Different Classes of Glutamate Receptors Mediate Distinct Behaviors in a Single Brainstem Nucleus

• Published in: Proceedings of the National Academy of Sciences - PNAS 1989-11, Vol.86 (22), p.8993-8997
• Main Authors: Dye, John, Heiligenberg, Walter, Keller, Clifford H., Kawasaki, Masashi
• Format: Article
• Language: English
• Subjects: 2-Amino-5-phosphonovalerate - pharmacology; Agonists; Animal vocalization; Animals; Anticonvulsants - pharmacology; Apteronotus leptorhynchus; Artificial pacemakers; Aspartic Acid - pharmacology; Avoidance Learning - drug effects; Biological and medical sciences; Brain Stem - drug effects; Brain Stem - physiology; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Dicarboxylic acids; Eigenmannia; Electric fields; Electric Fish; Electric Organ - physiology; Electrodes; Excitatory amino acid antagonists; Fundamental and applied biological sciences. Psychology; Glutamate receptors; Glutamates - pharmacology; Glutamates - physiology; Glutamic Acid; Glutamine - pharmacology; Kainic Acid - pharmacology; N-Methylaspartate; Neurobiology; Neurons; Oxadiazoles - pharmacology; Pipecolic Acids - pharmacology; Quisqualic Acid; Receptors, Glutamate; Receptors, Neurotransmitter - physiology; Vertebrates: nervous system and sense organs
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.86.22.8993

We have taken advantage of the increasing understanding of glutamate neuropharmacology to probe mechanisms of well-defined vertebrate behaviors. Here we report a set of experiments that suggests distinct roles for two major classes of glutamate receptors in a discrete premotor nucleus of the brainstem. The medullary pacemaker nucleus of weakly electric fish is an endogenous oscillator that controls the electric organ discharge (EOD). Its regular frequency of firing is modulated during several distinct behaviors. The pacemaker nucleus continues firing regularly when isolated in vitro, and modulatory behaviors can be reproduced by stimulating the descending input pathway. Glutamate agonists applied to the pacemaker in vitro produced increases in frequency, while glutamate antagonists selectively blocked stimulus-induced modulations. Experiments with glutamate antagonists in the intact animal resulted in specific effects on two well-characterized behaviors. Our data indicate that these behaviors are separately mediated in the pacemaker by receptors displaying characteristics of the kainate/quisqualate and N-methyl-D-aspartate subtypes of glutamate receptor, respectively.