Pesticides oxidative stress

Asztalos, B., J. Nemcsok, I. Benedeczky, R. Gabriel, A. Szabo, and OJ. Refaie. 1990. The effects of pesticides on some biochemical parameters of carp (Cyprinus carpio L). Arch. Environ. Contam. Toxicol. 19 275-283. Autor, A.P. (ed.). 1977. Biochemical Mechanisms of Paraquat Toxicity. Academic Press, New York. 240 pp. Babich, H., M.R. Palace, and A. Stern. 1993. Oxidative stress in fish cells in vitro studies. Arch. Environ. Contam. Toxicol. 24 173-178. 

From Table 29.1, it is obvious that chemicals with many different functional groups are cardiovascular toxins. These include hydrocarbons, chlorinated hydrocarbons, ketones, pesticides, heavy metals, and others. A unifying mechanism for the action of these far different chemicals has been proposed. This mechanism is based on a consideration of oxidative stress (OS) and postulates that chemicals or their metabolites that give rise to reactive oxygen species (ROS) that are formed by electron transfer (ET) may be cardiovascular toxins. The ET-OS-ROS mechanistic perspective has been used to account for the cardiotoxicity of the chemicals listed in Table 29.3. ... 

Dorval, J., V.S. Leblond and A. Hontela. Oxidative stress and loss of cortisol secretion in adrenocortical cells of rainbow trout Oncorhynchus mykiss) exposed in vitro to endosulfan, an organochlorine pesticide. 

Kovacic P (2003). Mechanism of organophosphates (nerve gases and pesticides) and antidotes electron transfer and oxidative stress. Curr Med Chem, 16, 2705-2709. 

This enzyme is important in its ability to metabolize organophosphates such as paraoxon and the association of the enzyme with high-density lipoprotein (HDL) and the protection of low-density lipoproteins from the effects of oxidative stress (Costa et al. 1990 Feingold et al. 1998 Costa and Furlong 2002 Costa et al. 2005 Costa, Vitalone, et al. 2005). The enzyme exists in several polymorphisms and it is synthesized mainly in the liver. The enzyme activity can be measured using paraoxon as substrate (Hasselwander et al. 1998). Although the measurement of the enzyme has been used mainly in monitoring the effects of pesticides, more recently the enzyme has received increased attention as a measure of hepatic injury (Gil et al. 1994 Hernandez et al. 1997 Ferre et al. 2002) and in the study of causation of atherosclerosis. 

Banerjcc, B. D. (2001). Pesticide-induced oxidative stress Perspectives and trends. Rev. Etndron. Health 16, 1-40. 

Ranjbar, A., Pa.salar, P, and Abdollahi, M, (2002). Induction of oxidative stress and acetylcholine.sterase inhibition in organophosphorou,s pesticide manufacturing workers. Hum. Exp. Toxicol. 21, 179-182. 

Reactive Oxygen Species (ROS) may serve as common mediators in programmed cell death w apoptosis in response to many toxicants and pathological conditions. Studies have demonstrated that ROS may be involved in the cytotoxicity of widely used OP pesticides, such as chlorpyrifos and fenthion. Highly toxic chlorpyrifos and fenthion are organic triesters of phosphoric acid and phosphorothioic acid and arc also lipophilic (Murphy, 1986). Neuroiransmitter systems play a key role in behavioral function and disturbances. Other OPs, such as phosphamidon, irichlorfon, and dichlor-vos, have also been reported to induce oxidative stress, both... 

DNA SSBs are another index of oxidative stress and cellular damage (Bagchi ct al, 1995 Poovala et ai, 1999 Pound and Lawson, 1976), In a parallel study, the effects of the pesticides on DNA SSBs were determined in cultured neuroactive PC-12 cells and in the hepatic and brain tissues of OP-treated rats (Bagchi cf al, 1995). 

The results of these experiments clearly indicate PKC activation, following exposure to these OPs, which arc also known to enhance the production of oxygen free radicals and induce oxidative stress (Bagchi et at., 1995, 1997). These results demonstrate that PKC activation occurs in hepatic and brain tissues of rats as well as in cultured cells following treatment with OPs, which arc known to induce oxidative stress. Thus. OP pesticides can modulate a vital ctrmponent In the cell signaling pathway. 

This chapter has only scratched the surface of the opportunities and possibilities to demonstrate the natural relationship between chemistry and toxicology. Some of the topics that were not discussed include oxidation and oxidative stress, the influence of electrolytes on calcium homeostasis, immunotoxicology, focusing on biochemistry and applying frontier molecular orbital theory to predicting adverse outcomes. A discussion of catalysis may include the role of enzymes in toxication and detoxication, for example the mechanisms of action of organophosphate pesticides on the function of acetylcholinesterase. 

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