Nocturnal ghrelin, ACTH, GH and cortisol secretion after steep deprivation in humans

Ghrelin is an endogenous ligand of the growth hormone (GH) secretagogue (GHS) receptor. It is hypothesised to play a key role in energy balance stimulating food intake and body weight. Besides GH-releasing hormone (GHRH) and somatostatin, it is thought to be a regulating factor of GH release. Ghrelin also appears to be involved in steep regulation. We showed recently that ghrelin promotes slow-wave steep and the nocturnal release of GH, cortisol and prolactin in humans. Similarly, promotion of non-rapid-eye-movement (NREM) steep was reported in mice after systemic ghrelin. If ghrelin is a factor that induces and/or maintains steep, it should be enhanced after a period of steep deprivation (SD). To clarify this issue, nocturnal ghrelin, GH, ACTH and cortisol plasma concentrations were determined and simultaneously steep electroencephalogram (EEG) was recorded (2300-0700 h) during steep before and after 1 night of total SD in 8 healthy subjects. Compared to baseline, ghrelin levels increased earlier by a nonsignificant trend, already before the beginning of recovery steep. Further a nonsignificant trend occurred, suggesting higher ghrelin secretion in the first half of the night. The ghrelin maximum was found significantly earlier after SD than at baseline. GH secretion during the first half of the night and total night after SD were elevated. ACTH and cortisol were also elevated, which was most pronounced during the second half of the night. No effects of SD on the time of the maximum were found for GH, ACTH and cortisol. The increase in ACTH after SD is a novel finding. Whereas the effects of SD on ghrelin levels were relatively weak, our findings are in tine with the hypothesis that ghrelin is a steep-promoting factor in humans. Ghrelin may be involved in steep promotion after SD. (c) 2006 Elsevier Ltd. All. rights reserved.