Effect and mechanism of vitamin K2 on vascular calcification in type 2 diabetic rats
Objective:To investigate the effect and mechanism of vitamin K2 on vascular calcification in a type 2 diabetes rat model.Methods:Thirty male Wistar rats,6 weeks old,were acclimatized for 7 days.Ten rats were randomly selected as the negative control group,fed a normal diet,and injected with an equal amount of citrate buffer.The remaining rats were fed a high-fat and high-sugar diet for 4 weeks,and then type 2 diabetes was induced by intraperitoneal injection of streptozotocin.After successful induction of the diabetes model,the diabetic rats were numbered by body weight and divided into the diabetes group and the diabetes+vitamin K2 group according to the principle of stratified random grouping.These two groups were fed a high-fat diet and a high-fat diet containing vitamin K2,respectively,while the control group continued to be fed a normal diet.After 13 weeks of feeding,the rats were sacrificed for sample collection,and blood glucose and vascular calcium concentration were measured.Von Kossa staining was used for histopathological detection.The relative expression levels of hypoxia-inducible factor-1α(HIF-1α),pyruvate dehydrogenase kinase 4(PDK4),matrix Gla protein(MGP),and bone morphogenetic protein-2(BMP-2)mRNA and proteins were measured by qRT-PCR and Western blot,respectively.Results:Compared with the control group,blood glucose levels in the diabetes group and diabetes+vitamin K2 group were significantly elevated(P＜0.01),but there was no significant difference between the two groups.There was no significant difference in vascular calcium concentration among the three groups(P＞0.05).Von Kossa staining showed that the control group exhibited normal vascular structures,while the diabetes group showed a large number of brown-black calcification plaques between elastic fibers in the vascular media.The diabetes+vitamin K2 group had either no calcification plaques or only a few brown-black calcification plaques.Compared with the control group,the expression levels of PDK4,MGP,and BMP-2 mRNA and proteins were higher in the diabetes group(P＜0.05),but there was no significant difference in the expression level of HIF-1α.Only the expression level of PKD4 protein had significance between the control group and diabetes+vitamin K2 group(P＜0.05).There was no significant difference in the above indexes between the diabetic group and diabetic+vitamin K2 group(P＞0.05).Conclusions:Type 2 diabetes mellitus may cause vascular calcification by increasing the expression of PDK4,which in turn leads to increased expression of BMP-2 and MGP.Vitamin K2 can inhibit vascular calcification in diabetes.
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