Preventive effects of oligomerized polyphenol on estradiol-induced prostatitis in rats

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS, NIH category III) accounts for 90-95% of prostatitis cases. However, standard treatment has not yet been established. It is known that polyphenols have an inhibitory effect on inflammation by their antioxidative capacity, and oligonol, a polyphenol derivative, has much higher bioavailability and bioactivity than common polyphenols. We investigated the anti-inflammatory effects and mechanisms of oligonol in estradiol-induced prostatitis rat models.

Prostatitis was induced by 17 beta-estradiol (E2) and dihydrotestosterone (DHT) in Wistar male rats (n = 20). Ten rats were placed in the oligonol-treated group and 10 in the E2 + DHT-treated group. The other 10 rats were also included as normal control group. Oligonol (60 mg/kg/day) was administered via gavage tube for 4 weeks. Superoxide dismutase (SOD), glutathione peroxidase (GPx), and tumor necrosis factor-alpha (TNF-alpha) were quantified, and phosphorylation of IkappaBa and histological changes were also evaluated in prostatic tissue.

The SOD and GPx activity showed tendencies to increase in the oligonol-treated group compared to the normal control group. TNF-alpha expression was slightly reduced in the oligonol-treated group. Western blotting demonstrated that phosphorylation of IkappaBa in the oligonol-treated group was significantly lower than in the normal control group. The E2 + DHT-treated group revealed severe atrophy of acinar epithelial cells and infiltration of leukocytes and lymphocytes in the prostate, however, the oligonol-treated group showed overall reduction in inflammatory features.

This study demonstrates that oligonol improves estradiol-induced non-bacterial prostatitis by regulating phosphorylation of IkappaBa. These findings suggest that oligonol has a beneficial effect on prevention and treatment of CP/CPPS.