Neuronal Aralar/AGC1 deficiency impairs social behavior through dopaminergic and redox dysfunction and is rescued by β-hydroxybutyrate

Abstract

Background: Pathogenic variants in SLC25A12/AGC1 (Aralar) have been linked to autism spectrum disorder (ASD), yet the mechanisms connecting neuronal metabolic dysfunction to altered social behavior remain poorly understood. Aralar is a key component of the malate-aspartate shuttle, supporting neuronal oxidative metabolism and lactate utilization. Here, we investigated the consequences of postnatal neuronal Aralar deletion and the therapeutic potential of {beta}-hydroxybutyrate (BHB). Methods: We generated neuron-specific Aralar knockout mice (Neu Aralar-KO) using CamKII-Cre, producing efficient recombination in cortex, hippocampus, and striatum. Behavioral, transcriptomic, neurochemical, morphometric, histological, and biochemical analyses were performed in adult mice. The effects of systemic BHB administration were assessed using behavioral, metabolic, oxidative stress, and transcriptomic endpoints. Results: Despite a 55-65% reduction of Aralar expression in forebrain regions, Neu Aralar-KO mice displayed normal growth, survival, brain structure, and myelination. Unexpectedly, loss of neuronal Aralar did not impair spatial memory, episodic memory, or reversal learning. In contrast, Neu Aralar-KO mice exhibited hyperactivity and a marked deficit in sociability, revealing an ASD-relevant behavioral phenotype. Morphological analysis showed significant remodeling of striatal dendritic spines without changes in spine density. Transcriptomic profiling identified 433 differentially expressed genes, the vast majority being upregulated, with enrichment of pathways related to neuropeptide signaling, synaptic transmission, membrane excitability, and behavior. Notably, genes involved in dopamine (DA) and glutamate handling, synaptic connectivity, neuromodulatory signaling, and ASD-associated pathways were strongly induced. Neurochemical analyses revealed preserved glutamate and GABA levels but reduced striatal DA content accompanied by an increased DOPAC/DA ratio, indicating enhanced DA degradation. DAergic neurons of the ventral tegmental area (VTA) showed minimal recombination, suggesting that DA dysfunction arises through non-cell-autonomous mechanisms. Consistent with increased DA oxidative catabolism, Neu Aralar-KO striata displayed elevated lipid peroxidation, induction of glutathione-related pathways, upregulation of antioxidant genes, and astrocyte activation. Remarkably, BHB treatment restored sociability, normalized striatal metabolic alterations, reduced oxidative stress, and abolished genotype-dependent neurochemical abnormalities. Transcriptomic analyses further revealed that Aralar deficiency recapitulates a substantial fraction of the fasting/BHB-induced epigenetic transcriptional program. Conclusions: Postnatal neuronal Aralar deficiency uncouples social behavior from cognitive performance and drives ASD-like phenotypes through a mechanism linking neuronal metabolic dysfunction, oxidative stress, glial activation, and impaired DAergic homeostasis. The rescue of behavioral, metabolic, and redox abnormalities by BHB identifies restoration of metabolic homeostasis as a major therapeutic mechanism and highlights metabolic interventions as promising strategies for AGC1 deficiency and ASD-associated disorders involving neuronal metabolic dysfunction.