Protective effects of Y-27632 on acute dichlorvos poisoning in rats.

Anticholinesterase poisoning is an important health problem in developing countries, and understanding of its underlying mechanisms is essential for the effective treatment. This study is designed to examine the effects of Y-27632, a selective Rho-kinase inhibitor, on organophosphate-induced cardiac toxicity and mortality in rats. Rats were randomly divided into 4 groups: control (corn oil), dichlorvos (30 mg/kg intraperitoneally), and 1- and 10-mg/kg Y-27632 + dichlorvos groups. After 6 hours of intraperitoneal injection, venous blood and cardiac samples were obtained, biochemical or immunohistochemical analyses were performed, and the intensity of muscle fasciculation was recorded. Serum cholinesterase activities were suppressed with dichlorvos, and these reductions were inhibited with Y-27632 pretreatment. Serum creatine kinase, creatine kinase-MB activities, and myoglobin and N-terminal probrain natriuretic peptide concentrations were not markedly affected with poisoning or Y-27632. Although serum nitric oxide concentrations did not change with dichlorvos, cardiac nitric oxide levels were markedly increased with Y-27632 pretreatment. Cardiac glutathione levels also increased with 1 mg/kg Y-27632. There was no staining for apoptosis, and immunohistochemical analyses of inducible nitric oxide synthase showed no change in cardiac tissue for all of the groups. Both doses of Y-27632 abolished mortality in rats with acute dichlorvos exposure (100% survival). These results show that administration of Rho-kinase inhibitor can produce protective effects against dichlorvos intoxication in rats. These findings may provide new possibilities for the treatment of organophosphate poisoning.