CASTRATION ATTENUATES PROTEINURIA AND GLOMERULAR INJURY IN HYPERLIPIDEMIC MALE IMAI RATS

Hyperlipidemic Imai rats spontaneously develop proteinuria and glomeru losclerosis, especially in males. We investigated the effect of castra tion on spontaneous proteinuria and progressive renal injury in male I mai ats. Male Imai rats (n = 16) were castrated at 5 weeks of age. Bod y weight, blood pressure, urinary protein excretion and serum constitu ents were checked and compared with sham-operated control rats (n = 16 ) up to 24 weeks. Sham-operated group 1 (n = 5) and castrated group 2 (n = 6) underwent morphological study after 16 weeks of observation an d sham-operated group 3 (n = 11) and castrated group 4 (n = 10) were f ollowed for an additional 8 weeks and used for morphological study. Gr owth rate was significantly stunted in castrated rats as compared with the controls. Castration significantly reduced proteinuria almost thr oughout the experiment (167+/-84 vs. 46+/-24 mg/kg/day, p < 0.001, at 8 weeks and 688+/-211 vs. 458+/-97, p < 0.01, at 20 weeks. The glomeru losclerosis index was significantly higher in sham-operated control ra ts than in castrated rats (28.8+/-18.0 vs. 7.3+/-3.1, p < 0.01, at 16 weeks, and 92.1+/-35.5 vs. 39.5+/-8.9, p < 0.001, at 24 weeks). There were no significant differences in blood pressure, serum cholesterol, plasma renin activity, plasma somatomedin C levels between the two gro ups. These results raise the possibility that sex hormones may partly contribute to spontaneous proteinuria and progressive renal injury in male Imai rats.