NOCTURNAL SECRETORY PATTERNS OF MELATONIN, LUTEINIZING-HORMONE, PROLACTIN AND CORTISOL IN MALE-PATIENTS WITH GONADOTROPIN-RELEASING-HORMONEDEFICIENCY

To clarify whether disorders of gonadotropin releasing hormone (GnRH) deficiency are associated with altered melatonin and pituitary hormone s secretory patterns, we studied male patients with hypogonadotropic h ypogonadism (IGD; n = 6), delayed puberty (DP; n = 7) and age-matched pubertal controls (n = 7). Serum samples for the determination of mela tonin, luteinizing hormone (LH), prolactin and cortisol levels were ob tained at 15 min intervals from 1900 to 0700 in a controlled light-dar k environment, complete bed-rest and fasting with simultaneous sleep r ecordings. Mean (+/- SD) dark-time melatonin levels were significantly higher in IGD (286 +/- 26 pmol/L) and DP (205 +/- 44 pmol/L) compared with 178 +/- 64 pmol/L in controls (P < 0.003). So were the mean (+/- SD) peak melatonin levels (453 +/- 63, 346 +/- 106 and 292 +/- 96 pmo l/L) in IGD, DP and controls, respectively (P < 0.03). Integrated noct urnal melatonin (AUG) values were also higher in IGD and DP (184 +/- 1 5 and 134 +/- 28 pmol/min/L x 10(3)) compared with 116 +/- 42 pmol/min /L x 10(3) in controls (P < 0.003). The time of onset of the nocturnal melatonin rise was observed earlier in IGD and DP patients as compare d to controls, No correlations were found between melatonin and LH lev els, between melatonin and prolactin levels, or between melatonin and cortisol levels, These data indicate that melatonin secretion is enhan ced in male patients with GnRH deficiency. The lack of correlation bet ween melatonin and LH suggest that circulating gonadal steroids, rathe r than LH, modulate melatonin secretion in a reverse fashion.