ATTENUATING EFFECT OF CASTRATION ON GLOMERULAR INJURY IS AGE-DEPENDENT IN UNILATERALLY NEPHRECTOMIZED MALE SPRAGUE-DAWLEY RATS

To clarify a role of sex hormones in greater susceptibility of young r ats than adults to the development of focal and segmental glomeruloscl erosis (FSGS), we castrated animals at different ages and investigated whether the attenuating effect of castration on FSGS is age-dependent in unilaterally nephrectomized male Sprague-Dawley (SD) rats. At 6 we eks of age, all groups received unilateral right nephrectomy (Nx) and group 2 was simultaneously castrated, while group I received a sham op eration. Group 3 was castrated at 3 months of age, and group 4 at 6 mo nths of age. Body weight, blood pressure, urinary protein and serum co nstituents were investigated every 2 months from 4 to 14 months of age . At 6 and 14 months of age, rats were studied morphologically. Castra tion at 6 weeks of age or at 3 months of age significantly inhibited t he compensatory glomerular hypertrophy and hyperfunction with regard t o the creatinine clearance as seen in Nx rats at 6 months of age and s ignificantly reduced glomerular injury at the end of the experiment, w hile castration at 6 months produced neither an inhibitory effect on g lomerular hypertrophy nor an attenuating effect on glomerular injury. Serum levels of growth hormone (GH) and somatomedin-C (SmC) were decre ased by castration to a greater extent when castrated at younger age. These findings indicated that GH and SmC influenced by male sex hormon e seem to play a more important role at younger age than in adults in exerting its effect on glomerular growth, leading somehow to glomerula r injury in aging, unilaterally nephrectomized male SD rats.