The Study On Myocardial Remodeling During Experimental Atherosclerosis Development And The Intervention Effects Of PACAP

Object:To study myocardial remodeling during rabbit experimental atherosclerosis development and the intervention effects of pituitary cyclase-activating polypeptide (PACAP) on myocardial remodeling and its possible intervention mechanisms by detecting the changes of the collagen content and composition in myocardium and the changes of proliferation and apoptosis of cardiomyocytes and fibroblasts.Methods:60 male New Zealand rabbits were divided randomly and equally into three groups: control group (C group), atherosclerosis model group (AS group, treated with high-cholesterol diet), and PACAP intervention group (P group, treated with high-cholesterol diet and PACAP by injection). At the 0, 2^nd, 4^th, 8^th and 12^th weekends of the experiment, the concentration of serum lipid were measured. Meanwhile, at the 0, 4^th, 8^th and 12^th weekends, 4⁶ cases of rabbits in each group were sacrificed randomly, cardiac tissues with coronary arteries were harvested to make paraffin sections. some of sections were stained with hematoxylin-eosin (HE) and picrosirus red respectively. The morphological changes of myocardium and the changes of the collagen content and composition were observed qualitatively and analysed quantitatively with the light microscope and the polarization microscopy respectively. The others were stained with immunohistochemical method to detect proliferating cell nuclear antigen; at the same time, the sections from the 12^th myocardium were stained with terminal deoxynucleotidyltransferase mediated dUTP nick end labeling (TUNEL) method to detect cell apoptosis. Then the proliferation index (PI) and apoptosis index (AI) of cardiomyocytes and interstitial cells were calculated.Results:1. The concentration of serum lipid in AS group and P group were increased, but compared with that in AS group, the triglyceride (TG) level in P group was significantly lower after the 4^th weekend and the total cholesterol (TC) level was also significantly lower by the end of the 12^th week (P<0.05).