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Nature Jan 2024Oxytocin (OXT), a nine-amino-acid peptide produced in the hypothalamus and released by the posterior pituitary, has well-known actions in parturition, lactation and...
Oxytocin (OXT), a nine-amino-acid peptide produced in the hypothalamus and released by the posterior pituitary, has well-known actions in parturition, lactation and social behaviour, and has become an intriguing therapeutic target for conditions such as autism and schizophrenia. Exogenous OXT has also been shown to have effects on body weight, lipid levels and glucose homeostasis, suggesting that it may also have therapeutic potential for metabolic disease. It is unclear, however, whether endogenous OXT participates in metabolic homeostasis. Here we show that OXT is a critical regulator of adipose tissue lipolysis in both mice and humans. In addition, OXT serves to facilitate the ability of β-adrenergic agonists to fully promote lipolysis. Most surprisingly, the relevant source of OXT in these metabolic actions is a previously unidentified subpopulation of tyrosine hydroxylase-positive sympathetic neurons. Our data reveal that OXT from the peripheral nervous system is an endogenous regulator of adipose and systemic metabolism.
Topics: Animals; Humans; Mice; Adipose Tissue; Adrenergic beta-Agonists; Lipolysis; Neurons; Oxytocin; Tyrosine 3-Monooxygenase
PubMed: 38093006
DOI: 10.1038/s41586-023-06830-x -
Gut Microbes Dec 2023Intestinal microbes impact the health of the intestine and organs distal to the gut. is a human intestinal microbe that promotes normal gut transit, the...
Intestinal microbes impact the health of the intestine and organs distal to the gut. is a human intestinal microbe that promotes normal gut transit, the anti-inflammatory immune system, wound healing, normal social behavior in mice, and prevents bone reabsorption. Oxytocin impacts these functions and oxytocin signaling is required for -mediated wound healing and social behavior; however, the events in the gut leading to oxytocin stimulation and beneficial effects are unknown. Here we report evolutionarily conserved oxytocin production in the intestinal epithelium through analysis of single-cell RNA-Seq datasets and imaging of human and mouse intestinal tissues. Moreover, human intestinal organoids produce oxytocin, demonstrating that the intestinal epithelium is sufficient to produce oxytocin. We find that facilitates oxytocin secretion from human intestinal tissue and human intestinal organoids. Finally, we demonstrate that stimulation of oxytocin secretion by is dependent on the gut hormone secretin, which is produced in enteroendocrine cells, while oxytocin itself is produced in enterocytes. Altogether, this work demonstrates that oxytocin is produced and secreted from enterocytes in the intestinal epithelium in response to secretin stimulated by . This work thereby identifies oxytocin as an intestinal hormone and provides mechanistic insight into avenues by which gut microbes promote host health.
Topics: Humans; Animals; Mice; Secretin; Oxytocin; Gastrointestinal Microbiome; Gastrointestinal Hormones; Intestinal Mucosa; Limosilactobacillus reuteri
PubMed: 37698879
DOI: 10.1080/19490976.2023.2256043 -
NEJM Evidence May 2024Accumulating preclinical and preliminary translational evidence shows that the hypothalamic peptide oxytocin reduces food intake, increases energy expenditure, and... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Accumulating preclinical and preliminary translational evidence shows that the hypothalamic peptide oxytocin reduces food intake, increases energy expenditure, and promotes weight loss. It is currently unknown whether oxytocin administration is effective in treating human obesity.
METHODS
In this randomized, double-blind, placebo-controlled trial, we randomly assigned adults with obesity 1:1 (stratified by sex and obesity class) to receive intranasal oxytocin (24 IU) or placebo four times daily for 8 weeks. The primary end point was change in body weight (kg) from baseline to week 8. Key secondary end points included change in body composition (total fat mass [g], abdominal visceral adipose tissue [cm], and liver fat fraction [proportion; range, 0 to 1; higher values indicate a higher proportion of fat]), and resting energy expenditure (kcal/day; adjusted for lean mass) from baseline to week 8 and caloric intake (kcal) at an experimental test meal from baseline to week 6.
RESULTS
Sixty-one participants (54% women; mean age ± standard deviation, 33.6 ± 6.2 years; body-mass index [the weight in kilograms divided by the square of the height in meters], 36.9 ± 4.9) were randomly assigned. There was no difference in body weight change from baseline to week 8 between oxytocin and placebo groups (0.20 vs. 0.26 kg; P=0.934). Oxytocin (vs. placebo) was not associated with beneficial effects on body composition or resting energy expenditure from baseline to week 8 (total fat: difference [95% confidence interval], 196.0 g [-1036 to 1428]; visceral fat: 3.1 cm [-11.0 to 17.2]; liver fat: -0.01 [-0.03 to 0.01]; resting energy expenditure: -64.0 kcal/day [-129.3 to 1.4]). Oxytocin compared with placebo was associated with reduced caloric intake at the test meal (-31.4 vs. 120.6 kcal; difference [95% confidence interval], -152.0 kcal [-302.3 to -1.7]). There were no serious adverse events. Incidence and severity of adverse events did not differ between groups.
CONCLUSIONS
In this randomized, placebo-controlled trial in adults with obesity, intranasal oxytocin administered four times daily for 8 weeks did not reduce body weight. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and others; ClinicalTrials.gov number, NCT03043053.).
Topics: Humans; Oxytocin; Female; Male; Administration, Intranasal; Adult; Obesity; Double-Blind Method; Energy Metabolism; Body Composition; Energy Intake; Weight Loss
PubMed: 38815173
DOI: 10.1056/EVIDoa2300349 -
Physiological Reviews Jul 2024Parturition is a complex physiological process that must occur in a reliable manner and at an appropriate gestation stage to ensure a healthy newborn and mother. To this... (Review)
Review
Parturition is a complex physiological process that must occur in a reliable manner and at an appropriate gestation stage to ensure a healthy newborn and mother. To this end, hormones that affect the function of the gravid uterus, especially progesterone (P4), 17β-estradiol (E), oxytocin (OT), and prostaglandins (PGs), play pivotal roles. P4 via the nuclear P4 receptor (PR) promotes uterine quiescence and for most of pregnancy exerts a dominant block to labor. Loss of the P4 block to parturition in association with a gain in prolabor actions of E are key transitions in the hormonal cascade leading to parturition. P4 withdrawal can occur through various mechanisms depending on species and physiological context. Parturition in most species involves inflammation within the uterine tissues and especially at the maternal-fetal interface. Local PGs and other inflammatory mediators may initiate parturition by inducing P4 withdrawal. Withdrawal of the P4 block is coordinated with increased E actions to enhance uterotonic signals mediated by OT and PGs to promote uterine contractions, cervix softening, and membrane rupture, i.e., labor. This review examines recent advances in research to understand the hormonal control of parturition, with focus on the roles of P4, E, PGs, OT, inflammatory cytokines, and placental peptide hormones together with evolutionary biology of and implications for clinical management of human parturition.
Topics: Parturition; Humans; Female; Pregnancy; Animals; Progesterone; Oxytocin; Uterus; Prostaglandins; Estradiol
PubMed: 38329421
DOI: 10.1152/physrev.00019.2023 -
Expert Review of Endocrinology &... 2023Known for its effect on labor and lactation and on emotional and social functions, oxytocin has recently emerged as a key modulator of feeding behavior and indeed... (Review)
Review
INTRODUCTION
Known for its effect on labor and lactation and on emotional and social functions, oxytocin has recently emerged as a key modulator of feeding behavior and indeed suggested as a potential treatment for obesity. The potential positive effect of oxytocin on both metabolic and psychological-behavioral complications of hypothalamic lesions makes it a promising tool in the management of these conditions.
AREAS COVERED
The aim of the present review article is to provide an overview of the mechanism of action and clinical experience of the use of oxytocin in different forms of obesity.
EXPERT OPINION
Current evidence suggests a potential role of oxytocin in the treatment of obesity with different causes. Several challenges remain: an improved understanding of the physiological regulation, mechanisms of action of oxytocin, and interplay with other endocrine axes is fundamental to clarify its role. Further clinical trials are needed to determine the safety and efficacy of oxytocin for the treatment of different forms of obesity. Understanding the mechanism(s) of action of oxytocin on body weight regulation might also improve our understanding of obesity and reveal possible new therapeutic targets - as well as promoting advances in other fields in which oxytocin might be used.
Topics: Female; Humans; Oxytocin; Obesity; Hypothalamus
PubMed: 37232186
DOI: 10.1080/17446651.2023.2216794 -
Trends in Biochemical Sciences Apr 2024Neurohypophysial peptides are ancient and evolutionarily highly conserved neuropeptides that regulate many crucial physiological functions in vertebrates and... (Review)
Review
Neurohypophysial peptides are ancient and evolutionarily highly conserved neuropeptides that regulate many crucial physiological functions in vertebrates and invertebrates. The human neurohypophysial oxytocin/vasopressin (OT/VP) signaling system with its four receptors has become an attractive drug target for a variety of diseases, including cancer, pain, cardiovascular indications, and neurological disorders. Despite its promise, drug development faces hurdles, including signaling complexity, selectivity and off-target concerns, translational interspecies differences, and inefficient drug delivery. In this review we dive into the complexity of the OT/VP signaling system in health and disease, provide an overview of relevant pharmacological probes, and discuss the latest trends in therapeutic lead discovery and drug development.
Topics: Animals; Humans; Oxytocin; Vasopressins; Receptors, Vasopressin
PubMed: 38418338
DOI: 10.1016/j.tibs.2024.01.010 -
Endocrine Regulations Jan 2024Oxytocin plays an important role in brain development and is associated with various neurotransmitter systems in the brain. Abnormalities in the production, secretion,... (Review)
Review
Oxytocin plays an important role in brain development and is associated with various neurotransmitter systems in the brain. Abnormalities in the production, secretion, and distribution of oxytocin in the brain, at least during some stages of the development, are critical for the pathogenesis of neuropsychiatric diseases, particularly in the autism spectrum disorder. The etiology of autism includes changes in local sensory and dopaminergic areas of the brain, which are also supplied by the hypothalamic sources of oxytocin. It is very important to understand their mutual relationship. In this review, the relationship of oxytocin with several components of the dopaminergic system, gamma-aminobutyric acid (GABA) inhibitory neurotransmission and their alterations in the autism spectrum disorder is discussed. Special attention has been paid to the results describing a reduced expression of inhibitory GABAergic markers in the brain in the context of dopaminergic areas in various models of autism. It is presumed that the altered GABAergic neurotransmission, due to the absence or dysfunction of oxytocin at certain developmental stages, disinhibits the dopaminergic signaling and contributes to the autism symptoms.
Topics: Oxytocin; Humans; Dopamine; gamma-Aminobutyric Acid; Autistic Disorder; Brain; Animals; Synaptic Transmission; Autism Spectrum Disorder
PubMed: 38656256
DOI: 10.2478/enr-2024-0012 -
The Journal of Endocrinology Jul 2024Menopause marks the cessation of fertility and the transition to post-reproductive years. Nearly 1 million US women experience menopause annually, but despite the... (Review)
Review
Menopause marks the cessation of fertility and the transition to post-reproductive years. Nearly 1 million US women experience menopause annually, but despite the significant impact it has on their physical and mental health, menopause has been insufficiently studied. Oxytocin is a neurohormone that regulates emotionality, social behaviors, and fundamental physiological systems. Localization of oxytocin receptors in the brain, reproductive tissues, bone, and heart support their role in mental health and potentially sleep, along with reproductive and cardiovascular functions. While experimental data linking oxytocin to behavior and physiology in animals are largely consistent, human data are correlative and inconclusive. As women transition into menopause, oxytocin levels decrease while their susceptibility to mood disorders, poor sleep, osteoporosis, and cardiovascular diseases increases. These concurrent changes highlight oxytocin as a potential influence on the health and mood of women along their reproductive life span. Here, we summarize experimental rodent and non-human primate studies that link oxytocin to reproductive aging and metabolic health and highlight the inconclusive findings in studies of women. Most human studies relied on a single oxytocin assessment in plasma or on intranasal oxytocin administration. The pulsatile release and short half-life of plasma oxytocin limit the validity of these methods. We discuss the need for oxytocin assessments in stable bio-samples, such as urine, and to use valid assays for assessment of associations between changing oxytocin levels and well-being across the reproductive life span. This work has the potential to guide therapeutic strategies that will one day alleviate adverse health outcomes for many women.
Topics: Oxytocin; Humans; Female; Animals; Menopause; Women's Health; Aging; Receptors, Oxytocin; Middle Aged
PubMed: 38670161
DOI: 10.1530/JOE-23-0396 -
Obstetrics and Gynecology Jan 2024To evaluate whether prophylactic administration of 1 g of intravenous calcium chloride after cord clamping reduces blood loss from uterine atony during intrapartum... (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVE
To evaluate whether prophylactic administration of 1 g of intravenous calcium chloride after cord clamping reduces blood loss from uterine atony during intrapartum cesarean delivery.
METHODS
This single-center, block-randomized, placebo-controlled, double-blind superiority trial compared the effects of 1 g intravenous calcium chloride with those of saline placebo control on blood loss at cesarean delivery. Parturients at 34 or more weeks of gestation requiring intrapartum cesarean delivery after oxytocin exposure in labor were enrolled. Calcium or saline placebo was infused over 10 minutes beginning 1 minute after umbilical cord clamping in addition to standard care with oxytocin. The primary outcome was quantitative blood loss, analyzed by inverse Gaussian regression. Planned subgroup analysis excluded nonatonic bleeding, such as hysterotomy extension, arterial bleeding, and occult placenta accreta. We planned to enroll 120 patients to show a 200-mL reduction in quantitative blood loss in planned subgroup analysis, assuming up to 40% incidence of nonatonic bleeding (80% power, α<0.05).
RESULTS
From April 2022 through March 2023, 828 laboring parturients provided consent and 120 participants were enrolled. Median blood loss was 840 mL in patients allocated to calcium chloride (n=60) and 1,051 mL in patients allocated to placebo (n=60), which was not statistically different (mean reduction 211 mL, 95% CI -33 to 410). In the planned subgroup analysis (n=39 calcium and n=40 placebo), excluding cases of surgeon-documented nonatonic bleeding, calcium reduced quantitative blood loss by 356 mL (95% CI 159-515). Rates of reported side effects were similar between the two groups (38% calcium vs 42% placebo).
CONCLUSION
Prophylactic intravenous calcium chloride administered during intrapartum cesarean delivery after umbilical cord clamping did not significantly reduce blood loss in the primary analysis. However, in the planned subgroup analysis, calcium infusion significantly reduced blood loss by approximately 350 mL. These data suggest that this inexpensive and shelf-stable medication warrants future study as a novel treatment strategy to decrease postpartum hemorrhage, the leading global cause of maternal morbidity and mortality.
CLINICAL TRIAL REGISTRATION
ClinicalTrials.gov , NCT05027048.
Topics: Pregnancy; Female; Humans; Oxytocin; Calcium; Calcium Chloride; Cesarean Section; Postpartum Hemorrhage; Calcium, Dietary
PubMed: 37917943
DOI: 10.1097/AOG.0000000000005441 -
American Journal of Obstetrics and... Mar 2024Oxytocin is a reproductive hormone implicated in the process of parturition and widely used during labor. Oxytocin is produced within the supraoptic nucleus and... (Review)
Review
Oxytocin is a reproductive hormone implicated in the process of parturition and widely used during labor. Oxytocin is produced within the supraoptic nucleus and paraventricular nucleus of the hypothalamus and released from the posterior pituitary lobe into the circulation. Oxytocin is released in pulses with increasing frequency and amplitude in the first and second stages of labor, with a few pulses released in the third stage of labor. During labor, the fetus exerts pressure on the cervix of the uterus, which activates a feedforward reflex-the Ferguson reflex-which releases oxytocin. When myometrial contractions activate sympathetic nerves, it decreases oxytocin release. When oxytocin binds to specific myometrial oxytocin receptors, it induces myometrial contractions. High levels of circulating estrogen at term make the receptors more sensitive. In addition, oxytocin stimulates prostaglandin synthesis and release in the decidua and chorioamniotic membranes by activating a specific type of oxytocin receptor. Prostaglandins contribute to cervical ripening and uterine contractility in labor. The oxytocin system in the brain has been implicated in decreasing maternal levels of fear, pain, and stress, and oxytocin release and function during labor are stimulated by a social support. Moreover, studies suggest, but have not yet proven, that labor may be associated with long-term, behavioral and physiological adaptations in the mother and infant, possibly involving epigenetic modulation of oxytocin production and release and the oxytocin receptor. In addition, infusions of synthetic oxytocin are used to induce and augment labor. Oxytocin may be administered according to different dose regimens at increasing rates from 1 to 3 mIU/min to a maximal rate of 36 mIU/min at 15- to 40-minute intervals. The total amount of synthetic oxytocin given during labor can be 5 to 10 IU, but lower and higher amounts of oxytocin may also be given. High-dose infusions of oxytocin may shorten the duration of labor by up to 2 hours compared with no infusion of oxytocin; however, it does not lower the frequency of cesarean delivery. When synthetic oxytocin is administered, the plasma concentration of oxytocin increases in a dose-dependent way: at infusion rates of 20 to 30 mIU/min, plasma oxytocin concentration increases approximately 2- to 3-fold above the basal level. Synthetic oxytocin administered at recommended dose levels is not likely to cross the placenta or maternal blood-brain barrier. Synthetic oxytocin should be administered with caution as high levels may induce tachystole and uterine overstimulation, with potentially negative consequences for the fetus and possibly the mother. Of note, 5 to 10 IU of synthetic oxytocin is often routinely given as an intravenous or intramuscular bolus administration after delivery to induce uterine contractility, which, in turn, induces uterine separation of the placenta and prevents postpartum hemorrhage. Furthermore, it promotes the expulsion of the placenta.
Topics: Pregnancy; Female; Humans; Oxytocin; Receptors, Oxytocin; Peripartum Period; Labor, Obstetric; Oxytocics; Labor, Induced
PubMed: 38462255
DOI: 10.1016/j.ajog.2023.04.011