Effects of arginine vasopressin on the transcriptome of prefrontal cortex in autistic rat model

Mini review of molecules involved in altered postnatal neurogenesis in autism

The neurobiology of autism is complex, but emerging research points to potential abnormalities and alterations in neurogenesis. The aim of the present review is to describe the advances in the understanding of the role of selected neurotrophins, neuropeptides, and other compounds secreted by neuronal cells in the processes of postnatal neurogenesis in conjunction with autism. We characterize the fundamental mechanisms of neuronal cell proliferation, generation of major neuronal cell types with special emphasis on neurogenic niches - the subventricular zone and hippocampal areas. We also discuss changes in intracellular calcium levels and calcium-dependent transcription factors in the context of the regulation of neurogenesis and cell fate determination. To sum up, this review provides specific insight into the known association between alterations in the function of the entire spectrum of molecules involved in neurogenesis and the etiology of autism pathogenesis.

Effects of Arginine Vasopressin on Hippocampal Myelination in an Autism Rat Model: A RNA-seq and Mendelian Randomization Analysis

BACKGROUND

To explore the therapeutic role of arginine vasopressin (AVP) and its possible mechanisms in autism.

METHODS

Mid-trimester pregnant rats treated with valproate on embryonic day 12.5 and their offspring were selected as autism model. The autism rats were randomly assigned to autism group and AVP treatment group that given AVP by inhalation per day from postnatal days 21 to 42. The changes in social behavior and the hippocampus transcriptome were compared, and the hub genes were confirmed by quantitative real-time polymerase chain reaction (qPCR) and Mendelian randomization (MR).

RESULTS

403 genes were found to be differentially expressed in the autism model, with the majority of these genes being involved in oligodendrocyte development and myelination. Only 11 genes associated with myelination exhibited statistically significant alterations following AVP treatment when compared to the autism group. Gene set enrichment, expression patterns, and weighted gene co-expression network analysis (WGCNA) analysis consistently indicated that the biological processes of oligodendrocyte development and myelination were markedly enriched in the autism group and exhibited improvement following treatment. The variation trend of various nerve cells demonstrated a notable increase in the proportion of oligodendrocytes and oligodendrocyte precursor cells in the autism group, which subsequently exhibited a significant decline following treatment. Five hub genes (MBP, PLIP, CNP, GFAP, and TAOK1) were verified by qPCR. Finally, MR studies have confirmed a causal relationship between hippocampal myelination-related gene expression and the risk of autism.

CONCLUSIONS

AVP could markedly enhance social interaction abilities in the autism rat model, possibly due to the significantly improved hippocampus oligodendrocytes development and myelination.

Three Decades of Valproate: A Current Model for Studying Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder with increased prevalence and incidence in recent decades. Its etiology remains largely unclear, but it seems to involve a strong genetic component and environmental factors that, in turn, induce epigenetic changes during embryonic and postnatal brain development. In recent decades, clinical studies have shown that inutero exposure to valproic acid (VPA), a commonly prescribed antiepileptic drug, is an environmental factor associated with an increased risk of ASD. Subsequently, prenatal VPA exposure in rodents has been established as a reliable translational model to study the pathophysiology of ASD, which has helped demonstrate neurobiological changes in rodents, non-human primates, and brain organoids from human pluripotent stem cells. This evidence supports the notion that prenatal VPA exposure is a valid and current model to replicate an idiopathic ASD-like disorder in experimental animals. This review summarizes and describes the current features reported with this animal model of autism and the main neurobiological findings and correlates that help elucidate the pathophysiology of ASD. Finally, we discuss the general framework of the VPA model in comparison to other environmental and genetic ASD models.

Vasopressin as Possible Treatment Option in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is rather common, presenting with prevalent early problems in social communication and accompanied by repetitive behavior. As vasopressin was implicated not only in salt-water homeostasis and stress-axis regulation, but also in social behavior, its role in the development of ASD might be suggested. In this review, we summarized a wide range of problems associated with ASD to which vasopressin might contribute, from social skills to communication, motor function problems, autonomous nervous system alterations as well as sleep disturbances, and altered sensory information processing. Beside functional connections between vasopressin and ASD, we draw attention to the anatomical background, highlighting several brain areas, including the paraventricular nucleus of the hypothalamus, medial preoptic area, lateral septum, bed nucleus of stria terminalis, amygdala, hippocampus, olfactory bulb and even the cerebellum, either producing vasopressin or containing vasopressinergic receptors (presumably V1a). Sex differences in the vasopressinergic system might underline the male prevalence of ASD. Moreover, vasopressin might contribute to the effectiveness of available off-label therapies as well as serve as a possible target for intervention. In this sense, vasopressin, but paradoxically also V1a receptor antagonist, were found to be effective in some clinical trials. We concluded that although vasopressin might be an effective candidate for ASD treatment, we might assume that only a subgroup (e.g., with stress-axis disturbances), a certain sex (most probably males) and a certain brain area (targeting by means of virus vectors) would benefit from this therapy.