title: Electrophysiological and morphological properties of neurons in the substantia gelatinosa of the mouse trigeminal subnucleus caudalis.
abstract: The excitability of the second order neurons within the trigeminal subnucleus caudalis underlies pain perception and processing in migraine and trigeminal neuralgia. These neurons were studied with whole-cell patch-clamp technique in slices from mouse brain stem. Electrical and morphological characteristics of 56 neurons were determined. Four categories were distinguished from electrophysiological properties: tonic (39%), phasic (34%), delayed (16%) and single spiking (11%). These categories did not show distinct morphological properties. Neurons had tetrodotoxin-sensitive sodium currents that activated and inactivated within milliseconds. They also showed a high voltage-activated, slowly inactivating calcium current: up to half of this current was blocked by omega-conotoxin GVIA (1microM) and omega-agatoxin IVA (100-300 nM), but it was not affected by nifedipine (10microM). Exogenously applied capsaicin (1microM) and alphabetamethylene-5'-adenosine triphosphate (100microM) elicited large amplitude, spontaneous excitatory postsynaptic currents that were blocked by capsazepine (10microM) and 5-[(3-phenoxybenzyl)-(1,2,3,4-tetrahydro-naphthalen-1-yl)-carbamoyl]-benzene-1,2,4-tricarboxylic acid (A-317491: 10microM), respectively. Thus, neurons of the mouse trigeminal subnucleus caudalis substantia gelatinosa exhibit N-type and P/Q-type voltage-gated calcium channels, and receive presynaptic afferents that express TRPV1 and P2X(2/3) receptors. These results suggest possible therapeutic interventions, and serve as a basis for the characterization of cellular changes that may underlie trigeminal neuropathic pain.
authors.affiliation: Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK. ajd09@snu.ac.kr
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Davies
authors.forename: R Alan
authors.initials: RA
authors.lastname: North
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000502:physiology* / Q000648:ultrastructure*; D009619:Nociceptors / Q000502:physiology; D018408:Patch-Clamp Techniques; D017661:Receptors, Presynaptic / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000502:physiology; D013376:Substantia Gelatinosa / Q000502:physiology* / Q000648:ultrastructure*; D050051:Transient Receptor Potential Channels / Q000819:agonists / Q000502:physiology; D014279:Trigeminal Nucleus, Spinal / Q000502:physiology* / Q000648:ultrastructure*
chemical_list: D017661:Receptors, Presynaptic; D018048:Receptors, Purinergic P2; D050051:Transient Receptor Potential Channels; D018698:Glutamic Acid; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D002211:Capsaicin