Oxytocin and social functioning

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

BACKGROUND

Postweaning 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.

METHODS

Both 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.

RESULTS

The 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.

CONCLUSION

Our 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.

Comparing the effects of infant maternal and sibling separation on adolescent behavior in rats (Rattus norvegicus)

Maternal separation in early life has been observed to have lasting, detrimental effects that impair personal and social development and can persist into adulthood. Maternal separation during infancy can be most detrimental during adolescence, leading to long-term adverse effects on development and social behavior. This research study compared the effects of sibling and maternal separation in infancy on anxiety, sociability, or memory later in adolescence (postnatal day, PND, 50-58) in male and female Long-Evans Rats (Rattus norvegicus). Rat pups were semi-randomly assigned into eight conditions for daily isolation (PND 1-14). The groups were separated by the duration of isolation between 15 minutes (control group) or 180 minutes (experimental group) and the sex of the rat. They were also separated by comfort conditions with the dam present in an adjoining cage versus not present and siblings present or not present during isolation. The result was a 2 (15-min vs. 180-min) x 2 (dam vs. no dam) x 2 (single vs. grouped) x 2 (male vs. female) design. Once pups had reached adolescence (PND 50), researchers tested for differences in anxiety, activity, and social behavior using elevated plus-maze, open field habituation, a three-chamber social interaction, and a social discrimination task. Results indicate that longer isolation was more stressful and caused lower body weight. The female rats showed more anxious behavior in the open field but only if they were in the shorter isolation group. Social interaction showed that the rats isolated with the dam had different effects of isolation. In males, shorter isolation with the dam increased sociability but decreased sociability in females. These complicated findings may be due to the effects of inoculation, which describes how moderate stress combined with comfort may produce adaptation or immunity to stress and affect males and females differently.

Supportive care of female hormones in brain health: what and how?

Female hormones, functioning as neuroactive steroids, are utilized beyond menopausal hormone therapy. The rapid onset of allopregnanolone analogs, such as brexanolone and zuranolone, in treating depression, and the effectiveness of megestrol acetate in addressing appetite and weight gain, prompted the Food and Drug Administration to authorize the use of progesterone for treating postpartum depression and cancer-related cachexia. Progesterone has also been found to alleviate neuropathic pain in animal studies. These off-label applications offer a promising option for patients with advanced cancer who often experience various mood disorders such as depression, persistent pain, social isolation, and physical complications like cachexia. These patients have shown low tolerance to opioids and mood-regulating medications. However, the potential risks and uncertainties associated with hormone therapy treatment modalities can be daunting for both patients and medical professionals. This review aims to offer a comprehensive understanding of the non-reproductive functions and mechanisms of female hormones in brain health.

Exploring the influence of stress on aggressive behavior and sexual function: Role of neuromodulator pathways and epigenetics

Stress is a complex and multifaceted phenomenon that can significantly influence both aggressive behavior and sexual function. This review explores the intricate relationship between stress, neuromodulator pathways, and epigenetics, shedding light on the various mechanisms that underlie these connections. While the role of stress in both aggression and sexual behavior is well-documented, the mechanisms through which it exerts its effects are multifarious and not yet fully understood. The review begins by delving into the potential influence of stress on the Hypothalamic-Pituitary-Adrenal (HPA) axis, glucocorticoids, and the neuromodulators involved in the stress response. The intricate interplay between these systems, which encompasses the regulation of stress hormones, is central to understanding how stress may contribute to aggressive behavior and sexual function. Several neuromodulator pathways are implicated in both stress and behavior regulation. We explore the roles of norepinephrine, serotonin, oxytocin, and androgens in mediating the effects of stress on aggression and sexual function. It is important to distinguish between general sexual behavior, sexual motivation, and the distinct category of "sexual aggression" as separate constructs, each necessitating specific examination. Additionally, epigenetic mechanisms emerge as crucial factors that link stress to changes in gene expression patterns and, subsequently, to behavior. We then discuss how epigenetic modifications can occur in response to stress exposure, altering the regulation of genes associated with stress, aggression, and sexual function. While numerous studies support the association between epigenetic changes and stress-induced behavior, more research is necessary to establish definitive links. Throughout this exploration, it becomes increasingly clear that the relationship between stress, neuromodulator pathways, and epigenetics is intricate and multifaceted. The review emphasizes the need for further research, particularly in the context of human studies, to provide clinical significance and to validate the existing findings from animal models. By better understanding how stress influences aggressive behavior and sexual function through neuromodulator pathways and epigenetic modifications, this research aims to contribute to the development of innovative protocols of precision medicine and more effective strategies for managing the consequences of stress on human behavior. This may also pave way for further research into risk factors and underlying mechanisms that may associate stress with sexual aggression which finds application not only in neuroscience, but also law, ethics, and the humanities in general.

Psychedelic Therapy: A Primer for Primary Care Clinicians-3,4-Methylenedioxy-methamphetamine (MDMA)

BACKGROUND

After becoming notorious for its use as a party drug in the 1980s, 3,4-methylenedioxy-methampetamine (MDMA), also known by its street names "molly" and "ecstasy," has emerged as a powerful treatment for post-traumatic stress disorder (PTSD).

AREAS OF UNCERTAINTY

There are extensive data about the risk profile of MDMA. However, the literature is significantly biased. Animal models demonstrating neurotoxic or adverse effects used doses well beyond the range that would be expected in humans (up to 40 mg/kg in rats compared with roughly 1-2 mg/kg in humans). Furthermore, human samples often comprise recreational users who took other substances in addition to MDMA, in uncontrolled settings.

THERAPEUTIC ADVANCES

Phase III clinical trials led by the Multidisciplinary Association for Psychedelic Studies (MAPS) have shown that MDMA-assisted psychotherapy has an effect size of d = 0.7-0.91, up to 2-3 times higher than the effect sizes of existing antidepressant treatments. 67%-71% of patients who undergo MDMA-assisted psychotherapy no longer meet the diagnostic criteria for PTSD within 18 weeks. We also describe other promising applications of MDMA-assisted psychotherapy for treating alcohol use disorder, social anxiety, and other psychiatric conditions.

LIMITATIONS

Thus far, almost all clinical trials on MDMA have been sponsored by a single organization, MAPS. More work is needed to determine whether MDMA-assisted therapy is more effective than existing nonpharmacological treatments such as cognitive behavioral therapy.

CONCLUSIONS

Phase III trials suggest that MDMA is superior to antidepressant medications for treating PTSD. Now that MAPS has officially requested the Food and Drug Administration to approve MDMA as a treatment for PTSD, legal MDMA-assisted therapy may become available as soon as 2024.

Empirical challenges from the comparative and developmental literature to the Shared Intentionality Theory - a review of alternative data on recursive mind reading, prosociality, imitation and cumulative culture

Humans have an irresistible inclination to coordinate actions with others, leading to species-unique forms of cooperation. According to the highly influential Shared Intentionality Theory (SITh), human cooperation is made possible by shared intentionality (SI), typically defined as a suite of socio-cognitive and motivational traits for sharing psychological states with others, thereby enabling individuals to engage in joint action in the mutually aware pursuit of shared goals. SITh theorises that SI evolved as late as 400,000 years ago, when our ancestors (in particular, Homo heidelbergensis) turned to a kind of food procurement that obligatorily required joint coordinated action. SI is, thus, hypothesized to be absent in other extant species, including our closest genetic relatives, the nonhuman great apes ("apes"). According to SITh, ape psychology is exclusively driven by individualistic motivations, as opposed to human psychology which is uniquely driven by altruistic motivations. The evolutionary scenario proposed by SITh builds on a series of findings from socio-cognitive research with apes and human children, and on the assumption that abilities expressed early in human development are human universals, unlikely to have been shaped by socio-cultural influences. Drawing on the primatological and developmental literature, we provide a systematic - albeit selective - review of SITh-inconsistent findings concerning psychological and behavioural traits theorised to be constitutive of SI. The findings we review pertain to all three thematic clusters typically addressed in SITh: (i) recursive mind reading; (ii) prosociality; (iii) imitation and cumulative culture. We conclude that such alternative data undermine two core SITh claims: the late evolutionary emergence of SI and the radical divide between ape and human psychology. We also discuss several conceptual and methodological limitations that currently hamper reliable comparative research on SI, in particular those engendered by Western-centric biases in the social sciences, where an overreliance on Western samples has promoted the formulation of Western-centric conceptualisations, operationalisations and methodologies.

Endogenous oxytocin levels in children with autism: Associations with cortisol levels and oxytocin receptor gene methylation

Alterations in the brain's oxytocinergic system have been suggested to play an important role in the pathophysiology of autism spectrum disorder (ASD), but insights from pediatric populations are sparse. Here, salivary oxytocin was examined in the morning (AM) and afternoon (PM) in school-aged children with (n = 80) and without (n = 40) ASD (boys/girls 4/1), and also characterizations of DNA methylation (DNAm) of the oxytocin receptor gene (OXTR) were obtained. Further, cortisol levels were assessed to examine links between the oxytocinergic system and hypothalamic-pituitary-adrenal (HPA) axis signaling. Children with ASD displayed altered (diminished) oxytocin levels in the morning, but not in the afternoon, after a mildly stress-inducing social interaction session. Notably, in the control group, higher oxytocin levels at AM were associated with lower stress-induced cortisol at PM, likely reflective of a protective stress-regulatory mechanism for buffering HPA stress activity. In children with ASD, on the other hand, a significant rise in oxytocin levels from the morning to the afternoon was associated with a higher stress-induced cortisol release in the afternoon, likely reflective of a more reactive stress regulatory release of oxytocin for reactively coping with heightened HPA activity. Regarding epigenetic modifications, no overall pattern of OXTR hypo- or hypermethylation was evident in ASD. In control children, a notable association between OXTR methylation and levels of cortisol at PM was evident, likely indicative of a compensatory downregulation of OXTR methylation (higher oxytocin receptor expression) in children with heightened HPA axis activity. Together, these observations bear important insights into altered oxytocinergic signaling in ASD, which may aid in establishing relevant biomarkers for diagnostic and/or treatment evaluation purposes targeting the oxytocinergic system in ASD.

The evolved nest, oxytocin functioning, and prosocial development

Prosociality, orientation to attuned, empathic relationships, is built from the ground up, through supportive care in early life that fosters healthy neurobiological structures that shape behavior. Numerous social and environmental factors within early life have been identified as critical variables influencing child physiological and psychological outcomes indicating a growing need to synthesize which factors are the most influential. To address this gap, we examined the influence of early life experiences according to the evolved developmental niche or evolved nest and its influence on child neurobiological and sociomoral outcomes, specifically, the oxytocinergic system and prosociality, respectively. To-date, this is the first review to utilize the evolved nest framework as an investigatory lens to probe connections between early life experience and child neurobiological and sociomoral outcomes. The evolved nest is comprised of characteristics over 30 million years old and is organized to meet a child's basic needs as they mature. Converging evidence indicates that humanity's evolved nest meets the needs of a rapidly developing brain, optimizing normal development. The evolved nest for young children includes soothing perinatal experiences, breastfeeding, positive touch, responsive care, multiple allomothers, self-directed play, social embeddedness, and nature immersion. We examined what is known about the effects of each evolved nest component on oxytocinergic functioning, a critical neurobiological building block for pro-sociomorality. We also examined the effects of the evolved nest on prosociality generally. We reviewed empirical studies from human and animal research, meta-analyses and theoretical articles. The review suggests that evolved nest components influence oxytocinergic functioning in parents and children and help form the foundations for prosociality. Future research and policy should consider the importance of the first years of life in programming the neuroendocrine system that undergirds wellbeing and prosociality. Complex, interaction effects among evolved nest components as well as among physiological and sociomoral processes need to be studied. The most sensible framework for examining what builds and enhances prosociality may be the millions-year-old evolved nest.

Evaluation of the effectiveness of oxytocin and enalapril in the prevention of epidural fibrosis developed after laminectomy in rats

INTRODUCTION

Except for methylprednisolone, there is no current low-cost and low-side-effect drug/barrier method to prevent epidural fibrosis after spine surgery. However, the use of methylprednisolone has led to substantial controversy because of its serious side effects on wound healing. This study aimed to evaluate the effects of enalapril and oxytocin on preventing the development of epidural fibrosis in a rat laminectomy model.

MATERIALS

Under sedation anesthesia, T9, T10, and T11 laminectomy was performed on 24 Wistar Albino male rats. The animals were then separated into four groups; Sham group (only laminectomy was performed; n = 6), MP group (laminectomy was performed and 10 mg/kg/day methylprednisolone was administered intraperitoneally (ip) for 14 days; n = 6), ELP group (laminectomy was performed and 0.75 mg/kg/day enalapril was administered ip for 14 days; n = 6), OXT group (laminectomy was performed and 160 µg/kg/day oxytocin was administered ip for 14 days; n = 6). Four weeks after the laminectomy, all the rats were euthanised, and the spines were removed for histopathological, immunohistochemical, and biochemical examinations.

RESULTS

Histopathological examinations revealed that the degree of epidural fibrosis (X²=14.316, p = 0.003), collagen density (X²=16.050, p = 0.001), and fibroblast density (X²=17.500, p = 0.001) was higher in the Sham group and lower in the MP, ELP, and OXT groups. Immunohistochemical examinations showed that collagen type 1 immunoreactivity was higher in the Sham group and lower in the MP, ELP, and OXT groups (F = 54.950, p < 0.001). The highest level of α-smooth muscle actin immunoreactivity was seen in the Sham and OXT groups, and the lowest was in the MP and ELP groups (F = 33.357, p < 0.001). Biochemical analysis revealed that tissue levels of TNF-α, TGF-β, IL-6, CTGF, caspase-3, p-AMPK, pmTOR, and mTOR/pmTOR were higher in the Sham group and lower in MP, ELP, and OXT groups (p < 0.05). The GSH/GSSG levels were lower in the Sham group and higher in the other three groups (X²=21.600, p < 0.001).

CONCLUSION

The study results showed that enalapril and oxytocin, which are known to have anti-inflammatory, antioxidant, anti-apoptotic, and autophagy-related regenerative properties, could reduce the development of epidural fibrosis after laminectomy in rats.

Oxytocin and eating disorders: Knowledge gaps and future directions

Eating disorders continue to be a major public health issue and important cause of morbidity and premature mortality, particularly for young people. Yet in a concerning dialectic, this occurs in the context of an epidemic of obesity which, with its medical complications, constitutes another vexing public health challenge. While it is not an eating disorder per se obesity is often comorbid with eating disorders. Effective treatment for both eating disorders and obesity has proven to be elusive and in the search for novel therapeutic interventions, the prosocial, anxiolytic, brain plasticity and metabolic effects of oxytocin (OT) have been examined from this perspective. The availability of intranasal oxytocin (IN-OT) has led to a number of interventional treatment studies in anorexia nervosa (AN), bulimia nervosa (BN), binge eating disorder (BED), their atypical and subclinical forms and in medical and psychiatric conditions co-occurring or comorbid with these, obesity with BED would be included here. The aim of this mini review is to collate recent findings on OT as a novel therapeutic intervention in eating disorders and obesity and to identify and address some of the knowledge gaps in the use of IN-OT. The wider clinical perspective utilised here might better address some of the gaps and identify future directions of research. Clearly much remains to be done for OT to fulfil its therapeutic promise in eating disorders. OT might yet be of therapeutic promise and will be appreciated where treatment advances have been hard to come by and prevention challenging for these disorders.

Effects of mesotocin manipulation on the behavior of male and female common waxbills

The oxytocin family of neuropeptides is implicated in the regulation of sociality across vertebrates. Non-mammalian homologs of oxytocin, such as isotocin in fish and mesotocin in amphibians, reptiles and birds, all play crucial roles modulating social and reproductive behavior. In this study, we exogenously manipulated the mesotocinergic system in a highly social bird, the common waxbill Estrild astrild, and tested the effects on affiliative and aggressive behavior by performing tests of competition over food. Birds treated with mesotocin showed a sedative state, decreasing almost all the behaviors we studied (movement, feeding, allopreening), while birds treated with an oxytocin antagonist showed a decrease only in social behaviors (aggressions and allopreening). We also found two sex-specific effects: mesotocin reduced allopreening more in males than females, and the oxytocin antagonist reduced aggressiveness only in females. Our results suggest sex-specific effects in the modulation of affiliative and aggressive behaviors via mesotocinergic pathways.

Novel Risk Variants in the Oxytocin Receptor Gene (OXTR) Possibly Linked to and Associated with Familial Type 2 Diabetes

The oxytocin system is well-known for its role in social bonding and reproduction. Recently, the oxytocin system was found to play other metabolic roles such as regulation of food intake, peripheral glucose uptake, and insulin sensitivity. Variants in OXTR gene have been associated with overeating, increased cardiovascular risk, and type 2 diabetes (T2D). We tested 20 microarray-derived single nucleotide polymorphisms in the OXTR gene in 212 Italian families with rich family history for T2D and found four novel and one previously reported variant suggestively significant for linkage and association with the risk of T2D. Our study has shed some light into the genetics of susceptibility to T2D at least in Italian families.

Plasma neuropeptide levels in patients with schizophrenia, bipolar disorder, or major depressive disorder and healthy controls: A multiplex immunoassay study

AIM

We aimed to compare neuropeptide levels between patients with major psychiatric disorders and healthy controls and examine their association with symptoms and cognitive function.

METHODS

The participants were 149 patients with schizophrenia, 115 patients with bipolar disorder (BD), 186 unremitted patients with major depressive disorder (MDD), and 350 healthy controls. Psychiatric (schizophrenic, manic, and depressive) symptoms, sleep state, and cognitive (premorbid intelligence quotient, general cognitive, and memory) functions were evaluated. A multiplex immunoassay kit was used to measure cerebrospinal fluid (CSF) and plasma α-melanocyte-stimulating hormone (MSH), β-endorphin, neurotensin, oxytocin, and substance P levels.

RESULTS

The verification assay revealed that CSF α-MSH, β-endorphin, neurotensin, oxytocin, and substance P levels were too low to be reliably measured, while plasma α-MSH, β-endorphin, neurotensin, oxytocin, and substance P levels could be successfully measured. Plasma α-MSH, β-endorphin, neurotensin, oxytocin, and substance P levels were not significantly different between patients with schizophrenia, BD, or MDD and healthy controls. Plasma α-MSH, β-endorphin, neurotensin, oxytocin, and substance P levels were not significantly correlated with psychiatric symptom scores in patients with schizophrenia, BD, or MDD and cognitive function scores in patients or healthy controls.

CONCLUSION

Our data suggest that plasma neuropeptide levels do not elucidate the involvement of neuropeptides in the pathology of schizophrenia, BD, or MDD.

The influence of manual semen collection in male trained dogs (Canis familiaris), in the presence or absence of a female in estrus, on the concentrations of cortisol, oxytocin, prolactin and testosterone

Sex pheromones are chemical substances secreted into the environment that affect the physiology and behavior of recipients. Females use these compounds during oestrus to attract males, which leads to attempts of mating. This study evaluates the influence of manual semen collection in male dogs, in the presence or absence of a female in estrus, on the blood concentrations of cortisol (CRT), oxytocin (OXT), prolactin (PRL) and testosterone (T), as hormones involved both in the physiology of reproduction and stress. Ten male dogs were used in Experiment 1 to measure the serum and plasma concentrations of the aforementioned hormones in the absence of semen collection. Subsequently in the same animals, the concentrations of these hormones were evaluated before and after semen collection in the presence (Exp. 2) or in absence of a female in estrus (Exp. 3). No significant changes in hormone concentration caused by the semen collection were found, either with, or without the presence of female in estrus. Obtained results suggest that the procedure of manual semen collection in dogs, probably due to its passive character, does not stimulate endocrine glands to secrete hormones, and the process of ejaculation is probably controlled by neural pathway. The lack of effect of semiochemical stimulation to the CRT, PRL, OXT and T level, could be caused by a short contact with female during semen collection. Further studies on involvement of the hormones during the process of natural mating, especially preceded by long courtships, similar to that observed under natural conditions, should shed a light on the physiology of mating and the connection between the endocrine system and semiochemical stimulation in dogs.

Linking Social Cognition, Parvalbumin Interneurons, and Oxytocin in Alzheimer's Disease: An Update

Finding a cure for Alzheimer's disease (AD) has been notoriously challenging for many decades. Therefore, the current focus is mainly on prevention, timely intervention, and slowing the progression in the earliest stages. A better understanding of underlying mechanisms at the beginning of the disease could aid in early diagnosis and intervention, including alleviating symptoms or slowing down the disease progression. Changes in social cognition and progressive parvalbumin (PV) interneuron dysfunction are among the earliest observable effects of AD. Various AD rodent models mimic these early alterations, but only a narrow field of study has considered their mutual relationship. In this review, we discuss current knowledge about PV interneuron dysfunction in AD and emphasize their importance in social cognition and memory. Next, we propose oxytocin (OT) as a potent modulator of PV interneurons and as a promising treatment for managing some of the early symptoms. We further discuss the supporting evidence on its beneficial effects on AD-related pathology. Clinical trials have employed the use of OT in various neuropsychiatric diseases with promising results, but little is known about its prospective impacts on AD. On the other hand, the modulatory effects of OT in specific structures and local circuits need to be clarified in future studies. This review highlights the connection between PV interneurons and social cognition impairment in the early stages of AD and considers OT as a promising therapeutic agent for addressing these early deficits.

Involvement of oxytocin receptor deficiency in psychiatric disorders and behavioral abnormalities

Oxytocin and its target receptor (oxytocin receptor, OXTR) exert important roles in the regulation of complex social behaviors and cognition. The oxytocin/OXTR system in the brain could activate and transduce several intracellular signaling pathways to affect neuronal functions or responses and then mediate physiological activities. The persistence and outcome of the oxytocin activity in the brain are closely linked to the regulation, state, and expression of OXTR. Increasing evidence has shown that genetic variations, epigenetic modification states, and the expression of OXTR have been implicated in psychiatric disorders characterized by social deficits, especially in autism. Among these variations and modifications, OXTR gene methylation and polymorphism have been found in many patients with psychiatric disorders and have been considered to be associated with those psychiatric disorders, behavioral abnormalities, and individual differences in response to social stimuli or others. Given the significance of these new findings, in this review, we focus on the progress of OXTR's functions, intrinsic mechanisms, and its correlations with psychiatric disorders or deficits in behaviors. We hope that this review can provide a deep insight into the study of OXTR-involved psychiatric disorders.

The regulatory effects of lactic acid on neuropsychiatric disorders

Lactic acid is produced mainly in astrocytes in the brain and serves as a substance that supplies energy to neurons. In recent years, numerous studies identified the potential effects of lactic acid on the central nervous system and demonstrated its role in regulating brain function as an energy metabolism substrate or cellular signaling molecule. Both deficiency and accumulation of lactic acid cause neurological dysfunction, which further lead to the development of neuropsychiatric disorders, such as Major depressive disorder, Schizophrenia, Alzheimer's disease, and Multiple sclerosis. Although an association between lactic acid and neuropsychiatric disorders was reported in previous research, the underlying pathogenic mechanisms remain unclear. Therefore, an in-depth understanding of the molecular mechanisms by which lactic acid regulates brain function is of significance for the early diagnosis and prevention of neuropsychiatric disorders. In this review, we summarize evidence that is focused on the potential mechanisms of lactic acid as a signaling molecule involved in the pathogenesis of neuropsychiatric disorders and propose a new mechanism by which lactic acid regulates brain function and disease through the microbiota-gut-brain axis to offer new insight into the prevention and treatment of neuropsychiatric diseases.

Estrogen can abolish oxytocin-induced spinal anti-hyperalgesia

Our previous study verified a sex difference of anti-hyperalgesia in rats and anti-allodynia in mice induced by intrathecal oxytocin (OT). In the model of intraplantar carrageenan-induced inflammatory hyperalgesia, intrathecal OT injection induced a substantial anti-hyperalgesia in male rats even at a low dose (0.125 nmol). In contrast, female rats only responded to an extremely high dose (1.25 nmol). This sex difference concurs with a lower expression of OT receptors and higher expression of insulin-regulated aminopeptidase (IRAP; OT degrading enzyme) in the spinal cords of female rats. In this study, we further determined the role of female hormones in this sex difference by using ovariectomized rats. Our results show that a low dose of intrathecal OT caused a significant anti-hyperalgesia effect in ovariectomized female rats, similar to that seen in male rats. Ovariectomy did not cause any change of paw edema except at the late stage of convalescence when compared with the sham-operated group. Ovariectomy-induced faster recovery from edema but did not affect the severity of hyperalgesia. Moreover, there was a similar amount of IRAP expression in ovariectomized and sham rats. When estradiol (E2) was given together with OT, OT-induced anti-hyperalgesia was abolished at the developmental stage of hyperalgesia in ovariectomized rats. These results show an inhibitory role of female hormones generated from ovaries (mainly estrogen) in the sex difference of anti-hyperalgesia induced by OT. This study suggests the feasibility of a novel OT-based remedy to treat hyperalgesia in men and in menopausal women no receiving hormonal supplements.

Neuroendocrine underpinning of social recognition in males and females

Social recognition is an essential skill for the expression of appropriate behaviors towards conspecifics in most social species. Several studies point to oxytocin (OT) and arginine vasopressin (AVP) as key mediators of social recognition in males and females. However, sex differences in social cognitive behaviors highlight an important interplay between OT, AVP and the sex steroids. Estrogens facilitate social recognition by regulating OT action in the hypothalamus and that of OT receptor in the medial amygdala. The role of OT in these brain regions appears to be essential for social recognition in both males and females. Conversely, social recognition in male rats and mice is more dependent on AVP release in the lateral septum than in females. The AVP system comprises a series of highly sexually dimorphic brain nuclei, including the bed nucleus of the stria terminalis, the amygdala and the lateral septum. Various studies suggest that testosterone and its metabolites, including estradiol, influence social recognition in males by modulating the activity of the AVP at V1a receptor. Intriguingly, both estrogens and androgens can affect social recognition very rapidly, through non-genomic mechanisms. In addition, the androgen metabolites, namely 3α-diol and 3β-diol, may also have an impact on social behaviors either by interacting with the estrogen receptors or through other mechanisms. Overall, the regulation of OT and AVP by sex steroids fine tunes social recognition and the behaviors that depend upon it (e.g., social bond, hierarchical organization, aggression) in a sex-dependent manner. Elucidating the sex-dependent interaction between sex steroids and neuroendocrine systems is essential for understanding sex differences in the normal and abnormal expression of social behaviors.

Oxytocin and Oxytocin Receptor Gene Regulation in Williams Syndrome: A Systematic Review

Williams Syndrome (WS) is a rare genetic multisystem disorder that occurs because of a deletion of approximately 25 genes in the 7q11.23 chromosome region. This causes dysmorphic facial appearances, multiple congenital cardiovascular defects, delayed motor skills, and abnormalities in connective tissues and the endocrine system. The patients are mostly diagnosed with mild to moderate mental retardation, however, they have a hyper sociable, socially dis-inhibited, and outgoing personality, empathetic behavior, and are highly talkative. Oxytocin (OT), a neuropeptide synthesized at the hypothalamus, plays an important role in cognition and behavior, and is thought to be affecting WS patients' attitudes at its different amounts. Oxytocin receptor gene (OXTR), on chromosome 3p25.3, is considered regulating oxytocin receptors, via which OT exerts its effect. WS is a crucial disorder to understand gene, hormone, brain, and behavior associations in terms of sociality and neuropsychiatric conditions. Alterations to the WS gene region offer an opportunity to deepen our understandings of autism spectrum disorder, schizophrenia, anxiety, or depression. We aim to systematically present the data available of OT/OXTR regulation and expression, and the evidence for whether these mechanisms are dysregulated in WS. These results are important, as they predict strong epigenetic control over social behavior by methylation, single nucleotide polymorphisms, and other alterations. The comparison and collaboration of these studies may help to establish a better treatment or management approach for patients with WS if backed up with future research.

Kuramoto Model-Based Analysis Reveals Oxytocin Effects on Brain Network Dynamics

The oxytocin effects on large-scale brain networks such as Default Mode Network (DMN) and Frontoparietal Network (FPN) have been largely studied using fMRI data. However, these studies are mainly based on the statistical correlation or Bayesian causality inference, lacking interpretability at the physical and neuroscience level. Here, we propose a physics-based framework of the Kuramoto model to investigate oxytocin effects on the phase dynamic neural coupling in DMN and FPN. Testing on fMRI data of 59 participants administrated with either oxytocin or placebo, we demonstrate that oxytocin changes the topology of brain communities in DMN and FPN, leading to higher synchronization in the FPN and lower synchronization in the DMN, as well as a higher variance of the coupling strength within the DMN and more flexible coupling patterns at group level. These results together indicate that oxytocin may increase the ability to overcome the corresponding internal oscillation dispersion and support the flexibility in neural synchrony in various social contexts, providing new evidence for explaining the oxytocin modulated social behaviors. Our proposed Kuramoto model-based framework can be a potential tool in network neuroscience and offers physical and neural insights into phase dynamics of the brain.

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.

Neural Burst Firing and Its Roles in Mental and Neurological Disorders

Neural firing patterns are critical for specific information coding and transmission, and abnormal firing is implicated in a series of neural pathologies. Recent studies have indicated that enhanced burst firing mediated by T-type voltage-gated calcium channels (T-VGCCs) in specific neuronal subtypes is involved in several mental or neurological disorders such as depression and epilepsy, while suppression of T-VGCCs relieve related symptoms. Burst firing consists of groups of relatively high-frequency spikes separated by quiescence. Neurons in a variety of brain areas, including the thalamus, hypothalamus, cortex, and hippocampus, display burst firing, but the ionic mechanisms that generating burst firing and the related physiological functions vary among regions. In this review, we summarize recent findings on the mechanisms underlying burst firing in various brain areas, as well as the roles of burst firing in several mental and neurological disorders. We also discuss the ion channels and receptors that may regulate burst firing directly or indirectly, with these molecules highlighted as potential intervention targets for the treatment of mental and neurological disorders.

Prenatal exposure to valproic acid and treatment with intranasal oxytocin have sex-specific effects on behavior in Long Evans rats

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social behaviors and communication. In rodents and humans, prenatal exposure to antiepileptic valproic acid is associated with an increased risk for autistic-like characteristics. One potential treatment is oxytocin, a prosocial neuropeptide that can be delivered intranasally. However, the sex-specific effects of valproic acid exposure and intranasal oxytocin treatment on behavior have not been fully explored. Pregnant Long Evans rats were administered valproic acid (500 mg/kg) or saline midday on gestational day 12, and after weaning, male and female pups were assigned to control (saline-saline), valproic acid-saline, or valproic acid-oxytocin groups. Oxytocin (0.8 IU/kg) or saline was delivered intranasally 30-60 min before tests for anxiety-like behaviors (elevated plus maze), social interactions (sociability) and sociosexual behaviors (partner preference, 50 kHz vocalizations and scent marking). Prenatal exposure to valproic acid resulted in sex-specific differences in behavior. When compared to controls, valproic acid males showed enhanced anxiety-like behaviors in adolescence and fewer scent marks in adulthood, while valproic acid females showed reduced sexual (partner) preference as adults. Intranasal oxytocin was anxiolytic for valproic acid males, but moderately anxiogenic for valproic acid females, and in both sexes it surprisingly impaired social interactions in the sociability test. Furthermore, intranasal oxytocin failed to improve sociosexual deficits in valproic acid rats. These findings highlight the importance of conducting preclinical studies in both sexes, and suggest that oxytocin may be an effective treatment in animal models with heightened anxiety-like behaviors.

Neural Basis of Dysregulation of Palatability-Driven Appetite in Autism

PURPOSE OF REVIEW

In research on autism spectrum disorder (ASD), cognitive, speech- and anxiety-related impairments have been the focus of the majority of studies. One consistently reported ASD symptom that has rarely attracted attention is disordered appetite. The goal of this paper is to assess whether ASD-related dysregulation of food intake impacts consumption of palatable foods, including sugar.

RECENT FINDINGS

Aberrant neural processing at the reward system level is at least partially responsible for excessive intake of palatable tastants, including sugar. Impaired oxytocin (OT) signaling likely contributes to the magnitude of this overconsumption. Since intake for reward is generally elevated in individuals with ASD, one strategy to curb sugar overconsumption might utilize presentation of alternative palatable food choices that are more nutritionally adequate than sucrose. Furthermore, OT, which is clinically tested to alleviate other ASD symptoms, might be an effective tool to curb overconsumption of sugar, as well as - likely - of other excessively ingested palatable foods, especially those that have sweet taste.

Patients with PWS and related syndromes display differentially methylated regions involved in neurodevelopmental and nutritional trajectory

Background

Prader–Willi syndrome is a rare genetic neurodevelopmental disorder caused by a paternal deficiency of maternally imprinted gene expression located in the chromosome 15q11–q13 region. Previous studies have demonstrated that several classes of neurodevelopmental disorders can be attributed to either over- or under-expression of specific genes that may lead to impairments in neuronal generation, differentiation, maturation and growth. Epigenetic changes that modify gene expression have been highlighted in these disorders. One recent study focused on epigenetic analysis and compared patients with PWS with patients with other imprinting disorders. No study, however, has yet focused on epigenetics in patients with PWS specifically by comparing the mutations associated with this syndrome.

Objective

This study investigated the epigenetic modifications in patients with PWS and patients with PWS-related disorders caused by inactivation of two genes of the PWS chromosomal region, SNORD116 and MAGEL2. Our approach also aimed to compare the epigenetic modifications in PWS and PWS-related disorders.

Methods

We compared genome-wide methylation analysis (GWAS) in seven blood samples from patients with PWS phenotype (five with deletions of the PWS locus, one with a microdeletion of SNORD116 and one with a frameshift mutation of MAGEL2 presenting with Schaaf–Yang syndrome), as well as two control patients. Controls were infants that had been studied for suspicion of genetic diseases that was not confirmed by the genetic analysis and the clinical follow-up.

Results

The analysis identified 29,234 differentially methylated cytosines, corresponding to 5,308 differentially methylated regions (DMRs), which matched with 2,280 genes. The DMRs in patients with PWS were associated with neurodevelopmental pathways, endocrine dysfunction and social and addictive processes consistent with the key features of the PWS phenotype. In addition, the separate analysis for the SNORD116 and MAGEL2 deletions revealed that the DMRs associated with the SNORD116 microdeletion were found in genes implicated in metabolic pathways and nervous system development, whereas MAGEL2 mutations mostly concerned genes involved in macromolecule biosynthesis.

Conclusion

The PWS is associated with epigenetic modifications with differences in SNORD116 and MAGEL2 mutations, which seem to be relevant to the different associated phenotypes.

Review of eating disorders and oxytocin receptor polymorphisms

BACKGROUND AND AIMS

Oxytocin, a nine amino acid peptide synthesised in the hypothalamus, has been widely recognised for its role in anxiolysis, bonding, sociality, and appetite. It binds to the oxytocin receptor (OXTR)-a G-protein coupled receptor-that is stimulated by the actions of oestrogen both peripherally and centrally. Studies have implicated OXTR genotypes in conferring either a risk or protective effect in autism, schizophrenia, and eating disorders (ED). There are numerous DNA variations of this receptor, with the most common DNA variation being in the form of the single nucleotide polymorphisms (SNPs). Two OXTR SNPs have been most studied in relation to ED: rs53576 and rs2254298. Each SNP has the same allelic variant that produces genotypes AA, AG, and GG. In this critical review we will evaluate the putative role of rs53576 and rs2254298 SNPs in ED. Additionally, this narrative review will consider the role of gene-environment interactions in the development of ED pathology.

FINDINGS

The OXTR SNPs rs53576 and rs2254298 show independent associations between the A allele and restrictive eating behaviours. Conversely, the G allele of the OXTR rs53576 SNP is associated with binging behaviours, findings that were also evident in neuroanatomy. One study found the A allele of both OXTR SNPs to confer risk for more severe ED symptomatology while the G allele conferred some protective effect. An interaction between poor maternal care and rs2254298 AG/AA genotype conferred increased risk for binge eating and purging in women.

CONCLUSIONS

Individual OXTR SNP are unlikely in themselves to explain complex eating disorders but may affect the expression of and/or effectiveness of the OXTR. A growing body of G x E work is indicating that rs53576G homozygosity becomes disadvantageous for later mental health under early adverse conditions but further research to extend these findings to eating pathology is needed. The GWAS approach would benefit this area of knowledge.

Decreased Plasma Oxytocin Levels in Patients With PTSD

Introduction

Although the pathophysiology of post-traumatic stress disorder (PTSD) is still unclear, growing preclinical evidences suggest that oxytocin (OT), a pleiotropic hormone, is possibly involved. However, direct studies on OT levels or clinical trials with this exogenous hormone in patients with PTSD led to inconsistent findings. Therefore, the aim of the present study was at exploring and comparing the plasma OT levels in a group of patients with PTSD and matched healthy subjects as the control group.

Materials and Methods

Twenty-six outpatients (13 men, 13 women, mean age: 40.3 ± 11.5 years) suffering from PTSD, according to the Diagnostic and Statistical Manual for Mental Disorders, fifth edition (DSM-5), and 26 healthy subjects (13 men, 13 women, mean age: 43.8 ± 12.7 years) were included. The patients were assessed through the structured clinical interview for DSM-5 research version, patient edition (SCID-I/P), and the Impact for Event Scale revised (IES-R). All fasting subjects underwent three venous blood samples for the subsequent oxytocin radioimmunoassay. We used unpaired Student’s t-test to assess OT levels and the intergroup difference of demographic characteristics, while anxiety, avoidance, and hyperarousal scores were compared among groups adjusting for the effect of gender and age by means of analysis of covariance (ANCOVA). The correlations between different variables were investigated by Pearson’s method.

Results

The most common traumatic events of patients with PTSD were the following: severe car accident, physical violence, sexual violence, sudden death of a loved one, and natural disaster. The IES total score was 55 ± 15. Student’s t-test revealed that the patients showed significantly lower OT levels (mean ± SD, pg/ml) than healthy control subjects (4.37 ± 1.61 vs 5.64 ± 2.17, p < 0.001). We detected no correlation between the IES total score, subscales, or single items and OT plasma levels. Again, no difference between men and women was detected in the patients’ group, while healthy control women showed higher OT levels than men.

Discussion

Our study, while reporting the presence of decreased plasma OT levels in outpatients with PTSD of both sexes, as compared with healthy control subjects, would support the possible involvement of OT in the pathophysiology of PTSD. However, given the complexity of the clinical picture, future investigations are necessary to better deepen the role and level of OT in PTSD.

Oxytocin and social anxiety: Interactions with sex hormones

Oxytocin has been associated with anxiolytic and stress reducing effects in a number of studies. Less is known about the associations of endogenous oxytocin concentrations and their interaction with other hormones such as sex hormones in relation to self-reported anxiety levels. In this study, endogenous oxytocin and sex hormone levels were analyzed in 99 high (51 women) and 100 low (50 women) socially anxious individuals. Regression analyses showed that women with high oxytocin and estradiol levels reported a lower total Liebowitz Social Anxiety Score (LSAS) as well as a lower score on the subscale LSAS Fear. This association of hormonal interaction with social anxiety scores was significant in the subsample of high socially anxious women. In men there were no significant associations for endogenous hormones with LSAS scores. These findings suggest that in women the link between oxytocin and anxiety might be dependent on basal anxiety levels as well as on individual sex hormone levels.

Neurochemistry of Visual Attention

Visual attention is the cognitive process that mediates the selection of important information from the environment. This selection is usually controlled by bottom-up and top-down attentional biasing. Since for most humans vision is the dominant sense, visual attention is critically important for higher-order cognitive functions and related deficits are a core symptom of many neuropsychiatric and neurological disorders. Here, we summarize the importance and relative contributions of different neuromodulators and neurotransmitters to the neural mechanisms of top-down and bottom-up attentional control. We will not only review the roles of widely accepted neuromodulators, such as acetylcholine, dopamine and noradrenaline, but also the contributions of other modulatory substances. In doing so, we hope to shed some light on the current understanding of the role of neurochemistry in shaping neuron properties contributing to the allocation of attention in the visual field.

Social anxiety is associated with poor quality of life in adults with epilepsy in Northeast China: A cross-sectional study

OBJECTIVE

This study aimed to investigate the factors influencing the level of social anxiety in patients with epilepsy (PWE) in Northeast China. We also identified the effect of social anxiety on the quality of life in these patients.

METHODS

A consecutive cohort of 148 adult PWE from The First Hospital of Jilin University were recruited. In this sample, 116 patients had focal epilepsy, 20 had generalized epilepsy, and 12 had unclassified epilepsy. Depressive symptoms, social anxiety, and quality of life were evaluated using the Chinese version of the Patient Health Questionnaire 9 (PHQ-9), 20-item Social Phobia Scale (SPS), 20-item Social Interaction Anxiety Scale (SIAS), and Quality-of-Life Inventory in Epilepsy-31 (QOLIE-31), respectively. Multivariate linear regression analyses were employed to identify independent factors influencing SPS scores and SIAS scores.

RESULTS

Correlation analysis suggested that sex, age at onset, seizure frequency over the last year, AED treatment model, >50% nocturnal seizures, PHQ-9 score, and QOLIE-31 score had a significant correlation with the SPS score. The age at onset, seizure frequency over the last year, AED treatment model, PHQ-9 score, and QOLIE-31 score correlated with the SIAS score. Multiple linear regression analysis showed that the total QOLIE-31 score (β = - 0.481; p = 0.001) was inversely associated with the SPS score in PWE. Additionally, earlier age of onset (β = -0.156; p = 0.022) and low total QOLIE-31 score (β = -0.457; p = 0.001) were risk factors for high SIAS scores.

CONCLUSION

We found that social anxiety was independently associated with poor quality of life. Earlier age of onset was also a risk factor for social anxiety. Future studies with large sample sizes are required to confirm our findings.

Current rodent models for the study of empathic processes

Empathy is a complex phenomenon critical for group survival and societal bonds. In addition, there is mounting evidence demonstrating empathic behaviors are dysregulated in a multitude of psychiatric disorders ranging from autism spectrum disorder, substance use disorders, and personality disorders. Therefore, understanding the underlying drive and neurobiology of empathy is paramount for improving the treatment outcomes and quality of life for individuals suffering from these psychiatric disorders. While there is a growing list of human studies, there is still much about empathy to understand, likely due to both its complexity and the inherent limitations of imaging modalities. It is therefore imperative to develop, validate, and utilize rodent models of empathic behaviors as translational tools to explore this complex topic in ways human research cannot. This review outlines some of the more prevailing theories of empathy, lists some of the psychiatric disorders with disrupted empathic processes, describes rat and mouse models of empathic behaviors currently used, and discusses ways in which these models have elucidated social, environmental, and neurobiological factors that may modulate empathy. The research tools afforded to rodent models will provide an increasingly clear translational understanding of empathic processes and consequently result in improvements in care for those diagnosed with any one of the many psychiatric disorders.

No changes in the oxytocin system in alcohol-dependent female rodents and humans: Towards a sex-specific psychopharmacology in alcoholism

A pronounced decrease of oxytocin and increase of oxytocin receptor binding sites were recently reported in male alcohol dependent rats and male alcohol dependent patients. Here we comment on this and emphasize that in female alcohol dependent rats and humans no changes occur in the oxytocin system. We therefore suggest specific intervention with oxytocin only in male subjects.

Effects of the Prenatal Administration of Tetanus Toxoid on the Sociability and Explorative Behaviors of Rat Offspring: A Preliminary Study

OBJECTIVE

Autism spectrum disorder (ASD) is a severely disabling psychiatric disease characterized by impairments in communication and social skills. Although efforts have been made to explore the etiology of ASD, its pathophysiology remains unclear. This issue is rendered more challenging by confounding data about the effects of vaccination on disease etiology. In this study, therefore, we investigated the neurodevelopmental effects of maternal tetanus toxoid administration on rat offspring. We hypothesized that the vaccine affects the sociability and preference for social novelty of rat offspring as well as the production of immunological and neurotrophic factors, including tumor necrosis factor-alfa (TNF-α), neuregulin-1 (NRG-1), neuron growth factor (NGF), and oxytocin.

METHODS

The study involved 12 female and 4 male adult Sprague-Dawley rats (238 ± 10 g), which were assigned to two groups. Group 1 (control group) was given 0.5 ml of normal saline (0.9% NaCl) on the 10th day of pregnancy, whereas Group 2 (experimental group) was administered 0.5 ml of tetanus vaccine (tetanus toxoid, 40 IU).

RESULTS

Maternal tetanus toxoid administration exerted beneficial effects on the sociability and explorative behaviors of the rats. The brain tissue levels of TNF-α, NGF, NRG-1, and oxytocin were higher in the experimental group than those among the controls. All these significant differences were found in both the male and female rats.

CONCLUSION

This study is the first to demonstrate the advantages of tetanus toxoid administration in relation to the sociability and explorative behaviors of rat offspring. The results showed that the vaccine also influences NRG-1, neuregulin, and oxytocin production.

Genetic, epigenetic, and environmental factors controlling oxytocin receptor gene expression

BACKGROUND

The neuropeptide oxytocin regulates mammalian social behavior. Disruptions in oxytocin signaling are a feature of many psychopathologies. One commonly studied biomarker for oxytocin involvement in psychiatric diseases is DNA methylation at the oxytocin receptor gene (OXTR). Such studies focus on DNA methylation in two regions of OXTR, exon 3 and a region termed MT2 which overlaps exon 1 and intron 1. However, the relative contribution of exon 3 and MT2 in regulating OXTR gene expression in the brain is currently unknown.

RESULTS

Here, we use the prairie vole as a translational animal model to investigate genetic, epigenetic, and environmental factors affecting Oxtr gene expression in a region of the brain that has been shown to drive Oxtr related behavior in the vole, the nucleus accumbens. We show that the genetic structure of Oxtr in prairie voles resembles human OXTR. We then studied the effects of early life experience on DNA methylation in two regions of a CpG island surrounding the Oxtr promoter: MT2 and exon 3. We show that early nurture in the form of parental care results in DNA hypomethylation of Oxtr in both MT2 and exon 3, but only DNA methylation in MT2 is associated with Oxtr gene expression. Network analyses indicate that CpG sites in the 3' portion of MT2 are most highly associated with Oxtr gene expression. We also identify two novel SNPs in exon 3 of Oxtr in prairie voles and a novel alternative transcript originating from the third intron of the gene. Expression of the novel alternative transcript is associated with genotype at SNP KLW2.

CONCLUSIONS

These results identify putative regulatory features of Oxtr in prairie voles which inform future studies examining OXTR in human social behaviors and disorders. These studies indicate that in prairie voles, DNA methylation in MT2, particularly in the 3' portion, is more predictive of Oxtr gene expression than DNA methylation in exon 3. Similarly, in human temporal cortex, we find that DNA methylation in the 3' portion of MT2 is associated with OXTR expression. Together, these results suggest that among the CpG sites studied, DNA methylation of MT2 may be the most reliable indicator of OXTR gene expression. We also identify novel features of prairie vole Oxtr, including SNPs and an alternative transcript, which further develop the prairie vole as a translational model for studies of OXTR.

Graph Theoretic Analysis Reveals Intranasal Oxytocin Induced Network Changes Over Frontal Regions

In this study, we aim to elucidate how intranasal oxytocin modulates brain network characteristics, especially over the frontal network. As an essential brain hub of social cognition and emotion regulation, we also explore the association between graphic properties of the frontal network and individual personality traits under oxytocin (OT) administration. Fifty-nine male participants administered intranasal OT or placebo were followed by resting-state fMRI scanning. The correlation-based network model was applied to study OT modulation effects. We performed community detection algorithms and conducted further network analyses, including clustering coefficient, average shortest path and eigenvector centrality. In addition, we conducted a correlation analysis between clustering coefficients and the self-assessed psychological scales. Modular organizations in the OT group reveal integrations of the frontoparietal network (FPN) and the default mode network (DMN) over frontal regions. Results show that frontal nodes within the FPN are characterized by lower clustering coefficients and higher average shortest path values compared to the placebo group. Notably, these modulation effects on frontal network property are associated with Interpersonal Reactivity Index (IRI) fantasy value. Our results suggest that OT elevates integrations between FPN, DMN and limbic system as well as reduces small-worldness within the FPN. Our results support graph theoretic analysis as a potential tool to assess OT induced effects on the information integration in the frontal network.

The neuroprotective effect of oxytocin on vincristine-induced neurotoxicity in mice

Vincristine (VCR) is commonly used to treat a variety of hematological malignancies and solid tumors in pediatric and adult patients. However, peripheral neuropathy is a dose-limiting side effect that leaves some patients with functional disability and long-term pain. Oxytocin (OT) has demonstrated analgesic and anti-inflammatory properties, but there is no evidence regarding its effects on VCR-induced neurotoxicity. Therefore, we evaluated the potential protective effects of OT on VCR-induced neurotoxicity. In vitro, VCR (0.005 ∼ 0.1 μmol/l) and OT (10^-8 ∼ 10^-5 mol/l) were added into cultured primary dorsal root ganglion (DRG) neurons of mice. The length of neurites was counted by using immunofluorescence. In vivo, neurotoxicity was induced in mice by administration of VCR (0.1 mg/kg, intraperitoneal injection for 14 days) with or without pretreatment of OT (0.1 mg/kg or 1 mg/kg). Atosiban, an OT receptor (OTR) antagonist and OTR knockout (KO) mice were used for evaluating effects of OTR. Mechanical hyperalgesia was measured by using von Frey filaments. Histology of plantar skin, sciatic nerve and DRG was observed by using transmission electron microscopy (TEM) and hematoxylin-eosin (HE) staining. Results indicated that OT alleviated VCR-induced neurite damage in cultured primary DRG neurons in vitro. In vivo, OT ameliorated VCR-induced hyperalgesia. Histologically, OT attenuated the VCR-induced damages of nerve endings, myelin sheaths and Schwann cells in sciatic nerve and DRG. These effects were antagonized by atosiban. In addition, OTR knockout mice exhibited more severe hyperalgesia than wild-type mice. Globally, these results indicated that OT may have neuroprotective effects on vincristine-induced neurotoxicity in mice.

Prefrontal Disinhibition in Social Fear: A Vital Action of Somatostatin Interneurons

Social fear and avoidance of social partners and social situations represent the core behavioral symptom of Social Anxiety Disorder (SAD), a prevalent psychiatric disorder worldwide. The pathological mechanism of SAD remains elusive and there are no specific and satisfactory therapeutic options currently available. With the development of appropriate animal models, growing studies start to unravel neuronal circuit mechanisms underlying social fear, and underscore a fundamental role of the prefrontal cortex (PFC). Prefrontal cortical functions are implemented by a finely wired microcircuit composed of excitatory principal neurons (PNs) and diverse subtypes of inhibitory interneurons (INs). Disinhibition, defined as a break in inhibition via interactions between IN subtypes that enhances the output of excitatory PNs, has recently been discovered to serve as an efficient strategy in cortical information processing. Here, we review the rodent animal models of social fear, the prefrontal IN diversity, and their circuits with a particular emphasis on a novel disinhibitory microcircuit mediated by somatostatin-expressing INs in gating social fear behavior. The INs subtype distinct and microcircuit-based mechanism advances our understanding of the etiology of social fear and sheds light on developing future treatment of neuropsychiatric disorders associated with social fear.

Decreased oxytocin plasma levels and oxytocin receptor expression in borderline personality disorder

INTRODUCTION

Borderline personality disorder (BPD) is characterized by intense affective reactions with underlying social and interpersonal cognitive deficits. Oxytocin has largely been associated with both stress regulation and social cognition in psychiatric patients and in non-clinical populations in previous studies. Finally, abnormal oxytocin levels have been preliminary reported in BPD patients.

METHODS

53 patients with moderate-severe BPD and 31 healthy control subjects were investigated for plasma levels of oxytocin and protein expression of oxytocin receptor in blood mononuclear cells. Clinical assessments were made for severity, functionality, and comorbidity with axis I and II conditions.

RESULTS

Oxytocin plasma levels were significantly lower in BPD patients compared with controls. In addition, protein expression of oxytocin receptor was significantly reduced in the BPD group. A positive correlation was found between plasma oxytocin levels and the activity index score of the Zuckerman-Kuhlman Personality Questionnaire (ZKPQ). Oxytocin receptor protein expression, on the contrary, had a negative correlation with the ZKPQ sociability index score.

CONCLUSIONS

Results support the evidence of a dysfunction of the oxytocin system in borderline personality disorder, which could be involved in emotional dysregulation and interpersonal disturbances in these patients.

Long term transcriptional and behavioral effects in mice developmentally exposed to a mixture of endocrine disruptors associated with delayed human neurodevelopment

Accumulating evidence suggests that gestational exposure to endocrine disrupting chemicals (EDCs) may interfere with normal brain development and predispose for later dysfunctions. The current study focuses on the exposure impact of mixtures of EDCs that better mimics the real-life situation. We herein describe a mixture of phthalates, pesticides and bisphenol A (mixture N1) detected in pregnant women of the SELMA cohort and associated with language delay in their children. To study the long-term impact of developmental exposure to N1 on brain physiology and behavior we administered this mixture to mice throughout gestation at doses 0×, 0.5×, 10×, 100× and 500× the geometric mean of SELMA mothers' concentrations, and examined their offspring in adulthood. Mixture N1 exposure increased active coping during swimming stress in both sexes, increased locomotion and reduced social interaction in male progeny. The expression of corticosterone receptors, their regulator Fkbp5, corticotropin releasing hormone and its receptor, oxytocin and its receptor, estrogen receptor beta, serotonin receptors (Htr1a, Htr2a) and glutamate receptor subunit Grin2b, were modified in the limbic system of adult animals, in a region-specific, sexually-dimorphic and experience-dependent manner. Principal component analysis revealed gene clusters associated with the observed behavioral responses, mostly related to the stress axis. This integration of epidemiology-based data with an experimental model increases the evidence that prenatal exposure to EDC mixtures impacts later life brain functions.

Acute effects of oxytocin in music performance anxiety: a crossover, randomized, placebo-controlled trial

RATIONALE

Individuals with music performance anxiety (MPA) present physical, behavioral, and cognitive manifestations of anxiety, in addition to information processing deficits, especially in facial emotion recognition (FER).

OBJECTIVES

To assess the effects of a single dose of intranasal oxytocin (24 IU) on FER in a sample of musicians with high and low MPA (primary outcome), as well as indicators of mood/anxiety and self-assessed performance (secondary outcomes).

METHODS

Crossover, randomized, double-blind, placebo-controlled trial involving 43 male musicians with different levels of MPA. Participants completed a static facial emotion recognition task and self-rated mood and performance scales. Data were analyzed using ANOVA 2 × 0 for crossover trials and the Omnibus test (measure of separability between intervention and carryover effects).

RESULTS

Only musicians with high MPA treated with oxytocin had a higher accuracy in the recognition of happiness (p < 0.03; d > 0.72). No effects of oxytocin were found on mood indicators or on self-perceived performance, regardless of MPA level.

CONCLUSIONS

The results indicate possible benefits of the acute treatment with oxytocin in MPA, which may improve the management of this common and disabling condition that affects professional musicians. The appropriate perception of positive feedback may increase confidence and feelings of social acceptance, reducing symptoms associated with the condition. The lack of effects on mood/anxiety and cognition may be explained by the context-dependent characteristic of the effects of oxytocin, since the experiment did not represent an actual situation of social threat.

TRIAL REGISTRATION

Brazilian Clinical Trials Registry (Registro Brasileiro de Ensaios Clínicos): No. RBR-9cph2q.

Oxytocin Differentiated Effects According to the Administration Route in a Prenatal Valproic Acid-Induced Rat Model of Autism

Background and objectives: The hormone oxytocin (OXT) has already been reported in both human and animal studies for its promising therapeutic potential in autism spectrum disorder (ASD), but the comparative effectiveness of various administration routes, whether central or peripheral has been insufficiently studied. In the present study, we examined the effects of intranasal (IN) vs. intraperitoneal (IP) oxytocin in a valproic-acid (VPA) autistic rat model, focusing on cognitive and mood behavioral disturbances, gastrointestinal transit and central oxidative stress status. Materials and Methods: VPA prenatally-exposed rats (500 mg/kg; age 90 days) in small groups of 5 (n = 20 total) were given OXT by IP injection (10 mg/kg) for 8 days consecutively or by an adapted IN pipetting protocol (12 IU/kg, 20 μL/day) for 4 consecutive days. Behavioral tests were performed during the last three days of OXT treatment, and OXT was administrated 20 minutes before each behavioral testing for each rat. Biochemical determination of oxidative stress markers in the temporal area included superoxide dismutase (SOD), glutathione peroxidase (GPx) and malondialdehyde (MDA). A brief quantitative assessment of fecal discharge over a period of 24 hours was performed at the end of the OXT treatment to determine differences in intestinal transit. Results: OXT improved behavioral and oxidative stress status in both routes of administration, but IN treatment had significantly better outcome in improving short-term memory, alleviating depressive manifestations and mitigating lipid peroxidation in the temporal lobes. Significant correlations were also found between behavioral parameters and oxidative stress status in rats after OXT administration. The quantitative evaluation of the gastrointestinal (GI) transit indicated lower fecal pellet counts in the VPA group and homogenous average values for the control and both OXT treated groups. Conclusions: The data from the present study suggest OXT IN administration to be more efficient than IP injections in alleviating autistic cognitive and mood dysfunctions in a VPA-induced rat model. OXT effects on the cognitive and mood behavior of autistic rats may be associated with its effects on oxidative stress. Additionally, present results provide preliminary evidence that OXT may have a balancing effect on gastrointestinal motility.

A Novel Role of CD38 and Oxytocin as Tandem Molecular Moderators of Human Social Behavior

Oxytocin is an important modulator of human affiliative behaviors, including social skills, human pair bonding, and friendship. CD38 will be discussed as an immune marker and then in more detail the mechanisms of CD38 on releasing brain oxytocin. Mention is made of the paralogue of oxytocin, vasopressin, that has often overlapping and complementary functions with oxytocin on social behavior. Curiously, vasopressin does not require CD38 to be released from the brain. This review discusses the social salience hypothesis of oxytocin action, a novel view of how this molecule influences much of human social behaviors often in contradictory ways. The oxytocinergic-vasopressinergic systems are crucial modulators of broad aspects of human personality. Of special interest are studies of these two hormones in trust related behavior observed using behavioral economic games. This review also covers the role of oxytocin in parenting and parental attachment. In conclusion, the effects of oxytocin on human behavior depend on the individual's social context and importantly as well, the individual's cultural milieu, viz. East and West. ACRONYMS: ACC = Anterior Cingulate ADP = Adenosine diphosphate AQ = Autism Quotient cADPR = Cyclic ADP-ribose CNS = Central nervous system DA = Dopamine eQTLC = Expression Quantitative Trait Loci LC-NE = Locus Coeruleus-Norepinephrine MRI = Magnetic Resonance Imaging OFC = Orbitofrontal cortices OXT = Oxytocin RAGE = Receptor for advanced glycation end-products SARM1 = Sterile Alpha and toll/interleukin-1 receptor motif-containing 1 TRPM2= Transient Receptor Potential Cation Channel Subfamily M Member 2 AVP = Vasopressin.

Imaging of intranasal drug delivery to the brain

Intranasal (IN) delivery is a rapidly developing area for therapies with great potential for the treatment of central nervous system (CNS) diseases. Moreover, in vivo imaging is becoming an important part of therapy assessment, both clinically in humans and translationally in animals. IN drug delivery is an alternative to systemic administration that uses the direct anatomic pathway between the olfactory/trigeminal neuroepithelium of the nasal mucosa and the brain. Several drugs have already been approved for IN application, while others are undergoing development and testing. To better understand which imaging modalities are being used to assess IN delivery of therapeutics, we performed a literature search with the key words "Intranasal delivery" and "Imaging" and summarized these findings in the current review. While this review does not attempt to be fully comprehensive, we intend for the examples provided to allow a well-rounded picture of the imaging tools available to assess IN delivery, with an emphasis on the nose-to-brain delivery route. Examples of in vivo imaging, for both humans and animals, include magnetic resonance imaging (MRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT), gamma scintigraphy and computed tomography (CT). Additionally, some in vivo optical imaging modalities, including bioluminescence and fluorescence, have been used more in experimental testing in animals. In this review, we introduce each imaging modality, how it is being utilized and outline its strengths and weaknesses, specifically in the context of IN delivery of therapeutics to the brain.

Oxytocin reduces post-stress sweet snack intake in women without attenuating salivary cortisol

Intranasal oxytocin produces anorectic effects on snack intake in men when tested in the absence of deprivation-induced hunger, but its effects on food intake in women without eating disorders have not been reported. Oxytocin may reduce food intake by reducing stress eating, since it inhibits ACTH release. The present study adopted a double-blind, repeated measures and fully concealed crossover protocol in which 38 women self-administered 24 IU of oxytocin or placebo intranasally, ate lunch, and underwent two consecutive stress tests. Snack intake was assessed 15-20 min after lunch, via a sham taste test. Salivary cortisol was measured throughout the test period every 15 min. Oxytocin significantly reduced sweet fatty snack intake independently of any effect on salivary cortisol, which declined over time at a similar rate after either drug or placebo. Ratings of sweet taste were slightly reduced by oxytocin, but only in self-reported stress eaters. These results differ from previous studies with men that found an effect of oxytocin on postprandial cortisol levels. However, previous research assayed the less active form of plasma cortisol and did not control for protein intake, which can drive elevated cortisol. The finding that oxytocin reduces snack intake in females after acute stress has important implications for appetite regulation and its treatment in obese people and in those with eating disorders.

Peripheral Blood Mononuclear Cell Oxytocin and Vasopressin Receptor Expression Positively Correlates with Social and Behavioral Function in Children with Autism

The peptide hormone oxytocin is an established regulator of social function in mammals, and dysregulated oxytocin signaling is implicated in autism spectrum disorder (ASD). Several clinical trials examining the effects of intranasal oxytocin for improving social and behavioral function in ASD have had mixed or inclusive outcomes. The heterogeneity in clinical trials outcomes may reflect large inter-individual expression variations of the oxytocin and/or vasopressin receptor genes OXTR and AVPR1A, respectively. To explore this hypothesis we examined the expression of both genes in peripheral blood mononuclear cells (PBMC) from ASD children, their non-ASD siblings, and age-matched neurotypical children aged 3 to 16 years of age as well as datamined published ASD datasets. Both genes were found to have large inter-individual variations. Higher OXTR and AVPR1A expression was associated with lower Aberrant Behavior Checklist (ABC) scores. OXTR expression was associated with less severe behavior and higher adaptive behavior on additional standardized measures. Combining the sum expression levels OXTR, AVPR1A, and IGF1 yielded the strongest correlation with ABC scores. We propose that future clinical trials in ASD children with oxytocin, oxytocin mimetics and additional tentative therapeutics should assess the prognostic value of their PBMC mRNA expression of OXTR, AVPR1A, and IGF1.

Interaction between polymorphisms of the oxytocinergic system genes and emotion perception in inpatients with anorexia nervosa

OBJECTIVE

The empirical literature describes the role of the oxytocinergic system in emotion perception (EP). Variants in the oxytocin (OXT) and oxytocin receptor genes have been associated with mental disorders, including anorexia nervosa (AN), that are characterized by difficulties in socioemotional functioning. Our study aimed to examine whether variability within the genes related to OXT pathways may play a role in facial EP in inpatients with AN.

METHOD

Single nucleotide polymorphisms (SNPs) of the following genes: oxytocin receptor (rs2254298, rs53576), OXT (rs6133010), OXT-arginine-vasopressin (rs2740204), CD38 (rs6449197, rs3796863), and human leucyl/cystinylaminopeptidase (rs4869317) were genotyped in 60 AN female inpatients and 60 healthy control females (HCs). Associations between genetic polymorphisms and EP as well as clinical symptoms were examined.

RESULTS

The AN group showed decreased EP abilities compared with HCs. SNPs of rs2740204, rs6133010, and rs53576 were associated with differences in EP in women with AN and in HCs. The SNP of rs4869317 was associated with the level of eating disorders symptoms in HCs.

CONCLUSIONS

The OXT system may be involved in EP difficulties in AN. SNPs within genes related to OXT pathways may influence EP abilities. The leucyl/cystinylaminopeptidase rs4869317 SNP may be involved in the development of eating disorders psychopathology.

Association of OXTR rs53576 with the Developmental Trajectories of Callous-Unemotional Traits and Stressful Life Events in 3- to 9-Year-Old Community Children

The objective was to obtain developmental trajectories combining callous-unemotional traits and the number of stressful life-events between ages 3 and 9 years and to ascertain their association with the polymorphism rs53576 at the Oxytocin Receptor gene (OXTR). A total of 377 children were assessed yearly from ages 3 to 9 years. Latent class growth analysis for parallel processes was used to identify distinct trajectories for callous-unemotional traits (assessed using the Inventory of Callous-Unemotional Traits, ICU) and number of stressful life-events, and then the influence of being an A allele carrier on class membership was included with OXTR genotypes as a binary time-invariant predictor, following a 3-step approach. A 3-class model showed the highest entropy (.859) and adequate posterior probabilities of class membership (≥.884). Class 1 (n = 226, 59.9%) included children with low and stable ICU scores and low and descending stressful life-events; class 2 (n = 127, 33.7%) included children with high and ascending ICU scores and low and slightly descending stressful life-events; and class 3 (n = 24, 6.4%) included children with persistently high profiles both for ICU scores and stressful life-events. Carrying an A allele (genotypes GA/AA) increased the odds of pertaining to class 3 (high and persistent ICU scores and stressful life-events) as opposed to class 2 (OR = 4.27, p = 0.034) or class 1 (OR = 3.81, p = 0.042). The results suggest the importance of considering callous-unemotional traits and stressful life-events in conjunction. In addition, the genetic variability of OXTR (rs53576) may help to understand individual differences in early development.