Melatonin: the placental antioxidant and anti-inflammatory

Abstract

Melatonin (N-acetyl-5-methoxytryptamine) is an indolamine hormone with many physiological and biological roles. Melatonin is an antioxidant, anti-inflammatory, free radical scavenger, circadian rhythm regulator, and sleep hormone. However, its most popular role is the ability to regulate sleep through the circadian rhythm. Interestingly, recent studies have shown that melatonin is an important and essential hormone during pregnancy, specifically in the placenta. This is primarily due to the placenta’s ability to synthesize its own melatonin rather than depending on the pineal gland. During pregnancy, melatonin acts as an antioxidant and anti-inflammatory, which is necessary to ensure a stable environment for both the mother and the fetus. It is an essential antioxidant in the placenta because it reduces oxidative stress by constantly scavenging for free radicals, i.e., maintain the placenta’s integrity. In a healthy pregnancy, the maternal immune system is constantly altered to accommodate the needs of the growing fetus, and melatonin acts as a key anti-inflammatory by regulating immune homeostasis during early and late gestation. This literature review aims to identify and summarize melatonin’s role as a powerful antioxidant and anti-inflammatory that reduces oxidative stress and inflammation to maintain a favorable homeostatic environment in the placenta throughout gestation.

Melatonin in Human Breast Milk and Its Potential Role in Circadian Entrainment: A Nod towards Chrononutrition?

“…Breast milk composition changes significantly over the day in terms of diurnal hormonal changes; one of the molecules that is intricately linked to and responsible for circadian rhythmicity is melatonin, with night-time milk showing higher melatonin levels than day-time milk [1]. During pregnancy, melatonin, a tryptophan-derived endogenous neurohormone, exerts a myriad of physiological and biological functions that account for a stable environment for both the Nutrients 2024, 16, 1422 2 of 16 mother and the fetus [2]. Besides influencing circadian rhythmicity, melatonin acts as a free radical scavenger with anti-apoptotic, anti-inflammatory, and mitochondrial-stabilizing functions [3][4][5].…”

Effects of Pinealectomy and Melatonin Supplementation on Elements Metabolism in Rat Testicular Tissue

“…Melatonin (MEL) is a hormone produced mainly by the pineal gland in the brain, which is defined as a neuroendocrine organ [1]. MEL, which plays a role in the sleep-wake cycle, is also a powerful antioxidant that clears free radicals directly and indirectly [2]. MEL, which also serves as a control mechanism that prevents the early onset of puberty, is closely related to the reproductive system [3].…”