Scientific Glossary

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GHRH is produced in the hypothalamus and travels to the anterior pituitary where it binds GHRH receptors on somatotroph cells, stimulating GH synthesis and secretion. Endogenous GHRH is released in pulses, particularly during deep sleep. Pharmaceutical GHRH analogues (sermorelin, CJC-1295, tesamorelin) extend this activity by increasing half-life. Importantly, GHRH-based compounds preserve the natural feedback loop — GH levels suppress further GHRH release, maintaining physiological regulation.

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GHRPs are synthetic peptides that act on the ghrelin receptor (GHSR-1a) to stimulate GH release. Unlike GHRH, GHRPs do not require GHRH activity — they activate a complementary and synergistic pathway. When GHRH and GHRP are combined, GH pulses are dramatically amplified (2-10x in some studies) compared to either alone. This synergy is the scientific basis for GHRH+GHRP combination research protocols. Examples: ipamorelin, GHRP-6, hexarelin.