Inhibitory Effect Of [Met～5]-enkephalin On Intimal Hyperplasia Of Autografted Vein Of Rat

ObjectiveThe endogenous opioid [ Met5 ] -enkephalin ( opioid growth factor ) is a toni-cally active, receptor - mediated inhibitory growth peptide in developing and a-dult vasculature. This study was designed to determine the role of [ Met5 ] - en-kephalin in neointimal hyperplasia.Methods1. Animal modelAutografted vein models for 90 Wistar rats was developed. The rats in this study were divided into 3 groups ( n = 30 ). After the operation each group was injected intraperitoneally daily for 28 days into the rats. The 1~st group received injection of [ Met5 ] - enkephalin( M - Enk: 10mg/kg) ; the 2~nd group: the opioid antagonist naltrexone (NTX:30mg /kg) , the 3~nd group with sodium chloride(0. 2ml) as the control group. The vein grafts were harvested at 1day ,3 days , 1 week , 2 weeks and 4 weeks after graft.2. Detect methods(1). histomorphology detect : These specimens were stained by the methods of HE and Verhoeff. Morphology of tissue was observed in optics microscope . The intimal thickness was measured by computer graph analysis system.( 2 ). Immunohistochemistry: The paraffin embedded specimens were stained with antibody of c - fos and c - myc. The change of protein of c - fos and c - myc gene was detected by using immunohistochemistry. These slides were detected in 200 x or 400 x optics microscope and calculated the positivecells of c - fos and c — myc.(3). Western blot: The observation of detect was as same as above.3. Statistical treatmentThe data was treated with SSPS11. 0 Statistical software. The result was presented with x ± s. ANOVA and q - test were exployed . Test criterion: a =0. 05.Results1. Morphometric analysisThe patency rate of the Autografted vein was 100% immedietly. In the month after grafts, the intiraal thickness in M - Enk - treated rats was decreased by 18% to 32% from control values , whereas intimal thickness was increased in the NTX group by 13% to 28% .2. c - fosNc - myc immuohistochemistryC - fos , c - myc gene protein located in cell nucleus. Positive SMCs were stained into Baffy or brown. In control group, In 1 day of postgraft , The positive cells almost located near the lumen of vessel. In three days, the c - fos expression began to decrease. In one week, the ratio of the positive cells decreased obviously compared with those cells in one day of postgraft, there was a significant difference between them. ( P < 0.05 ). C - fos expression of the M -Enk group was inhibited more obviously than the control group in ealier period of postgraft (1-3 day). The inhibition ratio was 35 -38%. But there was more a-bout 47-58 % increase in NTX group in ealier period of graft.. In one week, there was no significant difference between the NTX group and the control group. (table2 )In control group, after 1 day graft, there was a little positive expression of c - myc protein in the autografting vein. In three days, the c - myc expression began to increase gradually. In one week, the positive expression of c - myc protein reached the peak and there was significant difference compared with 1 day of postgraft ( P < 0. 05). In2 weeks of postgraft, the ratio of the positive cells decreased gradually with those cells in one day of postgraft, there was a...