GH response to hypoglycemia and clonidine in the GH-releasing hormone resistance syndrome.
Salvatori. R R; Serpa. M G MG; Parmigiani. G G; Britto. A V O AV; Oliveira. J L M JL; Oliveira. C R P CR; Prado. C M CM; Farias. C T CT; Almeida. J C JC; Vicente. T A R TA; Aguiar-Oliveira. M H MH
Key Findings
- Patients with a null GHRH‑R mutation still produced a small GH surge during an insulin tolerance test (hypoglycemia).
- Clonidine did not trigger a GH increase in the same GHRH‑R‑deficient subjects.
- Earlier work showed GHRP‑2 can also elicit a modest GH response in these individuals.
Practical Outcomes
- For biohackers, GHRP‑2 can modestly boost GH even when the primary GHRH pathway is non‑functional, but the effect is limited. Adding a controlled hypoglycemic stress (e.g., short‑term fast or low‑dose insulin) might give a slight extra boost, whereas clonidine is unlikely to help. Expect only small gains, so dosing should be conservative and safety monitored.
Summary
Even people who completely lack the normal growth‑hormone‑releasing hormone (GHRH) receptor still show a tiny but real rise in GH when given GHRP‑2 or when they experience a low‑blood‑sugar challenge. Clonidine, another GH‑stimulating drug, didn’t work in these patients.
Abstract
GH secretion by the pituitary is the result of the balance between the stimulatory effect of GHRH and the inhibitory effect of SS. Patients with mutations in GHRH receptor (GHRH-R) gene (GHRH-R) offer a unique model to study the mechanism of action of different GH secretion stimuli. In the past, we have demonstrated a small but significant GH response to a GH secretagogue (GHRP-2) in a homogenous cohort of patients with severe GH deficiency (GHD) due to a homozygous null mutation in GHRH-R (IVS1+1G-->A). Now, we sought to determine if we could detect a GH response to hypoglycemia (ITT: insulin tolerance test) or clonidine (CL) in these patients. Nine young GHD subjects underwent both ITT and CL tests, and 2 additional subjects underwent only CL test. There was a small but significant GH increase during ITT, but not during CL test. These results indicate that a minimal albeit significant GH response to ITT can occur despite complete lack of GHRH-R function.
Study Information
pubmed
2006
10.1007/bf03347374