Down-regulation of delta opioid receptor mRNA by an anabolic steroid in neuronal hybrid cells

Nandrolone, an anabolic androgenic steroid, reduced delta opioid receptor ( DOR) mRNA and the number of DOR binding sites in two neuronal hybrid cell l ines: NG 108-15 and the GT1-1 cells. Both cell lines express DOR but only G T1-1 cells express androgen receptors (AR). DOR mRNA levels were maximally decreased by similar to 45% in NG 108-15 cells and by similar to 38% in GT1 -1 cells exposed for 24h to 10(-6) M nandrolone. This action was partly due to a decrease in the rate of transcription of DOR mRNA and was not blocked by the androgen antagonist flutamide. Flutamide antagonized the repression of AR mRNA induced by nandrolone. The synthetic glucocorticoid dexamethaso ne (10(-6) M) did not modify DOR steady-state transcripts in either cell li ne. These results suggest that nandrolone presumably regulate DOR mRNA leve ls through mechanisms independent of the androgen and glucocorticoid recept ors. NeuroReport 11:863-867 (C) 2000 Lippincott Williams & Wilkins.