Phenylephrine-induced neurogenic prostatitis facilitates the promotion of PIN-like lesions in rats

Atypical prostate hyperplasia, resembling PIN lesions in men, together with chronic inflammatory exudates, have been reported after chronic administration of phenylephrine (PE). The present study aims to characterize the evolution of the expression of typical leukocyte markers immunohistochemically as correlated to the promotion of PIN lesions.

Adolescent rats received injections of PE (subcutaneously) (10 mg/kg BW/per day) and were euthanized 3, 8 hr, 1, 3, 7, 14 days thereafter. The dissected prostates were fixed in formalin, and paraffin embedded sections were cut and immunoreacted.

PE exerted a time related bi-phasic effect on the rat prostate. A first inflammatory reaction phase took place at 3-8 hr post injection characterized by vascular dilatation, congestion, edema, and massive leukocytic infiltrate, mainly of ED1+ cells. At 24 hr, the amount of ED1+ cells decreased approaching the equivalent values of ED2+, CD8+ cells, and mastocytes. Their values remained relatively high for the rest of the experimental period. A second phase of proliferative changes, consisting of healing fibrosis as well as dysplastic epithelial lesions, similar to human PIN lesions, appeared on the 7th day.

Neuro-immune interactions promote prostatic fibrosis and dysplastic changes; these being preceded by an acute and transient inflammatory reaction.