Development and validation of an animal model of prostate inflammation-induced chronic pelvic pain: evaluating from inflammation of the prostate to pain behavioral modifications.
BACKGROUND
Chronic prostatitis/Chronic pelvic pain syndrome (CP/CPPS) is the most common type of prostatitis. Due to the lack of a suitable animal model partly, the pathogenesis for this condition is obscure. In the current study we developed and validated an animal model for nonbacterial prostatitis and prostate inflammation-induced chronic pelvic pain in rats with the use of intraprostatic injection of λ-carrageenan.


METHODS
Male Sprague-Dawley rats weighing 250-350 g were used for the experiments. After intraprostatic injection of 3% λ-carrageenan, at different time points(after 24 h, 7 d, 14 d and 30 d of injection), radiant heat and von Frey filaments were applied to the scrotum of rats to measure the heat and mechanical thresholds respectively. Then the prostate was removed for histology, and cyclooxygenase (COX) 2 protein expression was determined by Western-blot. Evans blue(50 mg/kg) was also injected intravenously to assess for plasma protein extravasation at different time points after injection of λ-carrageenan.


RESULTS
Compared to control group, inflamed animals showed a significant reduction in mechanical threshold (mechanical allodynia) at 24 h and 7d(p = 0.022,0.046, respectively), and a significant reduction in heat threshold (thermal hyperalgesia) at 24 h, 7d and 14 d(p = 0.014, 0.018, 0.002, respectively) in the scrotal skin. Significant increase of inflammatory cell accumulation, COX2 expression and Evans blue extravasation were observed at 24 h, 7d and 14 d after injection.


CONCLUSIONS
Intraprostatic λ-carrageenan injection induced neurogenic prostatitis and prostate inflammation pain, which lasted at least 2 weeks. The current model is expected to be a valuable preclinical tool to study the neurobiological mechanisms of male chronic pelvic pain.
Department of Urology, Xiangya Hospital, Central South University, Changsha, Hunan, China.
Feng
F
Zeng
Department of Urology, Xiangya Hospital, Central South University, Changsha, Hunan, China.
Hequn
H
Chen
Department of Urology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
Jinrui
J
Yang
Department of Urology, Xiangya Hospital, Central South University, Changsha, Hunan, China.
Long
L
Wang
Department of Urology, Xiangya Hospital, Central South University, Changsha, Hunan, China.
Yu
Y
Cui
Department of Urology, Xiangya Hospital, Central South University, Changsha, Hunan, China.
Xiao
X
Guan
Department of Urology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
Zhao
Z
Wang
Department of Urology, Xiangya Hospital, Central South University, Changsha, Hunan, China.
Jiping
J
Niu
Department of Urology, Xiangya Hospital, Central South University, Changsha, Hunan, China.
Xiongbing
X
Zu
Department of Urology, Xiangya Hospital, Central South University, Changsha, Hunan, China.
Lin
L
Qi
Department of Urology, Xiangya Hospital, Central South University, Changsha, Hunan, China.
Xiangyang
X
Zhang
Department of Urology, Xiangya Hospital, Central South University, Changsha, Hunan, China.
Zhengyan
Z
Tang
Department of Urology, Xiangya Hospital, Central South University, Changsha, Hunan, China.
Longfei
L
Liu
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D051546:Cyclooxygenase 2 / Q000378:metabolism; D004195:Disease Models, Animal; D006930:Hyperalgesia / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D017288:Pain Threshold / Q000502:physiology*; D017699:Pelvic Pain / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D011467:Prostate / Q000378:metabolism / Q000503:physiopathology*; D011472:Prostatitis / Q000139:chemically induced / Q000150:complications / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D051546:Cyclooxygenase 2