**12. Protein metabolism**

**10. Metabolism and growth**

116 Insecticides - Development of Safer and More Effective Technologies

to more descriptions, because of breadth of the topic.

**11. Carbohydrate metabolism**

paraoxon-methyl (Küster, 2005) and sevin (Todd and Leeuwen, 2002).

The change from anabolic to catabolic processes in fish exposed to various insecticides involves important alterations in intermediary metabolism and has important consequences for somatic growth. Changing levels of stress hormones – catecholamine and corticosteroids –, alterations in the ability of digestive enzyme biosynthesis and behavioral changes – hunter and forage behavior – are main factors influencing on the metabolism and growth of fish. For example, histopathological damage to liver, pancreas or hepato-pancreas and intestine can also reduce efficiency of food digestion in fish. Because, these tissues have critical role in regulation biochemical parameters, especially proteins, lipids and carbohydrates, hormones as well as in synthesis and secretion of digestive enzymes, are a target organs for toxicity of insecticides. So, the effect of insecticides on these organs can change metabolism of proteins, lipids and carbohydrates. The purpose of this section of the chapter is to describe briefly the metabolic activity known to be sensitive to various forms of insecticides toxicity. However, it has refused

The most important factors decreasing fish growth consist of disorder in feeding behaviors, decrease in feeding rate, dysfunction in metabolism process and waste of energy to overcome the stress caused by insecticide exposure (Tripathi et al., 2003). For example, disorder in the metabolism of carbohydrates, proteins and lipids in various tissues, particularly liver of fish exposed to insecticides, may reduce their growth rates. Begum (2004) found out that protein and carbohydrate metabolism in the liver and muscle tissue is disrupted on the exposure to a carbofuran insecticide. In addition, exposure during embryonic or larval stage can result in behavioral abnormalities, such as decreased ability to capture prey after hatching, functional deficiencies or slowing of growth and finally death (Kuster, 2005; Viant et al., 2006; Arufe et al., 2007). These changes were observed in larvae and embryo of zebra fish (*Danio rerio*) in contact with endosulfan (Velasco-Santamaria et al., 2011), beta-cyprmethrin (Xu et al., 2010);

Most researchers have reported that the increased blood glucose is usually observed in fish under undesirable conditions and it helps the animal by providing energy substrates to vital organs to cope with the increased energy demand (Banaee et al., 2008; Banaee et al., 2011). Elevation of blood glucose levels was widely used as a secondary marker of a stress response (Toal et al., 2004). On the basis of our literature review it is clear that insecticides can be acted as a stressor in fish. Because, hyperglycemia has been reported in many fish exposed to different insecticides. For example, increases in blood glucose levels have been reported in *Heteropneustes fossilis*(Saha and Kaviraj, 2009) and *Cyprinus carpio* (Banaee et al., 2008), *O.mykiss*

Glycogenesis, glycogenolysis, glycolysis and gluconeogenesis are processes that play important roles in regulating blood glucose and carbohydrate metabolism. Glycogenesis is the

(Banaee et al., 2011) after exposure to cypermethrin and diazinon, respectively.

Proteins are vital ingredient involved in the architecture of the cell, which is the main source of amino acids for building up of new tissues and for the synthesis of biologically important molecules such as enzymes, hormones, etc as well as the source of energy for fish. Alterations in protein content of various tissues of fish exposed to different concentrations of insecticides are linked through a biochemical metabolic pathway. For example, Bose et al. (2011) reported the increase in the protein level in liver of freshwater fish (*Oreochromis niloticus*) was maybe due to check the influence of thiamethoxam and effort to recover from the stress of insecticide at lower doses. They found when the concentration of thiamethoxam was increased; there was decrease in liver protein level. Thus, reduce a significant portion of protein in different tissues, especially the liver, may have been due to their degradation and possible utilization for metabolic purposes. Increases in free amino acid levels were the result of breakdown of protein for energy and impaired incorporation of amino acids in protein synthesis. Since, free amino acids are used in gluconeogentic pathway to glucose production, reduced levels of protein synthesis in fish exposed to insecticides.

(Sulekha, 2002; Sulekha and Mercy, 2009) exposed to monocrotophos and phosphamidon. Histological damage to various tissues, especially the liver tissue, caused by exposure to insecticides can also decrease the tissue's ability to synthesis protein. For example, Murray et al., (2003) announced that organophosphate insecticides through methylation and phosphor‐ ylation of cellular proteins may lead to a reduction in the reconstruction of necrotic tissues. In case, due to the presence of unsaturated and sulphuric molecules in the biochemical structure of some amino acids such as phenylalanine, mitonin, cysteine, histidine, and tryptophan that they are sensitive and vulnerable to free radicals and specifically reactive oxygen species (Sureda et al., 2006; Tejada et al., 2007) and it helps breaking the sequence of amino acids, aggregation of amino acid chains and even changing the biochemical structure of amino acids and it leads to proteolytic changes in protein compounds (Stadmann, 1992,

Physiological Dysfunction in Fish After Insecticides Exposure

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

119

Albumin and globulin make up most of the protein within the body and are measured in the total protein of the plasma. Total protein, albumin and globulin tests are used to monitor the course of diseases in immune disorders, liver dysfunction and impaired kidney activity (Banaee et al., 2011). Banaee et al., (2011) showed that the levels of total protein, albumin and globulin were decreased in fish exposed to diazinon. Decreased total protein levels may be due to starvation, malnutrition and chronic liver diseases (Kirby et al., 1995; Martin et al., 2010). Other authors also found that the levels of total protein and albumin are decreased in the fish exposed to different pollutants and pesticides (Vijayan et al., 1997; Velisek et al., 2009).

Lipids play an important role as source of energy for fish. Since, most insecticides are lipophilic compounds, they can easy pass through biological barriers which content lipids and accumulate in fat tissue.Lipids molecules are highly susceptible to oxidative reactions. Due to cell membrane lipid peroxidation of unsaturated fatty acids, short chain fatty acids with R-COOH, R-OOH, R-CHO, and R-OH bases are created which seriously affect the cellular membrane functions such as the activity of hormone receptors and neural mediators, ion transport channels and the activity of membrane enzymes and the transportation of specific molecules. On the other hand, the formation of malondialdehyde (MAD) during peroxidation process of fatty acids having double bonds can create covalent bonds and polymerize cellular membrane components (Sureda et al., 2006; Tejada et al., 2007). In addition, accumulation of fatty acids in the cytosol increased peroxidation of fatty acids in peroxisomes and the

endothelial reticulum, resulting in overproduction of ROS and further damage.

Increased levels of stress hormones such as cortisol in blood of fish exposed to various insecticides, stimulates lipid breakdown in adipose tissue. Both elevated and reduced free fatty acids levels in plasma have been observed in different fish species exposed to insecticides. Changes in cholesterol and triglycerides levels in the blood and other tissues such as muscles and liver of fish treated insecticides indicated that effect of these compounds on lipid

1993; Asada and Barba, 2004).

**13. Lipid metabolism**

metabolism.

Transaminase play an important role in breakdown of protein to free amino acids which may be used an energy source for glyconegenic pathways or used to synthesis new proteins to repair damaged tissues. So, change in plasma free amino acid levels indicates either an increase or a decrease in protein catabolism or biosynthesis.

Aspartate transaminase (AST), or serum glutamic oxaloacetic transaminase (SGOT) is a pyridoxal phosphate (PLP)-dependent transaminase enzyme. AST catalyzes the reversible transfer of α-amino group between aspartate and glutamate and, as such, is an important enzyme in amino acid metabolism. Alanine transaminase or ALT is a transaminaseenzyme. It is also called serum glutamic pyruvic transaminase (SGPT). It catalyzes the transfer of an amino group from alanine to α-ketoglutarate, the products of this reversible transamination reaction being pyruvate and glutamate. Aspartate aminotransferase and alanine aminotransferase are found in the liver, heart, skeletal muscle, kidney, pancreas, spleen, erythrocyte, brain and gills (Banaee et al., 2011). Tyrosine aminotransferase (or tyrosine transaminase) is an enzyme present in the liver and catalyzes the conversion of tyrosine to 4-hydroxyphenylpyruvate. Alteration in deamination and transamination of amino acid are associated with changes in nitrogen metabolism, which can be detected in terms of plasma nitrogenous metabolite levels. Free amino acid is also contributed in the formation of excretory product by the process of conjugation.

The increase in intracellular levels of ROS can lead to lipid peroxidation resulting in an increased permeability of liver cell membrane. As a result, liver enzymes including AST and ALT are released into plasma. In this sense, if the cellular injury is chronic AST and ALT levels will remain elevated (Srivastava et al., 2004; Rao, 2006). Increased activities of AST and ALT were observed in plasma of *Channa punctatus* (Agrahari et al., 2007) exposed to organophos‐ phorus pesticides. Banaee et al., (2008) have reported increased levels of AST and ALT followed by the exposure of common carp to diazinon. Similarly, ROS produced from the metabolism of organophosphate insecticide could be damaged other tissues such as gills, muscle, heart, kidney and spleen causing the leakage of enzymes into plasma (Banaee et al., 2011).

Impact of different insecticides on the hormones involved in the process of protein synthesis can also affect the tissue protein levels. This was in conformity with the effects of dimethoate on *C. punctatus* (Tripathi et al., 2003). Similar changes in protein content was observed in *Labeo rohitha* (Ramani, 2001), *Etroplus maculatus* (Sulekha and Mercy, 2011), *Anabas testudineus* (Sulekha, 2002; Sulekha and Mercy, 2009) exposed to monocrotophos and phosphamidon. Histological damage to various tissues, especially the liver tissue, caused by exposure to insecticides can also decrease the tissue's ability to synthesis protein. For example, Murray et al., (2003) announced that organophosphate insecticides through methylation and phosphor‐ ylation of cellular proteins may lead to a reduction in the reconstruction of necrotic tissues.

In case, due to the presence of unsaturated and sulphuric molecules in the biochemical structure of some amino acids such as phenylalanine, mitonin, cysteine, histidine, and tryptophan that they are sensitive and vulnerable to free radicals and specifically reactive oxygen species (Sureda et al., 2006; Tejada et al., 2007) and it helps breaking the sequence of amino acids, aggregation of amino acid chains and even changing the biochemical structure of amino acids and it leads to proteolytic changes in protein compounds (Stadmann, 1992, 1993; Asada and Barba, 2004).

Albumin and globulin make up most of the protein within the body and are measured in the total protein of the plasma. Total protein, albumin and globulin tests are used to monitor the course of diseases in immune disorders, liver dysfunction and impaired kidney activity (Banaee et al., 2011). Banaee et al., (2011) showed that the levels of total protein, albumin and globulin were decreased in fish exposed to diazinon. Decreased total protein levels may be due to starvation, malnutrition and chronic liver diseases (Kirby et al., 1995; Martin et al., 2010). Other authors also found that the levels of total protein and albumin are decreased in the fish exposed to different pollutants and pesticides (Vijayan et al., 1997; Velisek et al., 2009).
