RT Journal Article SR Electronic T1 Immunochemical detection of cytochrome P450 enzymes in liver microsomes of 27 cynomolgus monkeys JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP jpet.111.185009 DO 10.1124/jpet.111.185009 A1 Shotaro Uehara A1 Norie Murayama A1 Yasuharu Nakanishi A1 Darryl C Zeldin A1 Hiroshi Yamazaki A1 Yasuhiro Uno YR 2011 UL http://jpet.aspetjournals.org/content/early/2011/08/19/jpet.111.185009.abstract AB The cynomolgus monkey is widely used as a primate model in preclinical studies due to its evolutionary closeness to humans. Despite their importance in drug metabolism, the content of each cytochrome P450 (P450) isoform has not been systematically determined in cynomolgus monkey livers. In this study, liver microsomes of 27 cynomolgus monkeys were analyzed by immunoblotting using selective P450 antibodies. Specificity of each antibody was confirmed by analyzing the cross-reactivity against 19 isoforms of CYP1-3 subfamilies using recombinant proteins. CYP2A, CYP2B6, CYP2C9/19, CYP2C76, CYP2D, CYP2E, CYP3A4, and CYP3A5 were detected in all 27 animals. In contrast, CYP1A, CYP1D, and CYP2J were below detectable levels in all liver samples. Average content of each P450 showed that among the P450s analyzed, CYP3A (3A4 and 3A5) was most abundant (40% of total immunoquantified P450), followed by CYP2A (25%) and CYP2C (14%), CYP2B6 (13%), CYP2E1 (11%), and CYP2D (3%). No Apparent sex differences were found for any P450. Inter-animal variations ranged from 2.6-fold (CYP3A) to 11-fold (CYP2C9/19), and most P450s (CYP2A, CYP2D, CYP2E, CYP3A4, and CYP3A5) varied 3-4-fold. To examine correlations of P450 content with enzyme activities, metabolic assays were performed in 27 cynomolgus monkey livers using 7-ethoxyresorufin, coumarin, pentoxyresorufin, flurbiprofen, bufuralol, dextromethorphan, and midazolam. CYP2D and CYP3A4 contents were significantly correlated with typical reactions of human CYP2D (bufuralol 1'-hydroxylation and dextromethorphan O-deethylation) and CYP3A (midazolam 1'-hydroxylation and 4-hydroxylation). The results presented in this study provide the useful information for drug metabolism studies using cynomolgus monkeys.