The noradrenergic innervation of spinal cord blood vessels in old rats.

The density and pattern of the sympathetic noradrenergic innervation of the extramedullary and intramedullary blood vessels of the spinal cord was studied in 3-, 12- and 25-month-old male Wistar rats using combined catecholamine histofluorescence and quantitative image analysis techniques. The study of innervation of intramedullary vessels was accomplished in spinal cord-transected rats to avoid the interference of descending spinal monoamine fibres in the observations. No age-related changes in the density of noradrenergic innervation of the anterior spinal artery or of sympathetic fibres associated with spinal cord blood vessels occurred. These results suggest that unlike perivascular noradrenergic nerves supplying the cerebrovascular tree, the sympathetic innervation of spinal cord blood vessels does not undergo age-dependent changes. It cannot be excluded that the lesser vulnerability of the spinal compared to the cerebral vascular tree to certain kinds of age-related diseases, may depend on the unchanged sympathetic trophic regulation of spinal vessels with age.