Fawn-hooded (FH) rats, primarily males, develop spontaneous low-
renin hypertension associated with reduced urinary excretion of
kallikrein as early
as 2 months of age, followed by progressive glomerular
sclerosis and
proteinuria as early as 3 months of age. In the present study we determined the effects of early (5-7 weeks) or late (5 months)
orchiectomy on the blood pressure and nephropathy of FH rats, compared to
sham-operated (control) FH males. Early
orchiectomy reduced significantly the progression of glomerular
sclerosis and of
proteinuria and ameliorated the
hypertension but had no significant effect on excretion of
urinary kallikrein. Late
orchiectomy, in contrast, had no significant effect on the progression of glomerular
sclerosis or
proteinuria but did significantly reduce the blood pressure and marginally increase the excretion of urine
kallikrein. These results suggest that (a) male
sex hormones may play a role in the pathogenesis of
hypertension and nephropathy in the FH rats and (b) renal disease in this strain progresses in spite of improvement in blood pressure.