Research progress on the association between melatonin and hypertensive disorder complicating pregnancy

Melatonin (N-acetyl-5-methoxytryptamine) is a polypotent neuroendocrine lipid-soluble small molecule secreted mainly by the pineal gland. During gestation, melatonin levels in the mother at night rise as the pregnancy progresses and return to normal after delivery. The etiology of hypertensive disorder complicating pregnancy (HDCP) is multifaceted. An increasing number of evidence suggests the involvement of melatonin in the pathogenic process, and the regulation is related to its expression level, secretion rhythm and receptor level. Abnormal placental blood circulation, ischemia and hypoxia and systemic vascular endothelium dysfunction are the main pathological processes of HDCP. Through direct antioxidant effect, melatonin improves mitochondrial dysfunction and protects trophoblast cells from oxidative damage, thus participating in the regulation of placental oxidative stress level, and plays a protective role in preventing oxidative damage caused by hypoxic ischemia reperfusion of placenta, thus maintaining placental functional homeostasis. In addition, there is also evidence that melatonin can protect maternal vascular endothelium from oxidative stress by reducing the production and secretion of pro-inflammatory cytokines and vasoactive compounds, and participating in the regulation of systemic blood pressure in pregnant women. These confidences suggest that melatonin can be involved in the maintenance of placental and systemic vascular functional homeostasis during pregnancy through the regulation of oxidative stress. In this article, the effects of melatonin on HDCP and the related mechanisms are reviewed, and the positive role of melatonin in the pathogenesis of HDCP is summarized.