Creation and Preliminary Characterization of Pregnane X Receptor and Constitutive Androstane Receptor Knockout Rats.

The nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR) are closely related transcription factors that regulate the expression of phase I (cytochrome P450s) and phase II metabolizing enzymes and transporter genes in response to stimulation from xenobiotics, including prescription drugs. PXR and CAR knockout and humanized mouse models have proven useful. However, the rat being bigger in size is a preferred model system for studying drug metabolism and pharmacokinetics.