Melatonin stimulates growth hormone secretion through pathways other than the growth

[Times Roman]

http://www.ncbi.nlm.nih.gov/pubmed/8370132

Abstract

OBJECTIVE:

There is evidence that melatonin plays a role in the regulation of GH secretion. The aim of this study was to investigate the neuroendocrine mechanisms by which melatonin modulates GH secretion. Thus we assessed the effect of oral melatonin on the GH responses to GHRH administration and compared the effects of melatonin with those of pyridostigmine, a cholinergic agonist drug which is likely to suppress hypothalamic somatostatin release.

DESIGN:

The study consisted of four protocols carried out during the afternoon hours. Study 1: oral melatonin (10 mg) or placebo were administered 60 minutes prior to GHRH (100 micrograms i.v. bolus). Study 2: GHRH (100 micrograms i.v. bolus) or placebo were administered at 0 minutes; oral melatonin or placebo were given at 60 minutes and were followed by a second GHRH stimulus (100 micrograms i.v. bolus) at 120 minutes. Study 3: placebo; oral melatonin (10 mg); oral pyridostigmine (120 mg); melatonin (10 mg) plus pyridostigmine (120 mg) were administered on separate occasions. Study 4: placebo; oral melatonin (10 mg); oral pyridostigmine (120 mg); melatonin (10 mg) plus pyridostigmine (120 mg) were administered on separate occasions 60 minutes prior to a submaximal dose (3 micrograms i.v. bolus) of GHRH.

SUBJECTS:

Four groups of eight normal male subjects, ages 22-35 years, were randomly assigned to each protocol.

MEASUREMENTS:

Growth hormone was measured by RIA at 15-minute intervals.

RESULTS:

Oral melatonin administration had a weak stimulatory effect on GH basal levels. Prior melatonin administration approximately doubled the GH release induced by supramaximal (100 micrograms) or submaximal (3 micrograms) doses of GHRH. Melatonin administration restored the GH response to a second GHRH challenge, given 120 minutes after a first GHRH i.v. bolus. The GH releasing effects of pyridostigmine, either alone or followed by GHRH, were greater than those of melatonin. However, the simultaneous administration of melatonin and pyridostigmine was not followed by any further enhancement of GH release, either in the absence or in the presence of exogenous GHRH.

CONCLUSIONS:

Our data indicate that oral administration of melatonin to normal human males increases basal GH release and GH responsiveness to GHRH through the same pathways as pyridostigmine. Therefore it is likely that melatonin plays this facilitatory role at the hypothalamic level by inhibiting endogenous somatostatin release, although with a lower potency than pyridostigmine. The physiological role of melatonin in GH neuroregulation remains to be established.

[M302_Imola]

Interesting! So theoretically supplementing with melatonin can help the body release even more GH after GHRP/GHRH administration?

[Times Roman]

Interesting! So theoretically supplementing with melatonin can help the body release even more GH after GHRP/GHRH administration?

that's the way i read it too.

[M302_Imola]

that's the way i read it too.

If that's the case then I'll add melatonin to my supplement list!

[Scabtree]

Thanks Times! I've heard this about melatonin before, but never could site a good resource. Very good info, thanks for sharing!

[Polish]

Awesome to know... I currently use melatonin to help me sleep. Glad it might be helping out in more than one way!