Physiological and Histological Studies on Imidacloprid Toxicity in Male Rabbits

Abstract

The present study is aimed to investigate the physiological and histological alterations associated with imidacloprid administration in male rabbits. The oral LD50 of imidacloprid in the male rabbits was calculated from logarithmic scale and found to be 172 mg/kg body weight. A dose of 1/10 LD50 (17.2 mg/kg body weight) imidacloprid was then used to test its toxicity. The experimental group were given orally the dose of 1/10 LD50 imidacloprid daily for eight weeks. Control animals were given distilled water. Upon imidacloprid administration, alanine aminotransferase generally showed significant increase throughout the experimental periods with maximum increase in the 2nd and 5th weeks compared to controls (70.8±4.1 v 52.0±3.0 and 65.3±3.9 v 49.8±3.0; % difference=36.2 and 31.1; P=0.017and 0.020, respectively). Aspartate aminotransferase was also increased with significant changes at the 3rd, 4th and 5th weeks (49.2±3.0 v 35.7±2.1; 43.2±2.7 v 34.8±1.5 and 43.0±2.1 v 36.1±1.7; % difference=37.8, 24.1 and 19.1; P=0.012, 0.031 and 0.047). Alkaline phosphatase increased in the first four weeks showing maximum increase during the 2nd week compared to controls (129.5±6.3 v 103.3±3.9, % difference= 25.4, P=0.012). In the last four weeks the enzyme activity decreased with maximum decrease at the 6th week (83.3±.5 v 107.8±5.7, % difference= 22.7, P=0.018). Similar effect was observed for cholinesterase with maximum increase at the 4th week (6167±235 v 4624±168, % difference= 33.4, P= 0.002) and maximum decrease at the 8th week (3831±233 v 4876±155, % difference= 21.4, P= 0.011). Urea was elevated with maximum increase at the 6th week compared to controls (48.2±1.9 v 36.4±3.0, % difference= 32.4, P= 0.011). Such increase was at the 7th week for creatinine (1.20±0.06 v 0.89±0.08, % difference= 34.8, P= 0.025). Protein profile showed statistically significant decrease in total protein levels all over the experimental periods showing maximum decrease at the 3rd week compared to controls (4.5±0.29 v 6.2±0.33, % difference= 27.4, P= 0.009). Similar result was observed for albumin and globulin with maximum changes at the 3rd week (3.2±0.17 v 4.1±0.18 and 1.40±0.07 v 2.03±0.11; % difference= 22.0 and 31.0; P= 0.010 and 0.003, respectively). Testosterone was significantly lower in imidacloprid-treated rabbits compared to controls particularly at the 3rd and 7th weeks (2.10±0.12 v 3.20±0.18 and 2.40±0.15 v 3.50±0.17; % difference= 34.3 and difference= 31.4; P= 0.002 and 0.003, respectively). On the other hand, the Histopthological alterations were manifested in liver, kidney and testis of the imidacloprid-treated rabbits. Hepatocellular damage as degenerative changes, destruction of architecture of hepatocytes, karyolysis the nuclei and congestion of sinusoids were observed on the treated rabbits. While the effect of imidacloprid was more prominent on kidney tissue. Mild hypertrophy in some individual glomeruli. Kidney section showing dilatation of the inter tubular blood vessels impacted by haemolysed blood, rupture of the renal tubules and necrobiosis in the epithelial cells lining the tubules were observed in the experimental animals. Light microscopic analyses revealed the Histopthological changes on testis tissue. Testis sections from rabbits treated with imidacloprid showed necrotic changes of spermatogonia, primary and secondary spermatocytes. On the other hand disorganization of spermatogenic layers, necrotic Sertoli cells and pyknotic lesions in spermatogonia showed in the treated rabbits. Furthermore, disappearance of interstitial cells of Leydig showed in the treated animals.