This study is conducted to investigate the prophylactic effect of thymoquinone (TQ), the major active ingredient of Nigella sativa seeds, against carbon tetrachloride (CCl4)-induced hepatic damage in Sprague-Dawley (SD) rats. Forty rats were divided into four even groups. The first group served as control. The second, third and fourth groups received CCl4, CCl4 and TQ, and TQ only, respectively for 5 weeks. CCl4 (2 ml/kg b.w.) was given orally by gastric tube twice a week on Sunday and Thursday. TQ (20 mg/kg b.w.) was given daily in corn oil by gastric tube. At the end of the experiment, rats were sacrificed, and blood samples and liver specimens were obtained for biochemical analysis and morphological examination, respectively. Control and TQ-treated rats showed normal serum activity for alanine (ALT) and aspartate (AST) aminotransferases, and normal liver histology. Treatment of rats with CCl4 significantly increased serum activity of ALT and AST aminotransferases compared to control rats. Histopathologically, livers from CCl4-treated rats showed dilatation of blood sinusoids and portal blood vessels, Kupffer cell activation, vacuolar degeneration of hepatocytes, focal areas of necrosis and mild hepatic fibrosis. Using transmission electron microscopy (TEM), CCl4 caused clear lesions in the liver including dilatation of endoplasmic reticula, increased extracellular matrix and formation of abundant fatty globules and numerous autophagosomes in hepatocytes. On the other hand, co-administration of TQ with CCl4 significantly decreased serum ALT and AST activities, and attenuated most of CCl4-induced hepatic pathological changes. The present study indicates that TQ has the potential to attenuate CCl4-induced hepatic damage in SD rats.
Key words: carbon tetrachloride, hepatotoxicity, histopathology, thymoquinone, ultrastructure
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