Prajapati, K. S.PRAJAPATI, NIRAVKUMAR K.2018-06-112018-06-112012http://krishikosh.egranth.ac.in/handle/1/5810050758The present research work was conducted on 24 male and 24 female Wistar rats to study the toxicopathological effects of repeated dose (28 days) of melamine. Wistar rats were randomly divided into 4 different groups with six males and six females in each group. Animals of group II to IV were given 500, 1000 and 2000 mg/kg b. wt melamine by gavage for 28 days where as group I was administrated only com oil as (vehicle) control. Clinical signs, mortality, feed intake, body weight, hematology, serum biochemical and pathomorphological studies were done. The extent and severity of observed symptoms varied according to the dosage administered to animals. Symptoms like dullness, depression, lethargy with shrunken eyes, rough hair coat, diarrhoeic faeces, polyuria, polydypsia, hematuria and crystalluria with "fan shaped" MEL crystals were noticed in rats of treatment groups. Mortality was observed only in group IV (58.33%) and group III (33.33%) with 54.55%) male and 45.45%) female. The dose dependent reduction in body weight and feed consumption was observed in animals of group II, III and IV. The significant decrease in RBCs count. PCV, haemoglobin and MCV was recorded with increase in the dose of melamine in group IV. Moreover, significant decrease in MCH count was noticed in male and highly significant decrease in female from group IV animals whereas significant increase in total leucocytes count was noticed in group III and highly significant increase in group IV animals. The differential leucocytes count revealed significant increase in neutrophil count in Group III and highly significant increase in Group IV animals whereas significant decrease in lymphocytes count in animals of melamine treated group IV. No significant change in monocyte, eosinophil and basophil counts were observed in any treatment groups. AST, creatinine, BUN and uric acid values were significantly increased in treatment group III whereas highly significantly increased in group IV. Moreover, ALT was increased significantly in group III and IV male animals. Whereas increased significantly and highly significantly in female animals of group III and IV respectively. The significant decrease in total protein and albumin was observed in treatment group III and highly significant decrease in group IV animals. All the rats exposed to three different dose levels of melamine revealed dose dependant pathological changes in groups III and IV only with lesions in kidneys, urinary bladder, liver, spleen, lung and intestine. The main target organs affected were kidney, urinary bladder and liver. Grossly, kidneys were enlarged, pale, pitted and misshaped with dilated renal pelvises and variable whitish fine birefringent MEL crystals located in the cortex and medulla. Moreover, corticomedullary junction was obscured by a dark-red band of hemorrhages. Microscopically, kidneys revealed congestion, haemorrhage, degeneration, necrosis, cystic dilatation of tubules, glomerular atrophy and hypercellularity, tubular hyperplasia, hyaline casts and deposition of melamine crystals of variable size in the tubules. Furthermore, wet mounting of small slices of fresh kidney revealed golden brown crystals of MEL lined up in renal tubules forming spherulites. Grossly, urinary bladder revealed hemorrhage and distention with fine crystalline granular material in the lumen whereas microscopic examination revealed transitional epithelial hyperplasia. Microscopically, liver from group IV revealed numerous, small, round, greenish, fan shaped MEL crystals scattered in the dilated bile duct. Furthermore, liver showed vacuolar degeneration of hepatocytes and mild fatty degeneration. The overall lesions gave impression that melamine was nephrotoxic as well as hepatotoxic in nature. The intensity and distribution of such lesions were more severe in rats of group IV, followed by rats of group III.enVETERINARY PATHOLOGYA STUDYThesis