The effectiveness of melittin injection in rats with chronic prostatitis pain

Abstract

Objective To test the effectiveness of melittin in chronic prostatic pain model. Methods Adult male Spraque-Dawley rats were injected with complete freunds adjuvant (CFA) into the prostate to make chronic prostatic inflammation. Melittin was injected into the prostates of these models 12 days later. The nociceptive effects were evaluated by using a behavior approach ( mechanical threshold measurement) at the 6th, 12th, and 18th day respectively after intraprostatic injection of CFA. The level of cyclooxygenase (COX-2) in prostate and glial fibrillary acidic protein (GFAP) expression in spinal cord were detected by immunohistochemistry. The rats in control group were injected with normal saline. Results CFA induced rats local allodynia, increases in inflammatory cell quantity and COX-2 expression in prostate, and GFAP expression in spinal cord. Melittin injection significantly raised pain mechanical threshold and decreased inflammatory cells quantity, COX-2 and GFAP expression as compared with control group. Conclusion Local injection of melittin can raise pain threshold, inhibit accumulation of inflammatory cells and expression of COX-2 and GFAP, produce some analgesic and anti-inflammatory effects in rat chronic prostate pain model. Key words: Prostatitis; Melittin; Chronic pain; GFAP