Investigation of mRNA levels of genes associated with apoptosis in the hippocampal tissues of maternally stressed mice

Early life stress, particularly maternal separation (MS), contributes to lifelong psychopathological conditions, including antisocial behaviors and personality disorders. In rodent models, early maternal separation has been associated with neuronal apoptosis and impaired hippocampal function, resulting in learning and memory deficits, depression-like behaviors, and alterations in anxiety-like behaviors. This study investigated the effects of early life stress, specifically unpredictable maternal separation (MS) and unpredictable maternal separation combined with unpredictable maternal stress (MSUS), on the mRNA expression levels of the pro-apoptotic genes Bax, Tp53 and Casp3, and the pro-survival gene Bcl2 in the hippocampus of BALB/c mice. Three groups were studied: a control group (n=24), a group exposed to MS (n=24), and a group exposed to MSUS (n=24). Total RNA was extracted from hippocampal tissues of mice on postnatal day 35 (PND35) using the phenol chloroform extraction method. Real-time PCR quantified mRNA levels of Bax, Bcl2, Tp53, and Casp3 genes. The qPCR data was analyzed using the delta delta Ct method, and statistical analyses were performed with GraphPad Prism software. Bax mRNA expression decreased significantly in the MS group compared to the control (p = 0.0464), while both MS and MSUS groups showed significant increases in Bcl2 mRNA expression compared to the control (p = 0.0005, p = 0.0057, respectively). Tp53 mRNA expression increased significantly in the MSUS group compared to the control (p = 0.0413). No significant differences were observed in Casp3 mRNA expression levels between the groups. Body weight analysis using two-way repeated measures ANOVA revealed that the offspring in the MS and MSUS groups had significantly lower body weights compared to the control group. Within the stressed groups, the MSUS group exhibited significantly lower body weights than the MS group. Significant changes in mRNA expression levels of pro-apoptotic genes Bax and Tp53, and the pro-survival gene Bcl2, along with the stable expression of Casp3, suggest that apoptosis was prevented in the hippocampus in response to early life stress, ensuring cell survival.