title: Responses of developing pedunculopontine neurons to glutamate receptor agonists.
abstract: The pedunculopontine nucleus (PPN) is involved in the generation and maintenance of waking and rapid eye movement (REM) sleep, forming part of the reticular activating system. The PPN receives glutamatergic afferents from other mesopontine nuclei, and glutamatergic input is believed to be involved in the generation of arousal states. We tested the hypothesis that, from postnatal days 9 to 17 in the rat, there are developmental changes in the glutamate receptor subtypes that contribute to the responses of PPN neurons. Whole cell patch-clamp recordings were conducted using brainstem slices from 9- to 17-day-old rats. All cells (types I, II, and III; randomly selected or thalamic-projecting) responded to bath application of the glutamate receptor agonists N-methyl-d-aspartic acid (NMDA) and kainic acid (KA). A developmental decrease in the contribution of the NMDA receptor and developmental increase in the contribution of the KA receptor was observed following electrical stimulation-induced glutamate input. These changes were also observed following bath application in different cell types (randomly selected vs. thalamic-projecting). KA bath application produced an increase in the paired-pulse ratio (PPR) and a decrease in the frequency of miniature excitatory postsynaptic currents (mEPSCs), suggesting that presynaptic KA autoreceptors may decrease the probability of synaptic glutamate input. In contrast, NMDA application produced no changes in the PPR or mEPSCs. Changes in glutamatergic excitability of PPN cell types could underlie the developmental decrease in REM sleep.
authors.affiliation: Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, 4301 West Markham St., Little Rock, AR 72205, USA.
authors.forename: Christen
authors.initials: C
authors.lastname: Simon
authors.forename: Abdallah
authors.initials: A
authors.lastname: Hayar
authors.forename: Edgar
authors.initials: E
authors.lastname: Garcia-Rill
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D004558:Electric Stimulation; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005260:Female; D007608:Kainic Acid / Q000494:pharmacology*; D023421:Models, Animal; D016202:N-Methylaspartate / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000502:physiology*; D018408:Patch-Clamp Techniques; D045042:Pedunculopontine Tegmental Nucleus / Q000166:cytology / Q000254:growth & development* / Q000502:physiology*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D017470:Receptors, Glutamate / Q000187:drug effects / Q000502:physiology; D018092:Kainic Acid Receptors / Q000187:drug effects / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology; D012895:Sleep, REM / Q000502:physiology
chemical_list: D018690:Excitatory Amino Acid Agonists; D007608:Kainic Acid; D016202:N-Methylaspartate; D017470:Receptors, Glutamate; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate