Which one more reflects atherosclerotic lesion status in rat carotid? Oxidized low density lipoprotein, activity of plasmatic antioxidant enzymes or atherogenic index of plasma: A comparative study

Abstract

Dyslipidemia, oxidative stress, inflammation and apoptosis are common features in atherosclerosis disease leading to stroke. However there are numerous diagnostic tools indicating atherosclerotic lesions status such as imaging tools and evaluation of circulating indexes such as atherogenic index of plasma (AIP). But these markers don't definitely reflect vessel inflammation and apoptosis signaling pathways in early stages. We therefore considered which circulating risk factors have stronger association with apoptosis related proteins in the carotid tissues. Hence the associations between the expression of inflammation or apoptosis related proteins content and antioxidant enzymes activity, serum levels of oxidized low density lipoproteins (OxLDLs) or AIP were assessed and compared. Twenty male wistar rats aged 8 weeks were randomly divided into two groups (n= 10) and fed the following diets for 8 weeks: normal diet, (ND); a high-cholesterol diet (HD) 2%. Immunoblotting technique was applied to assay of expression of B-cell lymphoma 2 (Bcl2) and cleaved caspase 3(c-caspase 3) proteins as well as phosphorylation of p38 mitogen activated protein kinase (MAPK) in carotid artery homogenate. Plasmatic lipid profile consist of triglyceride (TG), total cholesterol (TC), HDL-C and LDL-C were measured using colorimetric technique in end point manner. The serum levels of Ox-LDL were measured by ELISA. Log (TG/HDL-C) as aatherogenic index of plasma (AIP) was calculated. Correlations were assessed by use of the nonparametric Spearman correlation coefficient. After 8 weeks feeding with high cholesterol diet, the mean of lipidic profile including TC, LDL-C, TG, OxLDL and AIP, MDA were higher in HD vs. ND group (P<0.05 in all) as well as the immunoreactivity of p- p38 and c-caspase 3 were elevated in HD vs. ND(P<0.05 in both). Antagonistically, the expression of bcl2, the activity of SOD and GPx as well as the capacity of total antioxidants were reduced in HD vs. ND(P<0.05 in all). The association (with the expression of p- p38 or c-caspase 3) were significant also positive for variables of OxLDL and MDA (strongest; r= 0.874) but negative for SOD, GPx and TAC(P<0.05 in all). The association (with the expression of bcl2) were significant also negativefor variables of OxLDL and MDA but positive for SOD, GPx and TAC(P<0.05 in all). There is no significant association between AIP and the expression of c-caspase 3, p- p38 or bcl2 (r=0.45; p=0.08, r=0.44; p=0.08, r=-0.38; p=0.14 respectively). Findings suggest that MDA, anti oxidant enzymes activity and ox LDL are powerful predictor and monitoring tools for carotid tissue inflammation and apoptosis, two common feature for atherosclerotic lesions.