| OBJECTIVES To establish a model of diabetic rats; To research low density lipoprotein receptor-related protein 1 (Lrp-1) and Amyloid Beta (Aβ1-40) content in the brain tissue of rats with diabetic mellitus, as well as the relationship between them;To Investigate the possible damage mechanism of Lrp-1 and Aβ1-40 on the brain tissue and vessels with diabetic mellitus.METHODS 1)Type 2 diabetic rats model was induced by streptozotocin and high-carbonhydrate-fat diet. All wistar rats were randomly assigned into four groups:normal rats aged 3 months and 6 months, and diabetic rats aged 3 months(DM3) and 6 months(DM6).2)The expression of Lrp-1 and Aβ1-40 in the brain tissue and vessels of normal,diabetic rats and rats with different months was detected by immunohistochemistry..3)The content of Lrp-1 and Aβ1-40 in the brain tissue of normal,diabetic rats and rats with different months was detected by enzyme-linked immunosorbent assays(Elisa)4) The results were expressed as,The SPSS 13.0 statestic software was used in analying the results by ANOVA,q test and linear correlation analysis.RESULTS1) Expresson of Aβ1-40:Aβ1-40 was detected in several parts of brain tissue, such as cytoplasm or cytomembrane of neurons or neuroglial cells of cerebral cortex and hippocampus, adventitia or smooth muscle cells of pial artery or perforating branch, etc. Compared between groups of same age, more Aβ1-40 were detected in diabetic rats than normal ones (P<0.05). And the expression of Aβ1-40 increased with age in both group (P<0.05);2) Expresson of Lrp-1:Lrp-1 was also detected in several parts of brain tissue, such as cytoplasm or cytomembrane of neurons or neuroglial cells of cerebral cortex and hippocampus, intima of perforating arteries, capillary endothelial cells, etc. On the contrary, less Lrp-1 were detected in diabetic rats (P<0.05). And the expression of Lrp-1 decreased with age (P<0.05);3) A correlation study demonstrated that Aβ1-40 had a typical negative linear correlation with the Lrp-1 (r=-0.938, P<0.01).CONCLUSIONS1) More Aβ1-40 were detected in diabetic rats than normal ones,indicating that the deposition of Aβ1-40 in brain tissues and vessels involed in the pathological courses of diabetic brain damage.2) More Aβ1-40 were detected in diabetic rats than normal ones,On the contrary, less Lrp-1 were detected in diabetic rats. It suggested that diabete may play roles in their expressions;3) With aging, the expression of Aβ1-40 increased in diabetic and normal rats, On the contrary,the expression of Lrp-1 decreased.indicating age is another important factor on the expression of Aβ1-40 and Lrp-1.4) A correlation study demonstrated that Aβ1-40 had a typical negative linear correlation with the Lrp-1,indicating that there was a relationship between the deposition of Aβ1-40 and the down-regulation of Lrp-1.
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