Quantitative evaluation of glandular and stromal compartments in hyperplastic dog prostates: Effect of 5‐alpha reductase inhibitors

Abstract

The objective of this study was to determine the effects of 2 different 5-alpha reductase inhibitors (finasteride and MK-0434) on the glandular and stromal compartments of hyperplastic canine prostates. In this study, dogs received 1 of the 2 compounds orally, at a dose of 1 mg/kg/day for 16 weeks; control dogs received a placebo. The morphological changes in the glandular and stromal compartments in the prostate were quantitated by a point-counting method on Masson's trichrome-stained sections. Treatment with 5-alpha reductase inhibitors resulted in significant (P < or = 0.05) decreases in mean prostatic volumes, microscopic evidence of prostatic atrophy, and significant (P < or = 0.05) decreases in the absolute volumes of the prostatic glandular and stromal compartments compared to controls. In finasteride-treated dogs, the mean percent change from baseline was: epithelium, -52; lumens, -58; fibrovascular stroma, -41; and smooth muscle, -29. In MK-0434-treated dogs, the mean percent change from baseline was: epithelium, -77; lumens, -58; fibrovascular stroma, -38; and smooth muscle, -42. The effect on the glandular compartment in dogs treated with MK-0434 was slightly greater than in dogs treated with finasteride; however, the effect on the stroma was similar. These results clearly demonstrate that inhibition of 5-alpha reductase enzyme activity affects growth and maintenance of both glandular and stromal compartments of dog hyperplastic prostates. It is likely that the decrease in size of the prostate in finasteride-treated (Proscar) men is due to shrinkage of both glandular and stromal compartments.

Interstitial and transurethral photodynamic therapy of the canine prostate using meso-tetra-(m-hydroxyphenyl) chlorin

“…Also, care must be taken when extrapolating data from one organ to another and from one species to another. The glandular to stromal ratio and the embryological development of the prostate in dogs and humans are different, which could influence the PDT effects, although this is unlikely (Laroque et al, 1995). Selman and Keck (1994) used the photosensitiser Tin(I1) etiopurpurin dichloride (SnET2) with light delivered transurethrally for PDT on the normal canine prostate and showed similar results to ours with good healing of the urethra.…”

Regressive changes in finasteride-treated human hyperplastic prostates correlate with an upregulation of TGF-β receptor expression

“…These clinical effects occur particularly in prostates that are 40 g or larger [6]. Recently, prostatic atrophy has been reported histologically in men receiving finasteride [7] and demonstrated in experimental models [8,9]. The role of the complex stromal-glandular interactions in BPH development and regression following antiandrogen therapy is under extensive investigation, but is not yet fully characterized.…”

Effects of Mepartricin (S&ndash;160) on Spontaneous Canine Benign Prostatic Hyperplasia

“…Using this model, we demonstrated that S–160 reduced the prostatic volume and improved the hyperplastic state. This regression of hyperplasia was modest, and in contrast to antiandrogen [16]and 5α–reductase inhibitor [17], marked epithelial involution was not induced. However, the improvement of hyperplasia was observed both in the glandular and stromal component of prostate by the treatment of S–160.…”