Intranasal Oxytocin in Children and Adolescents with Autism Spectrum Disorder

Aptamers and MIPs as alternative molecular recognition elements for vasopressin and oxytocin sensing: A review

Arginine vasopressin (AVP) and oxytocin (OT) are two important hormones that regulate various physiological and behavioral functions, such as blood pressure, water balance, social bonding, and stress response. The detection and quantification of these hormones are of great interest in clinical diagnosis and research. However, the conventional methods based on antibodies or enzymes have some limitations, such as high cost, low stability, and ethical issues. Therefore, alternative molecular recognition elements, such as aptamers and molecularly imprinted polymers (MIPs), have been developed to overcome these drawbacks. Aptamers are short nucleic acid sequences that can bind to specific targets with high affinity and specificity, while MIPs are synthetic polymers with imprinted binding sites mimicking natural receptors. Both aptamers and MIPs have advantages such as low cost, high stability, easy synthesis, and modification. In this review, we summarize the recent advances in the development and application of aptamers and MIPs for the sensing of vasopressin and oxytocin, and compare their performances. We also discuss the challenges and future perspectives of aptamers and MIPs as alternative molecular recognition elements for vasopressin and oxytocin sensing.

Predictors of Placebo Response in the Study of Oxytocin in Autism to Improve Reciprocal Social Behaviors

Background: Although randomized clinical trials (RCTs) have investigated several treatments for social communication difficulties and repetitive behavior in autism, none has yet shown consistent superiority over placebo. Placebo response in autism RCTs may impede the ability to detect meaningful treatment effects. Objective: We sought to identify individual-level predictors of placebo response in Study of Oxytocin in Autism to improve Reciprocal Social Behaviors (SOARS-B), a 24-week RCT of intranasal oxytocin for social impairment in autistic youth. In our primary analysis, we examined predictors of change in the Aberrant Behavior Checklist-modified Social Withdrawal (ABC-mSW) score at 24 weeks in SOARS-B participants taking placebo. Secondary analyses examined predictors of ABC-mSW change at 12 weeks and of Clinical Global Impressions-Improvement at 24 and 12 weeks. We also examined predictors of response among SOARS-B participants taking oxytocin. Methods: For each analysis, we first used lasso (least absolute shrinkage and selection operator) regression to identify potentially influential predictors from a large group that included demographic factors, rating scale data, and prescribed medications. We then estimated an unpenalized linear regression model for the outcome of interest that included only variables retained by the optimal lasso. We considered variables with statistically significant coefficients to be influential predictors. Results: Higher baseline ABC-mSW score was the only significant predictor of greater ABC-mSW change in the placebo group at 24 and 12 weeks. Conclusions: In SOARS-B, higher baseline severity on a measure of reciprocal social communication predicted greater placebo response. This is consistent with the finding that lower social communication adaptive functioning was associated with greater placebo response in recent RCTs of balovaptan for social impairment in autism. However, it contrasts with findings from a trial of citalopram for repetitive behavior in autism, in which lower baseline severity of a composite of autistic and mood symptoms predicted greater placebo response. This may indicate that different factors contribute to placebo response in different symptom domains.

Random forest and Shapley Additive exPlanations predict oxytocin targeted effects on brain functional networks involved in salience and sensorimotor processing, in a randomized clinical trial in autism

Intranasal oxytocin (IN-OXT) has shown some promises in rescuing social deficits in autism spectrum disorder (ASD) as well as some inconsistencies in long-term trials. We conducted a target engagement study to study the precise effects of different doses of IN-OXT on brain resting-state functional connectivity (rsFC) in ASD. We examined the effects of varying doses of IN-OXT (0 IU, 8 IU, 24 IU, 48 IU) on rsFC in a double-blind, placebo-controlled, within-subject design in 30 male adults with ASD and 17 neurotypical controls (NT) receiving placebo. Random forest analysis was used to classify individuals as ASD or NT. Shapely Additive explanations values were calculated to rank brain functional networks by level of contribution to ASD deficits and to evaluate IN-OXT dose effects. The model predicted ASD diagnosis with an AUC of 94%. Hypoconnectivity between salience/empathy and visual networks, and hyperconnectivity between reward and sensorimotor networks and theory of mind networks were among the strongest predictors of ASD deficits. IN-OXT had a dose-dependent effect on rescuing both deficits described above. Overall, 48 IU dose was more effective, and 24 IU dose was more effective in those who have lower DNA OXT receptor methylation and lower severity of clinical symptoms. Higher doses of OXT might be necessary to enhance empathic responses, and ASD individuals with less support needs and with a preserved OXT system might benefit most from OXT treatment. Applying machine learning approaches in OXT research can provide data-driven unbiased results that can inform future clinical trials.

Development and validation of a highly-sensitive, quantitative LC-MS/MS assay to evaluate plasma oxytocin

Introduction

Oxytocin is a 9-amino acid peptide that serves as neuromodulator in the human central nervous system. This peptide is implicated in the regulation of diverse behaviors and plays a significant role in positive social interaction. Currently, oxytocin levels are measured using immunoassays. However, these methods have several limitations that can lead to false results and erroneous interpretation. Given the remarkably low endogenous level of oxytocin in human plasma (low ng/L levels), we developed and rigorously validated a novel and highly sensitive LC-MS/MS method for oxytocin quantification in plasma.

Methods

Oxytocin was initially extracted using solid-phase extraction with an Oasis HLB 30 mg plate and then subjected to LC-MS/MS analysis. PBS-0.1 % BSA served as surrogate matrix for the preparation of validation samples and the calibration curve, ensuring no endogenous interference. The validation design followed the Clinical Laboratory Standards Institute guidelines. Precision, accuracy, and measurement uncertainty were determined using single-nested analysis of variance and e.noval software.

Results

A lower limit of quantification of 1 ng/L was achieved. The method was validated for oxytocin concentrations ranging from 1 ng/L to 75 ng/L, with precision (coefficient of variation) below 10 %, accuracy ranging from 94 % to 108 %, and measurement uncertainty below 15 %.

Conclusion

In this work, we developed and validated a highly sensitive LC-MS/MS method for the quantification of oxytocin in plasma. Our novel methodology is well-suited for clinical applications.

Distribution of Intranasally Administered rIL-10 Along the Olfactory Nerve and Perivascular Space After Intracerebral Hemorrhage

RATIONALE

The utilization of anti-inflammatory therapy for treating brain diseases holds promise; however, research on intranasal administration of drug compounds remains limited. Quantitative data, particularly pharmacokinetics, are scant, and direct evidence of the distribution of intranasally administered recombinant interleukin 10 (rIL-10) within the brain is lacking.

METHODS

Employing fluorescent labeling, in vivo imaging, and confocal microscopy, we meticulously monitored the distribution and delivery pathways of intranasally administered rIL-10 in the brain.

RESULTS AND CONCLUSIONS

Our findings demonstrate that rIL-10 can permeate the blood-brain barrier and reach the perihematomal area in the striatum of mice with intracerebral hemorrhage. Intranasally administered rIL-10 primarily targets the cerebral cortex, striatum, and thalamus, traversing the olfactory nerve pathway and perivascular space to access these brain regions. This mode of delivery effectively mitigated secondary brain injury after intracerebral hemorrhage. This study contributes to intranasal drug delivery research, offering compelling evidence to support the intranasal delivery of anti-inflammatory cytokines or alternative drug candidates for treating brain diseases.

Oxytocin and autism: Insights from clinical trials and animal models

Autism spectrum disorder is a highly heritable and heterogeneous neurodevelopmental disorder, characterized by impaired social interactions and repetitive behaviors. Despite its complex etiology, increasing evidence has linked autism to the oxytocin system. The oxytocin peptide has long been known as the "social hormone," and has been shown to increase attention to social cues, elevate salience of socially relevant stimuli, and increase learning and reward in social situations. Reduced oxytocin levels and mutations in the oxytocin system have been reported in autism patients, while exogenously delivered oxytocin has been shown to alleviate social interaction deficits in both patients and animal models. Here, we summarize the results of recent clinical trials using oxytocin nasal spray to treat individuals with autism, as well as studies of autism animal models with oxytocin system deficits, and the rescue of their social behavior deficits by oxytocin. Finally, we discuss factors influencing clinical outcomes and reflect on future directions.

Extended kangaroo mother care - Examining the utility of skin-to-skin contact over the first year of life

OBJECTIVES

Kangaroo mother care which involves skin-to-skin contact (SSC) between mothers and newborns with support for exclusive breastfeeding, is an important innovation if practiced beyond the first week of life up to 1-year of age. We posit that extended SSC can benefit postpartum metabolic health.

STUDY DESIGN

Using a narrative literature review, we examine the interaction between hormones oxytocin and cortisol, which are either released or antagonized by the neural actions of skin-to-skin contact.

RESULTS

Oxytocin is released during SSC, which promotes attachment, improves parent-infant interactions and lowers levels of cortisol. No studies to date have reported SSC use beyond the first 5 to 7 weeks postpartum. Although no differences have been observed in infant body weight, increased head circumference has been noted among pre-term and low birth weight infants. Improved breastfeeding outcomes have also been observed. Oxytocin release is protective against type-2 diabetes and obesity in postpartum women, given its effects on β-cell function, improved insulin response and reduction of plasma glucose levels. Oxytocin has anti-inflammatory, analgesic and thermoregulatory effects. Hypothetical benefits due to oxytocin-cortisol dynamics, can be assumed for maternal posttraumatic stress, postpartum depression and anxiety. Sleep patterns, duration of crying and length of sleep are dose-dependent in effect. Postnatal skin-brain connection and thermoregulation via epidermal keratinocytes may mediate the relationship between SSC and autism spectrum disorder.

CONCLUSIONS

The extended use of SSC can lower dependence on pharmacotherapeutic options concerning postpartum mental health and galactagogue use while supporting maternal-infant psychosocial well-being and lowering stress via hormonal action and HPA-axis activation.

Oxytocin lipidation expanding therapeutics for long-term reversal of autistic behaviors in rats

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by deficits in social interaction and repetitive, stereotyped behaviors. There is no universally effective pharmacological treatment targeting its core symptoms.Oxytocin, an endogenous polypeptide known as the "social hormone", has shown potential in improving emotional recognition and social interactions in individuals with ASD. However, its clinical application has been limited due to its short half-life and poor blood-brain barrier penetration. To address these challenges, we utilized peptide lipidation technology to enhance the pharmacokinetic properties and brain bioavailability of oxytocin. A series of lipidated oxytocin analogs was designed and synthesized, exhibiting superior brain distribution and pharmacokinetic profiles in valproic acid-induced autistic rat models compared to unmodified oxytocin. Among theseanalogs, C16-modified oxytocin (C16-OT), administered intrathecally, achieved the most extensive brain distribution with limited presence in the blood, resulting in long-lasting improvements in autistic behaviors. These improvements, including enhanced social behaviors and reduced stereotypical actions, were sustained for up to 42 days, contrasting with the brief effects typically reported in previous studies. Furthermore, a comparison of administration routes revealed that intrathecal injection achieved higher brain concentrations and more prolonged social behavioral improvements than intranasal delivery. These findings provide robust preclinical evidence that C16-OT, through optimized lipidation and intrathecal delivery, offers sustained central nervous system activity and significant, long-term reversal of social behavioral deficits in rats with autism.

Oxytocin Protects PC12 Cells Against β-Amyloid-Induced Cell Injury

Background/Objectives: Neurodegenerative diseases, particularly Alzheimer's disease (AD), are characterized by progressive cognitive decline and non-cognitive symptoms that significantly affect health and quality of life. Beta-amyloid (Aβ) protein accumulation is a key factor in AD pathology, leading to neuronal damage. Oxytocin (OXT), a neuropeptide with neuroprotective potential, has garnered interest owing to its ability to mitigate neurotoxicity. We hypothesized that oxytocin could protect PC12 cells from Aβ-induced cytotoxicity through antioxidant effects and modulation of apoptotic pathways (i.e., mitochondrial and MAPK pathways). In this study, we aim to assess oxytocin's protective effects on cell viability, oxidative stress, mitochondrial function, and apoptotic signaling. Methods: PC12 cells were treated with Aβ25-35 and pre-treated with varying oxytocin concentrations to assess cell viability, reactive oxygen species (ROS) generation, and mitochondrial membrane potential. Western blotting was performed to analyze the effects on mitochondrial apoptosis and MAPK pathways. Results: Oxytocin treatment significantly improved cell viability in a dose-dependent manner and reduced Aβ-induced oxidative stress and mitochondrial dysfunction. Oxytocin-treated groups exhibited decreased ROS levels, increased mitochondrial membrane potential, and modulation of apoptosis-related proteins. Oxytocin upregulated phosphorylated ERK1/2 and Bcl-2 while downregulating BAX and caspase-3, reducing the BAX/Bcl-2 ratio. Conclusions: Oxytocin effectively protects PC12 cells from Aβ-induced neurotoxicity, highlighting its potential as a therapeutic agent for AD. Further research is needed to clarify oxytocin's mechanisms and clinical implications in AD treatment.

Oxytocin improves maternal licking behavior deficits in autism-associated Shank3 mutant dogs

Impaired social interaction and repetitive behavior are key features observed in individuals with autism spectrum disorder (ASD). SHANK3 is a high-confidence ASD risk gene that encodes an abundant scaffolding protein in the postsynaptic density. In wild-type (WT) domestic dogs, maternal behaviors such as licking and nursing (largely milk feeding) of puppies are most commonly observed. To address whether SHANK3 plays a role in social behaviors especially maternal behaviors, we analyzed Shank3 mutant dogs generated by CRISPR/Cas9 methodology. We found that Shank3 mutant dams exhibited a fewer and shorter licking behavior, as well as reduced nursing frequency when compared with WT dams. Additionally, a significant decrease in blood oxytocin (OXT) concentration was detected in Shank3 mutant dams. We thus conducted a vehicle-controlled experiment to examine whether a two-week intranasal OXT treatment, initiated on the 8th postpartum day, could rescue the maternal licking deficits in Shank3 mutant dams. We found that the decreased licking behavior in Shank3 mutant dams was significantly attenuated both acutely and chronically by OXT treatment. The rescue effect of OXT implicates an oxytocinergic contribution to the maternal defects in Shank3 mutant dams, suggesting a potential therapeutic strategy for SHANK3-associated ASD.

Toward effective oxytocin interventions in autism: Overcoming challenges and harnessing opportunities

Intranasal administration of oxytocin is emerging as a potential pharmacological option for mitigating social difficulties and regulating stress in autism spectrum disorder. However, initial single-dose and multiple-dose trials showed mixed results, with some demonstrating improvements in social and repetitive behavior and others showing no benefit over placebo. This perspective aims to elucidate factors contributing to this variability and to highlight pitfalls and opportunities in the field. We identified two major factors: design-related elements and individual participant characteristics. Pertaining to design-related elements, optimal dosing regimens have yet to be established, but appear to favor moderate intervention durations (i.e., 4-6 weeks) with intermittent and intermediate dosing (i.e., 24-32 IU every other day). Also, the context of the intervention seems crucial, as enhanced outcomes are mainly observed when oxytocin administration is paired with a socially stimulating and supporting environment. In addition, more adequate outcome measures have to be established to effectively assess oxytocin's impact, including behavioral scales and objective biophysiological markers tapping into stress and neurophysiological regulation. Future research should also account for individual participant differences in biological sex, developmental stage and cognitive and adaptive functioning, and incorporate (epi)genetic screening to identify responders. Overall, refining study designs and personalizing intervention protocols are essential for optimizing oxytocin's prosocial and anxiolytic effect in autism.

Intranasal oxytocin for apathy in people with frontotemporal dementia (FOXY): a multicentre, randomised, double-blind, placebo-controlled, adaptive, crossover, phase 2a/2b superiority trial

BACKGROUND

No treatments exist for apathy in people with frontotemporal dementia. Previously, in a randomised double-blind, placebo-controlled, dose-finding study, intranasal oxytocin administration in people with frontotemporal dementia improved apathy ratings on the Neuropsychiatric Inventory over 1 week and, in a randomised, double-blind, placebo-controlled, crossover study, a single dose of 72 IU oxytocin increased blood-oxygen-level-dependent signal in limbic brain regions. We aimed to determine whether longer treatment with oxytocin improves apathy in people with frontotemporal dementia.

METHODS

We conducted a multicentre, randomised, double-blind, placebo-controlled, adaptive, crossover, phase 2a/2b trial, enrolling participants from 11 expert frontotemporal dementia outpatient clinics across Canada and the USA. People aged 30-80 years with a diagnosis of probable frontotemporal dementia, a Neuropsychiatric Inventory apathy score of 2 or higher, a study partner who interacted with them for at least 3 h per day, and stable cognitive and behavioural medications for 30 days were eligible for inclusion. In stage 1, participants were randomly assigned (1:1:1:1:1:1) to one of three dose schedules (every day, every other day, and every third day) of 72 IU intranasal oxytocin or placebo and to the order they would received the intervention in the crossover; intranasal oxytocin or placebo were administered twice daily for 6 weeks, with a 6-week washout and then crossover to the other intervention. In stage 2, new participants were randomised (1:1) to the dose that had been determined as optimal in stage 1 or to placebo, with crossover as in stage 1. Randomisation used variable block sizes and was stratified by participant sex and Clinical Dementia Rating severity score. All kits of investigational product were identical and produced centrally, and all local teams, study staff, and participants were masked to treatment allocation and order. The primary outcome was difference in the change in Neuropsychiatric Inventory apathy scores for oxytocin versus placebo periods in the per-protocol population after 6 weeks of treatment. Safety was assessed at each visit via electrocardiogram, blood work, and collection of data on adverse events. This trial is registered at ClinicalTrials.gov (NCT03260920).

FINDINGS

Between Jan 31, 2018, and Dec 11, 2020, 70 patients were screened for stage 1 and 60 (86%) were enrolled. 45 (75%) completed both treatment periods of stage 1. 72 IU oxytocin every third day was the optimal dose schedule from stage 1 based on its Bayesian posterior probability (Pr(Best)=0·478). Between June 28, 2021, and Jan 31, 2023, 42 patients were screened for stage 2, and 34 (81%) were enrolled. 28 (82%) completed both treatment periods in stage 2. 38 (40%) of 94 participants were female and 56 (60%) were male (mean age 65·9 years, SD 8·2) Treatment with oxytocin every third day resulted in an improved Neuropsychiatric Inventory apathy score, with an estimated -1·32 points (95% CI -2·43 to -0·21) relative to placebo (one sided p=0·010). Two adverse events were reported in at least 5% of participants: upper respiratory tract infection (five [6%] of 78 participants on placebo and three [5%] on every third day at all doses of oxytocin) and headache (two [3%] participants on placebo, one [7%] of 15 participants on oxytocin every day, and two [4%] of 55 participants on oxytocin every third day). No adverse events were attributed to oxytocin treatment.

INTERPRETATION

Intranasal oxytocin given every third day was well tolerated and was associated with a small reduction in apathy in patients with frontotemporal dementia. Future trials might investigate intermittent dosing of more potent formulations than in this study, to establish whether larger effects are possible.

FUNDING

Canadian Institutes of Health Research and Weston Foundation.

How Do Common Marmosets Maintain the Balance Between Response Execution and Action Inhibition?

Socio-dynamic situations require a balance between response execution and action inhibition. Nonadaptive imbalance between response inhibition and execution exists in neurodevelopmental and neuropsychological disorders. To investigate the underlying neural mechanisms of cognitive control and the related deficits, comparative studies in human and nonhuman primates are crucial. Previous stop-signal tasks in humans and macaque monkeys have examined response execution (response time (RT) and accuracy in Go trials) and action inhibition (stop-signal reaction time (SSRT)). Even though marmosets are generally considered suitable translational animal models for research on social and cognitive deficits, their ability to inhibit behavior remains poorly characterized. We developed a marmoset stop-signal task, in which RT could be measured at millisecond resolution. All four marmosets performed many repeated Go trials with high accuracy (≥ 70%). Additionally, all marmosets successfully performed Stop trials. Using a performance-dependent tracking procedure, the accuracy in Stop trials was maintained around 50%, which enabled reliable SSRT estimates in marmosets for the first time. The mean SSRT values across sessions ranged between 677 and 1464 ms across the four marmosets. We also validated the suitability and practicality of this novel task for examining executive functions by testing the effects of a natural hormone, oxytocin, on response execution and action inhibition in marmosets. This marmoset model, for reliable (millisecond resolution) assessment of the balance between response execution and inhibition, will further facilitate studying the developmental alterations in inhibition ability and examining the effects of various contextual and environmental factors on marmosets' executive functions.

Oxytocin in autism: Rethinking treatment and research through a neurodivergent perspective

This perspective piece addresses critical challenges in oxytocin-based interventions for autism, drawing on neurodivergent perspectives to highlight key issues in research relevance and inclusivity. Although oxytocin has been posited to modulate social and routinized behaviors in autistic individuals, empirical findings on its efficacy remain inconsistent. We argue that these behavioral targets may reflect neurotypical biases, often disregarding autistic individuals' perspectives, thereby limiting intervention acceptability and efficacy. Past research has frequently excluded marginalized autistic populations, including individuals with intellectual disabilities or gender-diverse identities, exacerbating generalizability issues. This piece advocates for a reorientation of research objectives in autism, proposing a shift from modifying core autistic behaviors towards enhancing quality of life through participatory research. By integrating autistic perspectives into study design and outcome selection, researchers move away from deficit-oriented frameworks and instead prioritize socially valid outcomes, such as reducing anxiety and improving adaptive functioning. Further, the perspective piece critiques the reliance on animal models, which often lack translational validity due to autism's complex social and communicative dimensions. In closing, we underscore the importance of inclusive, reproducible autism research practices that align with the lived experiences and priorities of autistic individuals. Embracing participatory research, alongside rigorous methodological adjustments, can foster advancements that effectively support the well-being of the autistic community.

AST-001 versus placebo for social communication in children with autism spectrum disorder: A randomized clinical trial

AIM

This study examined the efficacy of AST-001 for the core symptoms of autism spectrum disorder (ASD) in children.

METHODS

This phase 2 clinical trial consisted of a 12-week placebo-controlled main study, a 12-week extension, and a 12-week follow-up in children aged 2 to 11 years with ASD. The participants were randomized in a 1:1:1 ratio to a high-dose, low-dose, or placebo-to-high-dose control group during the main study. The placebo-to-high-dose control group received placebo during the main study and high-dose AST-001 during the extension. The a priori primary outcome was the mean change in the Adaptive Behavior Composite (ABC) score of the Korean Vineland Adaptive Behavior Scales II (K-VABS-II) from baseline to week 12.

RESULTS

Among 151 enrolled participants, 144 completed the main study, 140 completed the extension, and 135 completed the follow-up. The mean K-VABS-II ABC score at the 12th week compared with baseline was significantly increased in the high-dose group (P = 0.042) compared with the placebo-to-high-dose control group. The mean CGI-S scores were significantly decreased at the 12th week in the high-dose (P = 0.046) and low-dose (P = 0.017) groups compared with the placebo-to-high-dose control group. During the extension, the K-VABS-II ABC and CGI-S scores of the placebo-to-high-dose control group changed rapidly after administration of high-dose AST-001 and caught up with those of the high-dose group at the 24th week. AST-001 was well tolerated with no safety concern. The most common adverse drug reaction was diarrhea.

CONCLUSIONS

Our results provide preliminary evidence for the efficacy of AST-001 for the core symptoms of ASD.

Oxytocin Reduces Noradrenergic-Induced Opioid-Like Withdrawal Symptoms in Individuals on Opioid Agonist Therapy

Background

Intranasal administration of the neuropeptide oxytocin has been explored as a potential therapeutic agent for substance use disorder including opioid use disorder (OUD).

Methods

This phase 1, crossover, randomized, double-blind, placebo-controlled trial tested the safety, tolerability, and efficacy of intranasal oxytocin (80 IU) twice a day for 7 days in participants (N = 20) with OUD who were taking an opioid agonist therapy. In the laboratory, participants underwent opioid cue exposure paired with noradrenergic activation produced by yohimbine (32.4 mg) or placebo. Assessments included, 1) subjective response: craving, withdrawal, anxiety, and stress; 2) biomedical markers: hypothalamic-pituitary-adrenal axis response (cortisol) and noradrenergic activation (α-amylase); and 3) safety measures: hemodynamics and adverse event evaluation. Generalized linear model with model-based estimator in the covariance matrix was used, with medication (oxytocin/placebo) and noradrenergic activation (yohimbine/placebo) as within-subject factors.

Results

Oxytocin significantly reduced opioid-like withdrawal, anxiety symptoms, and cortisol levels elicited by cue exposure under noradrenergic activation produced by yohimbine. This effect was specific because oxytocin did not reduce craving, hemodynamics, or α-amylase levels increased by yohimbine administration. A single dose of yohimbine elicited the noradrenergic stimulation, and 7-day oxytocin administration was safe and well tolerated among individuals diagnosed with OUD and taking opioid agonist therapy.

Conclusions

The findings of this study suggest that oxytocin alleviates opioid-like withdrawal symptoms and anxiety by modulating the hypothalamic-pituitary-adrenal axis.

Brain region-specific neural activation by low-dose opioid promotes social behavior

The opioid system plays crucial roles in modulating social behaviors in both humans and animals. However, the pharmacological profiles of opioids regarding social behavior and their therapeutic potential remain unclear. Multiple pharmacological, behavioral, and immunohistological c-Fos mapping approaches were used to characterize the effects of μ-opioid receptor agonists on social behavior and investigate the mechanisms in naive mice and autism spectrum disorder-like (ASD-like) mouse models, such as prenatally valproic acid-treated mice and Fmr1-KO mice. Here, we report that low-dose morphine, a μ-opioid receptor agonist, promoted social behavior by selectively activating neurons in prosocial brain regions, including the nucleus accumbens, but not those in the dorsomedial periaqueductal gray (dmPAG), which are only activated by analgesic high-dose morphine. Critically, intra-dmPAG morphine injection counteracted the prosocial effect of low-dose morphine, suggesting that dmPAG neural activation suppresses social behavior. Moreover, buprenorphine, a μ-opioid receptor partial agonist with less abuse liability and a well-established safety profile, ameliorated social behavior deficits in two mouse models recapitulating ASD symptoms by selectively activating prosocial brain regions without dmPAG neural activation. Our findings highlight the therapeutic potential of brain region-specific neural activation induced by low-dose opioids for social behavior deficits in ASD.

Nebulized vasopressin penetrates CSF and improves social cognition without inducing aggression in a rhesus monkey model of autism

Low cerebrospinal (CSF) arginine vasopressin (AVP) concentration is a biomarker of social impairment in low-social monkeys and children with autism, suggesting that AVP administration may improve primate social functioning. However, AVP administration also increases aggression, at least in "neurotypical" animals with intact AVP signaling. Here, we tested the effects of a voluntary drug administration method in low-social male rhesus monkeys with high autistic-like trait burden. Monkeys received nebulized AVP or placebo, using a within-subjects design. Study 1 (N = 8) investigated the effects of AVP administration on social cognition in two tests comparing responses to social versus nonsocial stimuli. Test 1: Placebo-administered monkeys lacked face recognition memory, whereas face recognition memory was "rescued" following AVP administration. In contrast, object recognition memory was intact and did not differ between administration conditions. Test 2: Placebo-administered monkeys did not respond to conspecific social communication cues, whereas following AVP administration, they reciprocated affiliative communication cues with species-typical affiliative responses. Importantly, AVP administration did not increase aggressive responses to conspecific aggressive or affiliative overtures. Study 2 (N = 4) evaluated the pharmacokinetics of this administration method. Following AVP nebulization, we observed a linear increase in cisternal CSF AVP levels, and a quadratic rise and fall in blood AVP levels. These findings indicate that nebulized AVP likely penetrates the central nervous system, selectively promotes species-typical responses to social information, and does not induce aggression in low-social individuals. Nebulized AVP therefore may hold promise for managing similar social symptoms in people with autism, particularly in very young or lower functioning individuals.

Oxytocin in neurodevelopmental disorders: Autism spectrum disorder and Prader-Willi syndrome

This manuscript reviews recent work on oxytocin and its use in neurodevelopmental disorders including spectrum disorder (ASD) and Prader-Willi syndrome (PWS). Oxytocin is involved in social recognition, bonding, maternal behaviors, anxiety, food motivation, and hyperphagia. While the pathophysiology of ASD and PWS involve abnormalities in the oxytocin system, clinical trials have shown discrepant results in the effectiveness of oxytocin as a treatment for core symptoms associated with these disorders. In this review, we outline oxytocin's clinical pharmacology, safety considerations, and results in recent clinical trials. We propose that oxytocin may be most beneficial in these populations if dosed in a dynamic regimen (PRN) and paired with social interventions.

Pharmacotherapy for the core symptoms of autism spectrum disorder

Autism spectrum disorder (ASD) is a range of neurodevelopmental diseases characterized by social dysfunction and stereotypic behaviors. The etiology of ASD remains largely unexplored, resulting in a diverse array of described clinical manifestations and varying degrees of severity. Currently, there are no drugs approved by a supervisory organization that can effectively treat the core symptoms of ASD. Childhood and adolescence are crucial stages for making significant achievements in ASD treatment, necessitating the development of drugs specifically for these periods. Based on the drug targets and mechanisms of action, it can be found that atypical psychotropic medications, anti-inflammatory and antioxidant medications, hormonal medications, ion channel medications, and gastrointestinal medications have shown significant improvement in treating the core symptoms of ASD in both children and adolescents. In addition, comparisons of drugs within the same category regarding efficacy and safety have been made to identify better alternatives and promote drug development. While further evaluation of the effectiveness and safety of these medications is needed, they hold great potential for widespread application in the clinical treatment of the principal symptoms of ASD.

Acute, chronic and conditioned effects of intranasal oxytocin in the mu-opioid receptor knockout mouse model of autism: Social context matters

Autism Spectrum Disorders (ASD) are neurodevelopmental disorders whose diagnosis relies on deficient social interaction and communication together with repetitive behaviours. Multiple studies have highlighted the potential of oxytocin (OT) to ameliorate behavioural abnormalities in animal models and subjects with ASD. Clinical trials, however, yielded disappointing results. Our study aimed at assessing the behavioural effects of different regimens of OT administration in the Oprm1 null mouse model of ASD. We assessed the effects of intranasal OT injected once at different doses (0.15, 0.3, and 0.6 IU) and time points (5, 15, and 30 min) following administration, or chronically, on ASD-related behaviours (social interaction and preference, stereotypies, anxiety, nociception) in Oprm1+/+ and Oprm1-/- mice. We then tested whether pairing intranasal OT injection with social experience would influence its outcome on ASD-like symptoms, and measured gene expression in the reward/social circuit. Acute intranasal OT at 0.3 IU improved social behaviour in Oprm1-/- mice 5 min after administration, with limited effects on non-social behaviours. Chronic (8-17 days) OT maintained rescuing effects in Oprm1 null mice but was deleterious in wild-type mice. Finally, improvements in the social behaviour of Oprm1-/- mice were greater and longer lasting when OT was administered in a social context. Under these conditions, the expression of OT and vasopressin receptor genes, as well as marker genes of striatal projection neurons, was suppressed. We detected no sex difference in OT effects. Our results highlight the importance of considering dosage and social context when evaluating the effects of OT treatment in ASD.

Deciphering autism heterogeneity: a molecular stratification approach in four mouse models

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by impairments in social interaction and communication, as well as restrained or stereotyped behaviors. The inherent heterogeneity within the autism spectrum poses challenges for developing effective pharmacological treatments targeting core features. Successful clinical trials require the identification of robust markers to enable patient stratification. In this study, we identified molecular markers within the oxytocin and immediate early gene families across five interconnected brain structures of the social circuit. We used wild-type and four heterogeneous mouse models, each exhibiting unique autism-like behaviors modeling the autism spectrum. While dysregulations in the oxytocin family were model-specific, immediate early genes displayed widespread alterations, reflecting global changes across the four models. Through integrative analysis, we identified Egr1, Foxp1, Homer1a, Oxt, and Oxtr as five robust and discriminant molecular markers that allowed the successful stratification of the four models. Importantly, our stratification demonstrated predictive values when challenged with a fifth mouse model or identifying subgroups of mice potentially responsive to oxytocin treatment. Beyond providing insights into oxytocin and immediate early gene mRNA dynamics, this proof-of-concept study represents a significant step toward the potential stratification of individuals with ASD. This work has implications for the success of clinical trials and the development of personalized medicine in autism.

Nontraditional models as research tools: the road not taken

Historical reasons resulted in the almost exclusive use of a few species, most prominently Mus musculus, as the mainstream models in biomedical research. This selection was not based on Mus's distinctive relevance to human disease but rather to the pre-existing availability of resources and tools for the species that were used as models, which has enabled their adoption for research in health sciences. Unless the utilization and range of nontraditional research models expand considerably, progress in biomedical research will remain restricted within the trajectory that has been set by the existing models and their ability to provide clinically relevant information.

The effects of oxytocin administration on social and routinized behaviors in autism: A preregistered systematic review and meta-analysis

Oxytocin administration has demonstrated considerable promise for providing individualized support for autistic people. However, studies evaluating the effects of oxytocin administration on autistic characteristics have yielded inconsistent results. This systematic review and meta-analysis investigates the effect of oxytocin administration on social and routinized behaviors in autism using recently developed methods to accurately assess the potential impact of effect size dependency and publication bias. Our frequentist meta-analysis yielded a significant summary effect size estimate for the impact of oxytocin administration on social outcomes in autism (d = 0.22, p < 0.001). The summary effect size estimate for routinized behavior outcomes was not statistically significant (d = 0.14, p = 0.22), with a follow up test indicating that the effect size estimate was not either statistically equivalent (Z = -1.06, p = 0.2), assuming a smallest effect size of interest of 0.25. Frequentist and Bayesian assessments for publication bias, as well as results from Robust Bayesian meta-analysis of oxytocin effects on social outcomes in autism, indicated that summary effect sizes might be inflated due to publication bias. Future studies should aim to reduce bias by preregistering analysis plans and to increase precision with larger sample sizes.

Digital interventions for autism spectrum disorders: A systematic review and meta-analysis

Importance

Digital technology is now widely available for the interventions of autism, but its validity and feasibility remain to be proved.

Objective

This study aimed to investigate the effectiveness of digital health interventions (DHIs) in improving core symptoms or intelligence quotient in patients with autism spectrum disorder (ASD).

Methods

Three databases including PubMed, Cochrane, and Scopus, were searched on November 15, 2022. Randomized clinical trials that enrolled patients with ASD who received DHIs and a control group without DHI treatment were included. Cochrane risk of bias tool (RoB 2) was applied to assess the risk of bias.

Results

A total of 33 studies, involving 1285 participants (658 [51.2%] in DHI groups and 627 [48.8%] in control groups), were analyzed to investigate the differences between DHI groups and control groups. Significantly greater improvements in the overall performance of ASD were observed in the DHI groups compared to the control groups (including active, waitlist, treatment-as-usual, and no treatment) with an effect size of 1.89 (Cohen's d 95% confidence interval [CI]: 1.26-2.52). Studies with treatment-as-usual, waitlist, and no treatment control demonstrated large effect sizes of Cohen's d 3.41 (95% CI: 0.84-5.97), Cohen's d 4.27 (95% CI: 1.95-6.59), and Cohen's d 4.52 (95% CI: 2.98-6.06) respectively. In contrast, studies with active control revealed insignificant effect sizes (Cohen's d 0.73, 95% CI: 0.12-1.33).

Interpretation

This meta-analysis found significantly greater improvements in core symptoms or intelligence quotient in ASD patients receiving DHIs compared to those in control conditions. ASD patients may benefit from the DHIs and reduce the economic burden.

Augmented-reality-based multi-person exercise has more beneficial effects on mood state and oxytocin secretion than standard solitary exercise

BACKGROUND

Exercise has positive effects on psychological well-being, with team sports often associated with superior mental health compared to individual sports. Augmented reality (AR) technology has the potential to convert solitary exercise into multi-person exercise. Given the role of oxytocin in mediating the psychological benefits of exercise and sports, this study aimed to investigate the impact of AR-based multi-person exercise on mood and salivary oxytocin levels.

METHODS

Fourteen participants underwent three distinct regimens: non-exercise (Rest), standard solitary cycling exercise (Ex), and AR-based multi-person cycling exercise (Ex+AR). In both Ex and Ex+AR conditions, participants engaged in cycling at a self-regulated pace to maintain a Rating of Perceived Exertion of 10. In the Ex+AR condition, participants' avatars were projected onto a tablet screen, allowing them to cycle alongside ten other virtual avatars in an AR environment. Mood states and saliva samples were collected before and immediately after each 10-minute regimen. Subsequently, salivary oxytocin levels were measured.

RESULTS

Notably, only the Ex+AR condition significantly improved mood states associated with depression-dejection and exhibited a non-significant trend toward suppressing anger-hostility in participants. Moreover, the Ex+AR condition led to a significant elevation in salivary oxytocin levels, while the Ex condition showed a non-significant trend toward an increase. However, changes in salivary oxytocin did not show a significant correlation with changes in mood states.

CONCLUSIONS

These findings suggest that Ex+AR enhances mood states and promotes oxytocin release. AR-based multi-person exercise may offer greater psychological benefits compared to standard solitary exercise, although the relationship between oxytocin and mood changes remains inconclusive.

Adaptive Behavior in Young Autistic Children: Associations with Irritability and ADHD Symptoms

Attention-deficit/hyperactivity disorder (ADHD) symptoms affect 40-60% of autistic children and have been linked to differences in adaptive behavior. It is unclear whether adaptive behavior in autistic youth is directly impacted by co-occurring ADHD symptoms or by another associated feature of both autism and ADHD, such as increased irritability. The current study examined relationships between irritability, ADHD symptoms, and adaptive behavior in 3- to 7-year-old autistic children. Results suggest that, after adjusting for co-occurring ADHD symptoms, higher levels of irritability are associated with differences in social adaptive behavior specifically. Understanding relationships between irritability, ADHD, and adaptive behavior in autistic children is critical because measures of adaptive behavior, such as the Vineland Scales of Adaptive Functioning, are often used as a proxy for global functioning, as well as for developing intervention plans and measuring outcomes as primary endpoints in clinical trials.

Oxytocin Protects Nigrostriatal Dopamine Signal via Activating GABAergic Circuit in the MPTP-Induced Parkinson's Disease Model

The most pronounced neuropathological feature of Parkinson's disease (PD) is the loss of dopamine (DA) neurons in the substantia nigra compacta (SNc), which depletes striatal DA. Hypothalamic oxytocin is found to be reduced in PD patients and closely interacts with the DA system, but the role of oxytocin in PD remains unclear. Here, the disturbances of endogenous oxytocin level and the substantia nigra (SN) oxytocin receptor expression in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model is observed, correlated with the striatal tyrosine hydroxylase (TH) expression reduction. Killing/silencing hypothalamic oxytocin neurons aggravates the vulnerability of nigrostriatal DA signal to MPTP, whereas elevating oxytocin level by intranasal delivery or microinjecting into the SN promotes the resistance. In addition, knocking out SN oxytocin receptors induces the time-dependent reductions of SNc DA neurons, striatal TH expression, and striatal DA level by increasing neuronal excitotoxicity. These results further uncover that oxytocin dampens the excitatory synaptic inputs onto DA neurons via activating oxytocin receptor-expressed SN GABA neurons, which target GABA(B) receptors expressed in SNc DA neuron-projecting glutamatergic axons, to reduce excitotoxicity. Thus, besides the well-known prosocial effect, oxytocin acts as a key endogenous factor in protecting the nigrostriatal DA system.

A clustering approach identifies an Autism Spectrum Disorder subtype more responsive to chronic oxytocin treatment

Over the last decade, a number of clinical trials have reported effects of chronic treatment with intranasal oxytocin on autistic symptoms but with inconsistent findings. Autism is a heterogeneous disorder and one factor which may influence treatment outcome is whether a subtype of individuals is more sensitive to oxytocin. In a recent cross-over trial on 41 young autistic children we reported that 44% showed a reliable improvement in clinical symptoms (Autism Diagnostic Observation Schedule, ADOS-2) after a placebo-controlled, 6-week intranasal oxytocin intervention where treatment was given every other day followed by a period of positive social interaction. In the current re-assessment of the data, we used an unsupervised data-driven cluster analysis approach to identify autism subtypes using 23 different demographic, social subtype, endocrine, eye-tracking and clinical symptom measures taken before treatment and this revealed an optimum of two different subtypes. We then assessed the proportion of identified responders to oxytocin and found that while 61.5% of one subtype included responders only 13.3% of the other did so. During the placebo phase there was no difference between the two subtypes for the small proportion of responders (19.2% vs 6.7%). This oxytocin-sensitive subtype also showed overall significant post-treatment clinical and eye-tracking measure changes. The oxytocin-sensitive subtype was primarily characterized at baseline by lower initial clinical severity (ADOS-2) and greater interest in the eye-region of emotional faces. These features alone were nearly as efficient in identifying the two subtypes as all 23 baseline measures and this easy-to-conduct approach may help rapidly and objectively screen for oxytocin responders. Future clinical trials using oxytocin interventions may therefore achieve greater success by focusing on children with this specific autism subtype and help develop individualized oxytocin intervention.

Unlocking potential of oxytocin: improving intracranial lymphatic drainage for Alzheimer's disease treatment

Background: The impediment to β-amyloid (Aβ) clearance caused by the invalid intracranial lymphatic drainage in Alzheimer's disease is pivotal to its pathogenesis, and finding reliable clinical available solutions to address this challenge remains elusive. Methods: The potential role and underlying mechanisms of intranasal oxytocin administration, an approved clinical intervention, in improving intracranial lymphatic drainage in middle-old-aged APP/PS1 mice were investigated by live mouse imaging, ASL/CEST-MRI scanning, in vivo two-photon imaging, immunofluorescence staining, ELISA, RT-qPCR, Western blotting, RNA-seq analysis, and cognitive behavioral tests. Results: Benefiting from multifaceted modulation of cerebral hemodynamics, aquaporin-4 polarization, meningeal lymphangiogenesis and transcriptional profiles, oxytocin administration normalized the structure and function of both the glymphatic and meningeal lymphatic systems severely impaired in middle-old-aged APP/PS1 mice. Consequently, this intervention facilitated the efficient drainage of Aβ from the brain parenchyma to the cerebrospinal fluid and then to the deep cervical lymph nodes for efficient clearance, as well as improvements in cognitive deficits. Conclusion: This work broadens the underlying neuroprotective mechanisms and clinical applications of oxytocin medication, showcasing its promising therapeutic prospects in central nervous system diseases with intracranial lymphatic dysfunction.

Resolving neuroinflammatory and social deficits in ASD model mice: Dexmedetomidine downregulates NF-κB/IL-6 pathway via α2AR

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that severely affects individuals' daily life and social development. Unfortunately, there are currently no effective treatments for ASD. Dexmedetomidine (DEX) is a selective agonist of α2 adrenergic receptor (α2AR) and is widely used as a first-line medication for sedation and hypnosis in clinical practice. In recent years, there have been reports suggesting its potential positive effects on improving emotional and cognitive functions. However, whether dexmedetomidine has therapeutic effects on the core symptoms of ASD, namely social deficits and repetitive behaviors, remains to be investigated. In the present study, we employed various behavioral tests to assess the phenotypes of animals, including the three-chamber, self-grooming, marble burying, open field, and elevated plus maze. Additionally, electrophysiological recordings, western blotting, qPCR were mainly used to investigate and validate the potential mechanisms underlying the role of dexmedetomidine. We found that intraperitoneal injection of dexmedetomidine in ASD model mice-BTBR T+ Itpr3tf/J (BTBR) mice could adaptively improve their social deficits. Further, we observed a significant reduction in c-Fos positive signals and interleukin-6 (IL-6) expression level in the prelimbic cortex (PrL) of the BTBR mice treated with dexmedetomidine. Enhancing or inhibiting the action of IL-6 directly affects the social behavior of BTBR mice. Mechanistically, we have found that NF-κB p65 is a key pathway regulating IL-6 expression in the PrL region. In addition, we have confirmed that the α2AR acts as a receptor switch mediating the beneficial effects of dexmedetomidine in improving social deficits. This study provides the first evidence of the beneficial effects of dexmedetomidine on core symptoms of ASD and offers a theoretical basis and potential therapeutic approach for the clinical treatment of ASD.

Transcriptome analysis identifies an ASD-Like phenotype in oligodendrocytes and microglia from C58/J amygdala that is dependent on sex and sociability

BACKGROUND

Autism Spectrum Disorder (ASD) is a group of neurodevelopmental disorders with higher incidence in males and is characterized by atypical verbal/nonverbal communication, restricted interests that can be accompanied by repetitive behavior, and disturbances in social behavior. This study investigated brain mechanisms that contribute to sociability deficits and sex differences in an ASD animal model.

METHODS

Sociability was measured in C58/J and C57BL/6J mice using the 3-chamber social choice test. Bulk RNA-Seq and snRNA-Seq identified transcriptional changes in C58/J and C57BL/6J amygdala within which DMRseq was used to measure differentially methylated regions in amygdala.

RESULTS

C58/J mice displayed divergent social strata in the 3-chamber test. Transcriptional and pathway signatures revealed immune-related biological processes differ between C58/J and C57BL/6J amygdala. Hypermethylated and hypomethylated genes were identified in C58/J versus C57BL/6J amygdala. snRNA-Seq data in C58/J amygdala identified differential transcriptional signatures within oligodendrocytes and microglia characterized by increased ASD risk gene expression and predicted impaired myelination that was dependent on sex and sociability. RNA velocity, gene regulatory network, and cell communication analysis showed diminished oligodendrocyte/microglia differentiation. Findings were verified using Bulk RNA-Seq and demonstrated oxytocin's beneficial effects on myelin gene expression.

LIMITATIONS

Our findings are significant. However, limitations can be noted. The cellular mechanisms linking reduced oligodendrocyte differentiation and reduced myelination to an ASD phenotype in C58/J mice need further investigation. Additional snRNA-Seq and spatial studies would determine if effects in oligodendrocytes/microglia are unique to amygdala or if this occurs in other brain regions. Oxytocin's effects need further examination to understand its' potential as an ASD therapeutic.

CONCLUSIONS

Our work demonstrates the C58/J mouse model's utility in evaluating the influence of sex and sociability on the transcriptome in concomitant brain regions involved in ASD. Our single-nucleus transcriptome analysis elucidates potential pathological roles of oligodendrocytes and microglia in ASD. This investigation provides details regarding regulatory features disrupted in these cell types, including transcriptional gene dysregulation, aberrant cell differentiation, altered gene regulatory networks, and changes to key pathways that promote microglia/oligodendrocyte differentiation. Our studies provide insight into interactions between genetic risk and epigenetic processes associated with divergent affiliative behavior and lack of positive sociability.

Oxytocin alleviates liver fibrosis via hepatic macrophages

Background & Aims

Previous studies demonstrated oxytocin treatment effectiveness in reducing mortality and reversing liver fibrosis in mice. However, the underlying mechanism remains obscure, given the absence of oxytocin receptor expression in hepatic stellate cells, the primary liver fibrosis effector cells.

Methods

A comprehensive map of cell populations in fibrotic liver was generated using single-cell sequencing. The map enabled our study of the target cells of oxytocin action in the liver in more dimensions. Furthermore, we elucidated the mechanism of the oxytocin signaling system in hepatic macrophages using oxytocin receptor-specific knockout mice and liver fibrosis animal models.

Results

The carbon tetrachloride-induced hepatic fibrosis and bile duct ligation hepatic fibrosis mouse models demonstrated that oxytocin reversed hepatic fibrosis in mice. The mapped liver cell populations demonstrated that oxytocin promoted the phenotypic switch from Ly6high to Ly6Clow in myeloid-derived macrophages. The phenotypic control of oxytocin signaling system activation on this phenotypic switch was validated using myeloid-specific oxytocin receptor knockout mice. Subsequent studies demonstrated that the calcium inward flow induced by oxytocin receptor activation activated the key orphan nuclear receptor NR4A1, which controls macrophage phenotypic switching. Specifically, calcium ions activated CREB, a key target regulator of NR4A1 expression.

Conclusions

The findings established hepatic macrophages as a hub responsible for the oxytocin-mediated alleviation of liver fibrosis. This study revealed a novel pathway where oxytocin regulates macrophage phenotype.

Impact and implications

Previous studies revealed for the first time the expression of oxytocin receptors in the liver. The present study shows that oxytocin reverses hepatic fibrosis and that hepatic macrophages are the central hub of oxytocin-mediated alleviation of hepatic fibrosis by promoting a phenotypic switch in hepatic macrophages, transitioning from Ly6high to Ly6Clow expression. The present study reveals a novel pathway by which oxytocin regulates macrophage phenotype. In addition, the potential applications of oxytocin and its analogues, as traditional drugs for clinical application, in the treatment of liver fibrosis deserve to be further explored.

Intranasal oxytocin as a treatment for anxiety and autism: From subclinical to clinical applications

Animal and human studies have demonstrated that intranasal oxytocin (OT) can penetrate the brain and induce cognitive, emotional, and behavioral changes, particularly in social functioning. Consequently, numerous investigations have explored the potential of OT as a treatment for anxiety and autism, conditions characterized by social deficits. Although both subclinical and clinical studies provide converging evidence of the therapeutic effects of OT in reducing anxiety levels and improving social symptoms in autism, results are not always consistent. Additionally, the pharmacological mechanism of OT requires further elucidation for its effective clinical application. Therefore, this review aims to examine the contentious findings concerning the effects of OT on anxiety and autism, offer interpretations of the inconsistent results from the perspectives of individual differences and varying approaches to OT administration, and shed light on the underlying mechanisms of OT. Ultimately, standardization of dosage, frequency of administration, formulation characteristics, and nasal spray devices is proposed as essential for future human studies and clinical applications of OT treatment.

Long-range projections of oxytocin neurons in the marmoset brain

The neurohormone oxytocin (OT) has become a major target for the development of novel therapeutic strategies to treat psychiatric disorders such as autism spectrum disorder because of its integral role in governing many facets of mammalian social behavior. Whereas extensive work in rodents has produced much of our knowledge of OT, we lack basic information about its neurobiology in primates making it difficult to interpret the limited effects that OT manipulations have had in human patients. In fact, previous studies have revealed only limited OT fibers in primate brains. Here, we investigated the OT connectome in marmoset using immunohistochemistry, and mapped OT fibers throughout the brains of adult male and female marmoset monkeys. We found extensive OT projections reaching limbic and cortical areas that are involved in the regulation of social behaviors, such as the amygdala, the medial prefrontal cortex, and the basal ganglia. The pattern of OT fibers observed in marmosets is notably similar to the OT connectomes described in rodents. Our findings here contrast with previous results by demonstrating a broad distribution of OT throughout the marmoset brain. Given the prevalence of this neurohormone in the primate brain, methods developed in rodents to manipulate endogenous OT are likely to be applicable in marmosets.

Altered projection-specific synaptic remodeling and its modification by oxytocin in an idiopathic autism marmoset model

Alterations in the experience-dependent and autonomous elaboration of neural circuits are assumed to underlie autism spectrum disorder (ASD), though it is unclear what synaptic traits are responsible. Here, utilizing a valproic acid-induced ASD marmoset model, which shares common molecular features with idiopathic ASD, we investigate changes in the structural dynamics of tuft dendrites of upper-layer pyramidal neurons and adjacent axons in the dorsomedial prefrontal cortex through two-photon microscopy. In model marmosets, dendritic spine turnover is upregulated, and spines are generated in clusters and survived more often than in control marmosets. Presynaptic boutons in local axons, but not in commissural long-range axons, demonstrate hyperdynamic turnover in model marmosets, suggesting alterations in projection-specific plasticity. Intriguingly, nasal oxytocin administration attenuates clustered spine emergence in model marmosets. Enhanced clustered spine generation, possibly unique to certain presynaptic partners, may be associated with ASD and be a potential therapeutic target.

From Parental Behavior to Sexual Function: Recent Advances in Oxytocin Research

Purpose of Review

Oxytocin plays many diverse roles in physiological and behavioral processes, including social activity, parental nurturing, stress responses, and sexual function. In this narrative review, we provide an update on the most noteworthy recent findings in this fascinating field.

Recent Findings

The development of techniques such as serial two-photon tomography and fiber photometry have provided a window into oxytocin neuroanatomy and real-time neuronal activity during social interactions. fMRI and complementary mapping techniques offer new insights into oxytocin's influence on brain activity and connectivity. Indeed, oxytocin has recently been found to influence the acquisition of maternal care behaviors and to mediate the influence of social touch on brain development and social interaction. Additionally, oxytocin plays a crucial role in male sexual function, affecting erectile activity and ejaculation, while its role in females remains controversial. Recent studies also highlight oxytocin's interaction with other neuropeptides, such as melanin-concentrating hormone, serotonin, and arginine vasopressin, influencing social and affective behaviors. Finally, an update is provided on the status of clinical trials involving oxytocin as a therapeutic intervention.

Summary

The exploration of oxytocin's complexities and its interplay with other neuropeptides holds promise for targeted treatment in various health and disease contexts. Overall, these findings contribute to the discovery of new and specific pathways to allow therapeutic targeting of oxytocin to treat disorders.

Psychopharmacology Management in Autism Spectrum Disorder

Persons with autism spectrum disorder (ASD) may have other psychiatric conditions that warrant treatment. Symptoms may not be easy to discern from rigidity or irritability that are sometimes considered to be constituent parts of ASD. Pathophysiology that involves hyperexcitable neurons and anomalous connectivity may provide justification for using psychopharmacologic agents, although nonmedical strategies may also be effective. Hyperactivity, irritability, and tantrums with or without aggression may be rational targets for psychopharmacological intervention. The best-studied drug class to date has been the second-generation antipsychotics targeting irritability.

An Update on Psychopharmacological Treatment of Autism Spectrum Disorder

While behavioral interventions remain the mainstay of treatment of autism spectrum disorder (ASD), several potential targeted treatments addressing the underlying neurophysiology of ASD have emerged in the last few years. These are promising for the potential to, in future, become part of the mainstay treatment in addressing the core symptoms of ASD. Although it is likely that the development of future targeted treatments will be influenced by the underlying heterogeneity in etiology, associated genetic mechanisms influencing ASD are likely to be the first targets of treatments and even gene therapy in the future for ASD. In this article, we provide a review of current psychopharmacological treatment in ASD including those used to address common comorbidities of the condition and upcoming new targeted approaches in autism management. Medications including metformin, arbaclofen, cannabidiol, oxytocin, bumetanide, lovastatin, trofinetide, and dietary supplements including sulforophane and N-acetylcysteine are discussed. Commonly used medications to address the comorbidities associated with ASD including atypical antipsychotics, serotoninergic agents, alpha-2 agonists, and stimulant medications are also reviewed. Targeted treatments in Fragile X syndrome (FXS), the most common genetic disorder leading to ASD, provide a model for new treatments that may be helpful for other forms of ASD. Appeared originally in Neurotherapeutics 2022; 19:248-262.

Melanocortin agonism in a social context selectively activates nucleus accumbens in an oxytocin-dependent manner

Social deficits are debilitating features of many psychiatric disorders, including autism. While time-intensive behavioral therapy is moderately effective, there are no pharmacological interventions for social deficits in autism. Many studies have attempted to treat social deficits using the neuropeptide oxytocin for its powerful neuromodulatory abilities and influence on social behaviors and cognition. However, clinical trials utilizing supplementation paradigms in which exogenous oxytocin is chronically administered independent of context have failed. An alternative treatment paradigm suggests pharmacologically activating the endogenous oxytocin system during behavioral therapy to enhance the efficacy of therapy by facilitating social learning. To this end, melanocortin receptor agonists like Melanotan II (MTII), which induces central oxytocin release and accelerates formation of partner preference, a form of social learning, in prairie voles, are promising pharmacological tools. To model pharmacological activation of the endogenous oxytocin system during behavioral therapy, we administered MTII prior to social interactions between male and female voles. We assessed its effect on oxytocin-dependent activity in brain regions subserving social learning using Fos expression as a proxy for neuronal activation. In non-social contexts, MTII only activated hypothalamic paraventricular nucleus, a primary site of oxytocin synthesis. However, during social interactions, MTII selectively increased oxytocin-dependent activation of nucleus accumbens, a site critical for social learning. These results suggest a mechanism for the MTII-induced acceleration of partner preference formation observed in previous studies. Moreover, they are consistent with the hypothesis that pharmacologically activating the endogenous oxytocin system with a melanocortin agonist during behavioral therapy has potential to facilitate social learning.

The neurobiological effects of childhood maltreatment on brain structure, function, and attachment

Childhood maltreatment is a risk factor for psychopathologies, and influences brain development at specific periods, particularly during early childhood and adolescence. This narrative review addresses phenotypic alterations in sensory systems associated with specific types of childhood maltreatment exposure, periods of vulnerability to the neurobiological effects of maltreatment, and the relationships between childhood maltreatment and brain structure, function, connectivity, and network architecture; psychopathology; and resilience. It also addresses neurobiological alterations associated with maternal communication and attachment disturbances, and uses laboratory-based measures during infancy and case-control studies to elucidate neurobiological alterations in reactive attachment disorders in children with maltreatment histories. Moreover, we review studies on the acute effects of oxytocin on reactive attachment disorder and maltreatment and methylation of oxytocin regulatory genes. Epigenetic changes may play a critical role in initiating or producing the atypical structural and functional brain alterations associated with childhood maltreatment. However, these changes could be reversed through psychological and pharmacological interventions, and by anticipating or preventing the emergence of brain alterations and subsequent psychopathological risks.

Autism spectrum disorder: pathogenesis, biomarker, and intervention therapy

Autism spectrum disorder (ASD) has become a common neurodevelopmental disorder. The heterogeneity of ASD poses great challenges for its research and clinical translation. On the basis of reviewing the heterogeneity of ASD, this review systematically summarized the current status and progress of pathogenesis, diagnostic markers, and interventions for ASD. We provided an overview of the ASD molecular mechanisms identified by multi-omics studies and convergent mechanism in different genetic backgrounds. The comorbidities, mechanisms associated with important physiological and metabolic abnormalities (i.e., inflammation, immunity, oxidative stress, and mitochondrial dysfunction), and gut microbial disorder in ASD were reviewed. The non-targeted omics and targeting studies of diagnostic markers for ASD were also reviewed. Moreover, we summarized the progress and methods of behavioral and educational interventions, intervention methods related to technological devices, and research on medical interventions and potential drug targets. This review highlighted the application of high-throughput omics methods in ASD research and emphasized the importance of seeking homogeneity from heterogeneity and exploring the convergence of disease mechanisms, biomarkers, and intervention approaches, and proposes that taking into account individuality and commonality may be the key to achieve accurate diagnosis and treatment of ASD.

Cannabinoid treatment for the symptoms of autism spectrum disorder

INTRODUCTION

Autism spectrum disorder (ASD) is a neurodevelopmental disorder affecting approximately 3% of school-age children. The core symptoms are deficits in social communication and restricted and repetitive patterns of behavior. Associated problems in cognition, language, behavior, sleep and mood are prevalent. Currently, no established pharmacological treatment exists for core ASD symptoms. Risperidone and aripiprazole are used to manage associated irritability, but their effectiveness is limited and adverse events are common.

AREAS COVERED

This mini-review summarizes existing scientific literature and ongoing clinical trials concerning cannabinoid treatment for ASD. Uncontrolled case series have documented improvements in both core ASD symptoms and related behavioral challenges in children treated with cannabis extracts rich in cannabidiol (CBD). Placebo-controlled studies involving CBD-rich cannabis extracts and/or pure CBD in children with ASD have demonstrated mixed efficacy results. A similar outcome was observed in a placebo-controlled study of pure CBD addressing social avoidance in Fragile X syndrome. Importantly, these studies have shown relatively high safety and tolerability.

EXPERT OPINION

While current clinical data suggest the potential of CBD and CBD-rich cannabis extract in managing core and behavioral deficits in ASD, it is prudent to await the results of ongoing placebo-controlled trials before considering CBD treatment for ASD.

Intranasal oxytocin in a genetic animal model of autism

Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders mainly characterized by deficient sociability and repetitive behaviors. Effective treatment for the core symptoms of ASD is still lacking. Behavioral interventions show limited effectiveness, while pharmacotherapy focuses on the amelioration of secondary symptomatology. Oxytocin (OXT) is a neuropeptide known for its prosocial impact, making it a candidate drug for ASD treatment. Its alleviating effect has been and still is widely researched, but outcomes reported by clinical studies are ambiguous. We examined the effect of daily intranasal OXT (0.8 IU/kg) administration for 4 weeks on the ASD-like phenotype in Shank3-/- adult mice. Animals treated with OXT spent twice as much time interacting with the social partner as early as after 2 weeks of treatment. Furthermore, OXT-treated mice exhibited reduced explorative behavior by 50%, after 4 weeks of treatment, and a 30% reduction in repetitive behavior, 4 weeks after treatment termination. One-fold higher sociability and 30% reduced exploration due to OXT lasted up to 4 weeks following the treatment termination. However, social disinterest was elevated by roughly 10% as well, indicating a form of social ambivalence. Obtained results support the therapeutic potential of intranasally administered OXT in alleviating social shortfalls in a genetic model of ASD. Subsequent research is necessary to elucidate the benefits and risks of the long-term OXT administration, as well as its applicability in other ASD models and the potential treatment effect on social communication, which was not measured in the present study.

Transcriptome Analysis Identifies An ASD-Like Phenotype In Oligodendrocytes And Microglia From C58/J Amygdala That Is Dependent On Sex and Sociability

Background

Autism Spectrum Disorder (ASD) is a group of neurodevelopmental disorders with higher incidence in males and is characterized by atypical verbal/nonverbal communication, restricted interests that can be accompanied by repetitive behavior, and disturbances in social behavior. This study investigated brain mechanisms that contribute to sociability deficits and sex differences in an ASD animal model.

Methods

Sociability was measured in C58/J and C57BL/6J mice using the 3-chamber social choice test. Bulk RNA-Seq and snRNA-Seq identified transcriptional changes in C58/J and C57BL/6J amygdala within which DMRseq was used to measure differentially methylated regions in amygdala.

Results

C58/J mice displayed divergent social strata in the 3-chamber test. Transcriptional and pathway signatures revealed immune-related biological processes differ between C58/J and C57BL/6J amygdala. Hypermethylated and hypomethylated genes were identified in C58/J versus C57BL/6J amygdala. snRNA-Seq data in C58/J amygdala identified differential transcriptional signatures within oligodendrocytes and microglia characterized by increased ASD risk gene expression and predicted impaired myelination that was dependent on sex and sociability. RNA velocity, gene regulatory network, and cell communication analysis showed diminished oligodendrocyte/microglia differentiation. Findings were verified using bulk RNA-Seq and demonstrated oxytocin's beneficial effects on myelin gene expression.

Limitations

Our findings are significant. However, limitations can be noted. The cellular mechanisms linking reduced oligodendrocyte differentiation and reduced myelination to an ASD phenotype in C58/J mice need further investigation. Additional snRNA-Seq and spatial studies would determine if effects in oligodendrocytes/microglia are unique to amygdala or if this occurs in other brain regions. Oxytocin's effects need further examination to understand its potential as an ASD therapeutic.

Conclusions

Our work demonstrates the C58/J mouse model's utility in evaluating the influence of sex and sociability on the transcriptome in concomitant brain regions involved in ASD. Our single-nucleus transcriptome analysis elucidates potential pathological roles of oligodendrocytes and microglia in ASD. This investigation provides details regarding regulatory features disrupted in these cell types, including transcriptional gene dysregulation, aberrant cell differentiation, altered gene regulatory networks, and changes to key pathways that promote microglia/oligodendrocyte differentiation. Our studies provide insight into interactions between genetic risk and epigenetic processes associated with divergent affiliative behavior and lack of positive sociability.

Precision microbial intervention improves social behavior but not autism severity: A pilot double-blind randomized placebo-controlled trial

Autism spectrum disorder (ASD) is characterized by the presence of restricted/repetitive behaviors and social communication deficits. Because effective treatments for ASD remain elusive, novel therapeutic strategies are necessary. Preclinical studies show that L. reuteri selectively reversed social deficits in several models for ASD. Here, in a double-blind, randomized, placebo-controlled trial, we tested the effect of L. reuteri (a product containing a combination of strains ATCC-PTA-6475 and DSM-17938) in children with ASD. The treatment does not alter overall autism severity, restricted/repetitive behaviors, the microbiome composition, or the immune profile. However, L. reuteri combination yields significant improvements in social functioning that generalized across different measures. Interestingly, ATCC-PTA-6475, but not the parental strain of DSM-17938, reverses the social deficits in a preclinical mouse model for ASD. Collectively, our findings show that L. reuteri enhances social behavior in children with ASD, thereby warranting larger trials in which strain-specific effects should also be investigated.