Impact of L-arginine on Azathioprine-Induced Chronic Hepatotoxicity in Mice: Biochemical and Ultrastructural Study

Introduction: Azathioprine (AZA) is a widely used immunosuppressant drug with an unpredictable hepatotoxicity. Aim of the Work: To study the possible protective role of L-arginine in Azathioprine-Induced chronic hepatotoxicity in mice. Materials and Methods: Forty mice were used in this study. Mice were divided into 4 groups, each included 10 mice: Group (I) control group, Group (II) mice received intraperitoneal (IP) injection of AZA (2 mg/kg body weight/day). Group (III) mice received AZA and L-arginine (100 mg/kg body weight/d/IP). Group (IV) mice received L-arginine. After 6 weeks, Blood samples and liver specimens were obtained for assessment of some biochemical parameters. Other liver specimens were obtained and processed for light and electron microscopic study. Results: AZA-induced liver injury was assigned by a significant elevation of serum indices of hepatotoxicity (Alanine aminotransferase and aspartate aminotransferase), hepatic lipid peroxidation (measured as Malondialdehyde, MDA,) and hydroxyl radicals (P 0.001). Moreover the markers of hepatic antioxidant activity (Reduced glutathione, superoxide dismutase, catalase, ceruplasmin and Ascorbic acid) were significantly decreased (P 0.001) in mice liver tissue of AZA-treated group compared to control. In addition AZA was found to not only reduce the blood platelet count, but it also decreased the DNA and total protein content of mice liver tissue significantly (P 0.001). Light microscopic examination revealed a sub-capsular well defined area surrounded by thick fibrous wall. This area contained necrotic cells, fragmented nuclei, mononuclear cellular infelterate and giant cells. The liver architecture was disorganized with multiple focal areas of necrosis. In addition, dilatation of the blood sinusoids and portal tract structures were noticed. The majority of hepatocytes were ballooned with central dark nuclei. Other hepatocytes appeared small in size with deeply acidophilic cytoplasm and dark nuclei most probably apoptotic hepatocytes. Ultrastructural study of hepatocytes revealed dilated perinuclear membrane, degenerated mitochondria, dilated cisternae of rER and multiple lipid droplets. Autophagic vacuoles engulfing degenerated cell organelles and lamellar bodies were also noticed. Moreover the bile canaliculi were markedly dilated. Conversely, the co-administration of L-Arginine with AZA (Group III) showed improved both the biochemical parameters and the histological changes. In group IV, the levels of all biochemical parameters and the histological sections were nearly similar to that of the control group. Conclusion: These findings implied that L-arginine plays an important role in protection against AZA-induced chronic hepatotoxicity. Therefore, addition of L-arginine to the therapeutic regimens of patients maintained on AZA treatment for long time may be recommended.