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Abstract
To study whether the transition to menopause is accompanied by changes in the paraurethral
connective tissue and if these changes are modified by estrogen replacement therapy.
Biopsies were obtained from the paraurethral tissue from 34 women; 12 menstruating,
14 postmenopausal without estrogen treatment, and 8 with estrogen treatment. Collagen
concentration and collagen extractability by pepsin digestion were measured. Proteoglycan
composition and concentration were analysed using Alcian blue. The mRNA levels for
collagen I and III, the small proteoglycans (PGS) decorin and biglycan, and the large
proteoglycan versican, were estimated.
The paraurethral biopsies consisted of fibrous connective tissue, with collagen fibers
as dominating structure. Several proteoglycans were identified; versican, heparansulphate
proteoglycans, biglycan and decorin. The small proteoglycan decorin represented 85%
of all proteoglycans. The collagen concentration was almost doubled in postmenopausal
biopsies compared to premenopausal. The collagen fibril organization was also changed
with higher cross-linking after menopause whereas the amount and the composition of
the proteoglycans were unchanged. The proteoglycan/collagen ratio was significantly
decreased. Estrogen replacement therapy resulted in decreased collagen concentration,
decreased cross-linking of the collagen and reversal of the PGS/collagen ratio to
almost premenopausal level. The therapy resulted in increased levels of mRNA for collagen
I and III which suggests that the changes are due to an increased turnover.
The decrease in estrogen levels at menopause results in a connective tissue with different
qualities after menopause. Estrogen replacement therapy tends to restore the metabolism
of the genitourinary connective tissue to premenopausal conditions.