Morphology and histomorphometry of the bladder and urethra in ovariectomized rats after long-term use of tibolone.
BACKGROUND
This study aimed to evaluate the effect of long-term high-dose tibolone on the bladders and urethras of ovariectomized rats.


METHODS
Bilateral ovariectomy was performed in 14 young adult rats randomly divided into 2 groups. Experimental rats (n = 9) received 1 mg/day of tibolone orally; control rats (n = 6) received a placebo. After 150 days, the bladders and urethras were removed. Bladder cell proliferation was analyzed by Ki-67 immunohistochemistry. A histomorphometric analysis was performed for epithelial thickness and the percent areas of collagen fibers and blood vessels. Data were compared using a Mann-Whitney test (significance level at p < 0.05).


RESULTS
Urothelial thickness and the percent area of collagen fibers and blood vessels were not significantly different between the tibolone and control groups in the bladder and urethra. In addition, urothelium cell proliferation in the bladder showed a low immunopositivity in both groups. Furthermore, the glycogen and glycoprotein contents in urethral epithelium were slightly modified by tibolone and no change was observed in the bladder.


CONCLUSIONS
Long-term administration of tibolone has no effect on urothelial trophism, collagen fibers, the number of vessels, or cell proliferation in the urethra and bladder of the ovariectomized rat.
Department of Pathology, Universidade Federal Fluminense, Niteroi, Brazil.
Helene Nara
HN
Henriques
Ana Carolina
AC
Bergmann de Carvalho
Jose Augusto Soares
JA
Pantaleão
Maria Angélica
MA
Guzmán-Silva
D000818:Animals; D020847:Estrogen Receptor Modulators / Q000008:administration & dosage*; D005260:Female; D006003:Glycogen / Q000032:analysis; D006023:Glycoproteins / Q000032:analysis; D009652:Norpregnenes / Q000008:administration & dosage*; D010052:Ovariectomy; D051381:Rats; D017208:Rats, Wistar; D014521:Urethra / Q000033:anatomy & histology / Q000187:drug effects*; D001743:Urinary Bladder / Q000033:anatomy & histology / Q000187:drug effects*; D019459:Urothelium / Q000033:anatomy & histology / Q000737:chemistry / Q000187:drug effects
D020847:Estrogen Receptor Modulators; D006023:Glycoproteins; D009652:Norpregnenes; D006003:Glycogen; C027385:tibolone