Differential alterations in levels of hepatic microsomal cytochrome P450 isozymes following intracerebroventricular injection of bacterial lipopolysaccharide in rats |
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Authors: | Yoshinori Shimamoto Hiroshi Kitamura Hidenobu Hoshi Akio Kazusaka Yoshinori Funae Susumu Imaoka Masayuki Saito Shoichi Fujita |
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Affiliation: | (1) Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060, Japan, JP;(2) Laboratory of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060, Japan, JP;(3) Laboratory of Chemistry, Osaka City University Medical School, Abeno-ku, Osaka 545, Japan, JP |
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Abstract: | To investigate the effect of central inflammation due to bacterial infection, such as meningitis, on the activities of hepatic cytochromes P450 (CYPs), rats were injected intracerebroventricularly (i.c.v.) with 0.1 μ g of bacterial lipopolysaccharide (LPS). The LPS i.c.v. injection significantly decreased the total P450 contents (by 30% of the levels of control rats treated with saline i.c.v.), the contents of CYP1A (48%), 2B (54%), 2C11 (37%) and 3A (40%) and related drug metabolizing activities, 7-ethoxycoumarin O-deethylation (36%), imipramine N-demethylation (41%) and erythromycin N-demethylation (33%) in liver microsomes 24 h after the treatment. In contrast, intraperitoneal (i.p.) injection of LPS at the same dose as i.c.v. (0.1 μ g) did not significantly affect the hepatic microsomal contents of total P450 or the content of each individual CYP isozyme and its activity. CYP2D1 protein and the activity of imipramine 2-hydroxylase were not significantly decreased by LPS injection regardless of the route of administration. The inhibitory effects of 0.1 μg i.c.v. LPS on the activities of these CYPs were almost equal to those of 10 μg i.p. LPS, and 0.01 μg of i.c.v. LPS significantly decreased the activity of imipramine N-demethylase only. Therefore, the LPS i.c.v. injection resulted in CYP isozyme-selective inhibition at an ineffective dose when injected i.p.. It is suggested that a central inflammation, such as meningitis, differentially decreases the levels of hepatic CYP isozymes. A possible involvement is discussed of the central nervous system in this down-regulation. Received: 2 September 1997 / Accepted: 5 May 1998 |
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Keywords: | Cytochrome P450 Drug metabolism Intracerebroventricular Lipopolysaccharide Meningitis |
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