The Protective Potential eff ect of Metformin during Acetaminophen Hepatotoxicity through Nrf2 Activation

Acetaminophen (N-acetyl-para-aminophenol [APAP]) is the most commonly used medication for the relief of pain and fever around the world. Although APAP is safe and eff ective at a therapeutic level, acute overdose causes hepatotoxicity and severe liver damage. The hepatotoxicity induced by APAP is a persistent global problem that results in hepatotoxicity cases; acute liver failure and even death worldwide. This toxicity is characterized by extensive oxidant stress which consequently causes hepatocyte cell death. On the other hand, scientifi c studies have proven that MET shows hepatoprotective eff ect against hepatotoxicity induced by APAP through numerous mechanisms, e.g., antioxidant activity that alleviate the hepatotoxicity by activating Nrf2 pathway. The activation of Nrf2 pathway is anticipated to protect cells from oxidative stress that forms during hepatotoxicity. The benefi cial of using MET to protect against hepatotoxicity after APAP has been performed in an in-vitro experiment using Hep2G cell culture. However, up to our knowledge non, an in-vivo study (experimental animal) has been used to approve the benefi t of MET. Justifi cation: Nrf2 pathway activation by MET is one of the most important issues that need to be explained and followed up in laboratory animals since it has been previously studied in-vitro. Our study focuses on studying Nrf2 pathway in-vivo, since the results of in-vivo study are more relevant and similar to that of human beings. Aim of the study: To examine the possible stimulant eff ect of MET on Nrf2 pathway in experimental animals and its role in protecting the liver from oxidative stress that formed during APAP-induced hepatotoxicity. Methodology: Twenty-four wistar rats were divided randomly into four groups (six rats/Grp). Grp1; normal saline orally, Grp2; toxic dose of APAP (1000 mg/kg) orally; Grp3; 200 mg/kg of MET ip after 1-hour of APAP (1000 mg/kg) orally, Grp 4; 200 mg/kg MET ip for 24 hours. Then sera from experimental animals were collected for subsequent assessments of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) enzyme activities. Liver tissue was harvested to detect the expression of keap1 which is the negative regulator of Nrf2, and HO-1 and GST A1, which are related to Nrf2 pathway, by western blotting technique. Results: The results were showed a signifi cant elevation in ALT and AST activities in APAP treated group while MET normalized these biomarkers (AST and ALT). Western blotting assay showed that keap1 expression increased in APAP-treated animals while MET showed a signifi cant decrement in keap1 expression. The expression of antioxidant proteins HO-1 and GST A1 are decreased signifi cantly in APAP-treated animals while increased signifi cantly by MET treatment. Conclusion: The present results demonstrated that MET has a hepatoprotective eff ect in experimental animals against hepatotoxicity induced by APAP through activating Nrf2 pathway.