Role of growth hormone-releasing hormone on pentag... - Mod GRF 1-29 Study

Key Findings

Pentagastrin infusion raises GH to about 9 ng/mL in normal males.

A single IV dose of GHRH‑1‑29 (250 µg) eliminates the GH response to later pentagastrin.

Gastrin does not affect GH release from isolated rat pituitary cells, indicating its action is at the hypothalamic level.

Practical Outcomes

For biohackers, using pentagastrin as a GH‑boosting tool may only work when the hypothalamic GHRH system is not already saturated. Combining pentagastrin with GHRH peptides (like CJC‑1295) is unlikely to give additive GH spikes. The finding mainly confirms existing ideas about GH regulation rather than providing a new, actionable protocol.

Summary

The study shows that giving a synthetic growth‑hormone‑releasing hormone (GHRH‑1‑29) blocks the ability of pentagastrin (a gastrin‑like drug) to raise growth hormone (GH) levels in healthy men. Pentagastrin alone can cause a modest GH spike, but this effect disappears if GHRH has already been administered, suggesting gastrin works upstream in the brain rather than directly on the pituitary.

Abstract

In order to investigate the mechanisms by which gastrin cause GH release in humans we measured the GH response to pentagastrin alone (1.5 micrograms/kg/hour from 120 to 210 min) and following pretreatment with GHRH (GHRH 1-29,250 micrograms, iv at 0 min) in normal male subjects. Prior GHRH administration abolished the GH response to the second bolus of GHRH (1 micrograms/kg) administered two hours later. Pentagastrin infusion induced a rise in GH levels maximal at 60 min (9.1 + 0.6 ng/ml, mean + SE), but this rise was abolished by pretreatment with GHRH. Finally, we found that gastrin did not modify basal GH release or GH responses to GHRH by rat anterior pituitary cells in monolayer culture. Taken together, these data suggest that gastrin regulates GH secretion by acting at hypothalamic level.

Study Information

Provider

pubmed

Year

1991

DOI

10.1007/bf03346800