Transcriptional Determination of Sexually Dimorphic Expression of Nuclear Receptor Constitutively Active Receptor (CAR) in Wistar Rats

Abstract

The mammalian constitutively active receptor (CAR) is a ligand-activated transcription factor that participates in controlling the expression of cytochrome P450 2B (CYP2B) genes in response to phenobarbital (PB) in rodents. CYP2B forms are highly inducible in liver and intestine in male Wistar rats. In contrast, PB-dependent increases in CYP2B activity are rarely observed in female Wistar rats. The profiles of CAR mRNA expression measured by RT-PCR in various organs in male and female Wistar rats were consistent with those of PB-dependent expression of CYP2B genes. The sex-related dimorphic PB-responses of CYP2B genes in Wistar rats might be determined transcriptionally as are the organospecific PB-responses in both males and females.