Presentation Authors: Naoyuki Yamanaka*, Kenichi Mori, Shinsuke Mizoguchi, Toshitaka Shin, Hiromitsu Mimata, Oita, Japan
Introduction: Central obesity is known to be involved in benign prostatic hyperplasia (BPH). Some study reports that increased fat tissue induces chronic intra-prostatic inflammation and the change of Estrogen ReceptorÎ±(ERÎ±) and ERÎ² ratio which contributes to the development of BPH. We already confirmed that the high-fat-diet (HFD) induced obesity rats increased urinary frequency and the weight of prostate. Furthermore the ERÎ± expression was significantly increased in the prostate of obesity rats. To find out the detailed mechanism of the ERs, the expression of the ERs and inflammatory cytokines in the prostate using a HFD induced obesity rat model were investigated.
Methods: Male Wistar rats (8 weeks, n=16) were divided into four groups; normal diet group (ND, n=4), high fat diet group (HFD, n=4), high fat diet+ERÎ± antagonist (HFD-ERÎ± antagonist, n=4), high fat diet+ERÎ² agonist (HFD-ERÎ² agonist, n=4). The ND formula contained 5%fat, meanwhile the HFD contained 32% fat. The rats were maintained on these diets for 16 weeks. HFD-ERÎ± antagonist and HFD-ERÎ² agonist rats were administered since 12 week. ERÎ± antagonist: MPP dihydrochloride 1mg/kg/day, ERÎ² agonist: S-Equol 5mg/kg/day. We investigated the prostate weight, analysis of mRNA expression and histopathology of the prostate in each group.
Results: In HFD, weight of the prostate and urinary frequency was significantly increased compared to ND. In addition, the mRNA expression of inflammatory cytokines (IL-1Î², IL-6) were significantly increased. In HFD-ERÎ± antagonist, weight of the prostate and urinary frequency was decreased compared to HFD. The mRNA expression of inflammatory cytokines were also significantly decreased compared to HFD. In Hematoxylin-Eosin stain and Masson Trichrome stain, inflammatory cells and collagen fibers were increased into prostatic stromal area in HFD, while ND and HFD-ERÎ± antagonist did not demonstrate.
Conclusions: HFD intake induced prostatic enlargement and inflammation in associated with altered immune-balance and the expression of ERs. ERÎ± antagonist could play the role of prevention to BPH associated with obesity.