Melatonin, menopause, and thyroid function in gynecologic endocrinology: what is the role?

Abstract

Melatonin (MTN), a neurohormone primarily synthesized and secreted mainly by the pine cone-shaped gland of the cerebrum, named as the conarium or epiphysis cerebri, from amino acid tryptophan, was first isolated from the bovine pineal gland by Lerner et al 1 . However, the 17th-century philosopher René Descartes hypothesized that the pineal gland of the brain, which remains poorly understood to date, represents the location of the homo sapiens soul; paleontologists described it as an ancestral "third eye"; and modern psychology declares perception beyond physical visual function 2,3 . This chemical messenger, per se, ensures high precision in the reconnoitering of the night period, is an endocrine marker for darkness, and participates in the regulation of circadian rhythm and the sleep-wake cycle. Of note, MTN can be produced by other organs, such as the brain, lungs, gastrointestinal tract, liver, thyroid, and reproductive and immune systems, and is present in mucus, saliva, breast milk, urine, sperm, amniotic fluid, Graafian follicle, etc. 1,4-9 . As such, various studies have shown that MTN affects many functions in the body and acts on different tissues, and some of its properties include significant antioxidant, anti-inflammatory, antiproliferative, and immunomodulatory capacity. MTN, per se, can directly neutralize toxic free radicals more effectively, suppresses chronic oxidative stress, has a significant impact on reproductive cells, enhances the quality of sperm and oocytes, has oncostatic and antitumoral cytoprotective effects 10,11 , alleviates some of the undesirable toxic effects of radiotherapy and chemotherapy by increasing the tolerance of healthy tissues, compared to other antioxidants, by stimulating responses to DNA damage. To this