Innervation of the arterial wall and its modification in atherosclerosis.

The autonomic nervous system (ANS) plays an essential role in the regulation of vascular tone. Sympathetic neurotransmitters epinephrine and norepinephrine are released from the terminals of perivascular nerves and suppress endothelial production of nitric oxide (NO), an important vasodilator. Sympathetic nerves also release neuropeptide Y, a co-transmitter that stimulates vasoconstriction and proliferation of vascular smooth muscle cells. Parasympathetic nerves release acetylcholine, which leads to vascular contraction when NO production is inhibited. The ANS produces a variety of other vasoactive substances including ATP, calcitonin gene-related peptide, dopamine, and serotonin. On the other hand, the vascular system can reciprocally influence ANS activity through the release of NO, reactive oxygen species (ROS), angiotensin II, and other mechanisms. In pathological conditions such as atherosclerosis, hyperactivation of sympathetic neural activity has pro-atherogenic effects on the vascular function by increasing vasoconstriction, accumulation of modified lipoproteins in the vascular wall, induction of endothelial dysfunction, and stimulation of oxidative stress and vascular remodeling. Indeed, suppression of the sympathetic ANS should be beneficial for the treatment of cardiovascular diseases.