Sex differences in the BTBR idiopathic mouse model of autism spectrum disorders: Behavioural and redox-related hippocampal alterations

Autism spectrum disorders (ASD) are highly heterogeneous neurodevelopmental diseases. Epidemiological data report that males have been diagnosed with autism more frequently than females. However, recent studies hypothesize that females’ low incidence might be underestimated due to standard clinical measures of ASD behavioural symptoms, mostly derived from males. Indeed, up to now, ASD mouse models focused mainly on males, considering the prevalence of the diagnosis in that sex. Regarding ASD aetiopathogenesis, it has been recently reported that oxidative stress might be implicated in its onset and development, suggesting an association with ASD typical repetitive behaviours that still need to be disentangled. Here, we investigated possible behavioural and molecular sex-related differences by using the BTBR mouse model of idiopathic ASD. To this aim, animals were exposed to behavioural tests related to different ASD core symptoms and comorbidities, i.e. stereotyped repertoire, social dysfunctions, hyperlocomotion and risk-taking behaviours. Moreover, we analyzed hippocampal levels of pro-oxidant and anti-oxidant enzymes, together with biomarkers of oxidative stress and lipid peroxidation.

Our results showed that BTBR females did not display the same patterns for repetitive behaviours as the male counterpart. From a biomolecular point of view, we found an increase in oxidative stress and pro-oxidant enzymes, accompanied by deficient enzymatic anti-oxidant response, only in BTBR males compared to C57BL/6 male mice, while no differences were retrieved in females.

Overall, our study suggests that in females there is an urgent need to depict the distinct ASD symptomatology, accompanied by the identification of sex-specific pharmacological targets.