What actually happens when I administer GHRP and GHRH?
Upon administration of GHRH, it will travel to the anterior pituitary gland and stimulate GHRH R, which, assuming the absence of Somatostatin, will stimulate the release of growth hormone.
Upon administration of GHRP, it will have two effects relevant to our cause. The first, is it will promote the release of GHRH, which will in turn cause the release of growth hormone. GHRP will also directly interact with the GHS-R (or Growth Hormone Secretagogue Receptor), which will also positively affect the release of HGH. GHRP also has the benefit of directly opposing (and, thus, inhibiting) Somatostatin.
In terms of effects on release, it is believed that GHRP increases the number of cells releasing HGH, but not the amount those cells release. GHRH, on the other hand, is believed to increase both the number of cells that are releasing HGH, as well as the amount they are releasing.
To summarize this process in a simplistic manner:
GHRP —–> Release GHRH, Increase number of somatotropes releasing HGH, inhibit Somatostatin
GHRH —–> Increase number of somatotropes releasing HGH, Increase amount of HGH release per Somatotropes
So, should I run just one of these peptides?
No. There is a synergy between coadministration of GHRP and GHRH that is not advisable to forego. The cumulative effect between these two becomes not the total of the individual parts, but a greater response caused by the synergy of their independent actions. GHRH can cause a pulse of HGH, but will not be effective if Somatostatin is present at the time of administration. The addition of the GHRP will inhibit the effects of the present Somatostatin allowing for the pulse to be successful. The single administration of GHRP can create a pulse on its own (greater than that of GHRH alone), but will not reach its potential had GHRH been administered at the same time.
If for whatever reason you can only run one peptide, it is advisable to use a GHRP, since a GHRP will always elicit some action, whereas a GHRH can cause no effect in the presence of Somatostatin.