Heymann nephritis of rats: beneficial effect of methysergide.

Since vasoactive amines may be involved in the pathogenesis of glomerular lesions in glomerulonephritis, the present study was undertaken to evaluate the effect of MS, a serotonin antagonist, on the course of HN in rats. MS was given in drinking water at a concentration of 6 mg/dl to 18 rats for 13 weeks; daily intake of MS varied between 1.3 and 3.9 mg. This intake prevented the effect of 10 to 100 microgram of serotonin on the vascular permeability of skin vessels. Effect of histamine (10 microgram) assessed similarly was not blocked. MS administration was started a week prior to the immunizations for the induction of HN and continued until the animals were sacrificed at 13 weeks. A control group of 20 immunized rats, also observed for 13 weeks, did not receive MS. MS treatment significantly decreased the incidence of heavy proteinuria (p less than 0.001), the severity of proteinuria at each week throughout the course of the disease (p less than 0.001), the amount of immune complex deposition in the glomeruli, and also delayed the onset of proteinuria (p less than 0.001). In addition, three of 18 MS-treated rats did not show evidence of immune complexes in the glomeruli, whereas each control animal did. It is concluded that MS treatment exerts a beneficial effect on the course of HN of rats and may also prevent it in some rats.