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.