Magnolol, a potent antioxidant from Magnolia officinalis, attenuates intimal thickening and MCP-1 expression after balloon injury of the aorta in cholesterol-fed rabbits

Background Restenosis is a common complication after balloon angioplasty. A number of cytokines, chemotactic factors and growth factors may be involve d. Several antioxidants have been shown to inhibit intimal thickening after balloon injury in hyperlipidemic animals. Objectives The effects of magnol ol on the expression of monocyte chemotactic protein-1 (MCP-1) and intimal response in balloon injured aorta of cholesterol-fed rabbits were investiga ted. Methods Male New Zealand white rabbits were fed a 2% high cholesterol (HC) diet together with daily intramuscular injection of either 1 mug/kg B. W. of magnolol (HC-M, n = 10) or vehicle (propylene glycol) as a control (H C-C, n = 10) for a total of 6 weeks. Another 10 rabbits fed a regular diet also served as a control (C) group. A balloon denudation of abdominal aorta was performed in each group at the end of the third week. The aortas were harvested at the end of 6 weeks. Results Magnolol treatment significantly i nhibited Cu2+-induced LDL oxidation in cholesterol-fed rabbits and reduced atheroma formation [atheroma area ratio: 0.10 +/- 0.03 (HC-M) versus 0.33 /- 0.07 (HC-C), p < 0.05] in thoracic aortas without lowering serum cholest erol. The intimal response was significantly attenuated in the HC-M rabbits when compared to those of the HC-C group [intimal thickness: 88.95 +/- 14. 91 mum (HC-M) versus 198.02 +/- 20.35 mum (HC-C), p < 0.05; intimal area: 2 78.2 +/- 143.16 x 10(3) mum(2) (HC-M) versus 642.70 +/- 65.01 x 10(3) mum(2 ) (HC-C), p < 0.05]. The MCP-1 mRNA and protein expression were reduced in the HC-M group compared to the HC-C and C groups. Conclusion The inhibitory effects on intimal hyperplasia and MCP-1 expression might be attributed to the antioxidant capacity of magnolol instead of lowering serum cholesterol . Magnolol may offer some protection against postangioplasty restenosis.