The Crosstalk between Melatonin and Sex Steroid Hormones

Abstract

Melatonin, an indolamine mainly released from the pineal gland, is associated with many biological functions namely the modulation of circadian and seasonal rhythms, sleep inducer, regulator of energy metabolism, antioxidant and anticarcinogenic. Although several evidences also recognize the influence of melatonin in the reproductive physiology, the crosstalk between melatonin and sex hormones is not clear. Here, we review the effects of sex differences in the circulating levels of melatonin and update the current knowledge on the link between sex hormones and melatonin. Furthermore, we explore the effects of melatonin on gonadal steroidogenesis and hormonal control in females. The literature review shows that despite the strong evidence that sex differences impact on the circadian profiles of melatonin, reports are still considerably ambiguous and these differences may arise from several factors, like the use of contraceptive pills, hormonal status and sleep deprivation. Furthermore, there has been an inconclusive debate about the characteristics of the reciprocal relationship between melatonin and reproductive hormones. In this regard, there is evidence for the role of melatonin in gonadal steroidogenesis brought about by research that shows that melatonin affects multiple transduction pathways that modulate Sertoli cell physiology and consequently spermatogenesis, and also estrogen and progesterone production. From the outcome of our research, it is possible to conclude that understanding the correlation between melatonin and reproductive hormones is crucial for the correction of several complications occurring during pregnancy, like pre-eclampsia and for the control of climacteric symptoms.

Melatonin Prevents Chronic Kidney Disease-Induced Hypertension in Young Rat Treated with Adenine: Implications of Gut Microbiota-Derived Metabolites

“…Additionally, melatonin showed beneficial effects against kidney injury in a sex-dependent manner, with melatonin mainly attenuating kidney injury in males but not females. Although melatonin has been shown to interact with sex hormones reciprocally [ 28 ], little information currently exists with regard to sex differences in terms of the therapeutic response of melatonin in CKD. Sex differences exist in CKD and women seem to be somewhat protected from developing end-stage renal disease [ 29 ].…”

Research progress of melatonin (MT) in improving ovarian function: a review of the current status

“…In the process of MT biosynthesis, norepinephrine secreted by the nerve endings of the superior cervical ganglion stimulates the pineal cells through b-adrenergic receptors, thereby accelerating the synthesis of the second messenger cyclic AMP and inducing the NAT activity [ 14 ]. This pathway is actually activated at night because the nerve activity of the upper cervical ganglia would be inhibited by the stimulation of light [ 14 ]. Therefore, darkness represents the only condition for the synthesis of MT.…”

“…In human beings, the MT secretion reaches its highest level between the ages of 3 and 5 years old, which begins to decrease from the beginning of puberty [ 11 , 14 ]. The secretion of MT is rather stable before the age of 35–40 years.…”

“…Therefore, MT protects cells from oxidative stress due to radical damages. The administration of exogenous MT can significantly reduce the oxidative damages in the follicle and the oxidative damages of essential molecules, thereby increasing the fertilization rate and pregnancy rate [ 11 , 14 ]. MT regulates the responses of follicles to LH by increasing the mRNA expression levels of LH receptors in human granulosa cells [ 60 ].…”

Alterations of Cortisol and Melatonin Production by the Theca Interna Cells of Porcine Cystic Ovarian Follicles

“…A significantly decreased expression was observed for the MT2 receptor in PCOS induced by letrozole in rats [23], and the mRNA expressions of MT1 and MT2 decreased in the theca cells of cystic follicles. Cortisol and MT are involved in regulating follicular development and maintain the follicular microenvironment through glucocorticoid receptors (GRs) and melatonin receptors (MTRs), respectively [24,25].…”