Simulation of Acute Destructive Pancreatitis with Damage to the Adjacent Adipose Tissue in Pigs

Abstract

The aim of the study was to develop a model of acute destructive pancreatitis with damage to the extra-organ adipose tissue. Materials and methods. Simulation of acute destructive pancreatitis with damage of the extra-organ adipose tissue was performed in 22 white breed boars aged 3 months. The animals were divided into groups in accordance with two series of studies, where the control (first) group included 15 animals with the pancreas and extra-organ adipose tissue remained intact. Acute destructive pancreatitis was simulated in 7 pigs of the experimental (second) group based on the proposed technique (patent for an invention No. 2668201). Ultrasound examination of the abdominal cavity and retroperitoneal region was applied to confirm the development of expected pathology in experimental animals. Intensity of blood supply was assessed using contrast radiography by injecting a contrast medium into the superior mesenteric artery. Complete blood count and biochemical assay were performed. In addition, during autopsy tissue samples were taken for histological and immunohistochemical investigations to assess changes in the internal organs. Results. Acute destructive pancreatitis with damage to the extra-organic adipose tissue was regarded as achieved when clinical manifestations of apathy, lethargy, feed refusal were registered in animals. Biochemical blood tests revealed a significant increase in the concentration of alkaline phosphatase and alpha-amylase enzymes. Nitrogenous toxins, in particular, creatinine, were accumulated in the body of the experimental animals. Complete blood count revealed leukocytosis, the fact supporting the onset of the expected inflammatory process in the pancreas and adjacent adipose tissue. The development of necrotic and inflammatory processes in the organ was evidenced by a sharp increase in the level of amylase, creatinine and alkaline phosphatase in the blood of animals. Ultrasound examination revealed a picture of the blurring of pancreatic contours, heterogeneity of the organ structure, increased echogenicity, and enlargement of the duct. Intensification of the vascular pattern and increase in pancreatic contours were detected during the contrast examination of the abdominal vascular system. At autopsy, there were signs of enzymatic peritonitis, namely, serous-hemorrhagic exudate in the abdominal cavity and the cavity of the omental bursa, increased pneumatization of the intestinal tube with a thinning of its wall and foci of small hemorrhages. The pancreatic tissue in all cases was edematous, full-blooded, with multiple foci of fatty necrosis and purulent inflammation. Similar changes were found in the adjacent adipose tissue. At the light-optical level, vascular congestion, small foci of steatonecrosis and micro-abscesses were determined in the pancreas. Immunohistochemical studies largely evidenced the onset of acute destructive pancreatitis with damage to the extra-organ adipose tissue.Conclusion. Thus, the proposed technique allows simulating acute destructive pancreatitis with damage to the extra-organ adipose tissue in pigs, the event frequently occurring in the clinical practice. In animals the disease is accompanied by clear clinical manifestations correlating with findings of instrumental and laboratory investigations, and autopsy results. Investigations of the pancreatic and extra-organ adipose tissue samples at the light-optical and molecular levels evidence the fact that the authors have simulated a model of acute destructive pancreatitis with involvement of the adipose tissue adjacent to the organ in the pathological process.