Autism spectrum disorder (ASD) is characterized by core social deficits. Prognosis is poor, in part, because existing medications target only associated ASD features. Emerging evidence suggests that the neuropeptide oxytocin (OXT) may be a blood-based biomarker of social functioning and a possible treatment for ASD. However, prior OXT treatment trials have produced equivocal results, perhaps because of variability in patients' underlying neuropeptide biology, but this hypothesis has not been tested. Using a double-blind, randomized, placebo-controlled, parallel design, we tested the efficacy and tolerability of 4-wk intranasal OXT treatment (24 International Units, twice daily) in 32 children with ASD, aged 6-12 y. When pretreatment neuropeptide measures were included in the statistical model, OXT compared with placebo treatment significantly enhanced social abilities in children with ASD [as measured by the trial's primary outcome measure, the Social Responsiveness Scale (SRS)]. Importantly, pretreatment blood OXT concentrations also predicted treatment response, such that individuals with the lowest pretreatment OXT concentrations showed the greatest social improvement. OXT was well tolerated, and its effects were specific to social functioning, with no observed decrease in repetitive behaviors or anxiety. Finally, as with many trials, some placebo-treated participants showed improvement on the SRS. This enhanced social functioning was mirrored by a posttreatment increase in their blood OXT concentrations, suggesting that increased endogenous OXT secretion may underlie this improvement. These findings indicate that OXT treatment enhances social abilities in children with ASD and that individuals with pretreatment OXT signaling deficits may stand to benefit the most from OXT treatment.A utism spectrum disorder (ASD) is a brain disorder of early childhood onset. ASD is characterized by core social communication impairments as well as restricted, repetitive behaviors, which jeopardize the development of appropriate social skills and the maintenance of social relationships (1). Despite being one of the most devastating childhood disorders in terms of prevalence [1 in 68 US children (2)] and societal cost [$236 billion expended annually in the United States (3)], ASD pathophysiology remains poorly understood. Consequently, there are no approved medications that enhance social abilities in individuals with ASD.

The social impairments of autism spectrum disorder (ASD) have a major impact on quality of life, yet there are no medications that effectively treat these core social behavior deficits. Preclinical research suggests that arginine vasopressin (AVP), a neuropeptide involved in promoting mammalian social behaviors, may be a possible treatment for ASD. Using a double-blind, randomized, placebo-controlled, parallel study design, we tested the efficacy and tolerability of a 4-week intranasal AVP daily treatment in 30 children with ASD. AVP-treated participants aged 6 to 9.5 years received the maximum daily target dose of 24 International Units (IU); participants aged 9.6 to 12.9 years received the maximum daily target dose of 32 IU. Intranasal AVP treatment compared to placebo enhanced social abilities as assessed by change from baseline in this phase 2 trial’s primary outcome measure, the Social Responsiveness Scale, 2nd Edition total score (SRS-2 T score; F1,20 = 9.853; P = 0.0052; ηp2 = 33.0%; Cohen’s d = 1.40). AVP treatment also diminished anxiety symptoms and some repetitive behaviors. Most of these findings were more pronounced when we accounted for pretreatment AVP concentrations in blood. AVP was well tolerated with minimal side effects. No AVP-treated participants dropped out of the trial, and there were no differences in the rate of adverse events reported between treatment conditions. Last, no changes from baseline were observed in vital signs, electrocardiogram tracings, height and body weight, or clinical chemistry measurements after 4 weeks of AVP treatment. These preliminary findings suggest that AVP has potential for treating social impairments in children with ASD.

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by core social impairments. ASD remains poorly understood because of the difficulty in studying disease biology directly in patients and the reliance on mouse models that lack clinically relevant, complex social cognition abilities. We use ethological observations in rhesus macaques to identify male monkeys with naturally occurring low sociality. These monkeys showed differences in specific neuropeptide and kinase signaling pathways compared to socially competent male monkeys. Using a discovery and replication design, we identified arginine vasopressin (AVP) in cerebrospinal fluid (CSF) as a key marker of group differences in monkey sociality; we replicated these findings in an independent monkey cohort. We also confirmed in an additional monkey cohort that AVP concentration in CSF is a stable trait-like measure. Next, we showed in a small pediatric cohort that CSF AVP concentrations were lower in male children with ASD compared to age-matched male children without ASD (but with other medical conditions). We demonstrated that CSF AVP concentration was sufficient to accurately distinguish ASD cases from medical controls. These data suggest that AVP and its signaling pathway warrant consideration in future research studies investigating new targets for diagnostics and drug development in ASD.

Autism is a brain disorder characterized by social impairments. Progress in understanding autism has been hindered by difficulty in obtaining brain-relevant tissues (eg, cerebrospinal fluid [CSF]) by which to identify markers of disease and targets for treatment. Here, we overcome this barrier by providing evidence that mean CSF concentration of the "social" neuropeptide arginine vasopressin (AVP) is lower in children with autism versus controls. CSF AVP concentration also significantly differentiates individual cases from controls and is associated with greater social symptom severity in children with autism. These findings indicate that AVP may be a promising CSF marker of autism's social deficits. Ann Neurol 2018;84:611-615.

An outbred rat model of the novelty-seeking phenotype is used to study nicotine vulnerability, where experimentally naïve rats were phenotype screened as high or low responders (HRs or LRs, ranking in the upper or lower 1/3 rd of the population respectively) based on locomotor activity displayed in a novel environment. Following nicotine training and abstinence, HR animals pretrained with nicotine showed expression of locomotor sensitization to nicotine challenge along with enhanced social anxiety-like behavior in the social interaction test compared to saline pretrained controls. HR rats also showed a downregulation in neuropeptide Y (NPY) mRNA levels in the medial nucleus of amygdala and the CA1 field of the hippocampus, an upregulation in Y2 mRNA levels in the CA3 field of the hippocampus, and an upregulation in the corticotropin releasing factor (CRF) mRNA levels in the central nucleus of the amygdala. These findings implicate dysregulations in the NPY-CRF systems in the HR hippocampus and amygdala associated with the emergence of social anxiety-like behavior, and a novel Y2R-mediated pathway in nicotine relapse. Keywordscentral nucleus of amygdala; medial nucleus of amygdala; hippocampus; novelty-seeking phenotype; locomotor sensitization; anxiety-like behavior The novelty-seeking phenotype is an outbred rat model of individual differences that has predictive value for nicotine vulnerability. Some rats display high locomotor reactivity in novel environments and are identified as high responders or HRs, whereas some display low locomotor reactivity in novel environments and are identified as low responders or LRs. HR rats are known to acquire nicotine self-administration more readily than LR rats and work more to obtain the drug when tested under the progressive ratio schedule of reinforcement [23]. Our laboratory reported that adolescent HRs develop locomotor sensitization to a low dose nicotine challenge following chronic intermittent nicotine training and 1 wk of abstinence [1,2], and even a single nicotine training with a mild dose is sufficient for the expression of locomotor sensitization to a low dose challenge [1], further validating this phenotype in the study of individual differences in vulnerability to nicotine.

An outbred rat model of novelty-seeking phenotype has predictive value for the expression of locomotor sensitization to nicotine. When experimentally naïve rats are exposed to a novel environment, some display high rates of locomotor reactivity (HRs, scores ranking at top 1/3rd of the population), whereas some display low rates (LRs, scores ranking at bottom 1/3rd of the population). Basally, HRs display lower anxiety-like behavior compared to LRs along with higher neuropeptide Y (NPY) mRNA in the amygdala and the hippocampus. Following an intermittent behavioral sensitization to nicotine regimen and 1 wk of abstinence, HRs show increased social anxiety-like behavior in the social interaction test and robust expression of locomotor sensitization to a low dose nicotine challenge. These effects are accompanied by a deficit in NPY mRNA levels in the medial nucleus of the amygdala and the CA3 field of the hippocampus, and increases in Y2R mRNA levels in the CA3 field and corticotropin releasing factor (CRF) mRNA levels in the central nucleus of the amygdala. Systemic and daily injections of a Y2R antagonist, JNJ-31020028, during abstinence fully reverse nicotine-induced social anxiety-like behavior, the expression of locomotor sensitization to nicotine challenge, the deficit in the NPY mRNA levels in the amygdala and the hippocampus, as well as result an increase in Y2R mRNA levels in the hippocampus and the CRF mRNA levels in the amygdala in HRs. These findings implicate central Y2R in neuropeptidergic regulation of social anxiety in a behavioral sensitization to nicotine regimen in the LRHR rats.

Autism spectrum disorder (ASD) is a brain disorder characterized by social impairments. ASD is currently diagnosed on the basis of behavioral criteria because no robust biomarkers have been identified. However, we recently found that cerebrospinal fluid (CSF) concentration of the “social” neuropeptide arginine vasopressin (AVP) is significantly lower in pediatric ASD cases vs. controls. As an initial step in establishing the direction of causation for this association, we capitalized upon a rare biomaterials collection of newborn CSF samples to conduct a quasi-prospective test of whether this association held before the developmental period when ASD first manifests. CSF samples had been collected in the course of medical care of 0- to 3-mo-old febrile infants (n = 913) and subsequently archived at −70 °C. We identified a subset of CSF samples from individuals later diagnosed with ASD, matched them 1:2 with appropriate controls (n = 33 total), and quantified their AVP and oxytocin (OXT) concentrations. Neonatal CSF AVP concentrations were significantly lower among ASD cases than controls and individually predicted case status, with highest precision when cases with comorbid attention-deficit/hyperactivity disorder were removed from the analysis. The associations were specific to AVP, as ASD cases and controls did not differ in neonatal CSF concentrations of the structurally related neuropeptide, OXT. These preliminary findings suggest that a neurochemical marker of ASD may be present very early in life, and if replicated in a larger, prospective study, this approach could transform how ASD is detected, both in behaviorally symptomatic children, and in infants at risk for developing it.

Autism spectrum disorder (ASD) is characterized by social impairments and repetitive behaviors, and affects 1 in 68 US children. Despite ASD's societal impact, its disease mechanisms remain poorly understood. Recent preclinical ASD biomarker discovery research has implicated the neuropeptides oxytocin (OXT) and arginine vasopressin (AVP), and their receptors, OXTR and AVPR1A, in animal models. Efforts to translate these findings to individuals with ASD have typically involved evaluating single neuropeptide measures as biomarkers of ASD and/or behavioral functioning. Given that ASD is a heterogeneous disorder, and unidimensional ASD biomarker studies have been challenging to reproduce, here we employed a multidimensional neuropeptide biomarker analysis to more powerfully interrogate disease status and symptom severity in a well characterized child cohort comprised of ASD patients and neurotypical controls. These blood-based neuropeptide measures, considered as a whole, correctly predicted disease status for 57 out of 68 (i.e., 84%) participants. Further analysis revealed that a composite measure of OXTR and AVPR1A gene expression was the key driver of group classification, and that children with ASD had lower neuropeptide receptor mRNA levels compared to controls. Lower neuropeptide receptor mRNA levels also predicted greater symptom severity for core ASD features (i.e., social impairments and stereotyped behaviors), but were unrelated to intellectual impairment, an associated feature of ASD. Findings from this research highlight the value of assessing multiple related biological measures, and their relative contributions, in the same study, and suggest that low blood neuropeptide receptor availability may be a promising biomarker of disease presence and symptom severity in ASD.