Acceleration of renal dysfunction with ageing by the use of androgen in Wistar/Tw rats

Age-related changes in the renal functions were examined in rats of the Wistar/Tw strain. In male rats, renal plasma flow (RPF) and glomerular filtration rate (GFR) began diminishing at 13 and 16 months of age, respectively. Filtration fraction increased markedly at 13 months of age. Urine: plasma osmolality ratio decreased gradually after 10 months of age. Fractional water excretion (FEH2O) at 13-16 months of age was significantly greater than those at younger ages. These results indicate that the renal function in male Wistar/Tw rats begins to attenuate at about 10 months of age and the dysfunction becomes conspicuous at 16 months. On the basis of these data, the effect of androgen on the kidney was examined by estimating the renal clearance rates in castrated male rats and ovariectomized female rats treated with testosterone propionate (TP). Water intake, GFR and RPF in 13-month-old castrated male rats were less than those in age-matched normal male rats. On the other hand, in 7-month-old ovariectomized female rats treated with TP for 6.5 months, RPF and GFR became greater than those in age-matched control female rats. These results suggest that long-term exposure to androgen accelerates the renal dysfunction with ageing, resulting in the earlier development of polydipsia and polyuria in male rats than in female rats.