endrin and alachlor

The chloroacetamide insecticide alachlor, polyhalogenated cyclic hydrocarbons endrin and chlordane and the organophosphate pesticides chlorpyrifos and fenthion induce oxidative tissue damaging effects including lipid peroxidation and nuclear DNA-single strand breaks. The mechanism involved in the induction of oxidative stress by these xenobiotics is unknown. No information is available regarding whether these pesticides can induce the expression of heat shock (stress) protein (Hsp) genes as a common protective mechanism against tissue damage. The pesticides were administered p.o. individually to female Sprague-Dawley rats in two 0.25 LD50 doses at 0 h and 21 h. The animals were killed at 24 h, and liver, brain, heart and lung tissues were removed to examine the induction of Hsps by Western and Northern blot analysis. In a separate series of experiments, cultured neuroactive PC-12 cells were treated 24 h with 50, 100 or 200 nM concentrations of these pesticides. Alachlor, endrin, chlorpyrifos and fenthion induced Hsp89 alpha and Hsp89 beta in hepatic and brain tissues, as well as in cultured PC-12 cells. Chlordane induced some expression of Hsp89 alpha but not Hsp89 beta in the hepatic and brain tissues of treated rats. Some expression of Hsp89 beta was observed in lung tissues of endrin and alachlor treated animals. These findings were substantiated by Western blot analysis using Hsp90 antibody. Except chlordane all these pesticides induced enhanced synthesis of Hsp90 in cultured PC-12 cells. The results indicate striking tissue differences in the patterns of the Hsps induced by the pesticides which were used, and demonstrate that these pesticides can induce the expression of Hsp89 alpha and Hsp89 beta genes in various target organs of rats. The results support the hypothesis that these genes may be mechanistically involved in protecting tissues against oxidative stress induced by structurally diverse pesticides.

Topics: Acetamides; Animals; Blotting, Northern; Blotting, Western; Brain; Cells, Cultured; Chlorpyrifos; Dose-Response Relationship, Drug; Electrophoresis, Polyacrylamide Gel; Endrin; Female; Fenthion; Gene Expression Regulation; Heart; Heat-Shock Proteins; Lethal Dose 50; Liver; Lung; Myocardium; Oxidative Stress; PC12 Cells; Pesticides; Rats; Rats, Sprague-Dawley; Tissue Distribution

Reactive oxygen species may be involved in the toxicity of various pesticides and we have, therefore, examined the in vivo effects of structurally dissimilar polyhalogenated cyclic hydrocarbons (PCH), such as endrin and chlordane, chlorinated acetamide herbicides (CAH), such as alachlor, and organophosphate pesticides (OPS), such as chlorpyrifos and fenthion, on the production of hepatic and brain lipid peroxidation and DNA-single strand breaks (SSB), two indices of oxidative stress and oxidative tissue damage. The selected pesticides were administered p.o. to female Sprague-Dawley rats in two 0.25 LD50 doses at 0 h and 21 h and killed at 24 h. In a parallel set of experiments, we have determined the in vitro effects of these pesticides on the DNA-SSB and enhanced lactate dehydrogenase leakage (LDH) from neuroactive PC-12 cells in culture. In vitro production of reactive oxygen species by these pesticides was also assessed by determining the enhanced chemiluminescence responses of hepatic and brain homogenates. Following treatment of rats with endrin, chlordane, alachlor, chlorpyrifos and fenthion, increases of 2.8-, 3.0-, 4.2-, 4.3- and 4.8-fold were observed in hepatic lipid peroxidation, respectively, while at these same doses, increases in lipid peroxidation of 2.4-, 2.1-, 3.6-, 4.6- and 5.3-fold, respectively, were observed in brain homogenates. Increases of 4.4-, 3.9-, 1.6-, 3.0- and 3.5-fold were observed in hepatic DNA-SSB following treatment of the rats with endrin, chlordane, alachlor, chlorpyrifos and fenthion, respectively, while at these same doses, increases of 1.9-, 1.7-, 2.2-, 1.4-, 1.4-fold, respectively, were observed in brain nuclear DNA-SSB. Following in vitro incubation of hepatic and brain tissues with 1 nmol/ml of each of the five pesticides, maximum increases in chemiluminescence occurred within 4-7 min of incubation and persisted for over 10 min. Increases of 3.0-, 2.7-, 3.6-, 4.9- and 4.4-fold were observed in chemiluminescence following in vitro incubation of the liver homogenates with endrin, chlordane, alachlor, chlorpyrifos and fenthion, respectively, while increases of 1.7-, 1.8-, 2.0-, 3.4- and 3.7-fold, respectively, were observed in the brain homogenates. Increases of 2.2-, 2.3-, 2.9-, 2.9- and 3.4-fold were observed in the chemiluminescence responses in the liver homogenates of the animals treated with endrin, chlordane, alachlor, chlorpyrifos and fenthion, respectively, while increases of 1.8-, 2.0-, 3.2-, 2.9- and 2.4-

Topics: Acetamides; Animals; Brain; Chlordan; Chlorpyrifos; DNA Damage; DNA, Single-Stranded; Endrin; Female; Fenthion; In Vitro Techniques; L-Lactate Dehydrogenase; Lethal Dose 50; Lipid Peroxidation; Liver; Luminescent Measurements; Oxidation-Reduction; PC12 Cells; Pesticides; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Structure-Activity Relationship