Development and characterisation of a novel animal model of prostate inflammation-induced chronic pelvic pain.

Abstract

Chronic pelvic pain due to prostate inflammation is a significant clinical problem. In the current study we developed and validated an animal model of inflammation-induced pelvic pain (NIH category IIIA). 3% carrageenan was injected into the ventral prostate in SD rats. At different time points (before and after 48 h, 72 h and 1 wk of injection), radiant heat and von Frey filaments (mechanical stimuli) were applied to different pelvic areas. The escape latency (s) from radiant heat, and the bending force (g) of the filament to which the animal responded by moving were taken as measures of heat and mechanical thresholds respectively. Inflamed animals showed a significant reduction in mechanical threshold (mechanical allodynia) at 72 h and 1 wk, and a significant reduction in heat threshold (thermal hyperalgesia) in the scrotal skin, compared to sham. Morphine (5 mg/kg., i.p.) significantly reduced both heat hyperalgesia and mechanical allodynia. It is expected that this novel model will prove to be useful in studying the neurobiological mechanisms of male pelvic pain.