Preputial sebocyte 5alpha-reductase isoform specificity.

We determined whether the 5alpha-reductase (5alpha-R) isozyme specificity in rat preputial sebocytes is in accordance with that of sebaceous glands (type 1 isoform) or with that of other genital tract androgen-dependent organs (type 2). Immunostaining indicated expression of type 1 5alpha-R in preputial epithelial cells in the gland as well as in culture. Northern blots and ribonuclease protection assays both showed the presence of the type 1 isozyme in preputial sebocytes, with little if any expression of the type 2 messenger RNA. Ribonuclease protection assay demonstrated that both homogenized preputial gland and freshly dispersed preputial cells express 2-fold more 5alpha-R type 1 messenger RNA than does skin and 7-fold more than cultured preputial cells. Since cultured preputial cells do not fully differentiate in monolayer culture, these findings suggest that 5alpha-R is increasingly expressed as sebaceous cells differentiate. The predominance of the type 1 isoform in preputial sebocytes is important because it indicates programming by a skin- and sebocyte-specific signal in the midst of the genital tract where the type 2 isoform otherwise predominates.