| Amyloid formation is a critical component of the pathology of many degenerative diseases, including Alzheimer's and type 2 diabetes mellitus (T2DM), The pathology of T2DM includes the presence of amyloid deposits in the pancreatic islets or the islets of Langerhans. The main component of these deposits, called pancreatic islet amyloid polypeptide (PIAP) or amylin, that is normally stored with insulin in secretory granules and secreted by islet B-cells. Islet amyloidosis in patients with T2DM is associated with a reduced mass of insulin-producing B-cells.In this study, we discussed the fine and ultrastructural changes of the rat pancreatic tissue after ligaturing thoracic duct. The special attention is focused on the deposition of PIAP within pancreas. The changes of blood glucose, lipide, insulin and C-peptide levels after blocking the circulation of lymph was touched on also. The contents and the results were showed below.Part 1 The Establishment of Pancreatic Lymph stagnation Animal Model Induced by Ligaturing Thoracic Duct in RatsObjective: In this study, we ligated the thoracic duct of rats on the abdomen, and wished to establish the lymph drainage block animal model, and observe the morphological changes of pancreatic tissue in fine structural level.Methods: 20 adult SD rats at ten months were divided into 2 groups randomly, as experimental (operation) group and control (sham operation) group; The rats were sacrificed at 6 months after operation, the pancreatic tissue paraffin sections were stained with conventional HE and Congo red and observed with light microscope.Results: 1. The conventional HE staining of pancreatic tissue sections in experimental group showed that the pancreatic glandular lobule interstitial space were both widen, connective tissue desmoplasia, fatty cumulated, pancreatic islet light coloured. 2. The Congo red staining sections in experimental group appeared that the pancreatic glandular lobule interstitial space was widen, pancreatic islet stained with cinnabar red colour.Conclusion: The morphological changes of rat pancreatic tissue structure after operation indicate that the ligation of thoracic duct may induce pancreatic lymph drainage block, lymphagiectasis, connective tissue interstitial space widen, fatty cumulation; These structural changes may affect the endocrine function of pancreatic islet.Part 2 Morphological Changes of Pancreatic Tissue Structure after Ligaturing Thoracic Duct in RatsObjective: Pancreatic islet amyloid peptide (PIAP or amylin) is a 37 amino-acid peptide. It is regulated in a similar fashion to insulin. It accumulates in B-cells with age and its accumulation is further increased in type 2 diabetes mellitus. Its physiological role is unclear.In this study, we ligated the thoracic duct of rats on the abdomen, and wished to observe whether lymph drainge block animal model can affect PIAP deposit in rat pancreas, and the morphological changes of pancreatic tissue in fine and ultrastructural structural level.Methods: 20 adult SD rats at ten months were divided into 2 groups randomly, as experimental (operation) group and control (sham operation) group; The rats were sacrificed at 6 months after operation, the pancreatic tissue paraffin sections were stained with conventional HE and Congo red, some sections were PIAP-immunohistochemistry stained and observed with light microscope.Results: 1. The conventional HE staining of pancreatic tissue sections in experimental group showed that the pancreatic glandular lobule interstitial space were both widen, connective tissue desmoplasia, fatty cumulated, pancreatic islet light coloured. 2.The Congo red staining sections in experimental group appeared that the pancreatic glandular lobule interstitial space was widen, pancreatic islet stained with cinnabar red colour. 3. The pancreatic sections in experimental group with PIAP-immunohistochemistry staining displayed that the pancreatic islet surrounding tissues were stained strong positive dark brown.Conclusion: The morphological changes of rat pancreatic tissue structure after operation indicate that the ligation of thoracic duct may induce pancreatic lymph drainage block, lymphagiectasis, connective tissue interstitial space widen, fatty cumulation, PIAP deposit in rat pancreas; These structural changes may affect the endocrine function of pancreatic islet.Part 3 PIAP Deposit in Pancreas after Ligaturing Thoracic Duct in Rats and the Effect to GlycometabolismObjective: In this study, we ligated the thoracic duct of rats on the abdomen, and wished to observe whether lymph drainge block animal model can affect pancreatic islet amyloid polypeptide(PIAP)deposit in rat pancreas, and the morphological changes of pancreatic tissue in fine structural level.Methods: The 30 adult SD rats at ten months were divided into 2 groups randomly, as exprimental (operation) group and control (sham operation) group; After operation for 6 months, the pancreatic tissue sections of exprimental rats were stained with conventional HE and Congo red with paraffin imbedding, some frozen sections were PIAP-immunohistochemistry stained and observed with light microscope; Transmission electron microscope (TEM) specimen preparation and observation were performed on other samples.Results: 1.The pancreatic sections at exprimental group rats with PIAP-immunohistochemistry staining displayed that surrounding the pancreatic islet was stained into dark brown being positive reacted with PIAP antigen. 2.The Congo red staining sections at exprimental group rats appeared that the pancreatic glandular lobule and islet interstitial space were both widen, pancreatic islet stained with cinnabar red colour. 3.TEM observation showed the pancreatic glandular interlobule space was widened, while blood vessels and enlarged lymphatic vessels were visible; Within widened pancreatic islet interstitial space, a great quantity of lipid droplets and some collagen fibril structures could be seen. 4.The concentration of insulin in the model group is significantly lower than that in the contral group. In the model group, the concentration of blood glucose is significantly higher after ligating the thoracic duct of rats. There is not significant difference in levels of C-P between the model group and the contral group.Conclusion: The morphological changes of rat pancreatic tissue structure after operation indicated that the ligation of thoracic duct might induce pancreatic lymph drainge block, fatty cumulated, PIAP deposited in rat pancreas; islet cell function was damaged, The concentration of insulin was lower and blood glucose was higher,These structural changes might affect the endocrine function of pancreatic islets.Part 4 Influence To The Pancreatic Tissue Structure And Lipide Metabolism after Ligaturing Thoracic Duct In RatsObjective:To explore the influence to the lipide metabolism by ligaturing rats thoracic duct, and reveal the fine and ultrastructural changes of their pancreatic tissue induced the dysfunction of lymphatic drainage.Methods:The 20 of 30 adult SD rats at ten months were taken randomly as model group and ligatured thoracic duct in order to establish animal models for lymph deposit, the others were as false operative control group. At 6 months after operation, the venous blood were taken for serum lipide examination; Some pancreatic specimens were embedded in paraffin wax, the tissue sections stained with HE or Congo red and observed with light microscope; The ultra-sections of the pancreatic tissue was prepared and observed with TEM.Results:1. The concentrations of free fatty acids (FFA) and triglyceride in the model group is significantly lower than that in the control group (P<0.001). There is not significant difference in cholestrol levels between the model group and the control group. 2.HE and Congo red stained sections showed that the pancreatic glandular lobule space was widened, significant connective tissue increased, and fat accumulated. 3.TEM observation displayed that the pancreatic glandular interlobule space was widened, while blood vessels and enlarged lymphatic vessels were visible; within intercellar space of pancreatic islets, a great quantity of lipid droplets, red cell and some collagen fibril structures could be seen.Conclusion:The ligation of rat thoracic duct can contribute to the dysfunctions of pancreatic lymph drainage and lipide metabolism, and result in the lymphagiectasis, connective tissue space and interstitial space widening, fatty accumulation, and lipids deposit within rat pancreas. These structural changes may affect the function of pancreatic islets.We ligated the thoracic duct of rats on the abdomen, and established the lymph drainage block animal model successfully. After operation for 6 months, The pancreatic sections at exprimental group rats appeared that the pancreatic glandular lobule and islet interstitial space were both widen, the pancreatic islet stained with cinnabar red colour. TEM observation displayed that the pancreatic glandular interlobule space was widened, while blood vessels and enlarged lymphatic vessels were visible; within widened intercellar space of pancreatic islets, a great quantity of lipid dropleted. The concentration of insulin in the model group was significantly lower than that in the contralled group. In the model group, the concentration of blood glucose was significantly higher after ligating the thoracic duct of rats. These structural changes of pancreas might affect the endocrine function of pancreatic islets. |
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