Sex-related incidence of tubular metaplasia in Bowman's capsule of aging rats.

Although chronic progressive nephropathy and proteinuria are well-known to affect old laboratory rats, the occurrence of tubular metaplasia of Bowman's capsule (TM) in aging rats has received little attention. We report here that old (24-26 months) male, but not female Sprague-Dawley rats show a high incidence of TM which is significantly (P less than 0.01) correlated with the levels of glomerular sclerosis and intracellular deposits of iron in the tubular epithelium. The incidence of these changes was not correlated with serum testosterone levels, which showed a significant age-related reduction in males. The reported findings suggest that the aging male Sprague-Dawley rat is a useful animal model to investigate the pathogenesis of TM and related morphologic changes in hematuric humans.