Environmental toxicant compromised reproductive health: Rescue by melatonin

Abstract

Several factors are responsible for declined male and female reproductive potential such as altered lifestyle, nutritional deficiency, global industrialization and increased exposure to environmental toxicants. The World Health Organization documents that around 15% couples face the problems of infertility but its underlying aetiology and treatment still need to be explored. Increased exposure to environmental toxins impair testicular and ovarian physiology through modulation of metabolic status (IR-GLUTs), redox (SIRT-1/Nrf-2/HO-1), inflammatory (NF-κB/COX-2) and apoptotic (Bax/Bcl-2 ratio, caspase-3) proteins and thus compromises reproductive health. Moreover, environmental contaminants have been reported in human blood, urine and milk. Melatonin, a pineal hormone, controls numerous physiological functions and act as an antioxidant, antiapoptotic, anti-inflammatory molecule in various organisms including human. Extra pineal organs such as retina, cerebellum, gastrointestinal tract and reproductive organs are also the source of melatonin. Within gonads, presence of Aralkylamine N-acetyltransferase (AANAT) and N-acetylserotonin O-methyltransferase (ASMT) convinced the intra gonadal synthesis of melatonin. Further, melatonin receptor (MT-1/2) has been reported in testicular Leydig cells, Sertoli cells, sperm and ovarian granulosa cells of mammals including humans that altogether reinforced its autocrine and paracrine role in regulation of reproductive physiology. Recently, melatonin has been reported to modulate various transcription factors and proteins that controls metabolic status and survival factors such as SIRT-1/Nrf-2 and its downstream signalling pathway in various organs including gonads. Therefore, advancement in melatonin research suggests that it could be use for the treatment of fertility related problems and improve the reproductive health. © 2021 Nova Science Publishers, Inc.