599 PREPUBERTAL CORTICOSTERONE TREATMENT AFFECTS BLADDER WALL IN RATS

Abstract

INTRODUCTION AND OBJECTIVES: Glucocorticoids (GC) excess can exert negative effects on body growth, negatively influencing cellular and extracellular matrix arrangement. At both prenatal and pubertal phases, GC helps normal body growth and the formation and maturation of genital organs, functioning together with thyroidal hormones, adrenal androgens and sexual hormones. The aim of this work was to analyze the structural and biochemical changes on the bladder wall resulting from the chronic treatment of prepubertal rats with high doses of corticosterone. METHODS: This study included 26 male Wistar rats assigned to four groups: T30 was treated with corticosterone until 29 days of age and killed at day 30, while T65 group received the same treatment but was killed at day 65. Each group had its own control group (C30 and C65). For treated animals, daily intraperitoneal injections of corticosterone (2 mg/100g body weight) were administered between 7th and 29th day of life. Bladders were removed and collagen, smooth muscle, elastic fibers system, vascular density and epithelium were analyzed by morphometrical methods, immunofluorescence, and biochemistry. Data was compared by Student’s-t-test. RESULTS: Blood vessels density was significantly reduced in group T65 when compared to C65 by 40.83% (p 0.0015). In animals killed with 30 days, this reduction was not found. Smooth muscle density increased by 19.4% in the T65 group in comparison to C65 (p 0.0239). Again, this difference was not observed between T30 and C30 animals. The analysis of the elastic system fibers by immunofluorescence showed an increase in elastic fibers in the treated animals T65 when comparing to its control group C65. The analysis of collagen in picrosirius red stained sections observed under polarization microscopy indicated an homogeneous distribution of different types of collagen in treated animals (both T30 and T65). The concentration of total collagen in bladder obtained by biochemical analysis showed no significant difference among the groups. Regarding epithelial height and cellular density no difference was found between the groups studied. CONCLUSIONS: In conclusion, prepubertal administration of corticosterone induces structural modifications in the bladder of rats with a decrease of vascular density, an increase of smooth muscle density and a predominance of collagen type III in lamina propria.