AIM:To explore the effects of atorvastatin (Atorv) on atherosclerosis in streptozotocin (STZ)-in-duced diabetic apolipoprotein E knockout ( ApoE-/-) mice with fat-rich diet and the possible mechanism .METHODS:C57 mice served as control.ApoE-/-mice (n=34) fed with high-fat diet were randomly divided into ApoE-/-group, STZ-ApoE-/-group and STZ-ApoE-/-+Atorv group.Intraperitoneal injection of streptozotocin was performed to create di-abetic animal model .Blood glucose was determined by glucose oxidase method .Blood lipid levels were detected by enzymic method or selective homogeneous method .The plaque area in the thoracic aorta was measured by HE staining .The protein level of nicotinamide-adenine dinucleotide phosphate ( NADPH) oxidase subunit gp91phox in the thoracic aorta was deter-mined by Western blotting .The levels of reactive oxygen species ( ROS) in blood and thoracic aorta homogenates were de-tected by Fenton reaction and Griess reagent .Human umbilical vein endothelial cells ( HUVECs ) were isolated from healthy umbilical cords by collagenase I and cultured .ROS production was detected by flow cytometry .NADPH oxidase ac-tivity was measured using lucigenin assay .Effects of retinoid X receptor α( RXRα) on inhibition of oxidative stress by ator-vastatin were evaluated by RNA interference and plasmid transfection .RESULTS: (1) Compared with C57 group, the plaque areas of the thoracic aorta in ApoE-/-group were increased .No difference of the fasting glucose between the 2 groups was observed.The levels of triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), thoracic aorta gp91phox protein and ROS in blood and thoracic aorta homogenates were higher in ApoE-/-group than those in C57 group.(2) Compared with ApoE-/-group, the plaque areas of the thoracic aorta in STZ-ApoE-/-group were further enlarged [(314.13 ±35.72) μm2 vs (215.88 ±34.19) μm2, P<0.05].The levels of blood glucose, TG, TC and LDL-C, thoracic aorta gp91phox protein and ROS in blood and thoracic aorta homogenates were higher in STZ-ApoE-/-group than those in ApoE-/-group (P<0.05).(3) Compared with STZ-ApoE-/-group, the plaque areas of the thoracic aorta in STZ-ApoE-/-+Atorv group were reduced [(217.47 ±24.56) μm2 vs (314.13 ±35.72) μm2, P<0.05].The levels of blood glucose , LDL-C, TC, HDL-C and TG showed no significant difference between the 2 groups.Thoracic aorta gp91phox protein level and ROS production in blood and thoracic aorta homogenates were lower in STZ -ApoE-/-+Atorv group than those in STZ-ApoE-/-group (P<0.05).(4) High glucose-induced increases in NADPH oxidase activity and gp91phox expression were significantly inhibited by atorvastatin (10-6 mol/L) in HUVECs.The inhibitory effects of atorvasta-tin on high glucose-induced ROS production and NADPH oxidase activation were largely impaired when the cells were trans -fected with RXRαsiRNA.However , the effect of atorvastatin was significantly strengthened when RXRαwas over-expressed in the HUVECs transfected with RXRαplasmid.CONCLUSION: Atorvastatin inhibits atherogenesis by depressing high glucose-induced oxidative stress in diabetic ApoE-/-mice with fat-rich diet.The anti-oxidative stress effect of atorvastatin is mediated by RXRα.

OBJECTIVETo explore the effect of retinoid X receptor (RXR) agonist bexarotene on atherosclerosis and the potential mechanism in streptozotocin (STZ) induced diabetic apolipoprotein E knockout (apoE(-/-)) mice.

METHODSEight C57BL/6 mice served as control, 46 apoE(-/-) mice were randomized into 4 groups: apoE(-/-) group (n = 10), STZ+apoE(-/-) group (n = 12), STZ+apoE(-/-)+Bex 10 (10 mg×kg⁻¹×d⁻¹)group (n = 12), STZ+ apoE(-/-)+Bex 30 (30 mg×kg⁻¹×d⁻¹) group (n = 12). Diabetic apoE(-/-) animal model was established by intraperitoneal injection of STZ. Blood glucose was determined by glucose oxidase method. Patch area in thoracic aorta was measured by HE staining. Western blotting was used to determine the RXR and gp91(phox) protein level in thoracic aorta. Reactive oxygen species (ROS) level in blood and thoracic aorta homogenates was detected by Fenton and Griess method.

RESULTS(1) Patch areas of thoracic aorta were larger in apoE(-/-) group than in C57BL/6 group [(38.40 ± 8.95)µm² vs. (0.10 ± 0.01) µm², P < 0.01], further increased in STZ+apoE(-/-) group [(94.06 ± 8.04)µm², P < 0.05 vs. apoE(-/-) group] and significantly reduced in STZ+apoE(-/-)+Bex 10 group [(78.72 ± 4.62)µm², P < 0.05 vs. STZ+apoE(-/-) group] and further educed in STZ+apoE(-/-)+Bex 30 group [(46.13 ± 7.56)µm², P < 0.05 vs. STZ+apoE(-/-)+Bex 10 group]. (2) Blood glucose level, TG, TC, LDL-C, thoracic aorta gp91(phox) protein level and ROS level in blood and thoracic aorta homogenates were significantly higher in STZ+apoE(-/-) group than in apoE(-/-) group (all P < 0.05). Blood glucose level and TG, TC, LDL-C levels were similar between STZ+apoE(-/-)+Bex10 and STZ+apoE(-/-) group. Thoracic aorta gp91(phox) protein level and ROS level in blood and thoracic aorta homogenates were lower in STZ+apoE(-/-)+Bex 10 group than in STZ+apoE(-/-) group (P < 0.05). Blood glucose level, TG, TC, LDL-C levels, gp91(phox) expression in thoracic aorta, ROS level in blood and thoracic in STZ+apoE(-/-)+Bex 30 group were lower than in STZ+apoE(-/-) group (all P < 0.05).

CONCLUSIONBexarotene treatment could attenuate arteriosclerosis progression in STZ induced diabetic apoE(-/-) mice, the underlying mechanism might be related to suppressing oxidative stress and decreasing blood glucose level and improving lipids metabolism.

Animals ; Apolipoproteins E ; genetics ; Atherosclerosis ; etiology ; metabolism ; prevention & control ; Blood Glucose ; metabolism ; Diabetes Mellitus, Experimental ; complications ; metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Oxidative Stress ; drug effects ; Reactive Oxygen Species ; metabolism ; Retinoid X Receptors ; agonists ; metabolism ; Tetrahydronaphthalenes ; pharmacology