Neuropeptide Y–Induced Acceleration of Postangioplasty Occlusion of Rat Carotid Artery

OBJECTIVE: Attempts to restore blood flow through atherosclerotic vessels by angioplasty often result in restenosis. Because the role of nerves in this process is unclear, we investigated whether neuropeptide Y (NPY), a sympathetic cotransmitter with vascular mitogenic activities, contributes to postangioplasty restenosis. METHODS AND RESULTS: Carotid artery balloon angioplasty upregulated vascular expression of NPY and its processing enzyme (DPPIV/cd26) and receptors (Y1, Y2, Y5 mRNA and protein) within 6 to 24 hours and stimulated neointima formation and accumulation of NPY in platelets after 14 days. NPY pellets (1 to 10 microg/pellet for 14 days) inserted next to the injured artery elevated platelet and vascular NPY immunoreactivity to stress-like levels and dose-dependently augmented angioplasty-induced neointima. Strikingly, 10 microg NPY for 14 days led to vessel occlusion with an atherosclerotic-like lesion, with thrombus and neointima containing neovessels, macrophages, matrix, and lipids. Y1 or Y5 receptor antagonist completely prevented the effect of NPY and reduced angioplasty-induced neointima by 50%. CONCLUSIONS: Angioplasty upregulates platelet and vascular NPY systems, which then contribute to neointima formation via Y1 and Y5 receptor activation. Increasing NPY to high stress levels triggers formation of a thrombotic atherosclerotic-like lesion and vessel occlusion. Thus, NPY may be a risk factor for accelerated atherosclerosis, and NPY receptor antagonists may be a possible new treatment for restenosis.