阮雍順1,2,3,4、 李懿倫4,5、 呂美津6,7、 吳文正1,2,3、 張美玉3、 何婉婷1、 劉克明8、 莊淑棉9
高雄醫學大學 泌尿科1，醫學研究所2， 解剖科8， 轉譯醫學中心9；
高雄市立小港醫院 泌尿科3；高雄醫學大學附設中和紀念醫院 泌尿科4；
衛生署立旗山醫院 外科部 泌尿科5； 國立東華大學6；國立海洋生物館7
The protective effect of epigallocatechin gallate on oxidative stress triggered through mitochondria and endoplasmic reticulum in a metabolic syndrome –induced bladder overactivity rat model
Yung-Shun Juan1,2,3,4, Yi-Lun Lee4,5, Mei-Chin Lu6,7, Wen-Jeng Wu1,2,3, Mei-Yu Jang3, Wan-Ting Ho1, Keh-Min Liu8*, Shu-Mien Chuang9*
1Department of Urology, 4Graduate Institute of Medical Science, 8Department of Anatomy, College of Medicine, 9Translational Research Center, Cancer Center, Kaohsiung Medical University, Kaohsiung, Taiwan; 2Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan;3Department of Urology, Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung, Taiwan;5Department of Urology, Chi-Shan Hospital, Department of Health, Executive Yuan, Kaohsiung, Taiwan; 6Graduate Institute of Marine Biotechnology, National Dong Hwa University, Pingtung 944, Taiwan; 7National Museum of Marine Biology & Aquarium, Pingtung 944, Taiwan;
Long-term metabolic syndrome develops lower urinary tract symptoms. The pathophysiology mechanism underlying the metabolic syndrome associated with bladder dysfunction is still not clear. The major aim of our study is to elucidate metabolic syndrome-induced bladder dysfunction in association with oxidative stress triggered through mitochondria and endoplasmic reticulum (ER) in a metabolic syndrome –induced bladder overactivity rat model. The other aim of the present study is to elucidate the protective effect of epigallocatechin gallate (EGCG) on metabolic syndrome –induced bladder overactivity.
Materials and Methods:
Female Sprague-Dawley rats are divided into control group, high fat high sugar (HFHS) diet group, HFHS diet with bilateral ovariectomy (OVX) (HFHS +OVX) group, HFHS diet with bilateral OVX and EGCG treatment (HFHS+OVX+EGCG) group, and HFHS diet with EGCG (HFHS+EGCG) group, respectively. Cystometry (CMG) and micturition frequency/volume studies were recorded for bladder voiding function. The terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay was performed to evaluate the distribution of apoptotic cells. Western blot was carried out to examine the expressions of interstitial fibrosis markers, muscarinic receptors (M2 and M3), oxidative stress markers, endoplasmic reticulum stress markers (GRP78, CHOP, caspase-12), apoptosis-associated proteins, and the subunits of mitochondrial respiratory complexes. The antioxidant enzymes, including superoxide dismutase and catalase, were investigated by real-time PCR.
The HFHS diet with OVX treated rats displayed bladder overactivity. Bladder contractility was considerably decreased in HFHS with OVX group in response to electric field, carbachol, and KCl stimulation as compared with those in the control group. Such bladder dysfunction was accompanied by a significant increase in oxidative stress markers, ER-associated oxidative stress proteins, apoptosis-associated proteins, and the subunits of mitochondrial respiratory complexes. Conversely, the mRNA expressions of antioxidant enzymes Mn-SOD, Cu/Zn-SOD and catalase were also decreased after long-term HFHS treatment with/without OVX. However, EGCG treatment can improve the extent of oxidative stress and lessen bladder hyperactivity.
Conclusions: HFHS combined with OVX enhanced the generation of oxidative stress mediated through mitochondria- and ER-dependent pathways, and consequently attributed to bladder apoptosis, whereas EGCG treatment could eliminate these oxidative stress and reverse bladder dysfunctions.
Key words: metabolic syndrome, ovariectomy, overactive bladder, apoptosis, EGCG