Nandrolone decreases mu opioid receptor expression in SH-SY5Y human neuroblastoma cells

Nandrolone and other anabolic androgenic steroids alter the expression and function of neurotransmitter systems and contribute to drug dependence. Nandrolone treatment (10-10 M) caused a time-dependent and concentration-dependent downregulation of mu opioid receptor (MOPr) transcripts in SH-SY5Y human neuroblastoma cells. This effect was prevented by the androgen receptor antagonist hydroxyflutamide. Receptor binding assays confirmed a decrease in MOPr of approximately 40% in nandrolone-treated cells. Treatment with actinomycin D (10 (-5)M), a transcription inhibitor, revealed that nandrolone might regulate MOPr mRNA stability. In SH-SY5Y cells transfected with a human MOPr luciferase promoter/reporter construct, nandrolone did not alter the rate of gene transcription. These results suggest that nandrolone may regulate MOPr expression through posttranscriptional mechanisms requiring the androgen receptor.