Expression of transforming growth factor-beta isoforms in the rat male accessory sex organs and epididymis.

We studied the expression and distribution of transforming growth factor-beta (TGF-beta) isoforms in the rat male accessory sex glands and the epididymis. Our data demonstrate the expression of both TGF-beta1 and -beta3 isoforms in ventral prostate (VP), seminal vesicle (SV), coagulating gland (CG), and epididymis (E) by Northern blot analysis. In addition, there was differential expression of TGF-beta3 in the three regions of epididymis, the corpus region being the highest. Immunostaining data showed intense staining for latent TGF-beta1 in all the male accessory glands. In contrast, no staining using antibodies specific for active TGF-beta1 was observed. No expression of TGF-beta2 was evident either by immunohistochemistry or Northern blot analysis. The presence of mature TGF-beta3 protein was observed in the secretory epithelium of VP, CG, and corpus E. There was no detectable staining of TGF-beta3 in the seminal vesicle and caput and cauda regions of epididymis. These data suggest possible differential regulation of TGF-beta isoform expression in the male reproductive system and predict unique roles for individual TGF-beta isoforms in sperm maturation and maintenance.