Ghrelin inhibits atherosclerotic plaque angiogenesis and promotes plaque stability in a rabbit atherosclerotic model
Intraplaque angiogenesis associates with the instability of atherosclerotic plaques. In the present study, we investigated the effects of ghrelin on intraplaque angiogenesis and plaque instability in a rabbit model of atherosclerosis. The rabbits were randomly divided into three groups, namely, the control group, atherosclerotic model group, and ghrelin-treated group, with treatments lasting for 4 weeks. We found that the thickness ratio of the intima to media in rabbits of the ghrelin-treated group was significantly lower than that in rabbits of the atherosclerotic model group. The number of neovessels and the levels of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor 2 (VEGFR2) decreased dramatically in rabbits of the ghrelin-treated group compared to those of the atherosclerotic model group. Ghrelin significantly decreased the plaque content of macrophages, matrix metalloproteinase (MMP)-2, and MMP-9, in a rabbit model of atherosclerosis. In addition, the level of the pro-inflammatory factor monocyte chemoattractant protein (MCP)-1 was significantly lower in rabbits of the ghrelin-treated group than in rabbits of the atherosclerotic model group. In summary, ghrelin can inhibit intraplaque angiogenesis and promote plaque stability by down-regulating VEGF and VEGFR2 expression, inhibiting the plaque content of macrophages, and reducing MCP-1 expression at an advanced stage of atherosclerosis in rabbits.