DIFFERENTIAL-EFFECTS OF CYTOCHROME-P-450 INDUCTION ON LIGAND-BINDING TO DELTA-RECEPTORS

The identity of the sigma-receptor as a form of cytochrome P-450 was investigated in rats treated with 3-methylcholanthrene or phenobarbital. The density of [H-3]N,N'-di(o-tolyl)guanidine (DTG) binding to sigma-2 receptors in hepatic subcellular fractions increased following both treatments, while [H-3](+)-pentazocine binding to sigma-1, receptors was unchanged. Furthermore, proadifen and piperonyl butoxide inhibited [H-3](+)-pentazocine and [H-3]DTG binding with low potency. The low affinity of cytochrome P-450 inhibitors for sigma-receptors, the similiar degree of enhancement of [H-3]DTG binding by agents with disparate cytochrome P-450 induction profiles and the lack of change in [H-3](+)-pentazocine binding are inconsistent with the identity of the sigma-receptor as a cytochrome P-450.