Green tea catechins decrease oxidative stress in surgical menopause-induced overactive bladder in a rat model.
What's known on the subject? and What does the study add? Ovary hormone deficiency and the age-related changes in post-menopausal women are subjected to a number of urological dysfunctions, including overactive bladder syndrome. Green tea is a popular healthy drink worldwide and its extract catechin has strong anti-inflammatory and antioxidant properties. EGCG, the major type of catechin, is an antioxidant polyphenol flavonoid isolated from green tea. EGCG supplement could prevent ovariectomy-induced bladder dysfunction in a dose-related manner through its anti-oxidant, anti-fibrosis and anti-apoptosis effects.


OBJECTIVE
To evaluate whether green tea extract, epigallocatechin gallate (EGCG), could prevent ovariectomy-induced overactive bladder (OAB) and to investigate its antioxidant, anti-apoptotic and anti-fibrosis effects.


METHODS
In all, 48 female Sprague-Dawley rats were divided into four groups. After bilateral ovariectomy, the first group served as the ovariectomy control, the second group received EGCG 1 µM/kg daily i.p. injection after ovariectomy surgery, and the third group received EGCG 10 µM/kg daily i.p. injection. The fourth group was taken as the sham without ovariectomy surgery. The rats were killed after 6 months after ovariectomy surgery. Cystometrograms were performed for the measure of bladder overactivity. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labelling (TUNEL) assay was used to evaluate apoptotic cells. Western immunoblots were performed to determine the expressions of inflammatory markers, apoptosis-associated proteins and oxidative stress markers.


RESULTS
Long-term ovariectomy significantly increased non-voiding contractions and decreased bladder compliance. Treatment with EGCG significantly increased bladder compliance and diminished non-voiding contractions. Ovariectomy significantly increased apoptotic cells and enhanced interstitial fibrosis in bladders. The expression of caspase-3 significantly increased, while that of Bcl-2 notably decreased after ovariectomy. Inflammatory and fibrosis markers, TGF-β, fibronectin and type I collagen expressions were significantly increased after 6 months of ovariectomy surgery. Treatment with EGCG significantly decreased TGF-β and type I collagen expressions. Oxidative stress markers, nitrotyrosine and protein carbonylation levels were significantly increased in the ovariectomy group. EGCG could attenuate this oxidative damage in dose-dependent fashion.


CONCLUSIONS
Ovariectomy increased oxidative damage, enhanced voiding frequency and decreased bladder compliance. EGCG could restore ovariectomy-induced bladder dysfunction in a dose-dependent fashion through antioxidant, anti-fibrosis and anti-apoptosis effects.
Department of Urology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
Yung-Shun
YS
Juan
Shu-Mien
SM
Chuang
Yi-Lun
YL
Lee
Cheng-Yu
CY
Long
Tzu-Hui
TH
Wu
Wei-Chiao
WC
Chang
Robert M
RM
Levin
Keh-Min
KM
Liu
Chun-Hsiung
CH
Huang
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D004195:Disease Models, Animal; D005260:Female; D008593:Menopause / Q000378:metabolism*; D010052:Ovariectomy; D018384:Oxidative Stress / Q000187:drug effects*; D010936:Plant Extracts / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013662:Tea; D053201:Urinary Bladder, Overactive / Q000378:metabolism*
D000975:Antioxidants; D010936:Plant Extracts; D013662:Tea; D002392:Catechin; C045651:epigallocatechin gallate