Histopathological Alterations in Liver, Kidneys and Lungs Induced by Cypermethrin Toxicity in Albino Rats Faten Hassan Yassin, Abdulhadi Abbas Hadi Department of Biology, Faculty of Science, University of Kufa Abstract Fourty adult female albino rats were used in this research. They were randomly divided into four groups. Three concentrations of cypermethrin were investigated (7.5, 15 and 30 mg/kg body weight). All treated doses were given orally every two days and the experiment was continued for 30 days. The histologic examination for the liver, kidneys and lungs in treated animals revealed different lesions. The dose-dependent histologic damages in this study reflect the potential toxicity of cypermethrin in mammals. Key words: cypermethrin; liver; kidneys; lungs; histopathology; rats. Introduction The use of pesticides is an important method for elimination of harmful animals and plants in order to increase agricultural production, and also used in public health to eradicate disease-carrying organisms for human and animal 1. The annual consumption of pesticides was estimated by approximately 2 million tons worldwide 2. The pyrethroids (synthetic forms of pyrethrins) are the main class of pesticides used worldwide, especially in the United States of America, due to high activity, low toxicity to mammals and fast biodegradation in the environment after use 3. Cypermethrin (a type II pyrethroid compound) was manufactured for the first time in 1974 and was marketed in 1979 4. It is widely used in agriculture, especially in the last two decades, because of the strong effectiveness of this pesticide against a wide range of harmful organisms. The systemic effects of cypermethrin almost targeted to the nervous system by inhibition of acetylcholinesterase 5. The other mechanism is the oxidative stress resulting from exposure to this pesticide 6. Pyrethroid pesticides, including cypermethrin, are one of the most pollutants in the ecosystems. Generally, the cypermethrin-induced toxicity has been reviewed in several experimental and clinical reports 4,6,7,8,9. Recently, cypermethrin and other pyrethroid compounds are the most widely used in Iraq. Application of pesticides in agricultural activities and over fishing in the south of Iraq represent the potential threat for many aquatic organisms (Yasser and Naser, 2010). The aim of this research is to investigate the influence of cypermethrin on histopathological changes in liver, kidney and lung tissues of adult rats. Materials and Methods Experimental animals Adult female albino rats (Rattus norvigicus) were purchased from Faculty of Pharmacy / University of Karbala- Iraq, were used for this study. The present study was conducted at the animal house of Faculty of Veterinary Medicine / University of Kufa- Iraq. Healthy rats weighing between 215-288 gm were used in this experiment. The animals were maintained in an air-conditioned room in individual stainless steel cages at 275
22-25 C throughout the study. The animals received standard pellet feed and water ad libitum. None of the rats had any clinically evident infection. Experimental design The study protocol was approved by the ethical committee of the Department of Biology- Faculty of Science - University of Kufa. The rats were acclimated with the laboratory conditions for a period of two weeks before initiation of the experiments. Forty mature female rats were randomly distributed into four groups (10 rats each). Three oral concentrations of cypermethrin (7.5, 15, 30 mg/kg body weight), dissolved in corn oil, were investigated. The orally concentrations of cypermethrin were determined according to Fang et al. (2013) 10. The control group received only the same volume of corn oil. The animals allowed free access to food and water immediately after ingestion. Histological study After one month, all rats were anesthetized, using a mixture of ketamine and xylazine i.m., and then they were sacrificed 11. For histopathological study, liver, kidneys and lungs were removed, cleaned, and weighed. Thereafter, these organs were fixed immediately in 10% formalin solution for later histological preparation. Ordinary histological processing are prepared for lungs, liver, and kidneys of rats in order to study the histopathological alterations that may be found in the experimental groups in compared with the animals of control group. The preparation of microscopic slides and staining technique were performed according to Bancroft and Stevens (1982) 12. Results and Discussion The histological observations in cypermethrin-treated rats for 30 days in present study showed various stages of pathological changes in many areas of liver, kidneys and lungs, while the organ sections of control group exhibited normal architecture. The dosedependent histologic damages in this study reflect the biochemical indices and functional status of these organs. Histopathological changes in the liver In contrast to liver tissue of control animal group, marked blood congestion in hepatic vein, diffusion of some inflammatory cells, sinusoidal dilatation, diffusion of inflammatory cells, hemorrhage, distortion in the arrangement cells, hypertrophy of hepatocytes, cellular degeneration and necrosis, presence of some pyknotic cells and cytoplasmic vacuolation were observed in liver of cypermethrin- treated rats. Figures (1, 2, 3 & 4). 276
Figure (1): Liver section of control group shows central vein (CV) and hepatic cords (HC). (H and E, 100x). Figure (2): Liver section of 7.5 mg/kg cypermethrin group shows blood congestion (BC) in hepatic vein and diffusion of some inflammatory cells (IC). (H and E, 100x). 277
Figure (3): Liver section of 15 mg/kg cypermethrin group shows hypertrophy of hepatocytes (HH), cellular degeneration (CD), and increase the inflammatory cells (IC). (H and E, 200x). Figure (4): Liver section of 30 mg/kg cypermethrin group shows necrotic foci (NF), nuclear pyknosis (NP), hemorrhage (H), and cytoplasmic vacuolation (CV). (H and E, 4005x). 278
According to Manna et al. (2004) 13, the increased level of malondialdehyde (MDA) in tissue and the increased ALT and ALP activity in serum suggest that cypermethrin induced pathological changes in the liver. Muthuviveganandavel et al. (2008) 14 noted that generating elevated MDA levels resulting in hepatic necrosis. It has been proposed that the alterations in different biochemical indices correlated with the histological changes in several organs. The oral administration of cypermethrin for 30 days in rats has been noted to raise the levels of AST, ALT and lactate dehydrogenase (LDH), and indicates a pathological damage of liver 15. Furthermore, cypermethrin caused oxidative stress by reducing the activity of superoxide dismutase and glycogen level, leading to hepatic degeneration and necrosis 13. Histopathological changes in the kidneys The results demonstrated that administration of cypermethrin for 30 days produced a variety of histopathological changes in the kidneys of exposed animals as compared to control rats. Figures (5, 6, 7 & 8). Gross changes included dilatation in Bowman's space, cellular degeneration in tubules, glomerular atrophy, hemorrhage, sloughing of epithelial cells, glomeruli nephritis, necrosis in tubular lining cells, deposition of eosinophilic materials in tubules, destruction of renal tubules, aggregation of inflammatory cells, disorganization in normal architecture, destruction of glomeruli and severe necrosis of tubules. The elevated plasma levels of urea and creatinine are considered to be the marker of renal dysfunction, which correlated with the histopathological changes in kidney 15. In addition, any process that interferes with the structural integrity of the glomeruli and renal tubules can cause toxic effect. In such cases, leakage of lysosomal enzymes may occur, thereby causing cell necrosis and renal damage 16. Histopathological changes in the lungs Histological study showed a typical structural organization of the lungs in the untreated rats. The histopathological changes in cypermethrin treated animals comprised marked dilatation in alveolar spaces, diffuse of inflammatory cells, thickening of alveolar walls, blood congestion in pulmonary vessels, destruction of interalveolar septa, fibroplasia in the parenchyma of lung, severe damage within the lung parenchyma, presence of edema fluid, thickening and congestion of alveolar septa, broken alveoli, abnormal distribution of cellular elements and hemorrhage in lung tissue. Figures (9, 10, 11& 12). In general, the different histopathological changes in the lung that observed in our study are in agreement with many previous reports 13,15,17,18,19,20. The histological observations in our research were consistent with other studies. In recent study, the lung sections of the cypermethrin group showed pathological changes in the form of alveolar exudate and congestion and increased bronchiolar secretion 21. Additionally, severe hemorrhage in lungs and liver may be the possible cause of leukocytosis 22. 279
Figure (5): Kidney section of control group shows normal renal corpuscles (RC) and renal tubules (RT). (H and E, 100x). Figure (6): Kidney section of 7.5 mg/kg cypermethrin group shows dilatation (D) in Bowman's space and cellular degeneration (CD) in tubules. (H and E, 200x). 280
Figure (7): Kidney section of 15 mg/kg cypermethrin group shows glomeruli nephritis (GN), necrosis (N) in tubular lining cells, and deposition of eosinophilic materials (EM) in tubules. (H and E, 200x). Figure (8): Kidney section of 30 mg/kg cypermethrin group shows destruction (D) of renal tubules, aggregation of inflammatory cells (IC), and disorganization in normal architecture. (H and E, 200x). 281
Figure (9): Lung section of control group shows alveoli (A), alveolar duct (AD), and alveolar walls (AW). (H and E, 200x). Figure (10): Lung section of 7.5 mg/kg cypermethrin group shows dilatation in alveolar spaces (A) and diffuse of inflammatory cells (IC). (H and E, 100x). 282
Figure (11): Lung section of 15 mg cypermethrin group shows marked dilatation (D) alveolar spaces, thickening (T) of alveolar walls, and congestion (C) in pulmonary vein. (H and E, 100x). Figure (12): Lung section of 30 mg/kg cypermethrin group shows sever damage within the lung parenchyma, edema (E), thickening (T) and congestion (C) of alveolar septa, and abnormal distribution of cellular elements. (H and E, 100x). 283
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