Toxicity of the Immune Suppressant Cyclosporin A in the Rat

The study investigated the toxicity of Cyclosporin A (Cy A) in adult Sprague-Dawley rats, administered at 100 mg/kg/24 hr for 21 days. The treatment led to significant functional and structural changes, including continuous hair loss, behavioral effects such as fits, and the death of 2 out of 8 rats. There were notable decreases in serum protein, albumin, and aspartate aminotransferase, with increases in alkaline phosphatase and bilirubin. Liver examination showed moderate fatty changes, while kidney analysis revealed proximal tubular cell vacuolation and necrosis. Cy A also caused marked lymphopenia, increased neutrophils and monocytes, reduced bone marrow cellularity, and depletion of lymphocytes in the thymus and spleen.