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KMID : 1134819990280030638
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Journal of the Korean Society of Food Science and Nutrition
1999 Volume.28 No. 3 p.638 ~ p.645
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Effects of γ - Irradiated Beef Feeding on Preneoplastic Hepatic Lesion, Cytochrome P450 System and Microsome Glucose 6 - Phosphatase Activity in Rat Hepatocarcinogenesis
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Kim Jung-Hee
Kim Mi-Joung
Kang Il-Jun
Byun Myung-Woo
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Abstract
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This study was done to investigate effects of γ-irradiated beef feeding on the formation of glutathione S-transferase placental form positive(GST -P^+) foci, lipid peroxidation, cytochrome P450 system and microsomal glucose 6-phosphate activity in diethylnitrosamine(DEN)-initiated rat hepatocarci-nogenesis. Weaning Sprague-Dawley male rats were fed the diet containing γ-irradiatied ground beef at the dose of 0, 3, 5kGy as a 20% of protein source for 8 weeks. One week after feeding, rats were intraperitoneally injected twice with a dose of DEN(50㎎/㎏ BW). As a promoter, 0.05% phenobarbital was fed in drinking water from one week after DEN treatment until the end of experiment. At the end of 8th week, rats were sacrificed and hepatic GST-P^+ foci, microsomal malondialdehyde(MDA) and conjugated diene contents were determined. In addition, cytochrome P450 content and the activities of NADPH cytochrome P450 reductase and glucose-6-phosphatase were also measured. There was no significant effect by gamma irradiation on microsomal MDA content, conjugated diene, cytochrome P450 content and activities of NADPH cytochrome P450 reductase and glucose-6-phosphatase. However with DEN treatment, microsomal MDA content and conjugated diene contents were significantly changed. Cytochrome P450 content was also significantly increased while microsomal glucose-6-phophatase activity was significantly decreased with DEN treatment. However activity of NADPH cytochrome P450 reductase was not affected. An interesting finding in this study was that the number and area of hepatic GST-P^+ foci of the rats fed gamma irradiated beef were significantly(p＜0.05) lower than those of the control. Such a lowering effect on GST-P^+ foci formation was highest at the dose of 3kGy than others. Overall results suggest that the consumption of low dose of gamma irradiated beef does not affect the formation of lipid peroxide, cytochrome P450 system and membrane stability.
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KEYWORD
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$\gamma$-irradiated beef, GST-P foci, lipid peroxidation, rat hepatogenesis, cytochrome P450, glucose 6-phosphatase
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