The toxicity of pyrethroid compounds in neural cell cultures studied with total ATP, mitochondrial enzyme activity...

Pyrethroids are important insecticides used largely because of their high activity as an insecticide and their low mammalian toxicity. Some studies have demonstrated that these products, especially compounds with an α-cyano group, show neurotoxic effects on the mammalian central nervous system (CNS). In this study, we investigate with different methods the cell toxic effects of commercial, chemically different pyrethroid compounds on neuronal cell line SH-SY5Y. Natural pyrethrin and permethrin (both with no α-cyano group) and cypermethrin (with an α-cyano group), were studied. For toxicity determinations, SH-SY5Y neuroblastoma cells were exposed to pyrethroids at 0.1-100μM concentrations for 1 day. The cell toxicity was evaluated by determining the total ATP with a luminescence method, the mitochondrial metabolic activity (WST-test) with a photometric method, and the morphological changes of the cell cultures with microscopic digital photographing at different dose levels of compounds. The results obtained with WST-1 method and with the measurement of total ATP were different. ATP measurement seemed to show cytotoxicity at lower concentrations than WST-1 method. There was induction of enzyme activities with WST-1 test with all pyrethroid compounds studied at low concentrations. With the ATP assay, exposure to 0.1-100μM of natural pyrethrin, as well as of permethrin and cypermethrin showed dose-dependent cytotoxicity. The most toxic pyrethroid was cypermethrin followed by permethrin and natural pyrethrin. Our study confirms that the cell toxicity was dependent on the chemical structure of pyrethroids and pyrethroids without an α-cyano group show the weakest physiological effect. Microscopic photographs of exposed cell cultures correlated to the toxic effects revealed by the metabolic tests.