Hepatic microsomal enzyme induction, beta-oxidation, and cell proliferation following administration of clofibrate, gemfibrozil, or bezafibrate in the CD rat.
Toxicol Appl Pharmacol
; 142(1): 143-50, 1997 Jan.
Article
em En
| MEDLINE
| ID: mdl-9007043
ABSTRACT
Male and female CD rats were administered one of two dose levels of clofibrate, gemfibrozil, or bezafibrate daily by oral gavage for a period of 14 days in order to establish an empirical data base using the Charles River CD rat with a single class of drugs against which the potency of novel proprietary compounds could be compared. Subsequent gross examination of the liver indicated significant and dose-related increases in relative and absolute liver weights in males following clofibrate and gemfibrozil. In females, absolute and relative liver weights were significantly elevated to a similar degree with either dose of gemfibrozil, and absolute liver weights were higher in clofibrate-dosed animals. Bezafibrate had no effect on female liver weights. Clofibrate and gemfibrozil increased hepatic palmitoyl CoA beta-oxidation in both sexes; however, clofibrate had the greater effect in males and gemfibrozil had the least effect in females. Bezafibrate treatment resulted in a very pronounced elevation of palmitoyl CoA beta-oxidation in the males but had no similar effect in the females. Concurrent ELISA analysis for cytochrome CYP4A revealed very good correspondence between beta-oxidation and cytochrome induction for each of the three compounds in males, but other cytochromes were not greatly affected, except CYP1A1 which was elevated in bezafibrate-dosed females. For males, further analysis for markers of cellular proliferation, namely cyclin-dependent kinases (CDK) and proliferating cell nuclear antigen (PCNA), indicated dose-related increases for both with clofibrate, increases at the high dose for gemfibrozil, and, for PCNA, a dose-related increase for bezafibrate. In females, both markers for cell proliferation showed either slight or no increases following any of the three drug treatments. These results demonstrate clear sex-dependent differences in terms of relative potency in the hepatic response of the Sprague-Dawley-derived rat to these peroxisome proliferators. Bezafibrate is most potent and gemfibrozil is least potent in stimulating peroxisome-associated beta-oxidation and cytochrome P450 4A induction in the males. Even though gemfibrozil significantly increased liver weights, beta-oxidation and cytochrome P450 4A in the females increased only after clofibrate treatment, although to a lesser degree than in the males administered the same dose. Similar sex-related differences were observed for cell proliferation. In conclusion, sex-related differences were noted in the potency to stimulate acyl Co-A oxidation, its association with hepatomegaly, and the stimulation of cell proliferation, but CYP4A induction always accompanied any substantial drug-dependent increases in beta-oxidation.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ratos Endogâmicos
/
Bezafibrato
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Microssomos Hepáticos
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Genfibrozila
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Clofibrato
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Quinases Ciclina-Dependentes
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Citocromo P-450 CYP1A1
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Sistema Enzimático do Citocromo P-450
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Oxigenases de Função Mista
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Isoenzimas
Limite:
Animals
Idioma:
En
Revista:
Toxicol Appl Pharmacol
Ano de publicação:
1997
Tipo de documento:
Article
País de afiliação:
Estados Unidos
País de publicação:
EEUU
/
ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
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EUA
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UNITED STATES
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UNITED STATES OF AMERICA
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US
/
USA