Growth hormone responses to growth hormone-releasing hormine (1–29)-NH 2 and a D-Ala 2 analog in normal men

Abstract

Synthetic analogs of growth hormone-releasing hormone, GHRH(1–29)-NH 2 and D-Ala 2 GHRH(1–29)-NH 2 were administered as a bolus intravenous injection to five normal men in a dose range of 0.015 to 0.5 μg/kg body weight. Vehicle only was administered in a control study. Peak responses to GHRH analogs occurred at 15 or 30 min. An increase in the integrated plasma growth hormone (GH) response was observed at each dose. The dose-response curve of GHRH(1–29)-NH 2 indicated that it has a similar molar potency to GHRH(1–40) and GHRH(1–44). The potency of D-Ala 2 GHRH(1–29)-NH 2 was approximately twice that of GHRH(1–29)-NH 2. Neither analog affected blood levels of PRL, TSH, LH, FSH, ACTH, insulin, glucagon, glucose, cortisol, free thyroxine, and free triiodothyronine. No side effects were noted other than transient flushing with the highest dose administered. The findings demonstrate GHRH(1–29)-NH 2 and its D-Ala 2 analog are potent stimulators of GH release and have potential application in clinical medicine.