QUANTITATIVE-EVALUATION OF GLANDULAR AND STROMAL COMPARTMENTS IN HYPERPLASTIC DOG PROSTATES - EFFECT OF 5-ALPHA REDUCTASE INHIBITORS

The objective of this study was to determine the effects of 2 differen t 5-alpha reductase inhibitors (finasteride and MK-0434) on the glandu lar and stromal compartments of hyperplastic canine prostates. In this study, dogs received 1 of the 2 compounds orally, at a dose of 1 mg/k g/day for 16 weeks; control dogs received a placebo. The morphological changes in the glandular and stromal compartments in the prostate wer e quantitated by a point-counting method on Masson's trichrome-stained sections. Treatment with 5-alpha reductase inhibitors resulted in sig nificant (P less than or equal to 0.05) decreases in mean prostatic vo lumes, microscopic evidence of prostatic atrophy, and significant (P l ess than or equal to 0.05) decreases in the absolute volumes of the pr ostatic glandular and stromal compartments compared to controls. In fi nasteride-treated dogs, the mean percent change from baseline was: epi thelium, -52; lumens, -58; fibrovascular stroma, -41; and smooth muscl e, -29. In MK-0434-treated dogs, the mean percent change from baseline was: epithelium, -77; lumens, -58; fibrovascular stroma, -38; and smo oth muscle, -42. The effect on the glandular compartment in dogs treat ed with MK-0434 was slightly greater than in dogs treated with finaste ride; however, the effect on the stroma was similar. These results cle arly demonstrate that inhibition of 5-alpha reductase enzyme activity affects growth and maintenance of both glandular and stromal compartme nts of dog hyperplastic prostates. It is likely that the decrease in s ize of the prostate in finasteride-treated (Proscar(R)) men is due to shrinkage of both glandular and stromal compartments. (C) 1995 Wiley-L iss, Inc.