**1. Introduction**

A fundamental contributor to the Green Revolution has been the development and application of insecticides for the control of a wide variety of insectivorous and herbaceous pests which would otherwise diminish the quantity and quality of food production (Ecobichon, 2001). Unfortunately, in spite of its advantages, chemistry has great disadvantages as well. Insecticides are threatening the long-term survival of major ecosystems by disruption of ecological relationships between organisms and loss of biodiversity. On the other hand, agriculture, as the largest consumer of freshwater and as a major cause of reduction of surface and groundwater resources through erosion and chemical runoff, are close related to the loss of water quality (Wauchope, 1978). The processing industry associated to agriculture is also a significant source of organic pollution in most countries. Conventionally, in most countries, all types of agricultural practices and land use, including animal farming, are treated as nonpoint sources. The main characteristics of non-point sources are not simply determined or controlled directly and therefore, are difficult to regulate their impacts on ecosystem health (Garcia et al., 2001). Non-point source pollutants are mainly transported overland and through the soil by runoff (Dubus et al., 2000). These pollutants ultimately find their way into groundwater, wetlands, rivers and lakes and, finally, to oceans in the form of sediment and chemical loads carried by rivers (Albanis et al., 1998; EPA, 2003; Aydın and Köprücü, 2005). The major insecticides that are usually applied in agriculture and public healthy sections include organophosphate, organocholorines, pyrethroids and carbamate. Contamination of water by insecticides is mainly due to intensive agriculture combined with surface runoff and subsurface drainage, usually within a few weeks after application (Banaee et al., 2011) Most of insecticides have been known to be highly toxic to non-target organisms that inhabit natural environments close to agricultural fields. Several studies reported that some of surface waters

© 2013 Banaee; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Banaee; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

and surrounding environments were contaminated with different insecticides (Arjmandi et al., 2010; Bagheri et al., 2000; Ghassempour et al., 2002; Rahiminezhhad et al., 2009; Tarahi Tabrizi, 2001). The continuous presences of insecticides are the consequence of application (timing, rate, frequency) and the rainfall during the application period (Lydy and Austin, 2004; U.S.A. EPA, 2005; Bouldin et al., 2007; Mast et al., 2007; Echols et al., 2008; Vryzas et al., 2009; Werimo et al., 2009; Ding et al., 2011; Hope, 2012). Although monitoring the presence of insecticides in surface water and ground water are generally poor in much of the world and especially in developing countries, the effect of these pollutants on aquatic animals' health frequently was investigated (Chambers et al., 2002; Richards and Kendall, 2002;Lam and Wu, 2003; Scott and Sloman, 2004; Cengiz, 2006; Box et al., 2007; Sun and Chen, 2008; Banaee et al., 2008; Banaee et al., 2011; Banaee and Ahmadi, 2011).

such as oxidative stress, histopathological damages, hormonal dysfunctions, reproductive

Physiological Dysfunction in Fish After Insecticides Exposure

http://dx.doi.org/10.5772/54742

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Hematological and biochemical studies, along with histopathology, are the major means to learn a toxicants mode of action. Hematological and clinical chemistry parameters can be detected rapidly and hence can be used for prediction and diagnosis of insecticides toxicity. Alterations in these parameters show toxic stress in the treated animals especially on blood and blood-forming organs. Alterations in blood biochemical parameters as important diagnostic tool can be used for the detection of abnormalities in the liver and other tissues (Banaee et al., 2011). This chapter describes some of the important hematological, biochemical and histopathological changes that occur in fish exposed to different insecticides. An initial description is given of the detoxification process, and then the other physiological dysfunction in various biological systems occurring in fish exposed to different insecticides will be

In fish, insecticides are readily converted into more polar compounds through biotransfor‐ mation and stored in the bile until their excretion. In general, detoxification process involves two phase, functionalization (phase I) and conjugation (phase II). The first biotransformation step (phase I) adds oxygen to the insecticides structure and the second step (phase II) conjugates the oxygenated product with and endogenous water-soluble small molecule present in the cell. The final products are highly water-soluble conjugates that are easier to eliminate than the parent compounds.Although, recently, anti-porter activity (p-glycoprotein or multidrug resistance) has been defined as the Phase III detoxification system, there is no exactly information about this detoxification system in fish.Classic detoxification pathways of

The phase I detoxification system, composed over 10 families of enzymes which played important role in the metabolism of various xenobiotic. The phase I detoxification system, composed mainly of the cytochrome P450 supergene family of enzyme, that are present in all eukaryotes and some prokaryotes and is generally the first enzymatic defense system against xenobiotic.A great diversity of cytochrome P450 enzymes in fish has been recognized (Stegeman and Hahn, 1994), and CYP1A, CYP2B, CYP2E1, CYP2K1 and CYP3A have been recently identified in liver of some freshwater fish (Nabb et al., 2006) which play an important role in the detoxification of organophosphate and carbamate insecticides (Ferrari et al., 2007). The common pathways of biotransformation of different kinds of insecticides include three cytochrome P450 (CYP) mediated reactions: *O*-dealkylation, hydroxylation, and epoxidation of insecticides (Keizer et al., 1995; Kitamura et al., 2000; Straus et al., 2000; Behrens & Segner,

disorders, immunosuppression syndrome and etc.

discussed.

**3. Phase I**

**2. Metabolism of insecticides**

insecticides in aquatic organisms are presented in Table 1.

Since fishes are important sources of proteins and lipids for humans and domestic animals, so health of fishes is very important for human beings. Fish like other aquatic organisms may be exposed to a great range of insecticides during the course of their life cycle. In fish, different insecticides can be absorbed through gills, skin or alimentary ducts (Schlenk, 2005; Banaee et al., 2011; Banaee, 2012). Fishes are particularly sensitive to environmental contamination of water. Hence, pollutants such as insecticides may significantly damage certain physiological and biochemical processes when they enter into the organs of fishes (Banaee et al., 2011). So, the effects of insecticides on fishes are of great concern.

Recently, many studies have been conducted to determine the mechanisms of insecticides' damage in fishes, with the ultimate goal of monitoring, controlling and possibly intervening in xenobiotics exposure and its effects on the aquatic ecosystem. The main mechanism of action of organophosphate and carbamate insecticides is block of enzyme acetylcholinesterase action that results in signs and symptoms of intensive cholinergic stimulation. Organochlorines are neurotoxins which effect on sodium and potassium channels in neurons. Decrease of potassium permeability and inhibition of cadmodulin, Na/K and Ca-ATPase activity occur by organochlorine insecticides. Pyrethroids can block Na channel and effect on the function of GABA-receptors in nerve fiber. Oxidative stress is another mechanism for toxicity of insectisides resulting in cell death includescellular necrosis and apoptosis and dysfunction in cellular physiology include alterations in metabolic and vital functions of the cells.Hence, fish should be able of managing environmental exposure by detoxifying these xenobiotic. In order to do this task, fish like aerobic animals have evolved complex of detoxification system, composed of two main parts including enzymatic and non-enzymatic components. Theroles of enzymatic and non-enzymatic detoxification system of animal's body lessen the potential damages caused by the toxicity of environmental pollutants. Although it is possible that reactive oxygen species (ROS) produced during the insecticides detoxification process in liver tissue may react with vital macromolecules such as lipid, protein, carbohydrate and nucleic acid and result in oxidative damage to aquatic organisms (Üner et al., 2006). ROS derived damage to natural and structure cellular components are generally considered a serious mechanism involved in the physiological and pathological disorders (Sepici-Dinçel et al., 2009).So, much literature suggests an association between impaired detoxification and disease such as oxidative stress, histopathological damages, hormonal dysfunctions, reproductive disorders, immunosuppression syndrome and etc.

Hematological and biochemical studies, along with histopathology, are the major means to learn a toxicants mode of action. Hematological and clinical chemistry parameters can be detected rapidly and hence can be used for prediction and diagnosis of insecticides toxicity. Alterations in these parameters show toxic stress in the treated animals especially on blood and blood-forming organs. Alterations in blood biochemical parameters as important diagnostic tool can be used for the detection of abnormalities in the liver and other tissues (Banaee et al., 2011). This chapter describes some of the important hematological, biochemical and histopathological changes that occur in fish exposed to different insecticides. An initial description is given of the detoxification process, and then the other physiological dysfunction in various biological systems occurring in fish exposed to different insecticides will be discussed.
