Sulfanilamide benzotriazole tetrazole inhibits neuronal apoptosis in neonatal rats by targeting JNK and p38 MAPK pathways

Abstract

Purpose: To investigate the neuroprotective effect of sulfanilamide benzotriazole tetrazole (SBT) in neonatal rats exposed to isoflurane, and also to elucidate the underlying mechanism. Methods: Rat pups (n = 60) were randomly assigned to six groups of 10 pups each: normal control group, negative control group, 5 mg/kg SBT group, 10 mg/kg SBT group, 15 mg/kg SBT group, and 20 mg/kg SBT group. With exception of normal control group, pups were exposed to isoflurane (0.75 %) for 6 h on postnatal day 7. The negative control group was not treated, while pups in the four treatment groups received 5, 10, 15 and 20 mg/kg SBT, respectively, 1 h after exposure to anaesthesia. TUNEL assay was used to determine the extent of apoptosis in cornu ammonis area-1 (CA-1), cornu ammonis area-3 (CA-3) and dentate gyrus of rat hippocampal tissues. Expressions of apoptotic and anti-apoptotic proteins were determined using Western blotting. Evaluation of learning and memorizing ability was done using Morris water maze test. Results: Isoflurane significantly increased the extent of apoptosis in CA-1, CA-3 and dentate gyrus of rat hippocampal tissues (p < 0.05). However, treatment with SBT significantly and dose-dependently reduced neuronal apoptosis (p < 0.05). The expression of caspase 3 was significantly upregulated by isoflurane, but was significantly and dose-dependently down-regulated by SBT (p < 0.05). Isoflurane significantly increased Bax expression, and decreased the expression of bcl-2 (p < 0.05). The effects of isoflurane on the expression of these proteins were significantly and dose-dependently reversed by SBT (p < 0.05). The expression of bcl xL in rat hippocampal tissues was significantly down-regulated by isoflurane, but was significantly and dose-dependently upregulated by SBT (p < 0.05). The escape latency of pups was significantly higher in negative control group than in normal control group, but SBT treatment significantly and dose-dependently reversed this trend (p < 0.05). Conclusion: These results suggest that SBT prevents neuronal apoptosis, and improves the ability to learn and memorize in neonatal rats exposed to isoflurane via regulation of apoptotic, JNK and p38 MAPK protein expressions.