Oxytocin in Women’s Health and Disease

Abstract

Oxytocin (OT) is a nonapeptide mainly produced in the supraoptic and paraventricular nuclei. OT in the brain and blood has extensive functions in both mental and physical activities. These functions are mediated by OT receptors (OTRs) that are distributed in a broad spectrum of tissues with dramatic sexual dimorphism. In both sexes, OT generally facilitates social cognition and behaviors, facilitates parental behavior and sexual activity and inhibits feeding and pain perception. However, there are significant differences in OT levels and distribution of OTRs in men from women. Thus, many OT functions in men are different from women, particularly in the reproduction. In men, the reproductive functions are relatively simple. In women, the reproductive functions involve menstrual cycle, pregnancy, parturition, lactation, and menopause. These functions make OT regulation of women’s health and disease a unique topic of physiological and pathological studies. In menstruation, pre-ovulatory increase in OT secretion in the hypothalamus and the ovary can promote the secretion of gonadotropin-releasing hormone and facilitate ovulation. During pregnancy, increased OT synthesis and preterm release endow OT system the ability to promote maternal behavior and lactation. In parturition, cervix expansion-elicited pulse OT secretion and uterine OT release accelerate the expelling of fetus and reduce postpartum hemorrhage. During lactation, intermittent pulsatile OT secretion is necessary for the milk-ejection reflex and maternal behavior. Disorders in OT secretion can account for maternal depression and hypogalactia. In menopause, the reduction of OT secretion accounts for many menopausal symptoms and diseases. These issues are reviewed in this work.

Potential of Endogenous Oxytocin in Endocrine Treatment and Prevention of COVID-19

“…Age-associated decreases in estrogen may also mediate proinflammatory reactions that could increase patient's risk of COVID-19 adverse outcomes ( 89 ). Thus, estrogen may be effective for postmenopausal women but not suitable for women with menstruation who have periodic fluctuations in estrogen versus progesterone levels ( 94 ). In addition, hormone replacement therapy in aged women has been found to possess cancer-evoking effect ( 95 ).…”

“…As stated above, oxytocin is one of the four compounds that strongly inhibit binding of SARS-CoV-2 to ACE2 ( 68 ). Oxytocin may reduce viral entry through influencing estrogen secretion ( 94 ). There is a high rate of asymptomatic infection in pregnant women ( 140 ) because of a marked down-regulation of the expression of ACE2 in the airway epithelium ( 92 ) and TMPRSS2 ( 141 ) and activation of other protective functions ( 93 ).…”

Neural Functions of Hypothalamic Oxytocin and its Regulation

“…Hormones are important factors for body development and adaptive responses to environmental changes. Among many hormones, oxytocin (OT) is not only the key factor in the milk-ejection reflex, the most classical neural humoral reflex ( Wakerley et al, 1994 ), but also possesses a variety of functions such as regulation of immunological, metabolic and endocrine activity and many other peripheral functions ( Liu et al, 2022 ; Wang et al, 2015 ; Wang et al, 2019b ; Wang et al, 2022 ; Yang et al, 2013 ) as outlined in Figure 1 . OT is mainly synthesized in OT neurons in the supraoptic nucleus (SON), paraventricular nucleus (PVN) and several accessory nuclei in the hypothalamus.…”

Oxytocin: Narrative Expert Review of Current Perspectives on the Relationship with Other Neurotransmitters and the Impact on the Main Psychiatric Disorders

“…Oxytocin is metabolized in the liver and plasma, with the help of oxytocinases and a much smaller percentage in the mammary glands. Oxytocin exerts its effects in the digestive system, in the reproductive organs (uterus, ovary, testis, placenta, amnion, corpus luteum, and mammary gland), where it is relevant in reproduction, in the cardiovascular system (heart and vascular endothelium), in renal, with a role in hydro-electrolytic regulation, and in muscular and adipose tissues, where it intervenes in metabolic processes [ 6 , 7 ].…”