THE INJURY RESPONSE OF PULPAL NPY-IR SYMPATHETIC FIBERS DIFFERS FROM THAT OF SENSORY AFFERENT-FIBERS

Light microscopic immunocytochemistry demonstrated that neuropeptide Y (NPY) containing sympathetic fibers in rat molars did not change morp hology or staining characteristics after pulp exposure injury. This re sult, in combination with recent findings concerning NGF synthesis in injured pulp and NGF-receptor localization on pulpal sensory fibers, s uggests that small diameter sensory fibers in pulp may be under NGF co ntrol, but NPY containing sympathetic efferent fibers are not. Thus, s ympathetic fibers in tooth pulp have a different response to NGF compa red to those in many other tissues.