Nocturnal melatonin and luteinizing hormone rhythms in women with hyperprolactinemic amenorrhea

Abstract

To examine the role of melatonin in pathological hyperprolactinemia we compared untreated young females (N = 5) with hyperprolactinemic amenorrhea owing to pituitary microadenoma to healthy female controls (N = 6). Serum samples for melatonin, prolactin, and luteinizing hormone (LH) concentrations were obtained every 15 min from 1900 hr to 0700 hr in a controlled light-dark environment with simultaneous sleep recordings. The mean (+/- SD) light-time period, dark-time period, and the integrated nocturnal melatonin secretion values (area under the curve, or AUC) in patients (51 +/- 11 pmol/L, 157 +/- 33 pmol/L, and 102 +/- 19 pmol/min.L x 10(3), respectively) were similar to the values obtained in controls (79 +/- 39, 165 +/- 44, 111 +/- 31, respectively). The onset of the nocturnal melatonin rise, peak level, and peak time were similar in the two groups. A significant nocturnal prolactin rise was observed in patients (112 +/- 9 vs. 65 +/- 11 micrograms/L, P < 0.006) and controls (19 +/- 2 vs. 10 +/- 3 micrograms/L, P < 0.006). The time of prolactin peak was similar in patients and controls (0424 +/- 3:36 vs. 0350 +/- 2:21) and paralleled that of melatonin (0354 +/- 1:46 vs. 0337 +/- 1:30). The mean +/- SD light-time period, dark-time period, and the AUC values of LH were similar in patients and controls. The number of LH pulses in patients (7.2 +/- 1.9 per 12 hr) were not different from those in controls (7.7 +/- 2.1). The LH pulse interval was 100 +/- 22 min in patients compared with 94 +/- 23 min in controls. The mean (+/- SD) nocturnal estradiol (E2) levels were significantly lower in patients (84 +/- 15 pmol/L) than in controls (224 +/- 77) (P < 0.005). Analysis of LH and melatonin secretory profiles revealed significant pulses for both hormones. No significant relationship was observed between the LH and melatonin pulses. However, a negative correlation between LH pulse amplitude and the number of melatonin pulses (P < 0.04) and a positive correlation between LH amplitude and duration of melatonin pulses (P < 0.04) were observed. Taken together, these data suggest that the suppression of normal ovarian cycles in women with hyperprolactinemic amenorrhea owing to pituitary microadenoma may be mediated by blocking of gonadotropin action by prolactin at the ovarian level; yet it remains possible that chronically elevated prolactin might prevent the LH surge and thus lead to amenorrhea. Pulsatile melatonin secretion is unaltered in these patients, and frequent occurrence of amenorrhea in this population is not mediated by melatonin.

Evidence for a Coupled Oscillator Model of Endocrine Ultradian Rhythms

“…GnRH release (Caraty and Locatelli, 1988; Clarke et al, 1987; Gore et al, 2004; Grattan et al, 1995; Levine and Ramirez, 1982; Meredith and Levine, 1992; Moenter et al, 1991; Phelps et al, 1992; Ramirez et al, 1991) and LH (Alexander and Irvine, 1987; Ar, 1985; Backstrom et al, 1982; Ben Jebara et al, 1994; Caraty and Locatelli, 1988; Czieselsky et al, 2016; Ellis and Desjardins, 1984; Evans et al, 1979; Ginther et al, 1998; Hodges, 1978; Irvine and Alexander, 1994; Jain et al, 2007; Joustra et al, 2016; Levine and Ramirez, 1982; Luboshitzky et al, 1996; Matsumoto and Bremner, 1984; Mulligan et al, 1995; Nordéus et al, 2012; Rossmanith et al, 1990b; Sisk and Desjardins, 1986; Soules et al, 1988, 1989; Steiner et al, 1982; Urban et al, 1988; van Leckwyck et al, 2016; Veldhuis et al, 1988; Vugt et al, 1984; Wu et al, 1996) oscillates with τ = ~ 1 to 4 h in both sexes, and these pulses are consistently coupled, within minutes within individuals (Alexander and Irvine, 1987; Bergendahl et al, 1996; Caraty et al, 1992; Caraty and Locatelli, 1988; Chandolia et al, 1997; Gazal et al, 1998; Irvine and Alexander, 1994; Levine and Ramirez, 1982). FSH exhibits low-amplitude URs that are often concomitant with LH (Booth et al, 1996; Genazzani et al, 1993; Joustra et al, 2016; Lockwo...…”

Pineal cyst-related sleep disorders – a narrative review

“…In another observational study, abnormalities in melatonin secretion were reported in 70,59% of patients with non-functioning pituitary macroadenomas [21] . In functional microadenomas, particularly for prolactinoma, melatonin levels and patterns remains proper [22] . Another tumor, which course may affect melatonin secretion, is craniopharyngioma.…”