No abstract

This study provides first evidence that ghrelin suppresses the secretion of FSH in humans.

Aims: In young normal male subjects, plasma renin activity (PRA) shows large oscillations with a distinct association to the cyclic occurrence of rapid eye movement (REM) and non-REM (NREM) periods. Until now the sleep-related course of active renin levels is unknown. Furthermore, there are no data on the effects of age and gender on nocturnal renin and the interaction between these variables, sleep, growth hormone (GH) and cortisol. Methods: We investigated simultaneously sleep EEG (23:00–07:00 h) and the plasma concentrations (23:00–07:00 h) of active renin (in 10-min intervals) and of GH and cortisol (in 20-min intervals) in 47 healthy volunteers (24 women and 23 men) aged 19–69 years. Results: In the total sample, significant positive correlations were found between renin concentrations and NREM sleep and the sleep efficiency index, whereas a significant negative correlation exists to wakefulness. Renin shows also a positive correlation to GH levels which is restricted to the younger subjects (<40 years) during NREM sleep. No association exists between renin and cortisol. The averaged nocturnal mean renin levels were significantly lower in female than in male subjects, and in subjects older than 40 years than in younger subjects. Oscillations of active renin levels were found with increases during NREM periods and decreases during REM periods. Conclusions: In all, nocturnal averaged renin levels are lower in women than in men, decrease during ageing and correlate positively with GH, whereas the interaction between renin and sleep is independent from age and gender.