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 pr otein (DBI/ACBP) expression is regulated by androgens in he human pros tatic adenocarcinoma cell line LNCaP prompted us to study whether andr ogen 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 coagulat ing glands. Castration caused a 1.7- to 2.7-fold reduction in the leve ls of DBI/ACBP transcripts over a period of 6 days. Readministration o f androgens during the last 3 days led to 4.2- to 7.5- fold higher lev els of DBI/ACBP transcripts than in untreated castrates. In situ hybri dization revealed that in the ventral prostate, DBI/ACBP transcripts w ere expressed predominantly in epithelial cells,and that the observed effects of androgens were due both to modulation of gene expression pe r cell and to changes in cell composition. Androgen regulation of DBI/ ACBP mRNA expression was also observed in the lacrimal glands, the adr enals, and the submandibular glands, but not in the liver and he kidne y. These findings demonstrate that DBI/ACBP is androgen-regulated in v ivo 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 physiol ogical processes.