Different effects of selective β1-adrenoceptor antagonists, nebivolol or atenolol in acetaminophen-induced hepatotoxicity of rats.

Acetaminophen (APAP) overdose is a common cause of acute liver failure, and beta-blockers are commonly used drugs in clinical practice. This study aimed to evaluate the effect of two different beta-blocker agents as nebivolol and atenolol against APAP-induced hepatotoxicity. Male Wistar rats were treated with APAP (2 g/kg/day, p.o.) to induce hepatotoxicity. Our results showed that nebivolol and atenolol reduced heart rate and blood pressure. Nebivolol (5 mg/kg/day, p.o.) for 14 days has a hepatoprotective effect shown by significant decrease in hepatic injury parameters (serum AST and ALT) with significant suppression of hepatic malondialdehyde (MDA) and nitric oxide (NO) which were elevated with APAP administration. Also, nebivolol increased reduced glutathione (GSH) which was reduced with APAP administration. Moreover, immunohistochemical examination revealed that nebivolol treatment markedly reduced inducible nitric oxide synthase (iNOS) expression, while expression of endothelial nitric oxide synthase (eNOS) was markedly enhanced, as compared to APAP group. The protective effects of nebivolol were also verified histopathologically. On the other hand, as compared to APAP group, oral administration of atenolol (50 mg/kg) increased hepatic injury parameters but did not change hepatic NO, MDA, and GSH. In conclusion, this study revealed that nebivolol not atenolol is protective against APAP-induced hepatotoxicity possibly, in part, through its antioxidant activity, inhibition of iNOS expression, and induction of eNOS expression.