الفهرس 
Introduction and the Aim of the workOnly 14 pages are availabe for public view
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Abstract
Aim: This study was designed to investigate the effects of green tea and/or licorice aqueous extracts on antioxidant defense system, histopathological perturbations, and biochemical parameters related to liver and thyroid functions in DMN-intoxicated male albino rats. Methods: The tested extracts were administered ad-libitum to the rats for 4 weeks while DMN was injected (i.p.) seven times in the first 2 weeks of the start of the experiment. At the end of the experimental period, the tested rats were fasted over night, then sacrificed under diethyl ether anesthesia. Blood samples were collected from jugular vein in a little amount of EDTA solution (15 %) then centrifuged at 3000 r.p.m. for 15 minutes. Plasma was quickly removed and kept at -20 °C till used for biochemical analysis of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and lactate dehydogenase (LDH) activities, total protein, albumin, total bilirubin, direct bilirubin, total cholesterol, HDL-cholesterol, triglycerides, T3, T4, and TSH levels. Liver tissues were quickly excised, weighed and homogenized in a saline solution (0.9 %), centrifuged at 3000 r.p.m. for 15 minutes and the supernatant were kept at -20 °C for the assay of ALT, AST, ALP, LDH, GSH-reductase (GSHR), GSH-peroxidase (GSHpx), GSH-S-transferase (GST), superoxide dismutase (SOD), catalse and thyroxine 5’-monodeiodinase (5’-DI) activities, and reduced glutathione (GSH), total thiols, vitamin C, thiobarbituric acid reactive-substances (TBARs), nitrite, collagen, elastin, and total protein levels. Thyroid glands and pieces of liver were also removed out from each animal and fixed in 10 % neutral buffered formalin. Results: It was found that DMN increased most of the antioxidant enzymes activities, while the tested extracts inhibited them. So, it can be hypothesized that the toxic metabolites produced by DMN metabolism induced those enzymes in order to scavenge the toxic metabolites and free radicals. Moreover, the withdrawal period may produce some degree of spontaneous recovery induced by compensatory mechanisms. In DMN-injected rats, it can be also hypothesized that the hepatoprotective effect of the tested extracts may be due to the alteration of drug-metabolizing enzymes more than due to activation of antioxidant enzymes without excluding the antioxidative capacity of the tested extracts themselves. DMN caused hepatobiliary inflammation and necrotic lesions as it estimated by histopathological studies and a profound rise of plasma CA 19.9 and bilirubin. DMN increased hepatic collagen and elastin contents indicating that DMN may cause liver fibrosis after further administration. On the other hand, the tested extracts decreased the hepatic collagen and elastin contents. So, they are considered to be cytoprotective agents against liver fibrosis. DMN showed degeneration, desquamation and atrophy of many acini of thyroid gland which was antagonized by the tested extracts as confirmed by the histological study. Conclusion: So, we can conclude that the tested extracts ameliorated the toxic effects resulted of DMN administration on liver and thyroid glands of male albino rats. Hence, the tested extracts can be used as a co-remedy of DMN toxicity.