Expression of vascular endothelial growth factor in the lower urinary tract in rats after castration and estrogen administration

Abstract

Objective: To evaluate quantitatively, by means of immune histochemistry, the expression of the vascular endothelial growth factor (VEGF) in the bladder, vesicourethral junction, and urethra in normal, castrated adult rats and under estrogen administration.Design: Sixty adult virgin rats (Rattus norvergicus albinus, Rodentia, Mammalia) from the CEDEME-UNIFESP Animal House were used. Rats were divided into three groups. Group I comprised noncastrated rats, group II comprised oophorectomized rats, and group III comprised castrated rats administered 17 beta-estradiol in the form of subcutaneous implants at the dose of 0.18 mg/implant for 30 days. After performing standard immunohistochemistry procedures, the intensity of the dark-brown color was used as the cytoplasmic protein expression of VEGF. Cells without this coloration or weakly stained were considered negative. Percentile of VEGF expression was obtained by counting 1,000 cells per slide and establishing the ratio between positive and total cells.Results: the VEGF expression was uniform and similar along the urinary tract in group I. After castration, protein expression was almost absent in the bladder and was low in the vesicourethral junction and urethra. With estrogen replacement, very little of the expression was recovered in the bladder, and the reaction became evident in the vesicourethral junction and urethral sections.Conclusions: the present study implies a potential relationship between VEGF and urinary tract physiology. the results suggest that there are quantitative differences in VEGF expression in these tissues depending on steroid hormone status.