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  • Author or Editor: Karyn D. Howard x
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Abstract

Objective—To investigate effects of bacteria-mediated inflammation on hepatic drug metabolizing enzymes (DMEs) in swine via a lipopolysaccharide (LPS) challenge technique.

Animals—22 Poland China–Landrace crossbred barrows.

Procedures—In experiment 1, 10 market-weight swine were treated with LPS (20 μg/kg, IV [n = 5 swine]) or sham-injected (5) 24 hours before slaughter. In experiment 2, 12 growing and finishing swine were treated with LPS at 2 or 20 μg/kg, IV (n = 3 swine/age group/treatment) 24 hours before slaughter. Hepatic DMEs, cytochrome P450 (CYP) isoforms, and CYP-mediated reactions were measured.

Results—In experiment 1, LPS administered at 20 μg/kg decreased most hepatic DME components and inhibited enzymatic activities. In experiment 2, both doses reduced protein content in subcellular fractions and inhibited some DME- and CYP-mediated activities. In growing and finishing swine, CYP2A and CYP2B isoforms were not detected after treatment with LPS; the CYP1A2 isoform was eliminated in growing but not in finishing swine. Lipopolysaccharide also reduced CYP2D6 content in growing and finishing swine but increased CYP2E content. Lipopolysaccharide had no effect on swine CYP2C11, CYP2C13, or CYP3A content. The CYP2B-mediated 7-pentoxyresorufin O-dealkylase activity in growing and finishing swine was totally eliminated, and 7-ethoxyresorufin (indicating CYP1A activity) and aniline (mediated by CYP2E) metabolism was decreased.

Conclusions and Clinical Relevance—Effect of LPS treatment on swine CYPs appeared to be isoform specific; age-related metabolic status of the swine and the LPS dose modified this effect. Lipopolysaccharide-induced inflammation may affect metabolism of drugs and xenobiotics in swine.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effect of oral administration of low doses of pentobarbital on cytochrome P450 (CYP) isoforms and CYP-mediated reactions in immature Beagles.

Animals—42 immature (12-week-old) Beagles.

Procedure—Dogs were grouped and treated orally as follows for 8 weeks: low-dose pentobarbital (50 µg/d; 4 males, 4 females), mid-dose pentobarbital (150 µg/d; 4 males, 4 females), high-dose pentobarbital (500 µg/d; 4 males, 4 females), positive-pentobarbital control (10 mg/kg/d; 2 males, 2 females), positivephenobarbital control (10 mg/kg/d; 2 males, 2 females), and negative control (saline [0.9% NaCl] solution; 5 males, 5 females). Serum biochemical and hematologic values were monitored. On necropsy examination, organ weights were determined, and histologic evaluation of tissue sections of liver, kidney, small intestine, testes, epididymis, and ovaries was performed. Hepatic and intestinal drug-metabolizing enzyme activities were measured, and relative amounts of CYP isoforms were determined by western blot analysis.

Results—The amount of a hepatic CYP2A-related isoform in dogs from the high-dose pentobarbital treatment group was twice that of dogs from the negative control group. CYP2C was not detectable in small intestinal mucosa of dogs from the negative control group; measurable amounts of CYP2C were found in dogs from the various (low-, mid-, and high-dose) pentobarbital treatment groups and from positive-pentobarbital and positive phenobarbital control groups. Several CYP-mediated reactions increased in a dosedependent manner. The lowest calculated effective dose of pentobarbital ranged from 200 to 450 µg/d.

Conclusions and Clinical Relevance—Several CYP isoforms and their associated reactions were induced in dogs by oral administration of low amounts of pentobarbital. (Am J Vet Res 2003;64:1167–1175)

Full access
in American Journal of Veterinary Research