title: Glutamate and GABA mediate suprachiasmatic nucleus inputs to spinal-projecting paraventricular neurons.
abstract: We used patch-clamp recordings in slice preparations from Sprague-Dawley rats to evaluate responses of 20 spinal-projecting neurons in the dorsal paraventricular nucleus (PVN) to electrical stimulation in suprachiasmatic nucleus (SCN). Neurons containing a retrograde label transported from the thoracic (T(1)-T(4)) intermediolateral column displayed three intrinsic properties that collectively allowed distinction from neighboring parvocellular or magnocellular cells: a low-input resistance, a hyperpolarization-activated time-dependent inward rectification, and a low-threshold calcium conductance. Twelve of fifteen cells tested responded to electrical stimulation in SCN. All of 10 cells tested in media containing 2,3,-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide disodium (5 microM) and D(-)-2-amino-5-phosphonopentanoic acid (20 microM) responded with constant latency (11.4 +/- 0.7 ms) inhibitory postsynaptic potentials, able to follow 20- to 50-Hz stimulation and blockable with bicuculline (20 microM). By contrast, all eight cells tested in the presence of bicuculline demonstrated constant latency (9.8 +/- 0.6 ms) excitatory postsynaptic potentials that followed at 20-50 Hz and featured both non-N-methyl-D-aspartate (NMDA) and NMDA receptor-mediated components. We conclude that both GABAergic and glutamatergic neurons in SCN project directly to spinal-projecting neurons in the dorsal PVN.
authors.affiliation: Neurosciences, Ottawa Health Research Institute, Ottawa Hospital Civic Site, and University of Ottawa, Ottawa, Ontario, K1Y 4E9, Canada.
authors.forename: L N
authors.initials: LN
authors.lastname: Cui
authors.forename: E
authors.initials: E
authors.lastname: Coderre
authors.forename: L P
authors.initials: LP
authors.lastname: Renaud
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005260:Female; D005456:Fluorescent Dyes; D018756:GABA Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008863:Microspheres; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D005456:Fluorescent Dyes; D018756:GABA Antagonists; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D015763:2-Amino-5-phosphonovalerate; D002118:Calcium