Despite the controversies, some scientists continued with additional studies and again proved IGF-1 to actually prolong life…at least in worms.  Then, in 2001, scientists discovered that the use of IGF-1 resulted in a proliferation of cancer cells, especially throughout the breast and colon, and a 2012 study found that both too much or too little IGF-1 could contribute to dying from cancer; implying that IGF-1 actually helped patients with terminal cancer live longer.

If you’re looking to increase your muscle growth and improve strength, whether for competitive bodybuilding or to achieve a personal physique goal, our Australian muscle building peptide supplements can help. Our dedicated research and product development team have consistently produced new products that perform better than other supplement brands, so you know you’ll be getting the best peptide supplements available. If you’re new to peptide supplements and have questions, read our FAQ’s, or alternatively email us at and our clinic doctor can help you with your questions.
Growth Hormone Releasing Peptide 6 ( GHRP-6) is a peptide which substantially activates the pituitary gland into releasing high levels of growth hormone for a few hours. The increase in growth hormone comes from your own body, not synthetic growth hormones which can suppress your natural production. GHRP 6 is a first generation GHRP and has a few side effects which could be annoying.

GHRP-6 while being the penultimate in strengths of GH release in its class, it is still quite potent and can be taken 2-3 times in a day. It is available in a freeze-dried powder and should be reconstituted in bacteriostatic water and stored in the refrigerator. It is available in 5 mg packets, and one dosage should not be more than 100 micrograms. A dosage of more than 200 micrograms does not any significant impact on the muscles. It should be injected using an insulin syringe either under the skin or between muscles.
But gene-therapy experiments have also resulted in patient deaths. The use of such therapies can cause the human body to experience fatal immune reactions to the vectors used to place the gene in the body. Another danger of gene therapy is an inability to control the expression of the gene, which could translate into a rapidly spreading cancer. Or the expression of the gene could spread from skeletal muscle into heart muscle, resulting in excessive heart muscle growth (known as left ventricular hypertrophy, or “athlete’s heart) that can cause premature heart failure.
Additionally and not less relevant, GHRP-6 appears as an excellent partner to combine with other molecules (ie, epidermal growth factor [EGF]) because their exclusive actions seem to achieve a kind of synergism, useful to target the multiples nodes of complex pathophysiological processes, and thus to enhance tissue repair processes.56 Garcia del Barco and coworkers in our group have opened unprecedented avenues, by combining GHRP-6 and EGF as a therapeutic approach to ameliorate the damages of multiple sclerosis,57 peripheral axonal pathology,58 and brain ischemia in animal models.59,60 They have demonstrated that in all these experimental substrates the combined action of GHRP-6 and EGF is associated with a better outcome in both clinical and pathological fields.
MuscleSport PCT Stack 1x MuscleSport PCT Revolution 1x MuscleSport Test Revolution Black The MuscleSport PCT Stack is the ultimate Post Cycle Therapy supplement combo. Perfect for anyone who has spent time using anabolics or SARMs and want to ensure that their natural testosterone production is at its peak and that any excess estrogen is taken care of.  

More than a decade ago, CD36 was identified as one of the GHRP-6 receptors [12]. This is a scavenger receptor endowed with multiligand and multifunctional capabilities and is expressed by a broad constellation of mammalian cells [13]. Granulation tissue neovascularization is perhaps the most renowned physiological role of CD36 in wound healing [14]. Serendipitous observations of our laboratory indicated that CD36 mRNA transcript appeared abundantly represented in clinical samples of granulation tissue of either acute (deep burn injuries) or chronic (pressure ulcers) wounds, as in laboratory rat’s controlled full-thickness wounds. This finding incited us to speculate on the effects associated with CD36 agonistic stimulation beyond that of the angiostatic action via thrombospondin binding [15]. Here we provide the first experimental evidence on the favorable impact of the topical administration of GHRP-6, as a candidate to qualitatively improve the healing process.

As previously explained, multiple GHRP-6 doses are required throughout the day due to the pulsatile nature of the HGH release, and the administration of these doses are typically administered on average 3 times daily spaced evenly apart. More administrations are acceptable for greater effects on physique and performance, but it is advised that approximately 3 hours in between each injection is ensured so as to allow the pituitary gland to restore its storage of HGH. The most common protocol is as follows:

So… now we get down to the individual peptides themselves. I will not go into length with a profile for each one, but instead I will provide two charts that should help in understanding which peptides are GHRH’s and which ones are GHRP’s. Of course, IGF and MGF have their own respective spots but do not have the synergy when combined like GHRP and GHRH.
Perhaps, the primary reason why peptides are used in bodybuilding has to do with how they improve growth hormone production. It is no longer a secret how HGH helps to improve lean muscle mass. Your body uses peptides to promote increased secretion of HGH. They, therefore, make it easier for interested persons to achieve bigger muscle mass. Their usage may help enhance strength. It is even said that these small amino acid chains could boost testosterone production.
The evidence derived from these experiments supports the notion that CD36 is an active and approachable receptor to modulate the healing process. Here we have observed that CD36 occupation by GHRP-6 attenuates wound inflammation, accelerates wound closure, and above all improved wound’s esthetic outcome by impacting ECM proteins accumulation. To our knowledge these findings are unprecedented for GHRP-6 within the context of cutaneous healing.

In March 1972, the Drugs and Poisons Schedule Subcommittee (DPSSC) decided to include vitamin D in Schedule 4 when the recommended daily dosage on the label exceeds 10 micrograms. This recommendation was based on a recommendation by the Nutrition Committee of the National Health & Medical Research Council that the attention of pharmaceutical firms be drawn to the dangers of vitamin A overdose.
Conclusions: Subcutaneous administration of CJC 1295 resulted 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 30 or 60 ug/ kg. There was evidence of a cumulative effect after multiple doses. These data support the potential utility of CJC 1295 as a therapeutic agent.
When using any GHRH, it should always be remembered that positive results cannot be achieved overnight. These compounds act steadily over time, and the best results can be achieved slowly, and with a nutritious diet and a proper exercise regime. Also, these peptides are not sex-specific, so they do not have any androgenic effects. They can be used by women in the same dosages that men do.
Cancer can often be a process of uncontrolled cellular division. IGF-1 is not only pro-growth in a way that could increase this cellular division, but IGF-1 also inhibits apoptosis, or programmed cell death. Hence the theory among some in the medical community that tumors could increase synthesis of IGF-1 to keep themselves alive and to encourage the spread of cancer throughout the body. This doesn’t mean that IGF-1 directly causes cancer.
In June 2011, the delegate decided to reschedule from Schedule 2 to Schedule 3, combination ibuprofen+paracetamol preparations (up to 200 mg of ibuprofen and 500 mg of paracetamol) when in packs of 30 dosage units or less. The delegate also decided that combination ibuprofen+paracetamol preparations in packs of more than 30 dosage units are to be captured by Schedule 4.
Depending on the intended use, and your desired results, the dosage levels are going to vary from person to person as well. So, keep this in mind when trying to determine how great the results are actually going to be when you are using Ipamorelin. So, what exactly can you expect when using this supplement? Some things you will see, for every user is:
I have questions about combined therapy of CJC 1295 and Ipamorelin at the same time on a daily basis for both. The compounding pharmacies do not clearly state whether the CJC is with or without DAC. If it is the CJC with DAC, which sustains elevated GH and IGF-1 for several days, would taking it nightly in conjunction with the Ipramorelin, that is suggested to be taken TID but is being recommended only once at night, be over-stimulatory? If the CJC is without DAC, why take two pepetides simultaneously ,that have similar effects? I am just not clear why taking a daily dose of CJC with Ipamorelin as a single dose is better than taking the CJC with DAC twice per week alone or take the CJC with DAC for a while then switch to the Ipamorelin for a while?
Mostly, these peptides are sold as lyophilized powder in 2mg containers. Bacteriostatic water should be mixed with the powder in order to reconstitute it. To make the dosage of 100mcg per injection, 2ml bacteriostatic water should be mixed into 2mg of lyophilized powder. This reconstituted mixture should be then injected inside the muscles or under the skin. The mixture should be kept under refrigeration at all times otherwise it will degenerate and will not be effective anymore.
But let’s say you’ve already implemented the IGF-1 boosting strategies of adequate calories, sufficient protein, weight training, plenty of sleep, smart supplementation, mineral intake and alcohol moderation. Should you take the next step, wander into an anti-aging clinic, find an online pharmacy, lurk in the depths of bodybuilding forums, and begin IGF-1 injections?
Very tough to say. I am not a doctor and this is not to be taken, interpreted or construed as medical advice. Please talk with a licensed medical professional about this. These are just my own personal thoughts and not a prescription or a diagnosis or any form of health care whatsoever. I could possibly help but would need to see your health history, blood, biomarkers, etc. I'd be happy to help you via a personal one-on-one consult. Just go to and then choose a 20 or 60 minute consult, whichever you'd prefer. I can schedule ASAP after you get that.
In more recent years, these data were further substantiated using again the TO-2 hamster DCM biomodel in which GHRP-2 reduced the progression of LV remodeling, dysfunction, and the ensued myocardial fibrosis by an antioxidant mechanism.36 The abovementioned myocardial fibrotic process amelioration reveals an additional potential use for GHRP in an unmet medical need. Chronic treatment with hexarelin in spontaneously hypertensive rats, in addition to decreasing ventricular hypertrophy, diastolic dysfunction, and high blood pressure, significantly reduced cardiac fibrosis by decreasing interstitial and perivascular myocardial collagen deposition and myocardial hydroxyproline content. Mechanistically, hexarelin treatment increased matrix metalloproteinase (MMP)-2 and MMP-9 activities and decreased myocardial mRNA expression of tissue inhibitor of metalloproteinase (TIMP)-1.37

Cerebrolysin—also known as FPE 1070—is a synthetic nootropic drug. Nootropic drugs are substances that enhance cognitive functions such as memory, creativity, and motivation in otherwise healthy individuals. This peptide is extremely small, allowing it to penetrate the blood-brain barrier and act directly on the neurons of the central nervous system. Cerebrolysin has been found to improve the metabolic activity of brain tissue, shield neurons from harmful substances, and stimulate the peripheral and central nervous systems. In addition to its utility as a nootropic substance, the drug has potential as part of a treatment plan addressing Alzheimer’s disease, stroke, and moderate to severe head injury.
MuscleSport PCT Revolution ADVANCED POST-CYCLE THERAPY PCT Revolution should be used after the use of any SARM. This ensures natural testosterone production increases and excess estrogen production is reduced. When your body produces abnormally high levels of testosterone for an extensive period of time you need to get your system back firing on all cylinders. Post-Cycle Therapy does just that.…
[2] Blocked growth hormone-releasing peptide (GHRP-6)-induced GH secretion and absence of the synergic action of GHRP-6 plus GH-releasing hormone in patients with hypothalamopituitary disconnection: evidence that GHRP-6 main action is exerted at the hypothalamic level. V Popovic, S Damjanovic, D Micic, M Djurovic, C Dieguez, and F F Casanueva. JCEM 1995 80: 942-7; doi:10.1210/jc.80.3.942.
The scheduling of paracetamol and caffeine when combined in a compound analgesic as the only active ingredients was again reviewed by the NDPSC at its 57th Meeting in October 2009 after the Committee had received a request to reconsider the scheduling on the grounds of potential toxicity if used in excess. This issue had been extensively reviewed at the June 2007 meeting and it was decided that Schedule 2 remained appropriate.
‘Peptides’ have become increasingly popular in bodybuilding/strength circles in the last 5 years or so, due in part to a reduction in availability of authentic steroids in the U.K., the legal aspects of steroid possession/use (peptides for ‘experimetal use are at press still considered legal), but mostly due to the fact that some mislead individuals are thinking they are the new Holy Grail of muscle growth (they aren’t). As a simple science lesson, synthetically produced GH, natural GH and Insulin are in fact complete protein peptide hormones, which as we know have been used in bodybuilding for the last 40-50 years or so. Before we get into what these designer peptides do though, I must supply a little scientific background as to what they actually are and even though I could go into a shit-load of scientific jargon here, you’ll just get bored and turn the page, so I’ll keep it as simple as I can.

These studies on human subjects were paralleled by contemporary experimental progresses in basic science, which demonstrated that hexarelin enhanced H9c2 cardiomyocyte proliferation in a dose-dependent manner. Since these were in vitro experiments, they completely excluded a potential intervention of the GH axis and clearly indicated a direct GHRP binding to cardiac cells membranes.32 Weekers et al33 demonstrated that 14 days of pretreatment with GHRP-2, but not GH, selectively protected against the postischemic diastolic dysfunction and myocardial stunning of excised hearts submitted to ischemia/reperfusion in isolated, perfused rabbit hearts.

In June 2007, the NDPSC decided to extend the exemption from the limit on paracetamol combinations being allowed as general sale products to include phenylephrine (as long as it also qualified as exempt from scheduling through the phenylephrine entries). At that time, the NDPSC considered that the safety profile of these substances was such that allowing a fixed combination to be unscheduled was reasonable.
The final verdict is to go for it. GHRP-6 is not your garden-variety performance enhancer. One of the most important aspects of it is that it does not cause desensitization. This means that it will not cause overdose and that works best for athletes. Also since it increases appetite, it forces you to make more calories available to your body for exercise and for recovery. It does not boost unnatural muscle growth like other performance enhancers and the result does not put extra pressure on your tendons and ligaments.
Thanks to the assiduousness of talented researchers around the globe, our contemporary understanding of the pharmacology and probably also the physiological regulation of growth hormone secretion, came about after the important discovery that GHRP increased pulsatile GH secretion in not only children, but also within normal younger and older men and women. Even though GHRP alone substantially releases GH from the pituitary in vitro without the addition of GHRH, this rhythmic endogenous secretion does require some GHRH.
Paracetamol/caffeine formulations have a long-established safety and efficacy profile over 25 years of use as an open-sale medicine in major markets around the world. The paracetamol/caffeine combination analgesic was registered as a schedule 2 product in Australia and has been marketed since 2010. Since that time no new significant issues or potential risks have been reported.

GHRP’s have been used whilst steroid cycling, but due to their nature and comparative weakness to steroids and the like, I find the best use of these compounds is during and after post cycle therapy in an attempt to keep as much of the steroid-induced gains as possible as well as helping the users mind-set as they still feel like they are ‘on’ something…sad but true. GHRP’s are also cycled in an alternate fashion with GH (and IGF), so as to keep the body’s natural GH production systems from de-sensitizing and shutting down completely…much in the same way that steroid users alternate HCG with steroids; to keep the natural testosterone system functioning optimally.
I take or did take organic colostrum at the beginning of last year after starting a paleo food plan after having a gut issue and every day am and pm after a period off about 3 months started to have to pee during the night ( I’m 60) but never the dribble or straining just pee and then during the day 4-5 times a day rush to the toilet and pee for what seems ages
There is no “one right way”, to use Ipamorelin. For example, if you are using 500 to 1000 mcg doses daily, twice a day, your cycle might run for an 8 week period. If on the other hand, you are an athlete training for a competition, you might be on 3 injections per day, at 300-500 mcg, and will stay on for a 12 week period. For new users, you might find a 300 mcg injection is too high, and you will cut back to 200 mcg until your body gets used to it, for an 8-week cycle.
Excerpt: I started taking Ipamorelin and CJC 1295 without DAC yesterday. I dont see many logs and i see a lot of people wondering what kind of results you can get wiith these peptides. I have enough to go a couple of months right now and see what this stuff is really about. Im taking each 3x a day. Morning, pwo, and before bed. Im taking 100mcgs of each in the morning and before bed. After my workout, I'll take 100mcgs of cjc and 100-200mcgs of Ipa. I weigh 215 and i have no idea what my bodyfat
Our first human GHRP-6 studies in normal young men were performed in collaboration with Michael Thorner (Bowers et al., 1990). These studies (Fig. 1.7, left panel) revealed that iv bolus GHRP-6 released GH and, when given together with GHRH, released GH synergistically. One of the most characteristic and consistent in vivo actions of GHRPs in various animals as well as humans of both sexes and all ages is the synergistic release of GH when GHRP is administered concomitantly with GHRH by iv bolus. Subsequently, this was also found for continuous 24/7 subcutaneous (sc) infusion. Also recorded in Fig. 1.7, right panel, is the comparative GH-releasing effects of iv bolus GHRP-6, -1, -2, and GHRH in normal young men. The potency of the three GHRPs we developed over several years was increasingly effective in releasing GH, and each released more GH than GHRH in normal young men. In addition, this was also found to occur in normal young women (Bowers, 1996).

This class of peptides is used to enhance the insulin-like growth of muscles by bodybuilders. These compounds are great for targeting specific muscle groups. Also known as Somatomedic C, IGF-1 has become one of the more popular peptides used for muscle building in the last 10 years or so. Englishman Dorian Yates, who was named Mr. Olympian for six straight years in the 1990s, is thought to have been a prominent user. This contributed to make many professional bodybuilders to include it in their regimen as well. IGF-1 is also available in different variants.
This is the most popular variant of IGF-1 that buyers will find on the market today. IGF-1 LR3 comprises 83 amino acids. That means it adds extra 13 amino acids to the sequence of the standard insulin-like growth factor-1. The polypeptide boasts qualities that make it much more powerful than normal IGF-1. It boasts a longer half life of up to 30 hours, compared to the latter’s 15 hours. In addition to bodybuilding, IGF-1 LR3 helps with fat burning, quicker recovery and slowing aging.
Prior to the 2008 Beijing Olympics, concerns were raised regarding cardarine which was creating significant and “remarkable” performance and endurance advantages without being regulated, so some athletes were potentially getting unfair advantages. While tests for cardarine weren’t developed in time for the Olympic Games, the following year PPARδ agonists (of which cardarine is included) were added to the WADA prohibited list.
Five of the submissions did not support the proposal while the sixth submission did. The former contend that potential risks of inadvertent use of caffeine in those at risk of an adverse event will be increased if selection of an analgesic is made without the assistance or intervention of a healthcare professional. There was also concern that the proposed exemption may result in an increase in liver damage due to excessive consumption of such a product. This was likely to result from people abusing these products as a source of stimulants.

The purpose for which peptides are used determines their legality. For research purposes, it is perfectly all right for you get these compounds if you need to. But then, the discussion here is not about medical research but bodybuilding. It is less likely you are interested in them for the former purpose. Do note that it is illegal to buy and use peptides for purposes other than research.
Another benefit of CJC 1295 is its ability to promote slow wave sleep. Slow wave sleep is also known as deep sleep and is the portion of sleep responsible for the highest level of muscle growth and memory retention. SWS decreases significantly in older adults and also with people who tend to exercise later in the evening. Clinical studies have shown that a once-daily administration of CJC 1295 normalizes the GHRH response and can induce significantly deeper sleep.
GHRPs can be administered alone or in combination with GHRH. Combined administration of GHRP-6 and GHRH is the most potent stimulus to GH release, with excellent reproducibility and no serious side effects [23]. GHRH/GHRP-6 is highly specific, but is less sensitive than ITT. It is a viable alternative to the ITT in patients with organic pituitary disease, but overlap has been reported between GH levels attained in the control group and severely GH-deficient patients. Since GHRH and GHRP act directly on the pituitary, coadministration restores GH secretion in patients with hypothalamic disease [266]. GHRP-2 administration has different diagnostic cut-off points in adult GHD compared to ITT, and is highly reproducible [267].
H.-M. Zhou, J. Wang, C. Elliott, W. Wen, D. W. Hamilton, and S. J. Conway, “Spatiotemporal expression of periostin during skin development and incisional wound healing: lessons for human fibrotic scar formation,” Journal of Cell Communication and Signaling, vol. 4, no. 2, pp. 99–107, 2010. View at Publisher · View at Google Scholar · View at Scopus
The delegates have decided that the relevant matters under subsection 52E(1) of the Therapeutic Goods Act 1989 are (a) the risks and benefits (b) the purpose for and the extent of use (c) the toxicity (d) the dosage, formulation, labelling, packaging and presentation (e) the potential for abuse and (f) any other matters considers necessary to protect public health.
The scheduling of paracetamol and caffeine when combined in a compound analgesic as the only two active ingredients was amended from Schedule 4 to Schedule 2 by the NDPSC at its 50th Meeting in June 2007. Evidence reviewed by the Committee at that time conclusively demonstrated that the key ingredient in terms of analgesic overuse and nephropathy was phenacetin and not caffeine. It was agreed that the indications for use, safety profile and potential for misuse met the criteria for a Schedule 2 medicine.
Triamcinolone acetonide (TA) has long been the steroid of choice for the treatment of skin fibrotic disorders, providing the best relief of local symptoms such as scars flattening. Nevertheless, TA is associated with adverse events such as dermal atrophy, telangiectasia, and immunosuppression [4, 5]. Despite the multitude of therapeutic strategies to prevent or reduce keloid and HTS formation, these conditions remain as orphan clinical niches of ultimately effective interventions [6].
Normal GH secretion, whether spontaneous or evoked by provocative stimuli, is markedly blunted in obese patients who display, as compared to normal weight subjects a reduced: half-life; frequency of secretory episodes; and daily production rate of the hormone. Scacchi, et al found that the combined administration of GHRH and GHRP-6 represented the most powerful GH releasing stimulus among obese patients, which was still less effective than in lean body mass subjects.They concluded that treatment with biosynthetic GH has been shown to improve the body composition, and the metabolic efficacy of lean body mass in obese patients undergoing therapeutic severe caloric restriction. GH and conceivably GHRPs might therefore have a place in the therapy of obesity.11

Side effects resultant from GHRP-6 are typically what would be expected from the use of HGH due to the fact that the end result of GHRP-6 use is that of vastly increased HGH levels. The difference between GHRP-6 and synthetic HGH is, of course, the fact that the HGH resultant from GHRP-6 use is endogenous HGH manufactured by the human body. Nevertheless, GHRP-6 side effects are primarily side effects that occur from HGH use, but there do exist GHRP-6 side effects that are unique to GHRP-6 itself. It is important to note that GHRP-6is not a steroid hormone, nor is it a sex specific hormone, and because of this it can be used by both females and males equally without fear of androgenic or virilization side effects, which GHRP-6 side effects are void of.
On the legality issue, peptides are always classed as ‘research chemicals’, not intended for human use. This is because anything that was intended for human use and especially compounds that are meant to be injected, would have to undergo intensive human research and testing, taking many years before approval. They are classed as research chemicals for use in lab experiments ONLY, which is why on the forums you will see guys talking about injecting their rat/rabbits/guinea pigs with peptides, etc., not specifically saying they are injecting themselves, as a get out clause if any legal repercussions came about.
While GHRP-6 is capable of inducing large increases in GH production when used alone, a given dose will show markedly more effect what a GHRH (growth hormone releasing hormone) peptide is taken at the same time. Alternately, when combining a GHRH with GHRP-6, only about half or a third as much GHRP-6 is needed to obtain the same increase in GH production.
The evidence derived from these experiments supports the notion that CD36 is an active and approachable receptor to modulate the healing process. Here we have observed that CD36 occupation by GHRP-6 attenuates wound inflammation, accelerates wound closure, and above all improved wound’s esthetic outcome by impacting ECM proteins accumulation. To our knowledge these findings are unprecedented for GHRP-6 within the context of cutaneous healing.
Conclusions: Subcutaneous administration of CJC 1295 resulted 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 30 or 60 ug/ kg. There was evidence of a cumulative effect after multiple doses. These data support the potential utility of CJC 1295 as a therapeutic agent.

Investigations reported that GHRP-6 is more efficient than GHRH itself in monkeys and performs synergistically when combined or applied together. An example of this combination would be GHRP-2 and CJC-1295. GHRP-6 is believed to be acting naturally on both pituitary and hypothalamic sites (Fairhall et al. 1995). In a time-dependent and dose-dependent manner, the primary pituitary cells of rats were demonstrated on. From the studies, the concentrations of the GHRP-6 needed for the half-maximal and maximal stimulation were 7 x 10(-9) and 10(-7) M, respectively.
Male pattern baldness is genetically switched on at an age that varies very widely (some men in their twenties, some men never – look at the onset in males in your family). When the genetically inherited tendency turns on, then testosterone and it’s stronger (but less concentrated) metabolite, dihydrotestosterone, trigger the slow death of the hair follicles on the scalp in a male baldness pattern.
Dosing will ordinarily be at least twice per day and preferably 3x/day for best effect, taken at least 30-60 minutes before a meal and at a time of non-elevated blood sugar (in other words, after blood sugar has had time to fall since the most recent meal.) The amount taken generally will be from 50-300 mcg at a time. When using a GHRH along with GHRP-6, dosing should be reduced to 50-100 mcg at a time.
The effect of GHSs on GH release is dose dependent and more reproducible than that of GHRH. The peptide GHSs (e.g., GHRP-6, GHRP-1, GHRP-2, and hexarelin) and the nonpeptide GHSs differ in terms of their pharmacokinetics. The nonpeptides MK-0677 and macimorelin have been developed specifically as orally active agents. The peptidyl GHSs are also active PO, but only at doses several hundred times higher than that required when administered IV.
The use of peptides is not necessarily a case of one or the other. While you can derive benefit from using either GHRH or GHRP, the effects can be amplified by using both. This, for one, will help to better keep levels of somatostatin under control. The amount of that hormone is an issue you will be forced to contend with when using only GHRH. This is because it is known to inhibit growth hormone.
The potent biologic effects of GHRPs and the identification of the GHS-R suggested the existence of a natural ligand for the receptor that is involved in the physiologic regulation of GH secretion. The acylated peptide ghrelin, produced and secreted into the circulation from the stomach, is this ligand (Fig. 7-22). The effects of ghrelin on GH secretion in humans are identical to or more potent than those of the non-natural GHRPs (see Fig. 7-20). In addition, ghrelin acutely increases circulating PRL, ACTH, cortisol, and aldosterone levels. There is debate con­cerning the extent and localization of ghrelin expression in the brain that must be resolved before the implications of gastric-derived ghrelin in the regulation of pituitary hormone secretion are fully understood. Furthermore, post-translational processing of pro-ghrelin gives rise to a second neuropeptide, obestatin, which may also have functional roles in activity of the GH/IGF-1 axis and metabolism. A proposed role for pro-ghrelin peptides in appetite and the regulation of food intake is discussed in Chapter 35.
Effect of GHRP-6 on the left ventricular ejection fraction in an experimental model of dilated cardiomyopathy (DCM). Echocardiography data were derived from our DCM model including the prevention and the regression study protocols in rats.35 The prevention protocol conceived the concurrent administration of GHRP-6 as part of a prolonged treatment with doxorubicin. The concomitant GHRP-6 completely prevented cardiac function failure evaluated as the percentage of ejection fraction by echocardiography. The regression approach examined the GHRP-6 intervention once LVEF was already deteriorated. As shown, the therapeutic administration schedule introduced a full functional recovery of cardiac muscle. Data corresponding to percentage of ejection fraction (%EF) are represented as a mean value ± standard error of the mean for each experimental group. (*), (**), and (***) represent the statistically significant differences between groups treated either with placebo or GHRP-6, according to Student’s t-test.