Plasma Levels of Immunoreactive Melatonin, Estradiol, Progesterone, Follicle Stimulating Hormone, and β‐Human Chorionic Gonadotropin During Pregnancy and Shortly After Parturition in Humans

Abstract

Plasma concentrations of immunoreactive melatonin, estradiol, progesterone, follicle stimulating hormone (FSH), and beta-human chorionic gonadotropin (beta hCG) were studied between 1000 and 1230 h in 105 Chinese females during six periods of normal pregnancy and 1-5 min after normal delivery. We have also examined the midday levels of immunoreactive melatonin in the cord blood of fetuses and plasma collected 1-5 min after and 24 h after delivery from their mothers. Concentrations of hormone immunoreactivities were determined by radioimmunoassay, and distinct fluctuations of all hormones were recorded during pregnancy. In the pregnant females, there were significant negative correlations between melatonin and estradiol, melatonin and progesterone, beta hCG and progesterone, and beta hCG and estradiol, and positive correlations between melatonin and FSH and progesterone and estradiol. Furthermore, plasma melatonin levels in the cord blood demonstrated no sex difference and were significantly lower than and correlated positively with the levels in their mothers. Our results suggest that sex steroids may inhibit and FSH may potentiate circulating melatonin levels in gravid women; changes in the levels of melatonin during pregnancy may affect the in utero development of the human embryo; and circulating melatonin in the mother may be the major source of blood melatonin in the fetus before parturition.

Evidence That Circadian Variations of Circulating Melatonin Levels in Fetal and Suckling Rats Are Dependent on Maternal Melatonin Transfer

“…There are some indications that hormones of the reproductive system can affect the biochemistry and histology of the pineal gland [22,23] and that gonad otropins and sex steroids may play a regulatory role on pineal melatonin secretion [30,34]. Thus, it has been re ported that gonadectomy or steroid treatment changed the activity of hydroxyindole-O-methyltransferase [3,4], that circulating melatonin changes during the menstrual cycle [34] and after gonadotropin administration [30] and that FSH may increase plasma melatonin concentrations in pregnant women [20]. Also, hyperprolactinemia in rats significantly decreases pineal gland melatonin content [31].…”

Interstitial Cells in the Pineal Gland of Pregnant and Nonpregnant Viscachas <b><i>(Lagostomus maximus maximus)</i></b>: A Morphometric and Biochemical Study

“…Ultrastructural changes have been described in the pineal gland of rats [Satodate et al, 1980;Karasek et al, 1982], moles [Pevet and Smith, 1975], guinea pigs [Vollrath and Schmidt, 1969], and sows [Wyrzykowski et al, 1987]. Likewise, pineal activity has been related to pregnancy by biochemical studies performed in rats [Tigchelaar and Nalbandov, 1975] and humans [Pang et al, 1987]. It has been suggested that the pineal gland in rats may be involved in the synthesis and release of gonadotropins.…”

Melatonin: pregnancy and labor

“…созревание шейки матки и раскры-тие маточного зева наблюдается с большей ча-стотой между 24.00 и 05.00 часами ночи [43,45]. Показана взаимосвязь между высоким уровнем мелатонина в амниотической жидкости, в крови матери и плода, что указывает на важную роль и плодового мелатонина в наступлении родов [47,68,73,76,101].…”