RT Journal Article
SR Electronic
T1 Latent Overexpression of Hepatic CYP2C7 in Adult Male and Female Rats Neonatally Exposed to Phenobarbital: A Developmental Profile of Gender-Dependent P450s
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 1027
OP 1033
VO 293
IS 3
A1 Arun K. Agrawal
A1 Bernard H. Shapiro
YR 2000
UL http://jpet.aspetjournals.org/content/293/3/1027.abstract
AB For more than 20 years it has been known that neonatal exposure to phenobarbital results in a delayed, but permanent overexpression of drug-metabolizing enzymes in adult male and female rats. Accordingly, to identify the specific isoform(s) of P450 responsible for the imprinted overexpression of hepatic monooxygenases, we have monitored the developmental profile of some dozen hepatic P450 isoforms in 4- to 150-day-old male and female rats neonatally treated with the barbiturate. Some of the cytochrome P450s (CYP), i.e., CYP2A1, 2A2, 2C6, 3A1, and 3A2, exhibit the typical transient response in which isoform levels (mRNA, protein, and/or specific catalytic activity) rise precipitously at the time of phenobarbital administration and rapidly decline to preinduction levels after withdrawal of the barbiturate. Other isoforms, i.e., CYP1A1, 1A2, 2C7, 2C11, 2C12, and 2C13, were neither constitutively expressed nor phenobarbital inducible in the neonate. Only one of these isoforms, female predominant (M:F,∼1:2) CYP2C7, exhibited a barbiturate-induced delayed, but persistent ∼30 to 50% overexpression from puberty through adulthood. We propose that at the time of exposure, neonatally administered phenobarbital produces a “silent” programming defect resulting in a delayed, but persistent overexpression of the isoform, contributing, at least in part, to a permanent elevation of hepatic drug-metabolizing enzyme activities. The American Society for Pharmacology and Experimental Therapeutics