PT  - JOURNAL ARTICLE
AU  - Warrington, Jill S.
AU  - Greenblatt, David J.
AU  - von Moltke, Lisa L.
TI  - Age-Related Differences in CYP3A Expression and Activity in the Rat Liver, Intestine, and Kidney
AID  - 10.1124/jpet.103.061077
DP  - 2004 May 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 720--729
VI  - 309
IP  - 2
4099  - http://jpet.aspetjournals.org/content/309/2/720.short
4100  - http://jpet.aspetjournals.org/content/309/2/720.full
SO  - J Pharmacol Exp Ther2004 May 01; 309
AB  - We evaluated the effect of age on CYP3A expression and function in the liver, intestine, and kidney from young (3-4 months), intermediate (13-14 months), and old (25-26 months) male Fischer-344 rats. The biotransformation of triazolam to its primary hydroxylated products, 4-OH-TRZ (triazolam) and α-OH-TRZ, was used as a marker of CYP3A activity in rat liver and intestine. Immunoactive CYP3A expression was evaluated by Western blot analysis in the rat intestine, liver, and kidney. Since testosterone and NADPH reductase levels may modulate CYP3A activity, we also examined free plasma testosterone concentrations and NADPH reductase expression in these rats. The effect of age on CYP3A expression was tissue-specific. Although both CYP3A activity and expression were reduced by approximately 50 to 70% in the old livers compared with the young animals, intestinal CYP3A activity and expression did not change significantly with age. The expression of one CYP3A isoform was increased by 1.5-fold in the old kidneys. NADPH reductase expression was reduced by 23 to 36% with age in all tissues; this reached statistical significance only in the liver. Plasma testosterone levels declined by 74% in the old animals. This study suggests that the effect of age on CYP3A expression and function is tissue-specific. In addition, changes in testosterone levels and NADPH reductase expression may contribute to age-related differences in hepatic CYP3A activity. The American Society for Pharmacology and Experimental Therapeutics