Effects of Testosterone Replacement on Renal Function and Apoptosis on Mesangial and Renal Tubule Cells in Rats

The effect of testosterone replacement in middle-aged rats on renal function and apoptosis of mesangial and renal tubule cells was evaluated. Middle-aged (13-month-old) male Wistar rats were divided into 2 groups, one of which was given high-dose and the other low-dose testosterone replacement for 2 months. Experiments were performed with the testosterone replacement groups and a non-replacement group when they had reached the age of 15 months. Serum levels of total and free testosterone were measured, and renal function was evaluated by glomerular filtration rate (GFR), serum levels of creatinine, blood urea nitrogen (BUN), urinary protein and N-acetyl-beta-d-glucosaminidase (NAG). Apoptosis was evaluated by counting the number of terminal deoxynucleotidyl transferase-mediated deUTP-biotin nick end labeling (TUNEL)-positive cells in the mesangial and renal tubule cells. Correlations between total and free testosterone and each parameter were evaluated. Also, 12-week-old rats were evaluated in the same manner as the age control. Among 15-month-old rats, testosterone replacement did not affect serum creatinine, BUN or urinary protein, but the GFR was found to correlate negatively with the total and free testosterone level, and the urinary NAG level was found to correlate positively with the free testosterone level to a significant extent (P < 0.01). Percentages of apoptosis of mesangial and renal tubule cells were found to correlate ,positively with the total and free testosterone levels to a significant extent (P < 0.01). In conclusion, the results of this study suggested that testosterone replacement affected the deterioration of renal function in middle-aged rats.