title: Substance P in principal sympathetic neurons: regulation by impulse activity.
abstract: Regulation of the putative peptide neurotransmitter substance P was examined in the superior cervical sympathetic ganglion of the neonatal rat. Surgical decentralization (denervation) of the superior cervical ganglion increased ganglion substance P content. In cultured ganglia, the amount of substance P increased more than 50-fold after 48 hours, and this rise was dependent on protein and RNA synthesis. Veratridine prevented the increase in substance P in vitro, and tetrodotoxin blocked the veratridine effect; this suggests that sodium influx and membrane depolarization prevent substance P elevation. Immunohistochemical analysis of cultured ganglia indicated that substance P was present in the perikarya of principal sympathetic neurons and in ganglionic nerve processes. Transsynaptic impulses, through the mediation of postsynaptic sodium influx, may decrease substance P in sympathetic neurons.
mesh_terms: D005728:Ganglia, Sympathetic / Q000502:physiology*; D008564:Membrane Potentials; D009474:Neurons / Q000502:physiology; D013373:Substance P / Q000378:metabolism*; D009435:Synaptic Transmission
chemical_list: D013373:Substance P