Pathway specific expression of neuropeptides and autonomic control of the vasculature

In this article, we review the immunohistochemical evidence for the pathway -specific expression of co-existing neuropeptides in autonomic vasomotor ne urons, and examine the functional significance of these expression patterns for the autonomic regulation of the vasculature. Most final motor neurons in autonomic vasomotor pathways contain neuropeptides in addition to non-pe ptide co-transmitters such as catecholamines, acetylcholine and nitric oxid e. Neuropeptides also occur in preganglionic vasomotor neurons. The precise combinations of neuropeptides expressed by neurons in vasomotor pathways v ary with species, vascular bed, and the level within the vascular bed. This applies to both vasoconstrictor and vasodilator pathways. There is a simil ar degree of Variation in the expression of neuropeptide receptors in the v asculature. Consequently, the contributions of different peptides to autono mic vasomotor control are closely matched to the functional requirements of specific vascular beds. This arrangement allows for a high degree of preci sion in vascular control in normal conditions and has the potential for con siderable plasticity under pathophysiological conditions. (C) 2000 Elsevier Science B.V. All rights reserved.