Low-dose growth hormone-releasing hormone tests: a dose-response study

Area of Science:

• Endocrinology
• Pharmacology

Background:

• Growth hormone (GH) secretion is pulsatile and regulated by GH-releasing hormone (GHRH).
• Understanding the dose-response relationship of GHRH analogues is crucial for therapeutic applications.

Purpose of the Study:

• To evaluate the dose-dependent effects of an amide analogue of GHRH (GHRH (1-29)NH2) on serum GH concentrations in adult males.
• To determine the optimal dose for stimulating GH release and assess the duration of its effect.

Main Methods:

• A randomized, placebo-controlled study involving 10 healthy adult males.
• Intravenous bolus administration of saline, 1, 10, and 100 micrograms of GHRH (1-29)NH2.
• Serial measurements of serum GH concentrations to analyze peak response, time to peak, and GH decline rates.

Main Results:

• Doses of 10 and 100 micrograms of GHRH (1-29)NH2 significantly increased peak GH levels compared to saline and 1 microgram.
• The rate of GH rise was similar for 10 and 100 microgram doses, but the decline was slower after the 100 microgram dose.
• Increasing GHRH (1-29)NH2 doses delayed the time to peak GH, with significant elevation persisting for 2 hours only after the 100 microgram dose.

Conclusions:

• GHRH (1-29)NH2 effectively stimulates GH release in a dose-dependent manner in adult males.
• Higher doses of GHRH (1-29)NH2 lead to a more sustained GH elevation, suggesting prolonged GHRH action.
• The 100 microgram dose demonstrated a significantly longer duration of GH elevation compared to lower doses.