Dopaminergic and cholinergic influences on the growth hormone response to growth hormone-releasing hormone in man.
Delitala. G G; Palermo. M M; Ross. R R; Coy. D D; Besser. M M; Grossman. A A
Key Findings
- Bromocriptine (a dopamine agonist) amplified the GH rise triggered by a GHRH analog.
- Pirenzepine (a muscarinic antagonist) reduced the GH response to the same peptide.
- Domperidone (a dopamine antagonist) had no effect on the GH response.
Practical Outcomes
- If you’re using sermorelin or similar GHRH peptides, a mild dopamine‑stimulating agent might enhance the hormone surge, whereas drugs that block dopamine or increase cholinergic activity are unlikely to help. Avoid strong anticholinergic blockers if you want maximal GH release, but weigh any side‑effects of dopamine agonists before adding them to a protocol.
Summary
The study shows that boosting dopamine activity with a drug like bromocriptine makes the growth‑hormone‑releasing peptide (similar to sermorelin) cause a bigger GH spike, while blocking muscarinic (cholinergic) receptors reduces the spike, and blocking dopamine with domperidone doesn’t change it. This suggests dopamine helps GH release beyond the peptide itself, and cholinergic signals can dampen it.
Abstract
It is well established that compounds that modify dopaminergic and cholinergic activity in man may induce changes in circulating growth hormone (GH). We have, therefore, investigated the effect of a dopamine agonist, bromocriptine, and a dopamine antagonist, domperidone, as well as a muscarinic cholinergic antagonist, pirenzepine, on the GH response to an analogue of GH-releasing hormone (GHRH) in normal male subjects. GHRH(1-29)NH2 induced a rise in serum GH that was augmented by bromocriptine, antagonized by pirenzepine, but was unaltered by domperidone. As this dose of GHRH(1-29) NH2 has been shown to be maximally stimulatory to GH release, it is suggested that there are dopamine stimulatory and cholinergic inhibitory receptors to GH release independent of GHRH in man.
Study Information
pubmed
1987
1987-03-01T00:00:00.000Z
10.1159/000124732
37