Collagen and blood vessels of the urethral submucosa of ovariectomized rats were studied following 28 daily subcutaneous injections of 17-β estradiol (n = 6, group 1), medroxy-progesterone acetate (n = 6, group 2), both drugs (n = 6, group 3) or vehicle (n = 6, control) and after sham surgery without castration or injection (n = 6). Investigations included the immunohistochemistry of estrogen and progesterone receptors and collagen fibres, Western blot analysis of collagen types I and III and counting periurethral vessels by light microscopy. Our results showed positive immunostaining with estrogen, progesterone and collagen types I and III in all samples. Collagen type I and III levels were lower in the controls than in the sham group. The other groups showed increases (2 > 3 > 1) over the controls with a relatively higher increase in type III. The type I/III collagen ratio progressively decreased (control > 1 > 2 > 3) below sham levels. The mean vessel count was significantly lower in control than in sham animals (P<0.00001). However, only estrogen treatment significantly increased the vessel number compared to controls (P = 0.04). Our results indicate that estrogen and progesterone, alone or in combination, have an effect on collagen types I and III, and that estrogen has an effect on blood vessels of the urethral submucosa in female rats.
- Urinary incontinence
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