Neurologic Mechanisms Underlying Voiding Dysfunction due to Prostatitis in a Rat Model of Nonbacterial Prostatic Inflammation

Park, Jee Soo; Jin, Mei Hua; Hong, Chang Hee

Abstract

PURPOSE
The neurological molecular mechanisms underlying the voiding dysfunction associated with nonbacterial chronic prostatitis/chronic pelvic pain syndrome remain poorly understood. In this study, we assessed whether prostate inflammation activated bladder afferent neurons, leading to bladder dysfunction, and sought to elucidate the underlying mechanisms.
METHODS
Thirty male Sprague-Dawley rats were divided into 3 groups: sham-saline, formalin-injected, and capsaicin-pretreated and formalin-injected. Chemical prostatitis was induced by 0.1 mL of 10% buffered formalin injected into the ventral prostate. Capsaicin was injected subcutaneously to desensitize capsaicin-sensitive nerves. In each group, conscious cystometry was performed, and c-fos expression within the spinal cord was determined immunocytochemically. Double immunofluorescent staining with c-fos and choline acetyltransferase (ChAT) was performed. On the third day after pseudorabies virus (PRV) infection, c-fos and PRV double-staining was performed.
RESULTS
Intraprostatic formalin significantly increased the maximal voiding pressure and decreased the intercontraction interval, compared with controls. Pretreatment with capsaicin significantly reversed these effects. More c-fos-positive cells were observed in the sacral parasympathetic nucleus (SPN) and dorsal gray commissure (DCM) in the prostatitis group than in the sham group. c-fos-positive cells decreased in the capsaicin-pretreated group. Preganglionic neurons labeled by c-fos and ChAT were observed in the SPN in rats with prostatitis. Interneurons labeled by c-fos and PRV were identified in the DCM after PRV infection.
CONCLUSIONS
Our results suggest that prostate inflammation activates afferent nerve fibers projecting to the lumbosacral spinal cord, producing reflex activation of spinal neurons innervating the bladder and bladder hyperreflexia. This is mediated by capsaicin-sensitive prostate afferent neurons.