Effects of melatonin on the prostatitis induced by bacterial Lipopolysaccharide and/or Escerichia coli in rats

Purpose: In this study, we created a prostatitis with intraperitoneal bacterial lipopolysaccharide (LPS) injection in the rats and aimed to assess the tonus changes on the prostatic tissues of rats with inflammation through pharmacologic methods and to investigate the effect of melatonin which is a strong antioxidant on the changes due to inflammation.Materials and method: Male Wistar Kyoto rats (200-300 g) were used in the experiments. The rats were categorized into two main groups as the control and the group which bacterial lipopolysaccharide (LPS) (10 mg/kg) was applied. The group which LPS was applied were divided into 5 sub-groups; (I) 24-hour LPS study group, (II) 72-hour LPS + intraurethral E.coli study group, (III) 72-hour LPS + intraurethral E.coli + aminoguanidin study group, (IV) 72-hour LPS + intraurethral E.coli + melatonin study group, (V) 4-week chronic LPS + intraurethral E.coli study group. The rats were killed under isoflorane anesthesia and their prostatic tissues were taken out 24 hours, 72 hours and 4 weeks after the LPS implementation. One lobe of each rat?s prostate was reserved for pathological examination, and the other lobe was isolated and placed into organ baths under 1 g tension which contained 37oC Krebs solution and was oxygenated with the mixture of 95% O2- 5% CO2 (pH:7,4). The tonus changes in the preparations were recorded into a computer through a data collection system. The responses to neurogenic spasms were recorded by giving electrical domain stimulation to the tissues, the responses to adrenergic spasms were recorded by administering fenilefrin which is an alpha-1 adrenergic receptor agonist and the responses to the cholinergic spasms were recorded by giving carbocol which is a cholinergic agonist. The comparison of the groups was assessed statistically by student t test.Findings: The responses to the neurogenic, adrenergic and cholinergic spasms in the groups to which bacterial LPS or LPS + intraurethral LPS were implemented meaningfully decreased. This decrease was more significant in the 72-hour group. The decreases in the 24-hour and 4-week groups were close to each other and they were prominent mostly in smaller frequencies and lower doses. The pathological examinations also confirmed that an acute prostatitis was developed in the 24-hour and 72-hour groups. It was seen that the infection became chronic in the 4-week groups. Melatonin and aminoguanidin, an INOS inhibitor, which were implemented to the 72-hour groups partially reversed the decrease in the responses of spasms.Results: Bacterial LPS implementation in the rat prostate tissues decreases the responses of adrenergic, neurogenic, and cholinergic spasms meaningfully. The main reason of this decrease in the responses of the spasms of the tissue might be the extreme increase of the oxidative activity and the pathology related with the inflammation in the tissue. Melatonin significantly improves the contractility defect due to oxidative damage.Since the INOS inhibitor and antioxidant effect of melatonin improves the histopathology and the contractility defect due to prostatic inflammation it can be concluded that antioxidants might be used in prostatic inflammations.Key Words: Bacterial Lipopolysaccharide, rats prostate, melatonin