High-fat Diets Affect The Submandibular Gland Ultrastructure, Upstream Stimulating Factor 1 And Trefoil Factor 3 Expressin In ApoE Knock-out Mice

Objective ①To observe the structure and ultrastructure characteristics by light microscope and electron microscope in submandibular gland of mice with hyperlipidaemia (HLP).②To observe the expresson of upstream stimulatory factor 1(USF1) and Trefoil factor family 3(TFF3) in submandibular gland of mice with HLP and analyze average optical density by using computer image analysis system. Methods 10 wild-type mice are given common diet and served as the control group (Group C).10 ApoE KO mice are given high-fat diet and served as the high-fat group (Group H). After mice were molding for 6 months, they were sent to inspect blood fat through inferior vena cava.,respectively;submandibular gland tissues of mice were taken to do HE dyeing, electron microscopy observation, immune histochemical stain and computer picture analysis.Results ①Blood fat:After molding for 6 months,by making a comparison between cholesterol in control group(2.97±0.39) and cholesterol in high fat group(33.37±16.38),it has significant difference(P<0.05);By making a comparison between triglyceride in control group(1.10±0.67) and triglyceride in high fat group (5.17±2.70), it has significant differencet(P<0.05); By making a comparison between very low density lipoprotein in control group(0.52±0.16) and very low density lipoprotein in high fat group(9.83±4.11), it has significant difference(P<0.05).②Results of HE (hematoxylin-eosin) staining:Submandibular gland acinar cells of mice in control group are plump and have distinct structure. Acinar cells are cone-shape.Cytoplasm dyeing is shallow.Cell nucleus is round and closes to basilar part.Submandibular gland acinar cells of mice in high fat group appear mild atrophy.Cell arrangement is disordered. Epithelial cells of granular convoluted tubule(GCT) are atrophy.Acidophilia secretory granules of cytoplasm in the top of cells are reduced. Connective tissue is hyperplasia.③Results of scanning electron microscope:Ductal epithelial cells in submandibular gland tissue of mice in control group have developed mitochondria.Mitochondrial cristae are distinct and complete; Mitochondria in epithelium of high fat conduits presented ridge breakage, turbulence, disappearance and stromatolysis.Submandibular gland cells of mice in control group have rough endoplasmic reticulum.Areole is uniform and distributes regularly.Partial rough endoplasmic reticulum in high fat group presents cystic dilatation and has looseness and disorder of structure.④Results of Immunohistochemical Staining:Positive expression of USF1 is mainly positioned on submandibular gland acinar cells of mice and cytoplasm and cell nucleus of ductal epithelial cells.Immumohistochemical staining regards brown granules or yellow granules as positive reaction.Ductal epithelial cytoplasm and cell nucleus in submandibular gland of mice in control group appear obvious brown and sepia granules.On the other hand,mice in high fat group appear light yellow granules. Moreover,staining granules in cytoplasm are reduced obviously.Positive expression of TFF3 is mainly positioned in the basilar part of ductal epithelial cells in submandibular gland of mice.Immumohistochemical staining regards brown granules or yellow granules as positive reaction.Ductal epithelial cytoplasm in submandibular gland of mice in high fat group appears light yellow granules.Moreover, staining granules in cytoplasm are reduced obviously.⑤Results of Computer-aided image analysis:MOD value of USF1 in submandibular gland of mice in control group is (0.67±0.12) and in high fat group is (0.56±0.06).Both of them have statistical significance (P<0.05);MOD value of TFF3 in submandibular gland of mice in control group is (0.51+0.13) and in high fat group is (0.28+0.09).Both of them have statistical significance (t=-5.699, P<0.001).Conclusions ①High fat diets might cause a series of pathological changes of submandibular gland conduits of ApoE knockout mice and ultrastructure in acinous cells.②High fat diets might cause reduction of USF1 and TFF3 expression in submandibular gland of ApoE knockout mice, reminding that they might participate in the lesion process of hyperlipemia.