contributions. There is substantial synergy such that 1 + 2 = 6.
This occurs as a result of GHSs actions within the Hypothalamus (region of the brain) rather then its direct pituitary actions. There are GHS receptors (GHS-R) in the hypothalamus; perhaps even subtype receptors. When GHSs bind to these receptors they behave like a hypothalamic neurohormone and as such exhibit a dual action.
They stimulate endogenous GHRH release and concurrently suppress endogenous Somatostatin release. How they do this is a complex process with much still unknown. Basically they incite electrical activation of arcuate neurons (within the hypothalamus). About seventy-five percent of the cells excited by GHRP-6 project outside the blood brain barrier (hypothalamus) into the median eminence (boundary between hypothalamus & the portal system which connects to the pituitary which lies just below the brain) and are neurosecretory involved in the regulation of pituitary function.
The activation of these neurons by GHRP-6 is extremely long lasting (longer than 1 hour) and reaches the peak rapidly (within 5 to 10 minutes). Non-peptide GHSs respond slower perhaps for the reason that they penetrate the blood brain barrier slower than GHRP-6.
GHRP-6s excitation of neuronal activity beyond those neurons that regulate GHRH & Somatostatin (i.e. the remaining 25%) may account for some of the impact GHRPs have on non-GH releasing activity.
The important point is to recognize that GHSs have an impact on GHRH release and Somatostatin suppression at the hypothalamus which appears to be responsible for the now well-recognized synergistic effect on GH release from concurrent administration of GHRH & GHRPs in vivo.
Furthermore it should now be firmly understood that GH release is regulated by the following trinity - GHRH, Somatostatin and GHSs.
NOTE: The information presented in this section was drawn generally from Refs: 13-5, 9, 18
Written by: M.M. a/k/a DatBtrue
Copyright 2008 by M.M. a/k/a DatBtrue
All rights reserved.
No part of this article may be reproduced in any form without the written permission of the copyright owner.
__________________
GHS Potency (i.e. efficacy) & Dosing in Humans
When administered at clinical research dosages, all GHSs (both peptides and non-peptides) release significantly larger amounts of GH (i.e. are more efficacious) than GHRH. This is not to be confused with the term potency which takes into account the molecular weight of a compound and thus measures GH output on a "per mol" basis. By this measure GHRH is more potent.
However if the desire is to administer these compounds and effect GH release then the only relevant standard is absolute amount of GH release and in that regard GHSs release more GH than GHRH. The following standards determined through clinical study will specifically clarify this concept.
In humans the maximal i.v. dose for GHRH has been found to be 1 mcg per kg of bodyweight. That is a level that saturates the receptors and beyond which there is no further benefit, until that dosage has dissipated.
In humans the maximal i.v. dose for GHSs such as hexarelin has been found to be 2 to 3 mcg per kg of bodyweight. In normal humans (i.e. those without disease or clinical malady) GH release is increased as the GHS dose increases up to the aforementioned maximal dose. Even very small amounts have been shown to have positive effects.
Unlike GHRH, GHSs are resistant to well-known inhibitors of GH secretion. Studies demonstrate that hexarelin-mediated GH secretion is reduced but not blocked by a rise in circulating free fatty acids or by a glucose load, nor by an infusion of Somatostatin nor drugs that enhance hypothalamic Somatostatin secretion.
GHRH is influenced by metabolic and hormonal factors that consequently make GHRH a very unpredictable GH stimulator, with large variations between individuals and a diversity of peaking times.
In contrast GHSs are not greatly influenced by metabolic and hormonal factors, the absence of which makes GHSs a very predictable GH stimulator. GHSs are potent and efficacious, their actions synchronized and reproducible, with no non-responders.
GHSs have been repeatedly demonstrated in studies to be very strong GH releasers in healthy young males. In addition GHSs have been shown in studies to be very strong GH releasers in females at all stages of the menstrual cycle. This again is important to note because GHSs are not greatly affected by changes in various hormone levels, be they thyroid hormone, estrogen, etc.
There may be an age-related reduction in the GH-releasing capability of GHSs. The studies have not yet been able to come to a consensus. However, the synergistic effect of GHRH and GHS on GH secretion is not reduced as humans age throughout the entire lifespan. This holds true even for the very old (Those in their 90's).
There are no reported side-effects with GHS usage. However both the peptidyl and non-peptidyl compounds have been found to induce slight increases (still within what is deemed the normal range) in prolactin and in adrenocorticotrophin(ACTH)/cortisol, and in a few studies dehydroepiandrosterone (DHEA). Low to moderate dose (1 mcg/kg) administration of GHRP-6 has been found to result in very large GH release with no significant effects on cortisol or prolactin. Of the peptides, Hexarelin appears to induce the highest level of these hormones (prolactin & cortisol). Ipamorelin a newer GHS has no effect on these hormones no matter what the dose.
NOTE: The information presented in this section was drawn generally from Refs: 19-31
Why you need both GHRH analog (CJC-1295) and GHRP
GHS Down Regulation
A single dose of a GHS in vivo brings about an immediate down-regulation of responsiveness to subsequent administration. This desensitization appears to abate and sensitivity fully restored within a few hours.
However continual infusion of large amounts of GHS brings about a substantial initial release of GH, followed, after several hours, by long-term down-regulation of GH secretion.
The only published comparison of the results of differing modes of GHS delivery (twice daily injections vs. continuous infusion) in vivo demonstrated a dramatic dissipation of anabolism following infusions of high-dose GHS. However a pronounced anabolic effect was maintained with the same dose of GHS administered by intermittent injection.
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From the results of this study graphed out above it is evident that with GHSs the optimal dosing pattern is administration by injection with sufficient intervals between dosing so as to maintain sensitivity.
The effectiveness is greatly diminished, perhaps to the point of having no benefit if GHSs duration of action becomes prolonged and sustained. GHSs unlike GHRH are best used to amplify those very import GH pulses while GHRH is effective at raising the total level of GH.
If we understand desensitization than we will easily understand why the oral GHS, MK-0677 in recent studies failed to demonstrate a "maintained acceleration of statural growth in children with GH-deficiency". MK-0677 was developed to be a long lasting orally active analogue of GHRP-6. MK-0677 is to GHRP-6 what CJC-1295 is to GHRH (i.e. long-lasting).
The problem is that while long-lasting analogues of GHRH do not result in desensitization and pronounced down-regulation, long-lasting analogues of GHRP-6 do desensitize and consequently lose effectiveness.
CJC-1295 brings about persistent and chronically elevated levels of GH while GHRP-6 if injected a couple of times a day amplifies the very important GH pulses. The two compounds greatly compliment each other. In the previous article on GHRH & CJC-1295 we discussed the importance of pulsation which has been shown to be necessary for growth. The other important component of anabolism is chronic GH elevation.
Continuously elevated levels of GH increase IGF-I levels more than intermittent increases in GH. The intermittent nature of GH release brought on by GHSs' mode of action does create a rise in IGF-I levels but the anabolic effect may not be pronounced.
It has been repeatedly demonstrated and is now recognized that in children the growth response to injections of IGF-I is far less than the growth response to injections of GH. This is in accordance with most animal studies, which demonstrate that treatment with IGF-I does "not produce the full anabolic and growth-promoting effects of GH treatment".
Protocols that elevate GH while maintaining and amplifying the pulses seem to be effective at producing anabolism. The combination of CJC-1295 and GHRP-6 do just that.
NOTE: The information presented in this section was drawn generally from Refs: 32-37
GHRH (and analogs) + GHSs = a lot of synergistic growth hormone release
There is not a lot of deviation in the published studies on the effect of these peptides and the saturation dose needed to bring about the effect in normal people (who often act as a control group).
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We need only to examine the results of the normal test subjects from three oft-cited studies that established the relevant protocol.
In the first study "Inhibition of growth hormone release after the combined administration of GHRH and GHRP-6 in patients with Cushing's syndrome", Alfonso Leal-Cerro..., Clinical Endocrinology 1994, 41 (5) , 649–654, three different peptide/peptide combinations were used.
GHRH was administered alone at 100mcg. This resulted in area under the curve (AUC) measured for 120 minutes of GH secretion of 1420 ± 330.
GHRP-6 was administered alone at 100mcg. This resulted in area under the curve (AUC) measured for 120 minutes of GH secretion of 2278 ± 290.
GHRH plus GHRP-6 was administered together at 100mcg each. This resulted in area under the curve (AUC) measured for 120 minutes of GH secretion of 7332 ± 592.
As a single dose these results show that GHRP-6 is about twice as effective as GHRH.
The synergy between GHRH & GHRP-6 is clearly evident as co-administration resulted in twice the benefit of the additive values of single doses of the two peptides.
The second study is the one that established the saturation dose for these peptides often used in other studies. "Growth hormone (GH)-releasing peptide stimulates GH release in normal men and acts synergistically with GH-releasing hormone ", CY Bowers..., J. Clin. Endocrinol. Metab., Apr 1990; 70: 975-982.
In that study GHRH at a dose of 1.0 microgram/kg was administered alone and then together with various doses of GHRP-6 (0.1, 0.3, and 1.0 microgram/kg). They found that the submaximal dosages of 0.1 and 0.3 microgram/kg GHRP-6 plus 1 microgram/kg GHRH did have the effect of stimulating GH release synergistically.
However the larger dose of 1 mcg/kg of GHRP-6 was found to be the saturation dose when used in combination w/ 1 mcg/kg of GHRH.
It is also noteworthy that serum prolactin and cortisol levels rose about 2-fold above base levels only at the 1 microgram/kg dose of GHRP-6 and not at the submaximal dosages.
The final study, "Preserved Growth Hormone (GH) Secretion in Aged and Very Old Subjects after Testing with the Combined Stimulus GH-Releasing Hormone plus GH-Releasing Hexapeptide-6", Micic D..., J Clin Endocrinol Metab. 1998 Jul;83(7):2569-72 is fascinating for several reasons.
By reference to citation it is noted that "GHRH plus GHRP-6 (both at saturating dose) is nowadays considered the most potent stimulus of GH secretion in man being able to restore the GH secretion in states associated with chronic blockade of somatotroph activity (as in obesity)...it elicits a near-normal GH discharge in obesity, in patients with hypothyroidism and in patients with type 2 diabetes mellitus."
This particular study examined the effects of combined administration of GHRH, immediately followed by GHRP-6 in a group of very old subjects (age higher than 75 yr), as compared with both normal adults (less than 40 yr) and aged subjects (age 46–65 yr). The dosing levels used were 90mcg of GHRH followed by 1mcg/kg of GHRP-6.
All the subjects had a positive GH secretory response to the combined administration with no differences observed between men and women. However the group comprising the very old had the highest level of GH release followed by the group comprising the aged subjects with the "less than 40 yr group" experiencing a substantial rise but not as high as the other two groups.
The study concluded that the lack of side-effects & safety of the protocol and the discovered lack of age-related decline in the "GHRH-GHRP-6-mediated GH release opens the possibility of using it as a therapeutical tool to revert some deleterious manifestations of aging in man."
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In CONCLUSION, Growth Hormone (GH) is regulated by a trinity composed of Growth Hormone Releasing Hormone (GHRH), Growth Hormone Secretagogues (GHS) and Somatostatin. GHRH and GHSs individually have a positive impact on GH secretion. These two compounds operate through distinct modes of action which complement each other and when administered together result in synergistic GH secretion.
Growth Hormone Releasing Peptides (GHRPs), a subclass of GHSs are effective across all age groups in amplifying GH pulses. Pulsation is a necessary component of growth generation in mammals. GHRH when co-administered with GHRPs has the effect of further increasing the amplitude and "area under the curve" of a GH pulse. The result is a GH pulse many multiples more effective then that achieved by an unaided GH pulse.
In addition to pulsation, overall growth is better accomplished when total levels of GH are elevated without hindering pulsation. Elevated GH levels appear to be a necessary component of growth generation as well. One of the reasons this is so appears to be that chronically elevated GH levels result in more pronounced sustained levels of IGF-1 then that achieved through intermittent GH elevations.
Persistent levels of GHRH do not result in desensitization. Elevated levels of GHRH result in sustained GH release. A long-lasting version of GHRH, CJC-1295 has demonstrated the ability to sustain elevated GH levels in humans.
GHRP-6 is perhaps the most well studied of all GHSs. In physiological doses there are virtually no side effects. It has been demonstrated to be effective for all age groups.
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Combined administration of CJC-1295 and GHRP-6 is a very effective, well studied method of increasing the total amount of GH secreted within the body. By adjusting the dosing of these compounds and accounting for such factors as age one may choose to achieve a "youthful" restoration, an above normal elevation or a substantially above normal elevation of both GH levels and pulsatile release.
Written by: M.M. a/k/a DatBtrue
Copyright 2008 by M.M. a/k/a DatBtrue
All rights reserved.
Growth Hormone Administration vs. CJC-1295/GHRP-6
Units of Measurement
Growth Hormone (GH) like other biologically active substances is measured in International Units (abbreviated as IU) which are based on the measured biological activity for that substance the establishment of which is determined by international agreement. International Units are specific to each substance and so one IU of one substance has no equivalence to one IU of another substance.
While it is fairly straightforward to compare the amount of GH among various dosing administrations (a two (2) iu dose is twice the amount of a four (4) iu dose) and it is easy to ask the manufacture the weight of each iu (Nutropin reveals that 1 iu of their GH is equal to 333 mcg) it is not so simple to compare Growth Hormone to other "Growth Hormone Releasing" compounds such as CJC-1295 and GHRP-6.
Practically all studies that use Growth Hormone (GH) or Growth Hormone Releasing Hormone (GHRH) or its analog CJC-1295 or Growth Hormone Releasing Peptides all take blood samples to measure the amount of GH present in blood plasma at various points in time. The unit of measurement is a standardized unit which can be used to make comparisons across different compounds.
The studies either report results as "nanograms (ng) per milliliter (ml)" or "micrograms (ug) per liter (L)". For the reason that ng = 1/1000 ug and ml = 1/1000 L, ng/ml will always equal ug/L. So no matter how the studies report results comparison is straightforward. In making the cross-comparisons contained herein for simplicity I have chosen to report results as ng/ml.
Therefore this examination will look to several studies involving administration of the compounds of interest and compare the blood plasma levels of IGF-1 and both peaks and total amount of GH blood plasma levels as a result of administration of each tested compound. The result of this cross-study examination will reveal the efficaciousness of various doses of GH, CJC-1295 and GHRH + GHRP-6 in increasing GH & IGF-1 in blood plasma.
Studies used for comparison
Growth Hormone Administration
In "Pharmacokinetics and Metabolic Effects of High-Dose Growth Hormone Administration in Healthy Adult Men", Toshiaki Tanaka, et al., Endocrine Journal 1999, 46 (4), 605-612, fifteen healthy normal Japanese adult males aged from 20 to 27 years were administered various doses of recombinant GH (Norditropin). The GH was administered in a single dose at 9:00 a.m. after overnight fasting. Blood samples were collected at 0, 1, 2, 3, 4, 5, 6, 9, 12 and 24 hours after the single injection.
The doses administered were: .075iu/kg; .15iu/kg and .30iu/kg
When the average weight of each test subject is accounted for the doses administered approximated: 5iu; 10iu and 20iu
CJC-1295 Administration
In "Prolonged Stimulation of Growth Hormone (GH) and Insulin-Like Growth Factor I Secretion by CJC-1295, a Long-Acting Analog of GH-Releasing Hormone, in Healthy Adults", Sam L. Teichman, et al. Journal of Clinical Endocrinology & Metabolism 91(3):799-805, sixty-six healthy normal men and women aged 21-61 were administered various doses of CJC-1295 (long-lasting GHRH analog). The CJC-1295 was administered in a single dose and again in some groups 7 days later and other groups 14 days later. For the reason that we are only examining a week's worth of data only the initial dose is of interest. Blood samples were collected before dosing and then at 15, 30, and 60 minutes and 2, 3, 4, 6, 8, 10, 12, and 24 hours afterdosing; and then every 8 hours on days 2–3, then daily on days 4, 5, 6, 7.
The doses administered were: 30mcg/kg; 60mcg/kg; 125mcg/kg; 250mcg/kg
GHRH + GHRP-6 Administration
While we are limited in our choice of GH administration studies (because no other study administered such high doses in normal men) and CJC-1295 studies (there are only two, the results of which are available to the public) we have many available studies measuring the effects of co administration of GHRH and GHRPs.
So we will briefly look at the results from two studies to give us an idea of how much GH release is contributed by the enhanced pulse brought on by this synergistic combination.
They are, "Inhibition of growth hormone release after the combined administration of GHRH and GHRP-6 in patients with Cushing's syndrome", Alfonso Leal-Cerro, et al., Clinical Endocrinology 1994, 41 (5) , 649–654 and "Growth hormone (GH)-releasing peptide stimulates GH release in normal men and acts synergistically with GH-releasing hormone", Bowers, C.Y., et al. J. Clin. Endocrinol. Metab. 70, 975–982.
What's Normal?
Before we look at the studies lets take a brief look at how much growth hormone (GH) is secreted naturally. There is a large variability among age groups, gender, fitness level and among individuals within a single age group. So the best we can do is generalize. The charts below are derived from GH blood plasma data collected over a 24 hour period for a normal man, a normal man after a fast, a normal woman and a normal woman after a fast. All ages were mid-20s.
Note that the night-time GH pulse peak for a man was about 20 ng/ml (aprox. 85% of 24hr GH release normally occurs at night).
Total GH release was as follows:
Men (Fed):
Area Under the Curve (AUC): 94 ng/ml per 24 hours
Men (Fasted):
AUC: 274 ng/ml per 24 hours
Women (Fed):
AUC: 168 ng/ml
Women (Fasted)
AUC: 264 ng/ml per 24 hours
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Comparing GH administration to CJC-1295 administration
It is difficult to compare based on the following GH release graphs so let's examine the numbers.
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Total GH Release:
When GH was administered at 5iu, 10iu & 20iu the total GH levels (area under the curve (AUC)) were respectively:
AUC: 311.5; 836.9; 1778.5 ng/ml per 24 hours
When CJC-1295 was administered at 30mcg/kg; 60mcg/kg; 125mcg/kg and 250mcg/kg the total GH levels (area under the curve (AUC)) were respectively:
AUC: 758; 969; 977; 1370 ng/ml per hour
NOTE: This is per hour while the GH study is per 24 hours
So based on the total GH concentration in blood plasma the lowest dose of CJC-1295 on a per hour basis results in more than twice the 24 hour GH secretion level of a 5iu dose of GH.
Peak Concentration:
However the GH release pattern results in a much higher mean maximum concentration for the GH administration than the CJC-1295 administration.
The GH study resulted in dose respected peaks of 55.4; 93.8; 180 ng/ml
The CJC-1295 study resulted in dose respected peaks of 6.6; 9.6; 9.9; 13.3 ng/ml
The graph indicates that for the GH study the bulk of the peak lasts about 12 hours followed by low levels of GH. As an aside clearly GH administration would be better if it were administered in at least two doses per day.
But even IF 5iu of GH were administered in the morning followed by 5iu twelve hours later the total amount of GH released would be less than a low dose of CJC-1295 (311.5 + 311.5 < 758 ng/ml). Furthermore the CJC-1295 was dosed just once in seven days while the GH would need to be dosed every one of those 7 days.
Written by: M.M. a/k/a DatBtrue
Copyright 2008 by M.M. a/k/a DatBtrue
All rights reserved.
No part of this article may be reproduced in any form without the written permission of the copyright owner.
IGF-1 Levels:
CJC-1295 elevates IGF-1 within the first day or two where it stays elevated for seven days.
GH elevates IGF-1 levels immediately where it stays elevated throughout the rest of the day.
Both the GH & CJC-1295 studies demonstrated a dose dependent increase in elevated IGF-1 levels. The highest GH dose of 20iu resulted in a similar IGF-1 level as the highest CJC-1295 dose. The lowest GH dose of 5iu resulted in an IGF-1 level not much different then the lowest CJC-1295 dose.
Again the CJC-1295 elevated IGF-1 for seven days from a single administration while GH would likely need to be dosed everyday (perhaps every other day) to match CJC-1295's chronic elevation of IGF-1.
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Can CJC-1295 plus GHRP-6 match GH adminstration's peaks?
Adding GHRPs to CJC-1295 three times a day can amplify peaks and greatly add to the total GH secretion level.
The Alfonso Leal-Cerro study demonstrated the following GH release:
GHRH by itself dosed at 100mcg resulted in:
(AUC) 120 minutes = 1420 ± 330 ng/ml
GHRP-6 by itself dosed at 100mcg resulted in:
(AUC) 120 minutes = 2278 ± 290 ng/ml
GHRH + GHRP-6 dosed together at 100mcg each resulted in:
(AUC) 120 minutes = 7332 ± 592 ng/ml
By adding GHRP-6 to CJC-1295 (long-lasting GHRH) it may be possible to add almost 6000 ng/ml of GH release at each GHRP-6 dosing. [Figure arrived at by taking synergy amount 7332 and subtracting GHRH's contribution of 1420]
But what about those peaks?
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Clearly adding GHRP-6 has the effect of matching GH's peaking power as measured by amplitude. The difference is that GH results in big hills lasting up to 12 hours. This really amounts to an elevation rather than a pulse. GH does not mimic the physiological pulsatile release of GH that naturally occurs while GHRP-6 particularly in the presence of GHRH does result in such a natural pulse. These pulses last for about 2 hours. If dosed three times a day the result would be three 2-hour pulses each of which exceed GH's 5iu and 10iu elevations and approach GH's 20iu elevation.
However 6 hours total of peak for the CJC-1295/GHRP-6 combination would be half of the 12 hours total of peak for the GH.
I do not know if it matters. I do not know if these two different peaking characteristics would result in different effects concerning growth.
In CONCLUSION, CJC-1295 appears to result in higher concentrations of GH in blood plasma than does GH administration. When CJC-1295 is combined with GHRP-6 the total GH release is exacerbated.
GH administration results in higher GH maximum concentration or peaks then CJC-1295 alone. However when CJC-1295 is combined with GHRP-6 the peaking amplitude exceeds the 5iu & 10iu GH doses and approaches the 20iu dose. GH administration's peaks however last for 12 hours while CJC-1296/GHRP-6 results in a natural 2 hour peak at each dosing (i.e. 6 hours total).
Both CJC-1295 and GH appear equally effective at elevating and sustaining IGF-1 levels.
Written by: M.M. a/k/a DatBtrue
Copyright 2008 by M.M. a/k/a DatBtrue
All rights reserved.
No part of this article may be reproduced in any form without the written permission of the copyright owner.
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