Vitamin A supplementation ameliorates motor incoordination via modulating RORα in the cerebellum in a valproic acid-treated rat autism model with vitamin A deficiency.

Motor dysfunctions are common comorbidities among autism spectrum disorder (ASD) patients. Abnormal cerebellar development throughout critical periods may have an effect on motor functions and result in motor impairments. Vitamin A (VA) plays a crucial role in the developing process of the nervous system. The correlation of VA deficiency (VAD) and ASD with motor dysfunctions, however, is not clear. Therefore, we built rat models with different VA levels based on the valproic acid (VPA)-treated autism model. ASD rats with VAD showed aggravated motor coordination abnormalities, Purkinje cell loss and impaired dendritic arborization of Purkinje cells compared to ASD rats with normal VA levels (VA normal, VAN). Additionally, the expression levels of retinoid-related orphan receptor α (RORα) and retinoic acid receptor α (RARα) were lower in the cerebellum of ASD rats with VAD than in those of ASD rats with VAN. VA supplementation (VAS) effectively improved motor coordination and cerebellar Purkinje cell abnormalities in ASD rats with VAD. Furthermore, the results of chromatin immunoprecipitation (ChIP) assays confirmed that the enrichment of RARα was detected on the RORα promoter in the cerebellum and that VAS could upregulate the binding capacity of RARα for RORα promoters. These results showed that VAD in autism might result in cerebellar impairments and be a factor aggravating a subtype of ASD with motor comorbidities. The therapeutic effect of VAS on motor deficits and Purkinje neuron impairments in autism might be due to the regulation of RORα by RARα.

Valproic Acid Induces Autism-Like Synaptic and Behavioral Deficits by Disrupting Histone Acetylation of Prefrontal Cortex ALDH1A1 in Rats.

OBJECTIVES: This study aimed to investigate the impact of valproic acid (VPA) on the histone acetylation of acetaldehyde dehydrogenase 1A1 (ALDH1A1) and the mechanism underlying VPA-induced autism-like behavior. METHODS: Female Sprague-Dawley rats were intraperitoneally injected with VPA during gestation to establish an autism model in their offspring. Some offspring prenatally exposed to VPA were randomly treated with MS-275, one histone deacetylase (HDAC) inhibitor, or retinoic acid (RA) after birth. Behavioral tests were conducted on the offspring 6 weeks after birth. Electrophysiological experiments were performed to investigate long-term potentiation (LTP) in the prefrontal cortex (PFC). The expression levels of AMPA receptors (GluA1 and 2), NMDA receptors (GluN1 and 2), synapsin 1 (SYN1), HDAC, acetylated histone 3 (AcH3), RA receptor alpha (RARα), and ALDH1A1 in the PFC were measured by Western blotting and quantitative polymerase chain reaction. ALDH enzyme activity in PFC tissue was detected using a Micro ALDH Assay Kit. The RA level in the PFC was measured using ultrahigh-performance liquid chromatography/tandem mass spectrometry. A chromatin immunoprecipitation (ChIP) experiment explored the interaction between the ALDH1A1 gene and AcH3. RESULTS: Offspring prenatally exposed to VPA showed autism-like behavior, upregulated the levels of LTP and GluN2A, GluA1, and SYN1 proteins relevant to synaptic plasticity in the PFC. The expression levels of HDAC3 mRNA and protein were increased. On the other hand, there was a significant reduction in the levels of AcH3, RARα, RA, ALDH1A1 mRNA and protein, the level of ALDH activity and AcH3 enrichment in the ALDH1A1 promoter region in VPA-induced offspring. Administration of MS-275 in VPA offspring significantly elevated the levels of AcH3, ALDH1A1 mRNA and protein, ALDH activity, RA, the level of RARα protein and the binding of AcH3 to the ALDH1A1 promoter. In addition, the GluA1 protein level and LTP were reduced, and most behavioral deficits were reversed. After RA supplementation in the VPA-treated offspring, the RA and RARα protein levels were significantly upregulated, GluA1 protein and LTP were downregulated, and most autism-like behavioral deficits were effectively reversed. CONCLUSION: These findings suggest that VPA impairs histoneacetylation of ALDH1A1 and downregulates the RA-RARα pathway. Such epigenetic modification of ALDH1A1 by VPA leads to autism-like synaptic and behavioral deficits.

Vitamin A deficiency exacerbates autism-like behaviors and abnormalities of the enteric nervous system in a valproic acid-induced rat model of autism.

The manifestations of autism spectrum disorder (ASD) are highly heterogeneous. As many individuals with ASD have gastrointestinal (GI) comorbidities, ASD with GI problems is considered to be a subtype of ASD. Vitamin A (VA) plays an important role in the development of both the central and peripheral nervous system. However, the relationship between VA deficiency (VAD) and ASD with GI comorbidities is still unclear. We established rat models with different VA levels based on the valproic acid-induced autism model. Compared to autism model rats with VA normal (VAN), autism model rats with gestational VAD showed more severe autism-like behavior, increased GI transit time, and impairment of the enteric nervous system (ENS). Besides, the expression levels of retinoic acid receptor α (RARα) and Ret in autism model rats with VAD were decreased compared with those in rats with VAN. Supplementation with VA was found to effectively ameliorate autism-like behaviors and impairments of GI motility and the ENS in autism model rats with VAD. Chromatin immunoprecipitation results suggested that RARa can bind to the promoter region of the Ret gene and regulate the Ret signaling pathway. We speculate that VAD in autism might lead to impairments of both the brain and ENS. VAD might be a factor that causes individuals to be more susceptible to ASD-related risk factors and aggravates a subtype of ASD with GI comorbidities.