Effects of insulin on proliferation and apoptosis of rat vascular smooth muscle cells

AIM To study the effects of insulin on the proliferation and apoptosis of rat vascular smooth muscle cells. METHODS The cells of 5~10 passages of cultured VSMC were used in the experiment and were divided into control group and insulin group. Insulin group was sabdivided into four groups by 1×10 -9 , 1×10 -8 , 1×10 -7 and 1×10 -6 mol·L -1 concentration. MTT assay, terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and immunocytochemistry were used respectively to detect the VSMC proliferation, apoptosis and expression of proliferating cell nuclear antigene (PCNA) at 24 h, 48 h and 72 h. RESULTS The value of MTT absorbance of 1×10 -9 mol·L -1 group (0.42±0.04) was higher than that of the control group (0.30±0.02), but lower than that of 1×10 -6 mol·L -1 group (0.52±0.05), P 0.05. The increased percentage of MTT absorbance of 1×10 -9 mol·L -1 group at 48 h (40%) was higher than that of 1×10 -9 mol·L -1 group at 24 h (27%), P 0.05. The percentage of PCNA expression of VSMCs with 1×10 -9 ~1×10 -6 mol·L -1 insulin (50~80%) at 48 h was higher than that of the control group. The percentage of apoptotic cells of 1×10 -6 mol·L -1 insulin group (30%) decreased compared with the control group (30%). CONCLUSION Insulin can stimulate the proliferation of VSMC in a time and dose dependent manner. Insulin can inhibit the apoptosis of VSMCs.