Ductal heterogeneity in rat dorsal-lateral prostate.

Given the lobar complexity of the rat prostate at the morphological level, differences in secretory protein expression were investigated in individual prostatic ducts that constitute the subdivisions of the dorsal-lateral prostate, ie., the dorsal prostate, lateral prostate type 1 and lateral prostate type 2. For this purpose, individual prostatic ducts were microdissected from these prostatic lobes, photographed, and secretions subsequently collected from individual prostatic ducts and analyzed by Western blot for the expression of DP-1 and probasin, two major proteins expressed in rat the dorsal-lateral prostate. Many individual glands constituting the dorsal prostate, lateral prostate type 1 and lateral prostate type 2 co-express DP-1 and probasin, but at vastly different levels. DP-1 is a major secretory protein of the dorsal prostate and lateral prostate type 1, while probasin is the major secretory protein of the lateral prostate type 2. A small percentage of individual ducts of the dorsal prostate, lateral prostate type 1 and lateral prostate type 2 express either DP-1 or probasin. However, most of the individual prostatic ducts constituting the dorsal prostate and lateral prostate type 1 express DP-1 at high levels and probasin at low levels. Conversely, most of the individual prostatic glands that constitute the lateral prostate type 2 express probasin at high levels and DP-1 at low levels. This study emphasizes the morphological and functional heterogeneity within the prostate gland.