The impact of probiotic treatment on sex-specific behavioral differences in valproic acid-induced autism animal model

Autism spectrum disorder (ASD) is defined by social impairments and disturbances of repetitive, stereotypical behaviors. However, its presentation shows sex-specific traits that may have shaped underlying mechanisms and treatment outcomes. The purpose of this study was to investigate the effects of a specific probiotic on behavioral outcomes and serotonin levels in adult rats prenatally exposed to valproic acid (VPA), an established experimental model of ASD. Wistar rats received either 500 mg/kg VPA or physiological saline on gestational day 12.5. Offspring of both sexes were assigned to 8 groups, with designated groups receiving a specific probiotic mixture. Animals were tested at postnatal day 111 in social, anxiety-related and locomotor tasks and platelet serotonin levels were measured after sacrifice. Our results suggest that VPA exposure and probiotic administration elicit distinct sex-specific behavioral responses and differences in platelet serotonin levels. ASD-related social symptoms persist only in male animals, while females generally exhibit higher activity levels and lower anxiety. The probiotic mixture appeared to alleviate social deficits in male VPA-exposed rats. However, the mixture showed no measurable effects on other ASD-related behavioral parameters and caused no adverse outcomes in either sex. Notably, female animals displayed distinct behavioral patterns and did not exhibit VPA-induced alterations, suggesting potential sex-specific protective mechanisms that may modulate both VPA effects and microbiota-related interventions. These findings highlight the importance of sex-specific analysis and timing in evaluating therapies. Therefore, sex differences should be carefully considered, given their impact on both the understanding and treatment of ASD.