BACKGROUND AND OBJECTIVE: Although there is extensive evidence that melatonin inhibits gonadotrophin secretion in animals, there is a parity of data on the relation between melatonin and ovarian function in humans. The purpose of this study was to evaluate the relation between endogenous oestrogen concentrations and nocturnal melatonin secretion occurring in patients with secondary amenorrhoea (SA). DESIGN AND PATIENTS: Nocturnal serum melatonin concentrations were determined in 20 women with SA, 5 women with endometriosis showing normal menstrual cycles and 11 volunteers with normal menstrual cycles. MEASUREMENT: Serum melatonin concentrations were determined by high performance liquid chromatography with electrochemical detection. Differences in melatonin concentrations were examined by analysis of variance. RESULTS: Nocturnal melatonin concentrations in patients with SA were significantly higher than in normal women (P < 0.01 vs women with normal menstrual cycles). There were significant negative correlations between cummulative melatonin levels (between 2000 and 0800 h) and serum 17 beta-oestradiol (r = -0.561, p < 0.01) and between peak serum melatonin values and the serum 17 beta-oestradiol (r = -0.608, P < 0.01) in SA. Intravenous administration of a conjugated oestrogen (Premarin 20 mg) significantly suppressed nocturnal melatonin secretion (P < 0.05). A low oestrogen state, induced by long-term (3.5 months) GnRH agonist treatment (900 micrograms/day of buserelin acetate) of the women with endometriosis produced an increase in nocturnal melatonin secretion comparable to that found in SA women. CONCLUSION: Our findings suggest that elevated nocturnal melatonin secretion in women with secondary amenorrhoea may be related to their low oestrogen concentrations.

Adolescent↗

PubMed1994

Serotonin metabolism in the fetus in preeclampsia.

We investigated serotonin (5-HT) metabolism in the fetus in preeclampsia by measuring free 5-HT, 5-hydroxyindoleacetic acid (5-HIAA) and tryptophan concentrations in umbilical cord plasma and amniotic fluid, and 5-HT content in platelets by high performance liquid chromatography with electrochemical detection. Free 5-HT and 5-HIAA levels in umbilical cord plasma were significantly higher in the severe preeclamptic group (S) than those in the non-preeclamptic group (N). The plasma 5-HIAA/5-HT ratio in group S was significantly lower than that in group N. Platelet 5-HT content in group S tended to be lower than that in group N. Mean plasma beta-thromboglobulin concentration in group S was significantly higher than that in group N. There was no significant difference in plasma tryptophan levels between group S and N. These findings suggest that the higher levels of plasma free 5-HT in umbilical cord plasma in preeclampsia are attributable to excess release of 5-HT from platelets as well as lower monoamine oxidase activity.

Female↗

PubMed1994

Stimulation of prolactin secretion by melatonin is not mediated by opioids.

To clarify the role the opioid system plays in mediating the stimulation of prolactin release by melatonin, we performed two separate studies between the 6th and 8th days of the follicular phase in normal young women. In the first study, serum prolactin concentrations were determined every 20 min over a 4-hour period following oral administration of melatonin (1 mg given at 13.00 h) in the presence of continuous intravenous infusion of saline or naloxone (1.6 mg/h), an opiate antagonist. In the second study, plasma beta-endorphin concentrations were measured over a 3-hour period following oral melatonin administration (1 mg given at 13.00 h). Oral melatonin administration alone induced a significant increase in serum prolactin concentration, which was maximal 3 h after melatonin administration. Prolactin release following melatonin administration was not affected by continuous intravenous infusion of naloxone. No significant change in plasma beta-endorphin concentrations was observed following melatonin administration. These findings strongly suggest that the stimulation of prolactin release by melatonin is not mediated by opioids.

Adult↗

PubMed1993

Role of melatonin in nocturnal prolactin secretion in women with normoprolactinemia and mild hyperprolactinemia.

OBJECTIVE: Our objective was to clarify the relationship between the nocturnal melatonin surge and the nocturnal prolactin release in women with normoprolactinemia and mild hyperprolactinemia. STUDY DESIGN: Nocturnal serum melatonin and prolactin levels were determined for a various awake/sleep and light/dark conditions in a total of 23 healthy normoprolactinemia and 9 mild hyperprolactinemia. Patterns of prolactin and melatonin levels were subject to analysis of variance. RESULTS: During sleep deprivation under continuous illumination in normoprolactinemia, neither melatonin nor prolactin increased in concentration. In contrast, during sleep deprivation in a dark environment, both hormones were increased. The maximal prolactin levels in mild hyperprolactinemia under physiologic sleep/dark were significantly higher (p < 0.01) and were reached 2 hours earlier than in normoprolactinemia. However, each woman with mild hyperprolactinemia had similar melatonin surges. Oral administration (1 mg) of melatonin to normoprolactinemia and mild hyperprolactinemia in the daytime resulted in release of prolactin in a fashion similar to that observed during the night. CONCLUSION: Melatonin can regulate nocturnal prolactin secretion independent of sleep-related factors. Furthermore, the nature of the response to exogenous melatonin administration suggests that mild hyperprolactinemia may be unusually sensitive to melatonin.

Adult↗

PubMed1993

Role of the free radical-scavenger system in aromatase activity of the human ovary.

The present study was undertaken to clarify the physiological role of the free radical-scavenger system in the control of estrogen production in the human ovary with age. Both superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in the homogenate of the ovary significantly decreased from the premenopausal period to the menopausal period. The lipid peroxide content, however, showed a small and gradual decrease from the premenopausal to the postmenopausal period. In the premenopausal women, aromatase (Ar) activity in the microsomal fraction of the ovary showed a sharp decline and a significant negative correlation with age. Significant positive correlations were found between SOD and Ar activity, and between GSH-Px and Ar activity. Treatments of homogenate of the ovary with 10, 50 and 100 microM of H2O2 resulted in a decrease in Ar activity in a dose-dependent manner. Moreover, treatment with 10 and 50 microM of H2O2 produced a more significant decrease in the Ar activity in the premenopausal women than that in the postmenopausal women. Treatments with 0.01, 0.1, 1.0 and 10.0 U of GSH-Px before administration of 50 microM of H2O2, on the other hand, induced a recovery of the Ar activity in a dose-dependent manner. The present study showed the inhibitory effect of peroxide on Ar activity, which was attenuated by GSH-Px. These results seem to suggest that these age-related, relatively free radical predominant environments in the human ovary may have an important role in the decrease of estrogen production through the effects on the Ar activity.

Adult↗

PubMed1992

Amplification of nocturnal melatonin secretion in women with nocturnal hyperprolactinemia.

In order to assess the pathophysiological role of melatonin (MLT) in nocturnal hyperprolactinemia (NH), nocturnal serum MLT and prolactin (PRL) levels were measured in samples collected every 2h over a 12-hour period (2000h-0800h) from 5 normal women and 9 women with NH under physiological light/dark condition (lights off from 2100h to 0600h). Furthermore, differences in the PRL response to acute oral administration of MLT (1 mg or 5 mg) during the daytime between the 2 groups was studied. Nocturnal MLT levels in patients with NH were significantly higher (p < 0.02) than in normal women. The maximal PRL levels (52.6 +/- 26.7 ng/ml at 2400h) during the night in patients with NH were significantly higher (p < 0.05) and were reached 4h earlier than in normal women. The response to administration of 1 mg of MLT was not different between the 2 groups. However, administration of 5 mg of MLT to normal women resulted in a rapid and prominent PRL release, similar to that observed at nighttime in patients with NH. These results indicate that the abnormal PRL release in patients with NH is not due to higher sensitivity to MLT. However, the elevated MLT levels in patients with NH may be related to the neuroendocrine disorder.

Adult↗

PubMed1990

[Study on serotonin metabolism in toxemia of pregnancy].

To evaluate the serotonin (5-HT) metabolism in toxemia of pregnancy, plasma free 5-HT, 5-hydroxyindoleacetic acid (5-HIAA), tryptophan and platelet 5-HT content were determined by high performance liquid chromatography (HPLC) with electrochemical detection. The mean plasma free 5-HT concentrations in the severe preeclamptic group (S) and the mild preeclamptic group (M) were significantly higher than those in the normal group (N). A significant correlation was found between plasma free 5-HT values and Gestosis Index scores. However, there was no significant difference between plasma 5-HIAA level and platelet 5-HT content in the preeclamptic groups and the N. The mean plasma beta-thromboglobulin (beta-TG) concentrations in the preeclamptic groups were significantly higher than those in the N. The mean platelet counts in the S were significantly lower than those in the N. The mean plasma 5-HIAA/5-HT ratio in the preeclamptic groups were significantly lower than those in the N. In conclusion, it is suggested that the higher plasma free 5-HT level in the toxemia of pregnancy seems to be attributed to the excess release of 5-HT from platelets in addition to the lower monoamine oxidase activity.

Blood Platelets↗

PubMed1990

[Serotonin metabolism in normal pregnant women and fetus].

To evaluate serotonin (5-HT) metabolism in normal pregnant women and their fetuses, plasma free 5-HT, 5-hydroxyindoleacetic acid (5-HIAA). Tryptophan (TRP) and platelet free 5-HT content were determined by HPLC with electrochemical detection. Plasma free 5-HT and TRP concentrations and platelet 5-HT content in pregnant women did not change during pregnancy. In contrast, plasma free 5-HIAA increased after 30 weeks of gestation and reached its peak at 37 weeks. 5-HT, 5-HIAA and TRP concentrations in umbilical cord plasma were significantly higher than in maternal plasma. However, platelet 5-HT content in the fetus was significantly lower than in the mother. No significant correlation was found between 5-HT concentrations in maternal and cord plasma. However, a significant correlation was found between 5-HIAA, concentrations in maternal and cord plasma. The total 5-HT/TRP ratio in cord blood was significantly lower than in the maternal vein. The 5-HIAA/5-HT ratio in cord plasma was markedly higher than in maternal plasma. In conclusion, we demonstrated the patterns of plasma free 5-HT, 5-HIAA, TRP and platelet 5-HT concentrations in normal pregnant women and their fetuses. Furthermore, rapid 5-HT metabolism in the fetus was suggested.

Female↗

PubMed1989

A case of ovarian leiomyoma.

A case of ovarian leiomyoma is reported, together with histologic, immunohistologic and electron microscopic findings. A solid firm tumor, measuring 6.5 X 5 X 5 cm, was found in the right ovary of a 65-year-old woman. The tumor had an obvious whorled pattern on the cut-surface. Well-differentiated, long spindle-shaped neoplastic cells revealed positive immunoreactivity for anti-desmin. Ultrastructural observations included numerous microfilaments with dense patches in the cytoplasm, micropinocytotic vesicles beneath plasma membranes and continuous basal laminae around neoplastic cells. These findings were compatible with leiomyoma. The possible histogenesis of ovarian leiomyoma was discussed.

Actin Cytoskeleton↗

PubMed1989