title: Glutamate N-methyl-D-aspartate (NMDA) and non-NMDA receptor antagonists administered into the brain stem depress the renal sympathetic reflex discharges evoked by single shock of somatic afferents in anesthetized rats.
abstract: The involvement of glutamate receptors in the central transmission of somatosympathetic reflexes was studied by examining, in anesthetized rats, the effects of MK-801, an N-methyl-D-aspartate (NMDA) receptor antagonist, and CNQX, a non-NMDA receptor antagonist, on two reflex components, the A- and C-reflexes evoked in the left sympathetic renal nerve by a single shock to the left tibial nerve. The A-reflex elicited by myelinated A fiber stimulation and the C-reflex elicited by unmyelinated C fiber stimulation were depressed, in a dose-dependent manner, following administration of either MK-801 or CNQX into the cisterna magna (i.c.m.). Intrathecal (i.t.) administration of MK-801 did not have any effect on either A- or C-reflexes, while i.t. administration of CNQX had a slight effect on the A-reflex (significantly on the A-reflex only when treated with the highest dose of 100 ng) and the C-reflex. These results indicate that both NMDA and non-NMDA receptors, stimulated by glutamate released possibly as a neurotransmitter, are involved in the central transmission pathways of somatosympathetic reflexes at the level of the brain stem, but not the spinal cord.
authors.affiliation: Department of Autonomic Nervous System, Tokyo Metropolitan Institute of Gerontology, Japan.
authors.forename: O
authors.initials: O
authors.lastname: Nagata
authors.forename: W M
authors.initials: WM
authors.lastname: Li
authors.forename: A
authors.initials: A
authors.lastname: Sato
mesh_terms: D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000758:Anesthesia; D000818:Animals; D001933:Brain Stem / Q000187:drug effects / Q000502:physiology*; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D007278:Injections, Spinal; D007668:Kidney / Q000187:drug effects / Q000294:innervation* / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*; D012018:Reflex / Q000187:drug effects*; D013116:Spinal Cord / Q000502:physiology; D013564:Sympathetic Nervous System / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
chemical_list: D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D016291:Dizocilpine Maleate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione