Preliminary acute toxicity study on imidacloprid in Swiss albino mice 2

Aim: To ascertain the maximum tolerated dose (MTD) and to investigate the acute oral toxic effects of imidacloprid towards Swiss albino male mice. Materials and Methods: The MTD of imidacloprid was determined in pilot dose range finding study following the standard method. Animals were observed for toxic signs and symptoms after oral administration of MTD of imidacloprid in single dose. th The body weights of animals were recorded on alternate day. Animals were sacrificed on 14 day and changes in hematological parameters (Hb, TEC, TLC and DLC) and morphometric measurements (length, breadth, thickness and weight) of various body organs (heart, liver, spleen, kidney, testis and epididymis) were examined. The student's t-test was applied to statistically analyze the results. Results: The MTD of imidacloprid was determined to be 110 mg/kg body weight. The sign and symptoms of acute toxicity were ataxia, rigidity and fasciculation of muscles, protrusion of eye ball and tremors of head. Imidacloprid treatment resulted in decreased body weight gain as compared to the control group. The changes in hematological parameters were not significant between imidacloprid treated and control groups. Also the values of relative organ weights and morphometric measurements of various body organs did not differ significantly between the control and imidacloprid treated animals. Conclusions: MTD of imidacloprid in Swiss albino male mice through oral route was determined for the first time. Study revealed a non-toxic effect of imidacloprid on body weight, relative organs weight, hematological parameters and morphometric measurements of various body organs in mice.


Introduction
acute toxicity study of insecticides.The LD of IMI in 50 mice is reported to be 131 mg/kg body weight (BW) [4, Contamination of natural resources by indiscri-5].The toxic effect of IMI on hematological and minate and hysterical use of pesticides is potential morphometric parameters of different body organs in threat to animal and human health.Imidacloprid (IMI) swiss albino mice is not known.is most widely used neonicotinoids insecticide in Thus in present study, the acute toxicity of IMI at agriculture with registration for use on over 140 crops MTD level was studied in swiss albino male mice in over 120 countries [1].Such large scale use can following oral administration.Subsequently, hematoexaggerate the toxic properties and adverse effects of logical changes and toxic effects on morphometric insecticide and can be fatal for human as well as animal parameters of heart, liver, kidney, spleen, epididymis health.The study of acute toxicity of IMI following and testis were studied.occupational, accidental or suicidal ingestion indicated mild clinical effects such as tachycardia, nausea,

Materials and Methods
vomiting to severe respiratory failure, seizures and Chemicals and experimental animals: IMI (technical even death in human [2,3].The analysis of toxic grade, >98% purity) originally obtained from Indofil properties of drugs and chemicals using in vivo Chemicals Company, Mumbai, India was used in the mammalian systems (mice or rat) is of enormous value present investigation.Swiss albino mice weighing which reflects indirect toxic effects on humans because between 17-27 g were procured from Disease Free of their high degree of presumptive human relevance.
Small Animal House, LLRUVAS, Hisar.The mice Since IMI is now being considered as replacement for were acclimatized to laboratory conditions for 2-3 days other available pesticides, relative benefits and risk before the experiments were conducted.The temperamust be considered.ture of animal house was maintained between 22 -Determination of maximum tolerated dose 27°C throughout the experiment.(MTD) or median lethal dose (LD ) is imperative for 22 min of administration.Body posture was abnormal in all groups were recorded on alternate day for 14 th with hind limbs abducted from body.The severity of all days.The animals were sacrificed on 14 day and blood clinical signs and symptoms decreased with the time was taken directly from heart using heparinized hypodermic syringe and collected in test tube rinsed and disappeared within 24 hours.The mice manifested with heparin saline solution (5 mg heparin/ml NSS).
the prominent abdominal respiration at slow rate in Hemoglobin (Hb), total erythrocytes count (TEC) and initial stages which later on became normal.Adminitotal leukocytes count (TLC) were estimated [8, 9].The stration of higher dose of IMI was associated with the blood smears were fixed with methanol for five min, increased severity and earlier onset of toxicity symptoms.stained with Giemsa's stain (1:10 dilution) for 25 min Animals introduced with the pesticide at dose higher and observed under oil immersion lens for differential than MTD exhibited very high respiratory rate just leukocytes count (DLC).before death.The occurrence of tremors, convulsions Necropsies were performed on sacrificed animals and high respiratory rate correlate with the agonist and morphometric measurements (length, breadth, nature of IMI at nicotinic acetylcholine receptors thickness and weight) of various body organs viz.heart, (nAChR) which induces neuromuscular paralysis [15].liver, kidney, spleen, epididymis and testis was The rapid appearance (within 10-15 min of recorded.In case of liver, major lobe was taken for administration) and disappearance (within 24 hours of length, breadth and thickness.The relative organ administration) of toxic signs and symptoms correlate weights were calculated using formula: organ weight with the earlier reports of prompt absorption (92-95% (g)/body weight (g) X 100.
within 1 hour) and excretion of more than 90% within Statistical analysis: The student's t-test using SPSS 24 hours of administration of IMI [16,17].The absence statistics 17.0 software (IBM Corporation, New York, of toxic sign and symptoms after 24 hours indicated no USA) was applied to statistically analyze the results delayed toxic effect of IMI.obtained with different study groups.

Results and Discussion
level on day 1, the body weights of mice were recorded MTD finding experiment and clinical profile: Following on alternate day for 14-days and are presented in Tablethe pilot dose range finding study, the MTD of IMI in 2. A transient decrease in BW gain was observed in IMI Swiss albino mice was found to be 110 mg/kg BW by treated animals compared to control group.The body oral route.To the best of our knowledge, the present growth was found to be slightly decreased as inferred study is the first to demonstrate that the MTD of IMI in from the transient decrease in BW which is reported to Swiss albino male mice through oral route is 110 mg/kg be a common symptom of IMI treated animals [18].BW. which is much lower when compared to the various pesticides is associated with the structural were found in IMI treated animals when compared to damage to organs and tissues along with pathological the control group.The mean values of Hb and TEC and inflammatory changes resulting into altered were decreased non-significantly in IMI treated morphology of affected organs in terms of its length, animals.However, the mean values of TLC were breadth and thickness.The values of morphometric increased non-significantly, which might be due to measurements of various vital organs were measured rebound effect of IMI on haemopoietic tissues as and presented in Table-5.No significant difference was suggested earlier [19].The non toxic nature of aqueous observed in the values of length, breadth and thickness leaf extracts of Ficus exasperata has been described of heart, liver, spleen, kidney, testis and epididymis of earlier based on its effects on hematological para-IMI treated animals as compared to the control group.meters (WBC count, platelet and hemoglobin estimation), The changes in morphometric parameters of body body weight and temperature [20].
organ relates with the toxic properties of chemicals.Acute toxicity study has been described earlier in terms

Table - 1
. Oral doses of imidacloprid (IMI) used for determination of maximum tolerated dose (MTD) in Swiss albino mice

Acute toxic effects of imidacloprid on various hemato- organs
viz. heart, liver, spleen, right kidney, left kidney,

logical parameters of mice:
The results of hematoright testis, left testis, right epididymis and left logical studies are presented in Table-3.No significant epididymis did not differ significantly between the changes in the hematological parameters (Hb, TEC, control and IMI treated groups.Acute exposure to TLC, differential neutrophilic and lymphocytic count)
The MTD of IMI in Swiss albino mice through 11.Paulson, S.K., Engel, L., Reitz, B., Bolten, S., Burton, E.G., oral route was determined for the first time.The MTD Maziasz, T.J., Yan, B. and Schoenhard, G.L.(1999)in Swiss albino mice was more than twice the reported Evidence for polymorphism in the canine metabolism of the MTD in BALB/c mice reflecting the existence of strain cyclooxygenase 2 inhibitor, celecoxib.Drug Metab.Dispos.authors read and approved the final manuscript.14 16.Klein, O. and Karl, W. (1990) Methylene [ C] imidacloprid: Metabolism part of the general metabolism ********