Serum Oxytocin Levels Research Articles

Gender-related romantic attachment and serum oxytocin level difference in adult patients with obsessive compulsive disorder

BackgroundGiven the scarcity of data on gender-related romantic attachment changes and the potential role of oxytocin (OT) in the pathophysiology of obsessive-compulsive illness (OCD), the current study aimed to assess gender-related differences in romantic attachment characteristics and their relationship to serum oxytocin in a set of forty OCD cases compared with a similar group of healthy controls .Simultaneously examining the gender differences in serum oxytocin levels in OCD patients, the diagnosis of OCD patients was determined using DSM-5 criteria, and the severity of OCD was determined using the Y-BOCS rating scale. All of the patients were drug-free and not depressed. The romantic attachment was assessed using the “Experiences in Close Relationship” Questionnaire. Standard ELISA kits were used to assess plasma OT levels.ResultsRegarding romantic attachments, patients with obsessive compulsive disorder scored higher on the anxiety and avoidance domains than controls with no significant gender difference. Serum oxytocin was higher in patients with OCD than in healthy controls, indicating a possible underlying pathophysiology of the illness. Also, there was a significant gender difference, with female patients having higher serum oxytocin and symptoms severity being negatively associated.ConclusionsTaken together, these findings propose that OT may play a role in OCD pathophysiology with gender specificity. Also, OCD associated with insecure romantic attachment.

Behavioral, hormonal, and neural alterations induced by social contagion for pain in mice

Neurobiology of social contagion/empathy aims to collaborate with the development of treatments for human disorders characterized by the absence of this response – autism spectrum disorder, schizophrenia, and antisocial personality disorder. Previous studies using sustained aversive stimuli (e.g., neuropathic pain or stress) to induce social contagion behaviors in rodents have demonstrated that these conditions may increase hypernociception, anxiogenic-like effects, and defensive behaviors in cagemates. To amplify the knowledge about behavioral, hormonal, and neural alterations induced by cohabitation with a pair in neuropathic pain, we investigated the effects of this protocol on (i) pain (writhing, formalin, hot plate tests) and depression (sucrose splash test) responses, (ii) the serum levels of corticosterone, testosterone, and oxytocin, (iii) noradrenalin, dopamine and its metabolite (DOPAC and HVA) levels in the amygdaloid complex and insular cortex, (iv) neuronal activation pattern (FosB labeling) in the ventral tegmental area (VTA), paraventricular nucleus of the hypothalamus (PVN) and supraoptic nucleus (SO). One day after weaning, male Swiss mice were housed in pairs for 14 days. Then, they were divided into two groups: sciatic nerve constricted cagemate [CNC; i.e., one animal of each pair was subjected to sciatic nerve constriction (NC)], and cagemate sham (CS; a similar procedure but with no nerve constriction), and housed for further 14 days. After 28 days of cohabiting, four independent groups were subjected to (a) behavioral analyses (Exp. 1) and (b) blood samples collected for Elisa assays of corticosterone, testosterone, and oxytocin (Exp. 2), remotion of brains for the (c) HPLC in the noradrenaline dopamine and metabolites quantification (Exp. 3) or (d) immunoassays analyses for FosB labeling (Exp. 4). Results showed that cohabitation with a conspecific in chronic pain induces hypernociception and antinociception in the writhing and formalin tests, respectively, and anhedonic-like effects in the sucrose splash test. Hormonal results indicated a decrease in plasma corticosterone only in nerve constricted mice, in testosterone (CNC and NC animals), and an increase in oxytocin serum levels. The neurochemical analyses demonstrated that the social contagion for pain protocol increases in dopamine turnover in the amygdala and insula. This assay also revealed an increase in noradrenaline levels and dopamine turnover within the insula of NC mice. In the FosB labeling measure, we observed a rise in the VTA, PVN and SO in the CNC group whereas for the NC group an increase of this activation pattern occurred only in the VTA. Present results suggest the role of hormones (testosterone and oxytocin) and neurotransmitters (dopamine) in the modulation of behavioral changes induced by social contagion in animals cohabitating with a conspecific in pain.This article is part of the special Issue on ‘Stress, Addiction and Plasticity'.

Serum Oxytocin Level Correlates With Gut Microbiome Dysbiosis in Children With Autism Spectrum Disorder.

To investigate the levels of serum oxytocin (OT) in children with autism spectrum disorder (ASD) and explore the association between OT levels and gut microbiota relative abundances, we recruited 39 children with ASD children–mother dyads and 44 healthy controls. Serum OT levels were determined via enzyme-linked immunosorbent assay and gut microbiota abundances were determined by 16S rRNA sequencing. We found that the OT level of ASD was lower than the healthy control group overall (P < 0.05). Furthermore, we present preliminary evidence of gut microbiome dysbiosis observed among children with ASD to lower levels of OT based on correlational analysis between serum OT and specific gut microbiota abundances (P < 0.05). We also found sex-related differences in serum OT levels and GIS index (P < 0.05). However, the generalizability of findings relevant to females with ASD require further validation in future studies involving larger sample sizes and balanced sex distributions due to the small number of females involved in this study. Nonetheless, these new findings further our understanding of the effects of low serum OT levels among individuals with ASD, which provides preliminary evidence in hopes of guiding future study design or mechanistic studies. The findings of the present study may be suggestive of potential ASD subtypes based on ASD severity and gut microbiome composition that may facilitate the prediction of the therapeutic responses of OT among those with ASD.

The effects of female-male friendships on male postcopulatory levels of oxytocin and vasopressin, and sperm parameters in Macacaarctoides

Male and female stump-tailed macaques (Macaca arctoides) form close relationships akin to human friendships. Oxytocin and vasopressin modulate these and other social relationships and reproductive behavior and physiology in various mammal species. Besides the behavioral effects of oxytocin, this hormone plays an essential role in the ejaculatory process, favoring sperm transport upward the female reproductive tract. Therefore, we investigated the influence of friendships on postcopulatory serum levels of oxytocin and vasopressin in the stump-tailed macaque (Macaca arctoides). In addition, we searched for a correlation between this kind of social relationship and sperm transport in the vagina during the periovulatory and luteal phases. Six female and six male adult macaques having different friendship indices served as experimental animals. Allocated in 57 mating pairs combinations, these animals were allowed to copulate once in the luteal and periovulatory phases. Blood samples were collected from each animal finishing copulation to measure oxytocin and vasopressin. Afterward, we profoundly sedated the females and collected three semen samples from the vagina every 10 min to perform spermatobioscopies. Males' post-copulation oxytocin values increased along with the friendship index, while vasopressin behaves oppositely. Sperm concentration and immotile and motile sperm decreased from one sample to another as male-female closeness increased. Finally, in the periovulatory phase, only in the first vaginal sample, sperm velocities significantly increased with friendship indices. Our results showed that in stump-tailed macaques, heterosexual friendships promote higher postcopulatory oxytocin concentrations and better physiological conditions to males, which probably enhance reproductive success.

Divergent effects of oxytocin on \u201cmind-reading\u201d in healthy males

The neuropeptide oxytocin (OT) has been associated with a broad range of human behaviors, particularly in the domain of social cognition, and is being discussed to play a role in a range of psychiatric disorders. Studies using the Reading The Mind In The Eyes Test (RMET) to investigate the role of OT in mental state recognition reported inconsistent outcomes. The present study applied a randomized, double-blind, cross-over design, and included measures of serum OT. Twenty healthy males received intranasal placebo or OT (24 IU) before performing the RMET. Frequentist and Bayesian analyses showed that contrary to previous studies (Domes et al., 2007; Radke & de Bruijn, 2015), individuals performed worse in the OT condition compared to the placebo condition (p = 0.023, Cohen’s d = 0.55, 95% confidence interval [CI] [0.08, 1.02], BF10 = 6.93). OT effects did not depend on item characteristics (difficulty, valence, intensity, sex) of the RMET. Furthermore, OT serum levels did not change after intranasal OT administration. Given that similar study designs lead to heterogeneous outcomes, our results highlight the complexity of OT effects and support evidence that OT might even interfere with social cognitive abilities. However, the Bayesian analysis approach shows that there is only moderate evidence that OT influences mind-reading, highlighting the need for larger-scale studies considering the discussed aspects that might have led to divergent study results.

Oxytocin levels in individuals with schizophrenia are high in cerebrospinal fluid but low in serum: A systematic review and meta-analysis : Oxytocin and Schizophrenia.

Schizophrenia is a debilitating mental illness. Levels of oxytocin have been proposed as a biomarker of schizophrenia; however, the observed levels of oxytocin in individuals with schizophrenia have been inconsistent across studies. We performed a meta-analysis to evaluate oxytocin levels in plasma, serum and cerebrospinal fluid to see if there are statistically different concentrations between individuals with schizophrenia and the comparison group. The meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Following the inclusion and exclusion criteria, 14 studies were included in the meta-analysis. The quality of the study was evaluated by the Newcastle-Ottawa Scale (NOS). A random-effects model was performed using the Comprehensive Meta-analysis software with the standardized mean difference (SMD) and 95% confidence intervals (CIs). Serum oxytocin levels in individuals with schizophrenia were significantly lower than that in comparison group (SMD = - 1.74, 95% CI = - 3.22 to - 0.26, p = 0.02) but cerebrospinal fluid oxytocin levels in individuals with schizophrenia were significantly higher than those in the comparison group (SMD = 0.55, 95% CI = 0.05 to 1.04, p = 0.03). Our results suggest that oxytocin levels in cerebrospinal fluid are increased in individuals with schizophrenia but decreased in serum. Therefore, the oxytocin system dysregulation may play a role in the pathophysiology of schizophrenia and it should be measured in more populations for a possible implementation as a biomarker of schizophrenia.

Evaluation of serum oxytocin levels in patients with depression, generalized anxiety disorder, panic disorder, and social anxiety disorder: A case-control study

Background/Aim: Oxytocin, an endogenous anti-stress, antidepressant, and anxiolytic hormone, is reported to increase in stressful situations to reduce the hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis and amygdala for coping with stress and improving social functioning. This study aimed to compare serum oxytocin levels of patients with depression, generalized anxiety disorder (GAD), panic disorder (PD), and social anxiety disorder (SAD) with that of healthy controls. Methods: The study included 50 patients (25 male, 25 female) with major depression, 26 patients (9 male, 17 female) with GAD, 31 patients (14 male, 17 female) with SAD, and 40 patients (17 male, 23 female) with PD and 30 healthy volunteers. Hamilton Depression Rating Scale (HDRS), Hamilton Anxiety Rating Scale (HARS), Perceived Stress Scale (PSS), and Anxiety Sensitivity Index-3 (ASI-3) were applied to all groups. In addition, Generalized Anxiety Disorder-7 (GAD-7), Panic Disorder Severity Scale (PDSS), and Liebowitz Social Phobia Scale were applied to patients with GAD, panic disorder, and social anxiety disorder, respectively. Serum oxytocin levels were measured by ELISA. Results: Serum oxytocin levels of patients with depression were significantly lower, and those of patients with generalized anxiety disorder, social anxiety disorder, and panic disorder with agoraphobia were significantly higher compared to the control group (2.46 (2.8) vs. 2.86 (0.72), P=0.004, 11.49 (11.35) vs. 2.86 (0.72), P=0.001, 10.67 (11.32) vs. 2.86 (0.72), P=0.001, and 6.97 (5.01) vs. 2.86 (0.72), P=0.001, respectively). Conclusion: Lower oxytocin levels in depressed patients and higher oxytocin levels in patients with GAD, and PD with agoraphobia suggest that oxytocin has a role in psychiatric disorders. Further studies are needed to better understand the relationship between depression, anxiety disorders, oxytocin, and the underlying mechanisms.

Effects of gonadal status and the estrogen milieu on hypothalamic oxytocin gene expression and serum oxytocin levels in female rats

Oxytocin (OT) and its receptor (OTR) play various roles in the central and peripheral regulation of appetite and body weight. Previously, we have shown that the administration of OT markedly decreased appetite and body weight gain in ovariectomized (OVX) obese rats. In addition, recent studies have shown that the endogenous OT system is also affected by endogenous or exogenous estrogen. In this study, we showed that ovariectomy decreased rats' hypothalamic OT/OTR mRNA and serum OT levels, but did not affect their visceral fat OTR mRNA levels. The chronic administration of estradiol (E2) abrogated these ovariectomy-induced changes; i.e., it increased the rats' hypothalamic OT/OTR mRNA and serum OT levels, and may be associated with reductions in food intake and body weight gain. In addition, acute E2 administration increased the rats' hypothalamic OTR mRNA and serum OT levels, but did not affect their hypothalamic OT mRNA levels. Taken together, these results suggest that endogenous OT and/or OTR expression might be positively regulated by E2 and that the suppressive effects of E2 on appetite and body weight gain might be mediated, at least in part, by the OT system. Thus, we consider that OT might be a target hormone to pursue subsequent interventions of menopause for menopause-induced metabolic disorders.

Oxytocin receptor gene polymorphism and low serum oxytocin level are associated with hyperphagia and obesity in adolescents.

In recent years, oxytocin (OXT) and polymorphisms in the oxytocin receptor (OXTR) gene have been reported to play roles in obesity pathogenesis. However, there was no study evaluating OXTR gene variants in childhood obesity. The aim of the study was to investigate the relation of OXTR gene polymorphisms and serum OXT levels with metabolic and anthropometric parameters in obese and healthy adolescents. The study was a multi-centered case-control study, which was conducted on obese and healthy adolescents aged between 12 and 17 years. Serum OXT and leptin levels were measured, and OXTR gene variants were studied by qPCR (rs53576) and RFLP (rs2254298) methods. A total of 250 obese and 250 healthy adolescents were included in this study. In the obese group, serum OXT level was lower and leptin level was higher than the control group. In the obese group, frequencies of homozygous mutant (G/G) and heterozygous (A/G) genotypes for rs53576 polymorphism were higher than the control group. Homozygous mutant(G/G) and heterozygous (A/G) genotypes for rs53576 polymorphism were found to increase the risk of obesity compared to the wild type (A/A) genotype [OR = 6.05 and OR = 3.06; p < 0.001, respectively]. In patients with homozygous mutant (G/G) and heterozygous (A/G) genotype for rs53576 polymorphism, serum OXT levels were lower than the wild type (A/A) genotype. In the obese group, hyperphagia score was higher than the control group and correlated negatively with serum OXT level. This study revealed that low serum OXT level, which is associated with hyperphagia may be an underlying cause for obesity in adolescents. For rs53576 polymorphism of the OXTR gene, obesity risk is higher in patients with homozygous mutant(G/G) and heterozygous(A/G)genotypes.

Serum Oxytocin Levels in Patients with Ankylosing Spondylitis and Non-Radiographic Axial Spondyloarthritis and their Association with Disease Activity

ABSTRACT Objectives Spondyloarthritis refers to a group of chronic inflammatory diseases that particularly involve the sacroiliac joints and spine but may also have an influence on extra-articular involvement in some patients. Oxytocin is a peptide hormone released from the hypothalamus and stored in the pituitary gland. It is known to have anti-inflammatory effects. The aim of this study was to investigate the serum levels of oxytocin and their potential association with disease activity and spinal mobility in patients with ankylosing spondylitis (AS) and non-radiographic axial spondyloarthritis (nrAxSpA). Material and Methods Seventy-one patients with nrAxSpA, 38 patients with AS and 67 healthy control subjects were included in this study. Disease activity was assessed by the Bath Ankylosing Spondylitis Disease Activity Index, and spinal mobility by the Bath Ankylosing Spondylitis Metrologic Index. Laboratory examinations included complete blood count, ESR, CRP and oxytocin tests. Results There was no significant difference in serum levels of oxytocin among the 3 groups (p=0.973). However, serum levels of oxytocin correlated negatively with both ESR (r=− 0.359, p=0.027), CRP (r=− 0.316, p=0.056) and BASDAI scores (r=− 0,448, p=0.005) in patients with AS. On the other hand, serum levels of oxytocin had a negative correlation only with ESR in patients with nrAxSpA (r=− 0.321 p=0.009).Conclusion This study lays the foundation for further studies that may aim to investigate how addition of oxytocin to the treatment regimen impacts on disease activity in patients with AS who exhibit particularly low levels of oxytocin during the active disease period.

Maternal blood and amnionic oxytocin receptor gene expression and serum oxytocin levels in preterm birth: a case-control study

BACKGROUND: The oxytocin (OXT)-oxytocin receptor (OXTR) system provides promising candidate gene for studies of genetic contributions to prematurity. OBJECTIVE: Quantification and comparison of oxytocin receptor (OXTR) gene expression and serum OXT levels in the blood and amnion of women delivering preterm and evaluation of the correlation between OXTR gene expression in blood and amnion with serum OXT levels in them. METHODS: 70 pregnant women in spontaneous labor delivering vaginally preterm i.e < 37 weeks and equal number of matched controls delivering spontaneously at term (37-42 weeks) were recruited. Maternal serum OXT levels taken in active stage of labor (i.e 4 cm cervical dilatation) were quantified by ELISA. Gene expression studies in the maternal blood and amnion were done by using real time quantitative polymerase chain reaction (RT-qPCR). RESULTS: The mean serum OXT level in PTL was 48.56 +- 6.97 pg/ml; significantly higher than in controls (43.00 +- 3.96 pg/ml), p<0.001. OXTR gene expression both in maternal blood (2.5 times) and amnion (3.5 times) were significantly higher in PTL. A significant positive correlation was observed between serum OXT levels and OXTR gene expression in amnion (r = -0.190, p = 0.025). CONCLUSIONS: The serum OXT levels and OXTR gene expression in amnion surge significantly in active phase of PTL. Thus, amnion probably links OXT-PTGs autocrine paracrine circuit to facilitate PTL. Future studies are needed to devise better OXTR receptor antagonists preferably acting on amnionic OXTRs to prevent PTL. KEYWORDS: Preterm birth, Preterm labor, Oxytocin, Oxytocin receptor, Placenta, Amnion

Personality traits and its relation to craving and serum oxytocin among male patients with opioid dependence

Background As craving is one of the main problems that affect substance users and their progress during treatment, it was important to investigate personality traits that affect it. Although oxytocin (OT) system is regarded as being of relevance for social interaction, very few studies have investigated the relationship between OT and personality traits in clinical psychiatric populations.Objectives The aim of the work is to assess the personality traits among patients with active opioid dependence in comparison with abstinent patients and healthy controls and to assess the relation of personality traits with the degree of craving and serum OT level.Patients and methods A consecutive sample of 30 opiate-dependent patients who fully meet the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) criteria for opiate dependence and 30 patients fulfilling the DSM-V criteria of opiate dependence with at least 6 months of abstinence were assessed regarding personality traits, serum craving levels, and OT levels using Personality Inventory for DSM-brief form, brief substance craving scale, and immunoassay kit, correspondingly. They were compared with each other and with a sample of 30 healthy controls matching both groups.Results Total personality dysfunction scores were statistically significantly higher in the patient group than the control group (P<0.001) and the abstinent group (P<0.05). There was no statistically significant difference between the abstinent group and the control group. A positive correlation was found between craving and total personality dysfunction (P<0.001) as well as each of the five traits [negative affect (P<0.05), detachment (P<0.001), antagonism (P<0.05), disinhibition (P<0.001), and psychoticism (P<0.05)]. Craving levels showed a statistically significant difference between the patient group and the abstinent group (P<0.001). There was a statistically significant difference between the patient group and the control group in serum OT levels (P<0.05). The correlation between personality dysfunction and serum OT level in the patient group was not significant.Conclusion The interaction between personality traits, craving, and serum OT levels should be considered when dealing with opiate-dependent patients as they affect and are affected by opiate dependence. Further studies regarding how to implement this during the patient’s treatment should be considered.

Serum Oxytocin Level Among Male Patients With Opioid Dependence and Its Relation to Craving

Introduction: Oxytocin (OT), a known hormone and neurotransmitter, has been lately known to be involved in the drug addiction cycle especially during developing tolerance, in relation to craving and during withdrawal. Objectives: The aim was to assess serum OT level in patients with active opiate dependency in comparison with abstinent patients and healthy controls, and its relation with craving among patients and abstinent patients. Materials and Methods: A consecutive sample of 30 opiate-dependent patients who fully meet the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria for opiate dependence, in addition to 30 patients fulfilling DSM-5 criteria of opiate dependence with at least 6 months of abstinence were assessed regarding serum OT levels, craving levels using immunoassay kit and brief substance craving scale, respectively. They were compared with each other and with a sample of 30 healthy controls matching both groups. Results: There was a statistically significant difference between the patient and the control groups in serum OT levels (P&lt;0.05) but not between the other 2 groups, that is, patient versus abstinent and abstinent versus controls. Craving levels showed a statistically significant difference between the patient and the abstinent groups (P&lt;0.001). A negative correlation was found between OT level and craving in the abstinent group (P&lt;0.05). Conclusions: The interaction between serum OT levels and craving should be considered when dealing with opiate-dependent patients as they affect and are affected by opiate dependence. Further studies regarding how to implement this during patients treatment should be considered.

The combined effects of probiotics and restricted calorie diet on the anthropometric indices, eating behavior, and hormone levels of obese women with food addiction: a randomized clinical trial

ABSTRACT Background and aim Food addiction (FA) is an important contributor to obesity. Alterations in gut microbiota (GM) diversity and composition have also been proposed to play a pivotal role in obesity pathogenesis. This trial aimed to assess the effects of probiotic supplementation on the anthropometric indices, eating behavior, and hormone levels of obese women with FA Methods This randomized, double-blind, placebo-controlled clinical trial was conducted among obese women with FA. Participants (n = 62) received a restricted calorie diet (RCD) plus either probiotic, or placebo for 12 weeks. Anthropometric measurements, biochemical markers, eating behavior and appetite were assessed during the study period. Results Probiotics administration significantly reduced weight, body mass index (BMI), waist circumference (WC), waist to hip ratio (WHR), body fat percentage (BFP), and trunk fat percentage (TFP) compared to the placebo group (p < 0.001). Also, a significant improvement was observed in eating behavior in the probiotic group compared to the placebo group (p < 0.001).Serum levels of oxytocin increased and NPY decreased significantly in the probiotic group compared to the placebo group (p = 0.02, p = 0.002, respectively). Moreover, leptin level significantly decreased in the probiotic group compared to the baseline values (p < 0.001), while probiotics did not cause a greater significant reduction in leptin level, compared to the placebo group. Conclusion Multi-probiotic supplementation may have beneficial effects on anthropometric indices, eating behavior, and some appetite-regulating hormones in obese women with FA. Trial registration: Iranian Registry of Clinical Trials identifier: IRCT20131228015968N5.

Polymorphism of the Oxytocin Receptor (OXTR) Gene Affects the Circulating Oxytocin Receptor Levels in Late-Term Pregnancy in a Turkish Population

Introduction: Postterm and late-term pregnancies still remain a serious health problem, and underlying exact mechanisms are not fully elucidated. These mechanisms are influenced by many factors. Objective: The aim of this study was to investigate the relationship between plasma oxytocin and oxytocin receptor levels and oxytocin receptor polymorphisms in term and late-term pregnant women. Methods: Sixty-eight singleton pregnant women with late-term pregnancy and 83 singleton pregnant women with term parturition were included in this study. A comparison was performed between pregnancies and neonates born at term (37 0/7 and 41 6/7 weeks’ gestation). Plasma oxytocin, oxytocin receptor, estradiol, and progesterone levels were measured by using enzyme-linked immunosorbent assay kits. TaqMan® SNP Genotyping Assays and qPCR ProbesMaster were used to investigate the polymorphisms of rs237911, rs2228485, rs53576, and rs2254298. Results: There was not any difference in gene distributions of 4 common single-nucleotide polymorphisms of oxytocin receptor of rs237911, rs2228485, rs53576, and rs2254298 between subjects in late-term and term pregnancy groups. With rs53576 of the GG genotype, serum oxytocin levels were 21.50 ± 10.69 (ng/L) in the late-term group and 62.71 ± 18.01 (ng/L) in the term group (p = 0.049). Oxytocin receptor levels in the late-term and term pregnancy groups of the GG genotype were 17.92 ± 8.15 (pg/mL) and 45.77 ± 11.66 (pg/mL), respectively (p = 0.046). Conclusion: Our findings suggest that the rs53576 oxytocin receptor single-nucleotide polymorphism is associated with late-term pregnancy through acting by direct modulation of oxytocin and oxytocin receptor levels.

Oxytocin and elderly MRI-based hippocampus and amygdala volume: a 7-year follow-up study

Oxytocin is deeply involved in human relations. In recent years, it is becoming clear that oxytocin is also involved in social cognition and social behaviour. Oxytocin receptors are also thought to be present in the hippocampus and amygdala, and the relationship between oxytocin and the structure and function of the hippocampus and amygdala has been reported. However, a few studies have investigated oxytocin and its relationship to hippocampus and amygdala volume in elderly people. The aim of this study is to investigate the association between serum oxytocin levels and hippocampus and amygdala volume in elderly people. The survey was conducted twice in Kurokawa-cho, Imari, Saga Prefecture, Japan, among people aged 65 years and older. We collected data from 596 residents. Serum oxytocin level measurements, brain MRI, Mini–Mental State Examination and Clinical Dementia Rating were performed in Time 1 (2009–11). Follow-up brain MRI, Mini–Mental State Examination and Clinical Dementia Rating were performed in Time 2 (2016–17). The interval between Time 1 and Time 2 was about 7 years. Fifty-eight participants (14 men, mean age 72.36 ± 3.41 years, oxytocin 0.042 ± 0.052 ng/ml; 44 women, mean age 73.07 ± 4.38 years, oxytocin 0.123 ± 0.130 ng/ml) completed this study. We analysed the correlation between serum oxytocin levels (Time 1) and brain volume (Time 1, Time 2 and Times 1–2 difference) using voxel-based morphometry implemented with Statistical Parametric Mapping. Analysis at the cluster level (family-wise error; P < 0.05) showed a positive correlation between serum oxytocin levels (Time 1) and brain volume of the region containing the left hippocampus and amygdala (Time 2). This result suggests that oxytocin in people aged 65 years and older may be associated with aging-related changes in hippocampus and amygdala volume.

Oxytocin in the dorsal raphe nucleus antagonizes the inhibition of maternal care induced by food deprivation

Lactation is indispensable for the pup's survival, but is considered a survival burden in dams under negative energy conditions. In the present study, we tested our hypothesis that oxytocin may facilitate energy investment to pups through behavioral control as well as milk ejection. Maternal care was observed in dams at 3 h but not 8 h after food deprivation. We investigated whether oxytocin in the dorsal raphe nucleus (DRN), which is involved in energy state-dependent regulation of maternal care, regulates maternal care. For this purpose, 2-pmol L368899, an oxytocin receptor antagonist, was injected into the DRN; after treatment, maternal care was inhibited in the dams with 3-h fasting, but not in the fed dams. In contrast, recovery of maternal care was observed in the dams with 8-h fasting who underwent 100-pmol oxytocin injection at the DRN. These results indicate that oxytocin in the DRN is required for displaying maternal behavior under fasting conditions, but not under fed conditions. Next, we investigated the site of oxytocin release. Presentation of pups decreased the oxytocin immunoreactivity at the paraventricular nucleus (PVN) of the hypothalamus in the 3-h-fasted dams, but not in the fed or 8-h-fasted dams. No change of the serum oxytocin level was observed. Few oxytocin-positive neurons projecting from the PVN to the DRN were detected through labeling with the retrograde tracer fluorogold. Oxytocin secreted at the PVN, which reaches the DRN, but not released as a hormone or neurotransmitter may mediate maternal care under food-restricted conditions.

Oxytocin Controls Chondrogenesis and Correlates with Osteoarthritis

This study investigated the relationship of oxytocin (OT) to chondrogenesis and osteoarthritis (OA). Human bone marrow and multipotent adipose-derived stem cells were cultured in vitro in the absence or presence of OT and assayed for mRNA transcript expression along with histological and immunohistochemical analyses. To study the effects of OT in OA in vivo, a rat model and a human cohort of 63 men and 19 women with hand OA and healthy controls, respectively, were used. The baseline circulating OT, interleukin-6, leptin, and oestradiol levels were measured, and hand X-ray examinations were performed for each subject. OT induced increased aggrecan, collagen (Col) X, and cartilage oligomeric matrix protein mRNA transcript levels in vitro, and the immunolabelling experiments revealed a normalization of Sox9 and Col II protein expression levels. No histological differences in lesion severity were observed between rat OA groups. In the clinical study, a multivariate analysis adjusted for age, body mass index, and leptin levels revealed a significant association between OA and lower levels of OT (odds ratio = 0.77; p = 0.012). Serum OT levels are reduced in patients with hand OA, and OT showed a stimulatory effect on chondrogenesis. Thus, OT may contribute to the pathophysiology of OA.

Regular moderate exercise alleviates gastric oxidative damage in rats via the contribution of oxytocin receptors.

A moderate level of exercise has beneficial effects for the prevention of gastric ulcers. Although regular aerobic exercise was shown to elevate serum oxytocin levels and exogenously administered oxytocin exerts an anti-ulcer activity, the role of endogenous oxytocin in the gastroprotective effects of exercise has not yet been elucidated. We showed that increased anxiety and oxidative gastric damage induced by gastric ulcers were reversed in pre-exercised rats, while reduced hypothalamic oxytocin expression and decreased myenteric oxytocin receptor expression due to gastric ulcers were abolished by exercise. We also reported that the blockade of oxytocin receptors exaggerated gastric damage in exercised rats with ulcers. Our data establish that endogenous oxytocin is the key mediator in the beneficial effects of regular physical activity in alleviating gastric injury. Exercise increases serum oxytocin levels and exogenous oxytocin exerts an anti-ulcer activity; but the role of oxytocin in the protective effects of exercise against gastric ulcers has not yet been evaluated. This study was designed to investigate the impact of regular swimming exercise on oxidative gastric injury, and the role of oxytocin receptor activity in the anxiolytic and anti-inflammatory actions of exercise. Adult Wistar albino rats of both sexes performed swimming exercise (30min/day, 5days) or stayed sedentary. At the end of the 6-week exercise/sedentary protocol, rats were injected intraperitoneally with atosiban (0.1mg/kg/day) or saline for 4days. On the 5th day, under anaesthesia, acetic acid (ulcer) or saline (sham) was applied onto the gastric serosa and the treatments were continued. On the 9th day, anxiety levels were determined; gastric blood flow was measured, and blood, gastric and brain tissues were obtained. Induction of ulcers in sedentary rats increased anxiety and serum corticosterone levels; but reduced gastric blood flow and resulted in apoptosis and oxidative gastric damage with increased cytokine expressions. However, when ulcers were induced in pre-exercised rats, behavioural and biochemical alterations due to gastric damage were reversed. The inhibition of oxytocin receptors by atosiban exaggerated pro-inflammatory cytokine expressions and gastric lipid peroxidation in the stomachs of exercised rats with ulcers. When rats had regularly exercised prior to ulcer induction, reductions in the immunolabelling of hypothalamic oxytocin and myenteric oxytocin receptors were abolished, suggesting that exercise-induced alleviation of gastric injury may involve the reversal of down-regulated oxytocinergic activity.

Serum Oxytocin Levels and Logical Memory in Older People in Rural Japan.

The present study aimed to investigate the relationship between serum oxytocin (OT) and logical memory among older people in rural Japan. This was a cross-sectional study using a survey conducted from October 2009 through March 2011. Most of the study was conducted as part of a national prevalence survey of dementia in Japan. The final sample comprised 385 community-dwelling people aged 65 years or older living in rural Japan. The mean age and standard deviation were 75.7 ± 6.76 years (144 men, mean age 75.0 ± 6.48 years; 241 women, mean age 76.2 ± 6.91 years). The participants underwent screening examinations for a prevalence survey of dementia. The screening examinations were the Mini-Mental State Examination, Clinical Dementia Rating, and "logical memory A" from the Wechsler Memory Scale-Revised (WMSR). We used the WMSR Logical Memory II delayed recall score (LM II-DR) to assess logical memory. Levels of serum OT were obtained using the enzyme immunoassay method. Serum OT levels were significantly higher among women than men. The present study revealed that serum OT levels were positively associated with LM II-DR in older women living in rural Japan in multiple linear regression analyses. The present results suggested a positive correlation between OT and logical memory in older women living in rural Japan.