| Objectives:Diabetes mellitus (DM) is a metabolic morphometric disorder which is characterized by chronic hyperglycemia and caused by many factors,than due to a clinical syndrome which leads to multi-system damage.For a long time,the painstaking research is done to the heart,kidney,nerve and retinal complications of diabetes,and there are few studys on diabetic pulmonary complication.In recent years,studys on diabetic pulmonary damage aiways turn around pulmonary function.But the lung damage possible pathological and physiological mechanism is poorly studied.In the mechanism of a state of chronic high blood sugar caused of injury,advanced glycation end products (AGEs) is closely related with a variety of chronic diabetic complications of starting and development.It has been regarded as one of the most important reasons for high glucose that causes the chronic tissue injury,there is nothing to be reported about the change of AGEs in the diabetic pulmonary damage. Connective tissue growth factor (connective tissue growth factor,CTGF) can come from the type 2 alveolar epithelial cells and activated fibroblasts by autocrine or paracrine secretion,CTGF can regulate fibroblasts and extracelluar matrix (ECM) to accumulate.It plays an important role in pulmonary fibrosis progress.CTGF is a cytokine which is newly discovered, which is regarded as the downstream response element of transforming growth factor-f31 (TGF-β1) which has four types,of those,TGF-β1 follows CTGF to promote fibroblast proliferation and the formation and accumulation of the extracellular matrix, thus, they both play a vital role.This study aimed to investigate the changes from AGEs,CTGF,TGF-β1 of diabetic rats lung tissue by immunohistochemical staining, To understand the mechanism about the lung tissue damage caused by the high glucose toxicity.Methods:48 male Sprague-Dawley (SD) rats were randomly divided into two groups:the control group and the diabetic group, there were 24 rats in each group.Streptozotocin (STZ) was injected into the tail veins of the rats that were in the diabetic group,the dose was 60mg/kg.It was instead by the same dose of saline in the control group.In the diabetic animal models, the glucose values were greater than 16.65mmol/L,it implied that modeling was successful. Respectively,the diabetic group group and the control group were randomly divided into 4 weeks-subgroup, 12 weeks-subgroup,20 weeks-subgroup,there were 8 rats in each group.Modeling success after 4,12,20 weeks,the rats were killed,the lung tissue was left,then it was fixed by Formalin that was ten percent volume fraction,at last it was paraffin-embedded and cut onto the slides.The changes of the site of deposition with AGEs,CTGF,TGF-131 in the lung tissue were observed by the way of immunohistochemical staining.The morphometric software-Morphometric Analyzer was used for morphometric analysis.Results:(1)After the successful modeling,the diabetic rats apparently had more drinks,more food, more urinary, weight loss,activity weakened, and poorly physical state.(2) Immunohistochemical observation and morphometric analysis with AGEs showed that:In the diabetic subgroups,lots of positive cells can be seen in thealveolar macrophages,trachea epithelial cells,a small amount of vascular endothelial cells and smooth muscle cells, and the number increased following the diabetic course.In the diabetic subgroups,the average gray values of the rat lung tissue's positive cells are significantly lower than those in the corresponding stage of the control groups (P<0.05),(?)and the number decreases significantly with the progression of the diabetic course (P<0.01).In control subgroups,a small amount of positive cells can be seen in the alveolar macrophages and trachea epithelial cells.(3) Immunohistochemical study and morphometric analysis with CTGF and TGF-β1 showed that:In diabetic 4 weeks-subgroups,a small amount of positive cells can be seen in the pulmonary interstitial cells and the tracheal epithelial cells;In control 4 weeks- subgroup,a small amount of positive cells can be seen in the few blood vessel endothelium cells,a few small amount of endothelial cells.The rats in the 4 weeks-group is compared with the control group,the average gray values of the rat lung tissue's positive cells are not statistically different.In diabetic 12 and 20 weeks-subgroups,lots of positive cells can be seen in the pulmonary interstitial cells and the bronchial epithelial cells,the average gray values of the rat lung tissue's positive cells are significantly lower than those in the corresponding stage of the control groups (P<0.05),and the number increased gradually following the diabetic course(P<0.01).(4) Pearson's correlation analysis showed: In diabetic Group, AGEs is significant positive correlated with CTGF and with TGF-β1 (γ=0.939,0.904;P<0.01) (show Table6,7,Graghl9,21).CTGF is significant positive correlated with AGEs and with TGF-β1 (γ=0.939,0.878;P<0.01).Conclusions:(1)It can be successfully prepared diabetic rat model with injecting STZ into the tail's vein only once.(2) Lung tissue of early diabetic rats has present the significant deposition of AGEs,following the diabetic course,gradually increasing significantly,shows that it due to high glucose toxicity performance.(3)CTGF and TGF-β1 both significantly increase in the mid-late stage of the diabetic lung tissue,both are significantly correlated with AGEs,it suggests:Interstitial lung changes may be related to high glucose toxicity,it is necessary to study in depth. |
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