RESUMEN
<p><b>OBJECTIVE</b>To investigate the expressions of transforming growth factor-beta(1) and Smad4 in the prostatic tissue of rat models of chronic nonbacterial prostatitis (CNP), and to explore the mechanisms of CNP and its fibrosis.</p><p><b>METHODS</b>Sixty 6-month-old SD rats were randomly allocated into three groups of equal number: normal control, 30 d CNP model and 45 d CNP model, the models made by castration + high-dose intramuscular injection of estradiol benzoate. The expressions of TGF-beta1 and Smad4 in the prostatic tissue were detected by immunohistochemistry and Western blot.</p><p><b>RESULTS</b>Compared with the normal controls, the 30 d and 45 d CNP rat models showed a significantly increased expression of TGF-beta1 and decreased expression of Smad4 (P < 0.05), even more significantly in the 45 d than in the 30 d group. And the expression of TGF-beta1 was negatively correlated with that of Smad4 in the CNP rat models.</p><p><b>CONCLUSION</b>TGF-beta1 and Smad4 may be involved in the pathogenesis of CNP, and prostatic fibrosis may make the condition difficult to cure.</p>