SUBACUTE IMMUNOTOXICITY STUDIES OF IMIDACLOPRID IN WHITE LEGHORN COCKERELS

Subacute Immunotoxicity Studies of Imidacloprid in White Leghorn cockerels Name of Student Name of Major Advisor Tarun Balani Dr. A.M. Thaker Department of Pharmacology and Toxicology College of Veterinary Science and Animal Husbandry Anand Agricultural University Anand 388 001 Gujarat, INDIA. The present study was conducted on day old White Leghorn cockerels, which were acclimatized for one week before the start of oral dosing of Imidacloprid. Imidacloprid is a neonicotinoid insecticide having widespread use in agriculture and is also used as an ectoparasiticide in dogs and cats. Approximate medium lethal dose (ALD50) of Imidacloprid used for the study was 50 mg/kg body weight. One hundred twenty five birds were divided into five different groups each comprising 25 birds. The birds of group C1 were given no treatment and served as control. Group C2 was administered groundnut oil (1ml/kg) and served as control (vehicle). Group I1 was given 1/40 of ALD50 (1.25 mg/kg), and Group I2 was put on 1/30 th of ALD50 (1.67 mg/kg), while group I3 received 1/20 of ALD50 (2.5 mg/kg) of Imidacloprid suspended in groundnut oil. Once daily oral dosing was carried out for 28 days. All the birds were monitored for any observable toxic symptoms throughout the experimental period and they were also weighed weekly to monitor body weight gain. Before sacrificing the birds blood samples were collected on day15 (after 14 days oral dosing) and day 29 (after 28 days oral dosing) of the study and were analyzed for hematological, biochemical and immunological parameters. Organ (liver, spleen, thymus and bursa) weights were measured and organs (liver, spleen, thymus, kidney, and bursa) were collected for histopathological examinations. There were no apparent clinical signs of toxicity at all the dose levels tested. Besides there was no mortality at all the dose levels tested. There was no significant effect on body weight gain of the imidacloprid treated birds as compared to control birds. Hematological parameters (Hb, PCV, TEC) remained unaffected except total leukocyte count which was decreased at the highest dose tested only at 28 day of experiment. Imidacloprid produced hypoglycemia during the entire period of study which was dose dependent. Imidacloprid treated birds showed significant increase in Serum Glutamic Oxaloacetic Transaminase level at 14 and 28 days of experiment, but Serum Glutamic Pyruvate Transaminase level was not significantly altered in all the treatment groups of imidacloprid. Increase in SGOT levels was dose dependent and indicates the toxic effect on liver function. Serum creatinine was not much altered. The total protein, total albumin and total globulin levels were not significantly changed in insecticide treated groups. There was no effect of imidacloprid on antibody titre against ND of treated birds at 14 and 28 days of experiment These findings indicate lack of significant effect on protein metabolism and humoral immune response at the administered doses of imidacloprid. Cellular immunity was also not affected as tested by DNCB dye test. Gross postmortem and histopathological changes in various organs of birds treated did not show any clear cut evidence of immunotoxicity. A decrease in thymus: body wt. ratio and hypotrophy of individual thymic lobes were however seen at necropsy. Mild depletion of lymphocytes in bursa and in some focal areas in splenic parenchyma was also seen. Liver and kidney showed mild degenerative changes only. These findings are suggestive of the fact that the doses of imidacloprid given were less to be immunotoxic. The changes were principally observed in the highest treatment group, (which were mild) indicating that some higher dose may produce significant signs of toxicity.