Subregion-Specific Transcriptomic Profiling of Rat Brain Reveals Sex-Distinct Gene Expression Impacted by Adolescent Stress

Abstract Stress during adolescence clearly impacts brain development and function. Sex differences in adolescent stress-induced or exacerbated emotional and metabolic vulnerabilities could be due to sex-distinct gene expression in hypothalamic, limbic and prefrontal brain regions. However, adolescent stress-induced gene expression changes in these key brain regions were unclear. RNA extraction from whole brain regions, instead of discrete nuclei, dilutes gene expression results. In this study, female and male adolescent Sprague Dawley rats received one-hour restraint stress every day from postnatal day (PD) 32 to PD44, their plasma corticosterone levels were measured, and their body weights, food intake and body composition were monitored. On PD44, their brains and blood samples were collected. Circulating levels of adioposity hormones (leptin and insulin) and sex hormones (estradiol and testosterone) were measured. Gene expression in nine subregions was measured using RNA sequencing (RNA-Seq). Differentially expressed (DE) genes were analyzed using bootstrapped receiver operating characteristic (bROC) approach. The results indicated that sex differences in stress-induced DE genes were widespread, being identified in the hypothalamus, limbic system, and prefrontal cortex of adolescent brains. Additionally, this study revealed canonical pathways enriched in stress compared to nonstress rats, which were predictive of well-known sex-distinct maladies in the literature, providing examples of the DE genes likely involved in producing sex-distinct and stress-induced diseases. In summary, findings from this study suggest sex biases in stress-induced transcriptional changes during adolescence, indicating a molecular basis for sex differences witnessed in stress-induced or exacerbated emotional and metabolic disorders throughout life. Future studies are warranted to test the implications of the DE genes identified in this study in sex-distinct stress-induced susceptibilities.