title: Glutamate receptor subtypes mediate excitatory synaptic responses of rat lateral parabrachial neurons.
abstract: We examined the role of specific excitatory amino acid (EAA) receptors in synaptic transmission within the lateral parabrachial nucleus (LPBN) using whole cell patch-recording techniques in a slice preparation. Two types of excitatory postsynaptic responses were observed. The first involved the contribution of non-N-methyl-D-aspartate (NMDA) receptors, which mediated a fast component, and NMDA receptors, which governed the late component of the excitatory postsynaptic current (EPSC). The second EPSC response was mediated solely by non-NMDA receptors. Both EPSC responses reversed near 0 mV. The fast component of the EPSC was attenuated by the non-NMDA antagonists [6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), 6,7-dinitroquinoxaline-2,3-dione (DNQX), and 6-nitro-7-sulfamobenzoquinoxaline-2-3,-dione (NBQX)]. The late component was reduced by D,L-2-amino-5-phosphonovaleric acid (APV) and augmented in Mg(2+)-free external medium. EPSCs mediated solely by non-NMDA receptors were completely blocked by CNQX and NBQX but not affected by APV or Mg(2+)-free external medium. EPSCs were also markedly attenuated by the metabotropic-receptor agonist, trans-(1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (trans-ACPD). We concluded that intra-LPBN stimulation causes the synaptic release of glutamate, which depolarizes LBPN neurons via non-NMDA and NMDA receptors. We also provide evidence that glutamate can negatively influence its own release via action on presynaptic metabotropic receptors.
authors.affiliation: Department of Medicine, Neurology, University of Alberta, Edmonton, Canada.
authors.forename: J A
authors.initials: JA
authors.lastname: Zidichouski
authors.forename: J C
authors.initials: JC
authors.lastname: Easaw
authors.forename: J H
authors.initials: JH
authors.lastname: Jhamandas
mesh_terms: D000818:Animals; D003515:Cycloleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D004594:Electrophysiology; D005071:Evoked Potentials; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000502:physiology*; D011149:Pons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000502:physiology; D017470:Receptors, Glutamate / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D018691:Excitatory Amino Acid Antagonists; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane