Serum Oxytocin Levels Research Articles

The hormonal trajectory along gestational age: Cortisol and oxytocin levels profiles

Pregnancy is accompanied by hormonal fluctuation, including increased cortisol and oxytocin (OT). Although the implications of these hormones during pregnancy are extensively studied, their normative variability is not well established. Therefore, we evaluated how serum cortisol and OT levels behave throughout pregnancy. This longitudinal study is part of a population-based cohort of pregnant women living in a city in Southern Brazil. Pregnant women up to 24 gestational weeks were evaluated at the time of identification (1st wave, N=983) and 60 days after the initial interview (2nd wave, N=840). At both times, blood samples were collected for hormonal dosage. We investigated the trajectory of these hormones throughout pregnancy using growth curve modeling. The best-fitting model was the exponential growth model, in which the variance explains approximately 79.1 % of the outcome. Thus, the cortisol level was, on average, at 44.2 μg/dl (95 %CI: 29.2;59.1, p<0.001) in the first gestational week, with an increase of approximately 2.0 % (95 %CI: 1.01;1.02, p<0.001) each week. OT showed no significant changes. While cortisol appears to follow a trajectory of exponential increase, possibly in response to the demands of fetal development, the variation in OT levels throughout pregnancy still remains constant subject to further investigation.

Effects of Probiotic Supplementation Added to a Weight Loss Program on Anthropometric Measures, Body Composition, Eating Behavior, and Related Hormone Levels in Patients with Food Addiction and Weight Regain After Bariatric Surgery: A Randomized Clinical Trial.

Weight regain after metabolic bariatric surgery is a common problem. Food addiction is an eating disorder that can be one of the reasons for weight regain in these patients. This study aimed to evaluate the effects of probiotic supplementation with a weight loss program and cognitive behavioral therapy (CBT) on anthropometric measures, eating behavior, food addiction, and related hormone levels, in patients with food addiction and weight regain after metabolic bariatric surgery. This randomized, triple-blind, placebo-controlled clinical trial was conducted on patients with food addiction and weight regain after metabolic bariatric surgery. Participants (n = 50) received a weight loss program and CBT plus probiotic, or placebo for 12weeks. Then, anthropometric measurements, biochemical markers, eating behavior, and food addiction were assessed. Weight and body mass index (BMI) decreased significantly in the probiotic group compared to placebo (p = 0.008, p = 0.001, respectively). Fat mass was significantly decreased in the probiotic group (p < 0.001). Moreover, a significant improvement was observed in the probiotic group's eating behavior and food addiction compared to the placebo group (p < 0.001). Serum levels of leptin decreased significantly (p = 0.02), and oxytocin serum levels increased significantly (p = 0.008) in the probiotic group compared to the placebo group. Adding probiotic supplements to the weight loss program and CBT is superior to the weight loss program and CBT alone in improving weight loss, eating behavior, and food addiction in patients with food addiction and weight regain after metabolic bariatric surgery.

The Effects of Testosterone on Hypothalamic and Serum Oxytocin Levels Are Affected by the Estrogen Milieu in Female Rats.

Previous studies have suggested that the effects of androgens on body weight (BW) and appetite are affected by the estrogen milieu in females; however, the mechanism underlying these effects remains unclear. We hypothesized that androgens may affect endogenous oxytocin (OT), which is a hypothalamic anorectic factor, and that these effects of androgens may be altered by the estrogen milieu in females. To investigate this hypothesis, in the present study, we examined the effects of testosterone on peripheral and central OT levels in ovariectomized female rats that did or did not receive estradiol supplementation. Ovariectomized female rats were randomly divided into non-estradiol-supplemented or estradiol-supplemented groups, and half of the rats in each group were concurrently supplemented with testosterone (i.e., rats were divided into four groups, n = 7 per each group). We also measured peripheral and central OT receptor (OTR) gene expression levels. As a result, we found that testosterone increased serum and hypothalamic OT levels and OT receptor mRNA levels in non-estradiol-supplemented rats, whereas it had no effects on these factors in estradiol-supplemented rats. In addition, testosterone reduced food intake, BW gain, and fat weight in non-estradiol-supplemented rats, whereas it did not have any effects on BW, appetite, or fat weight in estradiol-supplemented rats. These findings indicate that the effects of androgens on OT may be affected by the estrogen milieu, and elevated OT levels may be related to the blunting of appetite and prevention of obesity under estrogen-deficient conditions.

Correlation between brain-derived neurotrophic factor and oxytocin in older adults

BackgroundSeveral previous studies have demonstrated that brain-derived neurotrophic factor (BDNF) and oxytocin are associated with dementia, depression, and mental health. The aim of this study was to measure the serum BDNF and oxytocin levels of community-dwelling older adults and evaluate the relationship between the two biomarkers in the study cohort. MethodsThis survey was conducted between November 2016 and September 2017 in Kurokawa-cho, Imari, Saga Prefecture, Japan, and the participants were community-dwelling older adults aged ≥ 65 years old. Their blood samples were collected for the measurement of their serum BDNF and oxytocin levels using enzyme-linked immunosorbent assays. The relationship between serum BDNF and oxytocin levels was analyzed using correlation and multiple regression analyses. ResultsA total of 95 participants (25 men and 70 women; mean age: 78.24 ± 3.85 years and 77.96 ± 5.52 years, respectively) were analyzed. The results of the analyses indicated that serum BDNF level was positively associated with serum oxytocin level, even after adjusting for age, sex, and years of education. ConclusionThe results of this study suggest that BDNF and oxytocin may interact in older adults and may be associated with maintaining good mental health among them.

Postweaning sodium citrate exposure induces long-lasting and sex-dependent effects on social behaviours in mice

BackgroundPostweaning is a pivotal period for brain development and individual growth. As an important chemical used in medicines, foods and beverages, sodium citrate (SC) is commonly available. Although some effects of SC exposure on individual physiology have been demonstrated, the potential long-lasting effects of postweaning dietary SC exposure on social behaviours are still elusive. MethodsBoth postweaning male and female C57BL/6 mice were exposed to SC through drinking water for a total of 3 weeks. A series of behavioural tests, including social dominance test (SDT), social interaction test (SIT), bedding preference test (BPT) and sexual preference test (SPT), were performed in adolescence and adulthood. After these tests, serum oxytocin (OT) levels and gut microbiota were detected. ResultsThe behavioural results revealed that postweaning SC exposure decreased the social dominance of male mice in adulthood and female mice in both adolescence and adulthood. SC exposure also reduced the sexual preference rates of both males and females, while it had no effect on social interaction behaviour. ELISA results indicated that SC exposure decreased the serum OT levels of females but not males. 16S rRNA sequencing analysis revealed a significant difference in β-diversity after SC exposure in both males and females. The correlation coefficient indicated the correlation between social behaviours, OT levels and dominant genera of gut microbiota. ConclusionOur findings suggest that postweaning SC exposure may have enduring and sex-dependent effects on social behaviours, which may be correlated with altered serum OT levels and gut microbiota composition.

Investigation and Analysis of Emotional State and Oxytocin Level in Patients with Postpartum Depression.

Postpartum depression (PPD) is a common mental disorder in postpartum women, negatively impacting physical and mental health. Correlation analysis can predict the relationship between variables. By detecting the abnormal level of oxytocin, clinicians can timely know the emotional states of parturients to guide clinical practice. This study aimed to investigate the relationship between emotional states and oxytocin (OT) levels in patients with PPD. The medical records of 166 PPD patients admitted to Cangzhou Central Hospital from May 2020 to March 2023 were retrospectively analyzed. After excluding 9 patients who did not meet the inclusion criteria, the remaining 157 patients were included in this study. The 7-item Generalized Anxiety Disorder Scale and Patient Health Questionaire-9 items were used to evaluate the emotional states of 157 patients, and the included subjects were grouped according to the results of the scale. The serum OT levels of patients was measured, and the relationship between the OT levels and emotional states was analyzed. In this study, 75 patients were included in the mild anxiety group, and 82 patients were included in the moderate and severe anxiety group. Seventy-nine patients were selected as the mild depression group, and 78 patients were included in the moderate and severe depression group. The mild anxiety group had a higher OT level than the moderate and severe anxiety group (Z = -10.121, p < 0.001). The mild depression group had a higher OT level than the moderate and severe depression group (Z = -9.758, p < 0.001). OT level was negatively correlated with anxiety and depression scores (r = -0.676, r = -0.665, p < 0.001). There is a specific relationship between the emotional states of PPD patients and the OT levels in the body, and active clinical management strategies need to be implemented.

Irisin administration modifies ovary mast cell numbers, ovarian angiogenesis, and oxytocin levels in obese rats

Exercise hormone irisin, a thermogenic adipo-myokine, promotes energy expenditure by white adipose tissue browning. Considering that irisin improves the white adipose tissue metabolic profile and increases whole-body energy expenditure, it is thought that irisin may be a potential new therapeutic target for the treatment of the growing epidemic of obesity. The roles of mast cells and angiogenesis in the pathogenesis of obesity are known, and the importance of loss of mast cell function and antiangiogenic agents in the treatment of obesity has gained prominence in recent years. In addition, the therapeutic efficacy of oxytocin for obesity, by inducing browning and stimulating thermogenesis, is also noteworthy. To understand better the mechanisms involved in the therapeutic effect of irisin on obesity, the present study evaluated the effects of irisin treatment on high-fat diet-induced, obese female rats, focusing on the number of ovary mast cells, and ovarian angiogenesis and serum oxytocin levels. Our findings showed that ovary mast cell numbers, corpus luteum angiogenesis, and vascular endothelial growth factor (VEGF) immunoreactivity in ovarian tissues increased with obesity and then significantly decreased with irisin administration. Also, it was determined that the increased serum oxytocin levels with obesity, increased markedly depending on irisin administration in obese female rats. Taken together, our findings revealed that irisin can well be considered as a potential therapeutic agent in the treatment of obesity by reducing mast cells and angiogenesis, and promoting oxytocin secretion.

Robot therapy aids mental health in patients with hematological malignancy during hematopoietic stem cell transplantation in a protective isolation unit

Patients with hematological malignancy experience physical and psychological pain, such as a sense of isolation and confinement due to intensive chemotherapy in a protective isolation unit (PIU). We examined whether the intervention of a robotic puppy, aibo (manufactured by Sony), could improve patients' mental health as an alternative therapy for pet therapy, which is not feasible in PIU. This study included 21 patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) (n = 16) or autologous HSCT (n = 5). The patients were randomly divided into the aibo and control groups. Psychological effects were regularly assessed by measuring the levels of salivary stress hormone chromogranin A (CgA), serum oxytocin, and serum cortisol and the quick Inventory of Depressive Symptomatology Self-Report (QIDS-SR) scores. The aibo group demonstrated a significant decrease in CgA level, while the control group showed the opposite trend. In addition, changes in serum oxytocin and cortisol levels indicated that aibo helped reduce stress. There was no significant difference in the QIDS-SR scores between the two groups; however, the psychomotor activity in the aibo group improved significantly. These findings suggest that aibo intervention during a stay in a PIU can improve the mental health of patients with hematological malignancies who have undergone HSCT.

Progesterone treatment reduces food intake and body weight in ovariectomized female rats

While the effects of progesterone on body weight and appetite in pre-menopausal conditions have been well elucidated, its effects in post-menopausal conditions have not been clarified. On the contrary, the effects of estrogen on body weight and appetite in post-menopausal conditions have been well established. In this study, the effects of progesterone treatment on body weight, appetite, and fat mass in ovariectomized rats were evaluated. In addition, the central and/or peripheral levels of oxytocin (OT), leptin, and their receptors, which are potent anorectic factors, were examined. Female rats were ovariectomized and divided into control, progesterone-treated, and estrogen-treated groups. Body weight, food intake, and subcutaneous fat mass were lower in both the progesterone and estrogen groups than in the control group. The estrogen group exhibited higher serum OT levels than the control group, whereas the OT levels of the progesterone and control groups did not differ. The serum leptin levels of both the progesterone and estrogen groups were lower than those of the control group. Gene expression analysis of OT, leptin, and their receptors in the hypothalamus and adipose tissue found few significant differences among the groups. Hypothalamic neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) mRNA levels involved in appetite regulation were slightly altered in the progesterone and estrogen groups. These findings suggest that progesterone treatment may have favorable effects on body weight, appetite, and fat mass regulation in post-menopausal conditions and that the mechanisms underlying these effects of progesterone differ from those underlying the effects of estrogen.

Comparison of endogenous hypothalamic and serum OT levels between young and middle-aged perimenopausal female rats.

Oxytocin (OT) regulates food intake and body weight, particularly in obese individuals. Decreases in the effects of OT have recently been implicated in metabolic disturbances, and the administration of estradiol (E2) increased serum OT levels. Although weight gain is frequently observed in perimenopausal women, endogenous OT levels remain unclear. Therefore, we herein compared endogenous levels of hypothalamic and serum OT between young and middle-aged perimenopausal female rats and examined the relationship between serum estrogen and leptin levels. Body weight and visceral and subcutaneous fat weights were higher in middle-aged rats. Although no significant differences were observed in serum OT and E2 levels, serum leptin levels and hypothalamic mRNA levels of OT and the OT receptor (OTR) were significantly higher in middle-aged rats than in young rats. Serum OT levels did not correlate with hypothalamic OT mRNA levels or serum E2 levels. E2 maintains serum OT levels in perimenopausal rats, and other factors may elevate hypothalamic OT/OTR mRNA levels. Increases in body and fat weights in perimenopausal rats may be attributed to factors other than OT. Therefore, the administration of OT alone may not be sufficient to prevent metabolic disorders induced by the perimenopausal status. J. Med. Invest. 71 : 246-250, August, 2024.

Increased Serum Levels of Phoenixin-14, Nesfatin-1 and Dopamine Are Associated with Positive Pregnancy Rate after Ovarian Stimulation.

We study the relationship between phoenixin (PNX-14), nesfatin-1 (NES-1), dopamine (DA) and oxytocin (OT) levels together with pregnancy rates in women after ovarian stimulation (OS). In a prospective case-control study, 56 infertile women were enrolled from the Department of Gynecological Endocrinology University Hospital. Infertile women age < 40 years old, with polycystic ovary syndrome (PCOS), confirmed tubal patency and suitable sperm quality were included. Blood samples were drawn twice-before the initiation of OS and before the human chorionic gonadotropin (hCG) administration. Assessments of PNX-14, NES-1, DA and OT serum levels were performed. Pregnancy rates after OS were observed. Pregnant women showed higher baseline NES-1 and OT levels (+29.2% and +44%) but not PNX-14 and DA levels when compared to non-pregnant ones. In pregnant women, positive correlations between OT and prolactin, PRL (r = 0.47, p = 0.04), as well as between OT and NES-1 (r = 0.55, p = 0.02), were observed at baseline. At baseline, an OT level increase was associated with a positive pregnancy rate (per 100 pg/mL, OR = 1.39, 95% CI 1.04-1.74), while after OS, higher PNX-14 was a predictor of pregnancy (by 10 pg/mL, OR = 1.23, 95%CI 1.07-1.39). Post-stimulation PNX-14, NES-1 and DA concentrations were higher in pregnant women compared to non-pregnant ones (+17.4%, +26.1%, and +45.5%, respectively; all p < 0.05). In the pregnant group, OT levels were 2.7-times lower than in the remainder (p = 0.03). Moreover, in pregnant participants, a negative association between NES-1 and PNX (r = -0.53, p = 0.024) was observed. Elevated PNX-14, NES-1 and DA along with decreased OT levels were observed in women who achieved pregnancy.

THE RELATIONSHIP BETWEEN ATTACHMENT AND SERUM OXYTOCIN AND HEAT SHOCK PROTEIN-70 LEVELS IN ADOLESCENTS OF PARENTS WITH SCHIZOPHRENIA AND BIPOLAR DISORDER.

The aim of this study was to evaluate serum heat shock protein 70 (HSP70) and oxytocin levels, attachment and perceived social support levels in adolescents with parental bipolar disorder (BD) and Schizophrenia (SCZ). This study included 9 adolescents with SCZ parents, 30 adolescents with BD parents and 31 healthy adolescents. Brief Symptom Inventory (BSI), Relationship Scale Questionnaire-Adolescent Form (RSQ-A) and Multidimensional Scale of Perceived Social Support (MSPSS) were administered to all participants. In addition, serum HSP-70 and oxytocin levels were evaluated. There was no significant difference between the groups in terms of attachment style, psychiatric symptoms and perceived social support. Serum HSP-70 levels were found to be lower in adolescents whose parents had BD. Serum oxytocin levels of the SCZ group were significantly lower than those of the BD group. HSP-70 level was found to be lower in adolescents with BD parents. Oxytocin level was found to be lower in adolescents with SCZ parents. These findings suggest that HSP-70 and oxytocin may be a marker of early life stress in adolescents with parental psychopathology. However, studies are needed to evaluate the relationship between attachment, oxytocin and HSP-70 in adolescents exposed to parental psychopathology in early life.

Developmental Changes in Hypothalamic and Serum Oxytocin Levels in Prenatally Normally Nourished and Undernourished Rats.

Changes in the activities of some metabolic factors have been suggested to increase the risk of conditions associated with the Developmental Origins of Health and Disease (DOHaD). We examined changes in oxytocin (OT), a metabolic factor, and OT receptor (OTR) mRNA levels throughout the developmental period in rats of intrauterine undernutrition. Pregnant rats were divided into two groups: a maternal normal nutrition (mNN) and maternal undernutrition (mUN) group. Serum OT concentrations and hypothalamic mRNA levels of OT and OTR were measured in both offspring at various postnatal stages. Both offspring showed significant increases in serum OT concentrations during the neonatal period, significant reductions around the pubertal period, and significant increases in adulthood. Hypothalamic OT mRNA expression levels gradually increased from the neonatal to pubertal period and decreased in adulthood in both offspring. In the pre-weaning period, hypothalamic OT mRNA expression levels were significantly lower in the mUN offspring than in the mNN offspring. In the mUN offspring, hypothalamic OTR mRNA expression levels transiently increased during the neonatal period, decreased around the pubertal period, and increased again in adulthood, whereas transient changes were not detected in mNN offspring. These changes could affect nutritional and metabolic regulation systems in later life and play a role in the mechanisms underlying DOHaD.

Serum Oxytocin Levels Decrease 12 Months Following Sleeve Gastrectomy and Are Associated with Decreases in Lean Mass.

Oxytocin (OXT), an anorexigenic hormone, is also bone anabolic. Further, OXT administration results in increases in lean mass (LM) in adults with sarcopenic obesity. We examine, for the first time, associations of OXT with body composition and bone endpoints in 25 youth 13-25 years old with severe obesity who underwent sleeve gastrectomy (SG) and 27 non-surgical controls (NS). Forty participants were female. Subjects underwent fasting blood tests for serum OXT and DXA for areal bone mineral density (aBMD) and body composition. At baseline, SG vs. NS had higher median body mass index (BMI) but did not differ for age or OXT levels. Over 12 months, SG vs. NS had greater reductions in BMI, LM, and fat mass (FM). OXT decreased in SG vs. NS 12 months post-SG. While baseline OXT predicted a 12-month BMI change in SG, decreases in OXT levels 12 months post-SG were not associated with decreases in weight or BMI. In SG, decreases in OXT were positively associated with decreases in LM but not with decreases in FM or aBMD. Loss of LM, a strong predictor of BMD, after bariatric surgery may reduce functional and muscular capacity. OXT pathways may be targeted to prevent LM loss following SG.

The Association between Oxytocin and Lower Limb Osteoarthritis: A Prospective Cohort Study

Oxytocin (OT), a neuropeptide best known for its role in emotional and social behaviors, has been linked to osteoarthritis (OA). This study aimed to investigate the serum OT level in hip and/or knee OA patients and to study its association with disease progression. Patients from the KHOALA cohort with symptomatic hip and/or knee OA (Kellgren and Lawrence (KL) scores of 2 and 3) and follow-up at 5 years were included in this analysis. The primary endpoint was structural radiological progression, which was defined as an increase of at least one KL point at 5 years. Logistic regression models were used to estimate the associations between OT levels and KL progression while controlling for gender, age, BMI, diabetes and leptin levels. Data from 174 hip OA patients and 332 knee OA patients were analyzed independently. No differences in OT levels were found between the ‘progressors’ and ‘non-progressors’ groups among the hip OA patients and knee OA patients, respectively. No statistically significant associations were found between the OT levels at baseline and KL progression at 5 years, the KL score at baseline or the clinical outcomes. Higher structural damage at baseline and severe structural progression of hip and knee osteoarthritis did not appear to be associated with a low serum OT level at baseline.

Profile of maternal serum oxytocin in postpartum and non-pregnant rats

Oxytocin is primarly secreted in the brain as a neuromodulator that affects numerous neurophysiological and behavioral processes. It is also produced in the ovaries and uterus to stimulate delivery and lactation. Oxytocin mRNA is found in the endometrial epithelial cells of non-pregnant women during ovulation and menstruation. Until recently, there have been no data on scientific-level oxytocin in virgin female rats. This study aimed to compare the level of oxytocin in different physical biology between postpartum and non-pregnant experimental animals (virgin or had never given birth). This experimental study was conducted on 19 female white rats (Rattus norvegicus) allocated to two groups: T1 and T2. The ten rats in group T1 (nulliparous virgin) and the nine in group T2 (postpartum) were sacrificed on day two, except for group T1, which were sacrificed following vaginal delivery. Blood was collected intracardiacally, and serum oxytocin levels were evaluated using an ELISA assay. The T-test was used for statistical data analysis. The serum oxytocin level in the T2 group (628.06 ± 168.72 pg/mL) was significantly higher than in the T1 group (366.71 ± 185.03 pg/mL; P &amp;lt; 0.05). In conclusion, oxytocin levels were higher in postpartum animals than in virgin animals. Thus, oxytocin plays a greater role in female reproduction than in normal physiological condition.

Association between serum oxytocin levels and depressive state in community-dwelling older adults: A cross-sectional study.

Identifying peripheral biomarkers related to the prevention or modification of unhealthy mental conditions in older adults would be extremely beneficial. This study aimed to evaluate serum oxytocin levels in older adults living in a rural community and their association with cognitive function, anxiety, depressive state, and well-being. This survey was conducted between November 2016 and September 2017 in Kurokawa-cho, Imari, Saga Prefecture, Japan, among people aged ≥65 years. Blood samples were collected from the participants for serum oxytocin level analysis, which was performed using peptide enzyme immunoassay. Participants underwent neuropsychological assessments, including the Mini-Mental State Examination, Clinical Dementia Rating, Frontal Assessment Battery, State-Trait Anxiety Inventory, 15-item Geriatric Depression Scale, and 17-item Philadelphia Geriatric Center Morale Scale. We examined the association between serum oxytocin levels and neuropsychological assessment results. Out of 94 participants, 25 were men and 69 were women, with mean ages of 78.24 ± 3.85 years and 78.10 ± 5.43 years, respectively. Serum oxytocin levels were negatively associated with 15-item Geriatric Depression Scale scores. Additionally, nondepressive state/depressive state was classified by the 15-item Geriatric Depression Scale (cut-off 5/6). Logistic regression analysis showed that higher serum oxytocin levels tended to be associated with a less depressive state at that time. Serum oxytocin levels may be associated with depressive state in adults aged ≥65 years.

Variable Levels of Oxytocin During Sepsis: The Role of Oxytocin in Sepsis Pathophysiology.

Although the role of oxytocin in the pathophysiology of sepsis is still unknown, rising preclinical evidence suggests that oxytocin is possibly involved. However, no direct clinical studies have measured the levels of oxytocin during sepsis. In this preliminary study, the serum oxytocin levels were evaluated throughout the duration of sepsis. Twenty-two male patients over 18 years of age with a SOFA score of 2 points or more who were admitted to the ICU were included. Patients with a history of neuroendocrine, psychiatric, and neurologic disorders, cancer, an infection caused by COVID-19, shock due to reasons other than sepsis, a history of psychiatric or neurologic medication use, and those who died during the study were excluded. The main endpoint included the measurement of serum oxytocin levels using radioimmunoassay at 6, 24, and 48 h of the ICU admission. Mean serum oxytocin level was higher at 6 h of ICU admission (41.27 ± 13.14 ng/L) than after 24 and 48 h of ICU admission (22.63 ± 5.75 and 20.97 ± 7.61 ng/L respectively) (P-value < .001). Our study, while reporting increased serum oxytocin levels in the initial phase of sepsis and decline afterward, supports the possible contribution of oxytocin in the pathophysiology of sepsis. Given that oxytocin seems to modulate the innate immune system, future investigations are necessary to assess the potential role of oxytocin in the pathophysiology of sepsis.

The effect of olfactory odour stimulation on serum oxytocin levels and glucose metabolism: Data from the OLFAMET study

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

New discoveries on the interaction between testosterone and oxytocin in male rats ― Testosterone-mediated effects of oxytocin in the prevention of obesity

Sex steroid hormones are important for the maintenance of metabolism in both sexes. Oxytocin (OT) is a neuropeptide that is synthesized in hypothalamic regions, secreted from the posterior lobe of the pituitary gland, and is involved in the control of appetite, body weight, and metabolism. Estrogen and OT both play a role in the metabolism of nutrients, and OT has potential in the prevention of obesity. However, the relationship between testosterone and OT remains unclear. Therefore, the present study investigated the relationship between testosterone and OT in hypogonadal male rats and male rats receiving testosterone replacement therapy. The results obtained showed that testosterone increased serum OT levels and promoted the secretion of adiponectin from visceral fat, and reduced body fat directly and/or indirectly through OT and adiponectin. Testosterone also increased the expression of OT receptors in the hypothalamus to increase sensitivity to OT, and perhaps because of this, OT administration had the effect of reducing food intake and body weight gain in both normal and castrated rats, and this effect was stronger in normal rats. In other words, the preventative effects of OT on obesity may be synergistic with testosterone. Collectively, the present results indicate that testosterone exerts indirect effects to prevent obesity and atherosclerosis through OT and adiponectin. In conclusion, testosterone replacement therapy is useful for preventing obesity caused by hypogonadism, and OT has potential in supportive medicine to prevent obesity and adult diseases.