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Estrogen induced functional hypertrophy and increased force generation of the female rabbit bladder
Author(s) -
Lin Alpha DianYu,
Levin Robert,
Kogan Barry,
Whitbeck Catherine,
Chichester Paul,
Sokol Rebekah,
Mannikarottu Anita
Publication year - 2006
Publication title -
neurourology and urodynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 90
eISSN - 1520-6777
pISSN - 0733-2467
DOI - 10.1002/nau.20258
Subject(s) - estrogen , ovariectomized rat , medicine , endocrinology , contractility , genitourinary system , muscle hypertrophy , atrophy , estrogen receptor , urinary system , hormone , cancer , breast cancer
Aims Estrogen is essential for physiological maintenance of the female urogenital tract. It is believed that alterations in female sex hormones play a major role in the etiology and response to urinary tract dysfunctions. In animal studies, ovariectomy (Ovx) results in smooth muscle (SM) weakness and atrophy whereas estrogen supplementation reverses these effects. Our study seeks to establish the mechanisms by which estrogen augmentation results in increased contractility. Methods Twenty New Zealand White female rabbits were separated into five groups of four each. Group 1 served as control, rabbits of groups 2–5 were ovariectomized, group 2 ovariectomized received no estradiol, groups 3–5 were given 17‐β estradiol (1 mg/kg/day) by subcutaneous slow release tablet implant for 1, 3, and 7 days, respectively, beginning 2 weeks after Ovx. At the end of the experimental period, each rabbit was anesthetized and the urinary bladder was removed for contractile, histological, and biochemical studies. Results Ovx resulted in significantly decreased bladder contractile function, whereas bladders tested after estradiol administration showed increased contractility. Ovx resulted in a decrease in SM/collagen ratio, whereas estrogen resulted in an increase. The estrogen receptor (ER) density significantly increased following Ovx. After 1 day of estrogen treatment, the ER density decreased significantly below control levels, but rose progressively during the estrogen treatment. Conclusion The present study demonstrates that estrogen supplementation mediates a “functional hypertrophy,” that is a hypertrophy characterized by increased contractile responses to all forms of stimulation, and an increased ratio of SM/collagen. Neurourol. Urodynam. © 2006 Wiley‐Liss, Inc.