GHRP-2, GHRH and SRIF interrelationships during chronic administration of GHRP-2 to humans

Studies with chronic GHRP-2 or GHRH administration were performed to demonstrate and better understand the interrelationships between GHRP-2, GHRH and SRIF. Normal younger and older men and women received chronic GHRP-2, GHRH or GHRP-2 + GHRH for 7-30 days. It was demonstrated that chronic administration of either GHRP-2 or GHRH could convert an additive GHRP-2 + GHRH GH response to a synergistic one. In addition, the type of synergistic response induced by chronic GHRP-2 versus GHRH was different. Whether the GH response becomes desensitized during chronic administration depends in part on the dosage and frequency of administration. The potential to learn more about the in vivo actions of GHRP relative to the regulation of GH secretion is underscored by studying the GH responses to GHRP-2, GHRH and GHRP-2 + GHRH.