Effect of melatonin on contractile activity in intraurethrally instilled E. coli-induced acute prostatitis rat model

Aim: To investigate whether prostatic inflammation affects the contractile responses of prostate tissue and then whether melatonin has any restorative effect on the contractile responses in a rat model of bacterial prostatitis at early stages. Materials and methods: We evaluated the nerve-evoked, adrenergic agonist-induced or cholinergic agonist-induced contractions of isolated prostate tissue at 24 and 72 h after intraurethrally instilled Escherichia coli-treatment. We also analyzed the histological changes in the prostate. Secondarily, we investigated the effect of melatonin pretreatment (7 days, 10 mg kg(-1) day(-1)) on the contractile responses and the histopathologic changes. Results: The degrees of acute inflammatory cell infiltration, acinar changes, and interstitial fibrosis in the prostate glands indicated the development of acute prostatitis at 24 or 72 h after bacterial inoculation. These inflammatory changes were more pronounced at 72 h. Bacterial prostatitis attenuated contractile responses to electrical field stimulation, phenylephrine, or carbachol. The impairment in the contractions was more prominent at 72 h. Melatonin treatment reduced the pathologic changes and partially restored the contractile responses at 72 h of inflammation. Conclusion: Prostatic inflammation caused a diminution in the contractile mechanism of the prostate tissue and melatonin partially restored the contractile responses and histopathologic changes. Melatonin can be useful as an adjuvant to the main therapies for prostatitis to reduce the contractility problems.