Organochlorine Pesticide-Mediated Induction of NADPH Oxidase and Nitric-Oxide Synthase in Endothelial Cell.

Abstract

Organochlorine Pesticides (OCPs) are detected ubiquitously in human and have been shown to be associated with Cardiovascular Disease (CVD) and atherosclerosis. To find out the effect of organochlorine pesticides in endothelial cell with regard to oxidative stress and associated expression of enzymes producing superoxide and Nitric Oxide (NO). Human Umbilical Vein Endothelial Cells (HUVEC) were cultured and treated with four OCPs which were found in human blood at a concentration of 0.1μM. The cells were tested for Reactive Oxygen Species (ROS) generation, NO production and mRNA expression of NAPDH oxidase (p47phox) and endothelial Nitric Oxide Synthase (eNOS). ROS generation was measured by using 2', 7'-dichlorodihydrofluorescein diacetate (H2DCFDA) method. NO was analysed by Bioxytech nitric oxide assay kit method and mRNA of NADPH oxidase and eNOS was quantified by real time PCR. Data were expressed as the mean±SEM. Comparison between the groups were made by student's t-test (2-tailed) or one-way ANOVA with Tukey's post-hoc analysis depending on number of groups. For all statistical tests, p< 0.05 was considered to be significant. All the four pesticides generated ROS accompanied by enhanced expression of NADPH oxidase. Maximum effect was observed with β-endosulfan. Level of NO was found to be decreased significantly in endothelial cells treated with these pesticides accompanied by enhanced expression of eNOS. The antioxidant N-acetylcysteine (NAC) reduced ROS generation and enhanced NO formation. Pesticide-mediated ROS generation possibly reacts with NO forming peroxinitrite and thereby reducing the bioavailability of NO although eNOS expression is increased. OCPs induce endothelial dysfunction through increased ROS generation via NADPH oxidase expression and reduced bioavailability of nitric oxide.