Vitamin A Deficiency Induces Autistic-Like Behaviors in Rats by Regulating the RARβ-CD38-Oxytocin Axis in the Hypothalamus

Abstract

Scope: Vitamin A (VA) is an essential nutrient for the development of the brain. We previously found that children with autism spectrum disorder (ASD) have a significant rate of VA deficiency (VAD). In the current study, we aim to determine whether VAD is a risk factor for the generation of autistic-like behaviors via the transcription factor retinoic acid receptor beta (RARβ)-regulated cluster of differentiation 38 (CD38)-oxytocin (OXT) axis.

Methods and results: Gestational VAD or VA supplementation (VAS) rat models are established, and the autistic-like behaviors in the offspring rats are investigated. The different expression levels of RARβ and CD38 in hypothalamic tissue and serum retinol and OXT concentration are tested. Primary cultured rat hypothalamic neurons are treated with all-trans retinoic acid (atRA), and recombinant adenoviruses carrying the rat RARβ (AdRARβ) or RNA interference virus RARβ-siRNA (siRARβ) are used to infect neurons to change RARβ signal. Western blotting, chromatin immunoprecipitation (ChIP), and intracellular Ca²⁺ detections are used to investigate the primary regulatory mechanism of RARβ in the CD38-OXT signaling pathway. We found that gestational VAD increases autistic-like behaviors and decreases the expression levels of hypothalamic RARβ and CD38 and serum OXT levels in the offspring. VAS ameliorates these autistic-like behaviors and increases the expression levels of RARβ, CD38, and OXT in the gestational VAD pups. In vitro, atRA increases the Ca²⁺ excitability of neurons, which might further promote the release of OXT. Different CD38 levels are induced in the neurons by infection with different RARβ adenoviruses. Furthermore, atRA enhances the binding of RARβ to the proximal promoter of CD38, indicating a potential upregulation of CD38 transcriptional activity by RARβ.

Conclusions: Gestational VAD might be a risk factor for autistic-like behaviors due to the RARβ signal suppression of CD38 expression in the hypothalamus of the offspring, which improves with VAS during the early-life period. The nutritional status during pregnancy and the early-life period is important in rats.

Keywords: autism; oxytocin; retinoic acid receptor beta; vitamin A.