Transforming growth factor (beta 1) in testes of aged and diabetic rats: Correlation with testicular function

This study was conducted to evaluate the expression of transforming growth factor-beta1 (TGF-beta1) in testis with aging and progress of diabetes mell itus (DM) and correlated this with testicular function. Zucker diabetic fat ty rats (15, 40, and 75 weeks old) were used as models for non-insulin-depe ndent DM. The controls were age-matched nondiabetic Zucker fatty rats, Seru m testosterone levels and daily sperm production were evaluated. Testicular tissue was immunostained with anti-TGF-beta1. Labeled cells were assessed and the staining intensity was estimated. The 15-week control and diabetic animals the lowest levels of staining intensity but this started to increas e significantly in the older animals of both categories. However, the diabe tic animals had significantly deeper intensities relative to controls at th e different age groups. These changes in TGF-beta1 expression were negative ly correlated with both testosterone and sperm production. Therefore, aging and DM enhanced the expression of TGF-beta1 in testis, and this was parall el with progress of both conditions, although DM seems to be predominant. T hese alterations in TGF-beta1 expression may be related to changes in testi cular function associated with both conditions.