title: Autoradiographic and electrophysiological evidence for excitatory amino acid transmission in the periaqueductal gray projection to nucleus raphe magnus in the rat.
abstract: Selective retrograde labelling was used as an autoradiographic method to identify possible excitatory amino acid afferents to nucleus raphe magnus (NRM). Injections of 25-50 nl 10(-2) or 10(-3) M D-[3H]aspartate into the NRM resulted in prominent labelling of cells in ventrolateral mesencephalic periaqueductal gray (PAG). Electrophysiologically, stimulation in ventrolateral PAG excited cells in NRM with a latency of 2-12 ms. With many cells, microelectrophoretic application of the excitatory amino acid antagonists, kynurenate and gamma-D-glutamyl-glycine, resulted in a reversible reduction of the PAG-evoked response. Selective antagonists of N-methyl-D-aspartate (NMDA) were less effective. It is suggested that neurones in the ventrolateral PAG projecting to NRM utilize an excitatory amino acid or structurally related compound as a transmitter, and that this transmitter acts on receptors of the non-NMDA type.
authors.affiliation: Laboratoire de Physiologie Nerveuse, C.N.R.S., Gif-sur-Yvette, France.
authors.forename: L
authors.initials: L
authors.lastname: Wiklund
authors.forename: G
authors.initials: G
authors.lastname: Behzadi
authors.forename: P
authors.initials: P
authors.lastname: Kalén
authors.forename: P M
authors.initials: PM
authors.lastname: Headley
authors.forename: L S
authors.initials: LS
authors.lastname: Nicolopoulos
authors.forename: C G
authors.initials: CG
authors.lastname: Parsons
authors.forename: D C
authors.initials: DC
authors.lastname: West
mesh_terms: D000596:Amino Acids / Q000502:physiology*; D000818:Animals; D001345:Autoradiography; D004594:Electrophysiology; D009412:Nerve Fibers / Q000502:physiology; D018377:Neurotransmitter Agents / Q000502:physiology; D010487:Periaqueductal Gray / Q000502:physiology*; D011903:Raphe Nuclei / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D009435:Synaptic Transmission
chemical_list: D000596:Amino Acids; D018377:Neurotransmitter Agents