녹차 카테킨이 당뇨병 흰쥐의 대동맥 평활근 세포 증식에 미치는 영향

Abstract

ABSTRACT

Effects of green tea catechin on proliferation of aortic smooth muscle cell in diabetic rat

Lee JungIn Advisor : Prof. Lee Byoung-rai, Ph.D. Department of Medicine, Graduate School of Chosun University

The incidence of diabetic complication is closely related to the vascular dysfunction. The aim of this study is to investigate the effects of tea catechin on proliferation of vascular smooth muscle cells(VSMC) in diabetic rats. Diabetes mellitus of SD rats was induced by high fat diet/low-dose streptozotocin(STZ). The experimental group was divided into 3 different groups, non-diabetes control(NC) group, diabetes mellitus(DM) group, diabetes mellitus+green tea catechin (DM+GTC) group. GTC, polyphenon 60, administered with dissolved in 0.2%(W/V) dringking water. After 16 weeks of GTC administration, the altered-angiogenesis in diabetic rats examined by aortic ring assay and the expression of contractile and synthetic proteins in VSMC of thoractic aorta were also examined by qPCR and wastern blot. Fasting blood glucose level increased in the DM group compared to the NC group. In the DM+GTC group, it decreased by 31% compared to the DC group. The serum creatinine and blood urea nitrogen(BUN) levels were increased in the DM group and it decreased in the DM+P60 group compared to the DM group. Aortic ring assay using thoractic aorta showed that the length of cell sprout significantly increased in DM group compared with NC group and that of the DM+GTC group was decreased compared to the DM group. qRT-PCR for VSMC synthetic phenotype protein, cellular retinol binding protein 1(CRBP-1) and connexin 43, from thoratic aorta showed that CRBP-1 expression was increased by 70% in DM group, and decreased by 70% in DM+GTC compared to DM group. Connexin43 was not different between DM and NC group, and decreased in DM+GTC compared to DM group. qRT-PCR of VSMC contractile phenotype protein, Smooth muscle-myosin heavy chain(SM-MHC), myocardin, α-smooth muscle actin(α-SMA), were as follows. SM-MHC was increased 160% and 170% in DM group and DM+GTC group respectively, myocardin was increased by 75% in DM+GTC group compared with DM group. α-SMA was increased by 70% in DM group and DM+GTC group by 80% compared to NC group. The results of wetern blot of VSMC phenotype protein, ki-67, myocardin, α-SMA, were as follows. Ki-67 was increased by 277% in DM group and DM+GTC group decreased by 77% compared to DM group, myocardin was increased 240% and 540% in DM and DM+GTC group compared with NC group and α-SMA was increased by 120% in DM group compared to NC group. Immunohistochemical assay of thoratic aorta showed that MMP2 and Ki were increased in dibetes mellitus and decreased GTC treatments. This study shows that synthetic phenotype of VSMC in aorta was incresed in diabetes mellitus and GTC administration showed a decrease in the expression of synthetic phenotype specific protein. Dietary supplementation with GTC could potentially contribute to nutritional strategies for suppression of diabetic vascular complications.

Key words: Diabetes mellitus, catechin, Vascular smooth muscle cell