Androgen regulation of the messenger RNA encoding diazepam-binding inhibitor/acyl-CoA-binding protein in the rat

Our recent finding that diazepam-binding inhibitor/acyl-CoA-binding protein (DBI/ACBP) expression is regulated by androgens in the human prostatic adenocarcinoma cell line LNCaP, prompted us to study whether androgen regulation of DBI/ACBP also occurs in vivo in the prostate and in other organs of the rat. Northern blot analysis demonstrated that DBI/ACBP transcripts were expressed in male accessory sex organs such as ventral prostate, dorsolateral prostate, seminal vesicles and coagulating glands. Castration caused a 1.7- to 2.7-fold reduction in the levels of DBI/ACBP transcripts over a period of 6 days. Readministration of androgens during the last 3 days led to 4.2- to 7.5- fold higher levels of DBI/ACBP transcripts than in untreated castrates. In situ hybridization revealed that in the ventral prostate, DBI/ACBP transcripts were expressed predominantly in epithelial cells and that the observed effects of androgens were due both to modulation of gene expression per cell and to changes in cell composition. Androgen regulation of DBI/ACBP mRNA expression was also observed in the lacrimal glands, the adrenals, and the submandibular glands, but not in the liver and the kidney. These findings demonstrate that DBI/ACBP is androgen-regulated in vivo in various organs of the rat. In view of the proposed role of DBI/ACBP in the control of multiple biological processes, DBI/ACBP may be one of the target genes by which androgens affect a variety of physiological processes.