Expression of cytochrome CYP2B1/2 in nonpregnant, pregnant and fetal rats exposed to tobacco smoke.

Abstract

Four-month-old female Wistar rats were exposed for 20 days to tobacco smoke obtained from non-filter cigarettes. During the exposure, concentration of tobacco smoke was monitored indirectly by measuring the CO level (1500 mg/m 3 air). The efficacy of exposure was assessed by measuring urine nicotine and cotinine levels. Cigarette smoke did not change total cytochrome P450 and b 5 protein levels in any of the organs studied, and most of these organs did not show any changes in the activity of reductases associated with these cytochromes. Following exposure to tobacco smoke, fetal rat liver expressed CYP2B1/2 protein; in newborns (day 1) both liver and lung showed CYP2B1/2 protein expression and very low pentoxyresorufin O-dealkylase activity. Western blot analysis of adult liver, lung, heart, but not of brain microsomes, showed that tobacco smoke induced CYP2B1/2 in both nonpregnant and pregnant rats, though its expression was lower in the livers and hearts of pregnant females. In the rat and human placenta, neither rat CYP2B1/2 nor human CYP2B6 showed basal or tobacco smoke-induced expression at the protein level. This study shows clearly that the expression of CYP2B1/2, which metabolizes nicotine and some drugs and activates carcinogens, is controlled in rats by age-, pregnancy-, and tissue-specific regulatory mechanisms.The cytochrome CYP2B subfamily inducible by phenobarbital (PB) and other structurally unrelated compounds is widespread in rodents, in contrast to the human orthologous form CYP2B6 that exhibits low expression in liver and extrahepatic tissues and its role is unclear [1]. Both rat liver CYP2B1/2 and human liver CYP2B6 show catalytic activity to-

Characteristics of cytochrome P450-dependent metabolism in the liver of the wild raccoon, <i>Procyon lotor</i>

“…However, in this study, the PROD activity in raccoons was lower than in rats. The PROD activities of raccoons were less than one-tenth of those of rats in the previous study [ 10 ]. CYP2B isoforms have low substrate specificity but are involved in the detoxification of a wide range of chemicals, including organochlorine insecticides [ 42 ].…”

The amplex red/horseradish peroxidase assay requires superoxide dismutase to measure hydrogen peroxide in the presence of NAD(P)H

“…Future experiments are needed to determine the precise contributions of each cytochrome P450 enzyme to the generation of various species of reactive oxygen species including H 2 O 2 . Based on the high sensitivity of our assay, we speculate that NADPH oxidase related H 2 O 2 generation can be determined in other NAD(P)H requiring enzymes including microsomes from extrahepatic tissues which contain either very low levels of cytochrome P450 enzymes and/or distinct forms of cytochrome P450 enzymes [51,52].…”

Expression of cytochrome P450s in the liver of rats administered with Socheongryong-tang, a traditional herbal formula

“…[ 25 ] Rat hepatic CYP2B1/2 shows catalytic activity towards nicotine, activates carcinogens, and metabolizes some drugs. [ 26 ] Tobacco smoke induces the CYP1A1 and CYP2B1/2 expression in rats. [ 27 ] Therefore, the present studies suggest that smoking during the administration of SCRT may over induce CYP1A1 and 2B1/2.…”