Growth hormone-releasing peptides.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing preclinical and clinical studies on growth hormone secretagogues.
PubMed 9186261 · doi:10.1530/eje.0.1360445
What was done
This narrative review summarizes experimental and clinical findings on synthetic growth hormone-releasing peptides (GHRPs, including GHRP-6, GHRP-1, GHRP-2, and Hexarelin) and non-peptidyl mimetics (such as MK-0677). The authors describe their receptor mechanisms, routes of administration (intravenous, subcutaneous, intranasal, and oral), interactions with GHRH and somatostatin, and secretory responses across diverse physiological and pathological conditions in animals and humans.
What was found
The abstract reports no quantitative numerical data. It describes that GHRPs stimulate potent, dose-dependent growth hormone (GH) release across intravenous, subcutaneous, intranasal, and oral routes and synergize with GHRH. Prolonged administration increases IGF-1 levels, with partial desensitization occurring more during continuous infusion than intermittent dosing. GH-releasing activity is preserved across sexes, declines with age (remaining marked into the sixth decade), and is maintained in hypersecretory states (acromegaly, anorexia nervosa, hyperthyroidism). Secretory responses are reduced in obesity, hypothyroidism, and idiopathic short stature or GH deficiency, and are virtually absent in Cushing's syndrome or pituitary stalk disconnection. Chronic treatment was reported to increase height velocity in short children.
Why it matters
This paper synthesizes the foundational pharmacology of GH secretagogues acting through distinct non-GHRH receptors, highlighting their potential as orally active agents for diagnostic and therapeutic use in somatotrope hyposecretory states.
Limits
The abstract lacks quantitative effect estimates, confidence intervals, and participant numbers. As a narrative review, it does not employ systematic search methods, defined study selection criteria, or formal risk-of-bias assessment.
Cited by
- supports GHRP-2 and GHRP-6 are growth hormone-releasing peptides that stimulate the body's natural release of growth hormone.