Bax inhibitor-1 overexpression in prelimbic cortex protects rats against depression-like behavior induced by olfactory bulbectomy and reduces apoptotic and inflammatory signals.

Background and purpose: Depression is a mental disorder characterized by a pervasive low mood and loss of pleasure or interest in usual activities, and often results in the impairment of learning and memory. Bax inhibitor-1 (BI-1) has been reported to be involved in the pathological mechanisms for neurodegenerative disorders including depression. Here, we aimed to investigate the role of BI-1 in regulating depression-like behavior induced by olfactory bulbectomy (OB) in rats and the possible mechanism. Methods: Adeno-associated virus vectors expressing BI-1 (AAV-BI-1) were bilaterally microinjected into the prelimbic cortex (PFC-PL) to establish a BI-1 overexpression model in the PFC-PL of rats. TUNEL staining was used to evaluate the cellular apoptosis rate in the PFC-PL. Western blot analysis was performed to examine the expressions of apoptotic and inflammatory signals. Results: BI-1 overexpression significantly attenuated the OB-induced behavioral abnormalities, including the decreased hyperactivity in the open field, decreased immobility time in the forced swimming test, as well as the increased sucrose consumption. BI-1 overexpression significantly inhibited cellular apoptosis in the PFC-PL of OB rats. The expressions of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, B-cell lymphoma (Bcl)-2 associated X protein (Bax), and caspase-3 in the PFC-PL of OB rats were significantly increased as compared with the sham rats, but the Bcl-2 and IL-10 expressions were decreased, whereas BI-1 overexpression significantly suppressed the changes of these proteins in the PFC-PL of OB rats. Conclusion: These results indicated that BI-1 may play an anti-depression function with concurrent regulation of apoptotic and inflammatory signals.