Quantitative evaluation of collagen and muscle fibers in the lower urinary tract of castrated and under-hormone replacement female rats.
OBJECTIVE
To evaluate the number of collagen and muscle fibers in the muscle layer of the urethra and in the bladder wall of castrated and under-hormone replacement female rats.


METHODS
We studied 37 castrated female rats assigned to the following groups: Group C (n=9): received no medication; Group P (n=8) was given 0.1 ml of placebo, subcutaneous (SC) route; Group E (n=10): 17beta-estradiol, 10 microg/kg/day, SC route; Group PR (n=9): medroxyprogesterone acetate. 0.2 mg/kg/day, SC route; Group E+PR (n=9): association of 17beta-estradiol and medroxyprogesterone acetate. Sections were taken from the bladder wall and from the middle third of the urethra, and the specimens were stained with picrosirius for collagen and muscle fiber identification.


RESULTS
Groups C and P showed a similar amount of collagen in the bladder and in the urethra, however greater than the other groups. Group E showed the smallest number of collagen fibers in the urethra. Groups E and E+PR presented a larger number of muscle fibers in the bladder. Group PR presented a larger number of muscle fibers than groups C and P, however smaller than groups E and E+PR. In the muscle layer of the urethra, the number of collagen fibers was smaller in Group E than in all the other groups, which were similar among one another. In regard to the urethral muscles, Group E was found to present the largest number of muscle fibers as compared to the other groups analyzed, while Group PR showed a significant decrease in the muscle layer, even in relation to the groups that were given no hormone medication.


CONCLUSIONS
Estrogens significantly decrease the amount of collagen fibers, increase the amount of muscle fibers and determine a significantly decreased collagen/muscle ratio in both the detrusor muscle and in the urethral muscle layer. It is also noticed that isolated progestogen decreases the amount of collagen fibers and increases the number of muscle fibers in the detrusor muscle, but with less intensity than replacement with estrogens alone. It neither alters the number of collagen fibers nor decreases the muscle fibers in the muscle layer of the urethra, with increased collagen/muscle ratio in that structure. Finally, the estrogen-progestogen combination determines significantly decreased collagen fibers and increased muscle fibers in the detrusor muscle, causing no alteration to the collagen or muscle fibers in the muscle layer of the urethra.
Sartori
M G
MG
Gynecology Department, Federal University of São Paulo. Brazil.
Girão
M J
MJ
de Jesus Simões
M
M
Sartori
J P
JP
Baracat
E C
EC
Rodrigues de Lima
G
G
D000818:Animals; D003094:Collagen / Q000032:analysis / Q000096:biosynthesis*; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D020249:Hormone Replacement Therapy; D008525:Medroxyprogesterone / Q000494:pharmacology*; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism; D009130:Muscle, Smooth / Q000033:anatomy & histology / Q000187:drug effects* / Q000378:metabolism; D010052:Ovariectomy; D051381:Rats; D017208:Rats, Wistar; D014521:Urethra / Q000033:anatomy & histology / Q000187:drug effects*; D001743:Urinary Bladder / Q000033:anatomy & histology / Q000187:drug effects* / Q000378:metabolism
D004958:Estradiol; D003094:Collagen; D008525:Medroxyprogesterone