Effects of berberine and yohimbine on splenocyte apoptosis in septic mice

AIM: To observe the effects of berberine and yohimbine on splenocyte apoptosis in septic mice and underlying mechanisms. METHODS: The mice were subjected to cecal ligature and puncture (CLP). The drugs or vehicle were given intragastrically 2 h after the surgery according to the following 5 groups: sham, CLP, CLP+berberine, CLP+yohimbine, and CLP+berberine+yohimbine. The apoptosis of splenocytes stained by TUNEL was observed under laser scanning confocal microscope 20 h after CLP. The splenic lymphocytes were isolated and observed using flow cytometry. The activities of caspase-3, caspase-8 and caspase-9 in splenic lymphocytes were detected, and the expression of Fas, Bim, Bcl-2 and Bax in the splenocytes was also determined by Western blotting. RESULTS: The TUNEL staining showed that the apoptotic rate of the splenocytes in septic mice 20 h after CLP was significantly higher than that in sham and CLP+yohimbine groups (P＜0.05). Compared with CLP group, the proportion of apoptotic cells was decreased in septic mice in CLP+berberine+yohimbine and CLP+yohimbine groups (P＜0.05). Flow cytometry analysis demonstrated the similar results in the apoptosis of splenocytes and T lymphocytes. However, only yohimbine treatment reduced the apoptosis of B lymphocytes in the spleen of sepsis-challenged mice. Compared with CLP group, caspase-9 activity was significantly reduced in CLP+berberine group (P＜0.05), the activities of caspase-3, caspase-8 and caspase-9 were all statistically reduced (P＜0.05) in CLP+yohimbine group and CLP+yohimbine+berberine group. CLP significantly increased the expression of cytosolic Fas, Bim and mitochondrial Bax in the splenocytes, and decreased Bcl-2 expression compared with sham group. Compared with CLP group, the expression of cytosolic Bim and mitochondrial Bax in CLP+berberine group were reduced (P＜0.05). Fas expression decreased only in CLP+yohimbine group (P＜0.05). Berberine combined with yohimbine reduced the expression of cytosolic Fas, Bim and mitochondrial Bax in the septic mouse splenocytes (P＜0.05).CONCLUSION: Yohimbine reduces sepsis-induced splenic lymphocyte apoptosis in mice by inhibiting Fas expression and in turn blocking both extrinsic and intrinsic apoptosis pathways. Berberine reduces Bim expression and inhibits caspase-9 activation, but not caspase-3 activation and apoptosis in the septic mouse splenocytes. Berberine combined with yohimbine reduces splenocyte apoptosis in the septic mice by inhibiting both extrinsic and intrinsic apoptotic pathways.