Sex-dependent dysregulation of the gut-brain NPYergic system in a mouse model of autism spectrum disorder

The microbiome-gut-brain axis has been increasingly recognized for its role in the pathophysiology of autism spectrum disorder (ASD), yet the underlying molecular mechanisms remain poorly understood. Neuropeptide Y (NPY), a key modulator of gut-brain communication, may play a pivotal role in this axis. This study investigated the sex-specific molecular profile of the NPY system in gut-brain communication via a genetic mouse model of ASD, the Nf1^+/- mice. Quantitative real-time PCR was performed to assess the expression of NPY and its receptor transcripts in the amygdala, hippocampus, prefrontal cortex and intestinal tissue of juvenile male and female Nf1^+/- mice. Additionally, gut microbiota analysis focused on Lactobacillus species in stool samples. Special emphasis was placed on sex differences, an area underexplored in ASD research. Sex-specific differences in NPY and its receptor expression were observed in both the brain and intestinal tissues of Nf1^+/- mice. In mutant females, estrous cycle fluctuations were partly associated with changes in the NPY system. Notably, distinct correlations between the brain and intestinal NPY systems were identified in both sexes of wild-type (WT) and Nf1^+/- mice. Microbiota analysis revealed sex-dependent alterations in Lactobacillus abundance, which correlated with the intestinal NPY system. Importantly, the Y2 receptor exhibited sex-specific expression patterns in both the gut and brain of Nf1^+/- mice. This study provides novel evidence that the NPY system may play a critical role in gut-brain communication in ASD, with sex-dependent alterations in both the brain and gut. The intestinal Y2 receptor has emerged as a potential molecular biomarker for ASD, underscoring the importance of incorporating sex as a biological variable in future ASD research.