EXPERIMENTAL STUDIES ON ACUTE AND CHRONIC CHLORPYRIPHOS TOXICITY IN INDIGENOUS CHICKEN
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Date
2013-06
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Assam Agricultural University, Khanapara, Guwahati
Abstract
The present study was conducted in thirty two numbers of 3 months- old indigenous chickens. The birds were divided into three different groups viz. Group A, Group B and Group C. Group C was given no treatment and served as control for both the treatment groups. Group A Birds served as acute toxicity group and were administered a single LD50 dose of chlorpyriphos i.e. 32 mg/kg body weight. Blood was collected from wing vein or jugular vein at zero hours and post treatment at every 2 hrs interval up to 6 hrs, then at 12 hours and subsequently at 12 hrs intervals till death. Group B birds served as chronic toxicity group and were administered with 1/90th of LD50, i.e. 0.36 mg/kg body weight of chlorpyriphos WW in acute toxicity group were excitation, bloody diarrhoea and excessive salivation with drooping of wings. The birds sat on their hocks with curled toes, were unable to stand, showed tremor, convulsions and recumbency before death. In chronic toxicity group, birds showed slightly staggering gait, leg weakness, tremor and diarrhoea. Some of the birds developed curled toes with pale mucous membrane and prominent keel bones.
There was reduction in body weight gain of the insecticide treated chronic toxicity group of birds.
The haematological parameters (Hb, TLC, TEC) were significantly increased due to chlorpyriphos exposure in both the insecticide treated groups compared to control groups. In DLC, heterophil per cent was found to be increased and lymphocyte per cent was found to be decreased in both acute and chronic toxicity group compared to control group. Dose dependent significant increase in serum enzyme activities (alkaline phosphatase, aspertate aminotransferase, alanine aminotransferase) due to administration of chlorpyriphos were observed in both the treated groups. During the experimentation, inhibition of cholinesterase activities indicating neurotoxicity due to administration of chlorpyriphos in both the treated groups was observed.
Gross lesions of chlorpyriphos treated chickens showed congestion, patchy areas of pale discolouration in the liver, with distension of the gall bladder. The striking changes in other organs, viz. kidneys, lungs and brain, were mainly congestion and haemorrhages of variable intensity with dose and time of exposure to chlorpyriphos.
Histopathological alterations in the liver appeared to be dose and time dependent as evident from the severity of changes in low and high dosed chickens. The changes observed in acute toxicity were congestion, haemorrhages, focal mononuclear cell aggregation, hepatocellular necrosis, dilatation of sinusoids, mild fatty changes and disruption of hepatic cords. In addition, mild to moderate proliferation of the biliary epithelial cells around the portal vein with formation of new bile ducts were observed. Kidneys showed congestion and focal to diffuse haemorrhages in the parenchyma; cellular swelling and mild vacuolar degeneration in the tubules and focal areas of haemorrhage and coagulative necrosis along with dilatation of the Bowman’s space in the glomerulus. Lungs revealed congestion and diffuse haemorrhages with accumulation of edematous fluid and fibrous tissue proliferation in the interalveolar septa. Brain showed neuronal degeneration, satellitosis and neuronophagia in the cerebrum along with mild gliosis, demyelination and congestion. The cerebral neurons showed degeneration and formation of vacuoles in the cytoplasm. There were degenerative changes in the Purkinje cells along with demyelination in the molecular layer of the cerebellum. Intestine revealed mild haemorrhages, mononuclear cell infiltration and sloughing of mucosal epithelial cells from the basement membrane along with hyperplasia and hypertrophy of intestinal glands. The changes in the spleen were congestion and focal haemorrhages with isolated depletion of lymphocytes in the splenic follicles. Changes in the bursa of Fabricius consisted of moderate depletion of lymphocytes with congestion, interfollicular and intrafollicular haemorrhages. The harderian gland revealed mild haemorrhages, depletion of plasma cells and necrosis. Proventriculus showed mild hyperplasia of mucosal epithelium, glandular necrosis, elongation and distension of crypts and infiltration of mononuclear cells in the lamina propria. Heart showed mild haemorrhage in the myocardium. The histopathological changes in chronic toxicity were similar to that of acute toxicity but became prominent towards the end of the experimental period. Additionally, in chronic toxicity, there was mild haemorrhage in the caecal tonsils after the 3rd week of the treatment period, the intensity of which increased subsequently with mild depletion of lymphocytes in the follicles. Gross and histopathological changes in various organs of birds treated with chlorpyriphos were observed with typical organophosphorus dose dependent toxicity signs. Microscopic changes observed in different organs viz. liver, kidney, brain, lungs, spleen, caecal tonsils, bursa of Fabricius were typical to insecticide poisoning.
Considerable histochemical changes were noted in the hepatocytes and biliary epithelial cells of the liver. Alkaline phosphatase showed increased activity in the proliferated biliary epithelia and moderate to strong in the sinusoids of the degenerated areas in both the treated groups. Cholinesterase activities were inhibited in the degenerated areas of the brain particularly in the grey matter in both the treated groups.
Gas chromatography revealed maximum accumulation of CPF in the brain followed by muscle, liver and kidney in descending order.
Ultrastructural studies showed degenerative changes in the mitochondria, endoplasmic reticulum, nucleus and cell membrane.
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