Histopathologic and immunohistochemical study of pancreas in alloxan-induced diabetic dogs

Abstract

The aim of this study was to evaluate pancreatic microscopic lesions with the presence or absence of insulin in Langerhans islets at different times post-induction (p.i.) in alloxan-induced diabetic type I dogs. A group of 20 mixed breed, male adult dogs were used, subdivided in 2 groups: Control (n = 5) and Experimental (n = 15). The Experimental Group was subdivided into groups of 3 animals each which were alloxan-induced intravenously (75 mg/kg). Dogs were sacrificed at different times p.i. (2 hours, 24 hours, 7 days, 14 days, 21 days). Pancreatic samples were taken for histopathologic and immunohistochemical study against insulin and Ki-67. The Control Group considered 5 healthy dogs, one for each Experimental Group. Plasmatic evaluation of glucose and fructosamine were measured to confirm diabetes. The diabetic status of the Experimental Group was confirmed by the presence of sustained hyperglycaemia and high concentrations of fructosamine after 7 days p.i. Histopathologic results showed a significant decrease (P < 0.05) in the number Langerhans of islets through time, necrotic and vacuolar cellular changes after 2 hours post-induction and fibrosis in the groups with more time p.i. At 7, 14 and 21 days p.i. it was possible to observe proliferation of ductular cells. Immunohistochemistry showed a decrease in immunomarked cells against insulin in groups with more time after induction, and evidence of ductular proliferation. The results allowed establishing a direct relationship between histopathologic lesions in endocrine pancreas and immunohistochemistry against insulin and also showed the proliferation of pancreatic ducts.