title: GABAergic and serotonergic modulation of calcium currents in rat trigeminal motoneurons.
abstract: We investigated the effects of a GABA(B) agonist baclofen, and serotonin, on the high voltage-activated Ca channel (HVACC) currents in trigeminal motoneurons. Immunohistochemical and reverse transcription-polymerization chain reaction (RT-PCR) studies demonstrated the expression of alpha(1C), alpha(1B), alpha(1A), and alpha(1E) subunits in the trigeminal motoneurons, which form L-, N-, P/Q-, and R-type Ca channels, respectively. By use of specific Ca blockers, it was found that N-type (38%), P/Q-type (27%), L-type (16 %), and R-type Ca currents (19%) contribute to HVACC I(Ba). Baclofen inhibited HVACC I(Ba) in the majority of trigeminal motoneurons tested (n=15 out of 16), whereas serotonin only did in a small population (n=5 out of 18). The I(Ba) inhibition by baclofen and serotonin was associated with slowing of activation kinetics, relieved by strong prepulse, and prevented by N-ethylmaleimide (NEM), indicative of mediation of Gi/Go. These data provide evidence that GABAergic and serotonergic inputs to trigeminal motoneurons regulate neuronal activities through the inhibition of HVACC currents.
authors.affiliation: Department of Physiology, College of Dentistry and Dental Research Institute, Seoul National University, South Korea.
authors.forename: Seog Bae
authors.initials: SB
authors.lastname: Oh
authors.forename: Zheng Gen
authors.initials: ZG
authors.lastname: Piao
authors.forename: Sang Sup
authors.initials: SS
authors.lastname: Shin
authors.forename: Dongjun
authors.initials: D
authors.lastname: Ren
authors.forename: Kyungpyo
authors.initials: K
authors.lastname: Park
authors.forename: Joong Soo
authors.initials: JS
authors.lastname: Kim
mesh_terms: D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D004594:Electrophysiology; D005033:Ethylmaleimide / Q000494:pharmacology; D018682:GABA Agents / Q000494:pharmacology*; D007150:Immunohistochemistry; D007700:Kinetics; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012701:Serotonin / Q000494:pharmacology; D018490:Serotonin Agents / Q000494:pharmacology*; D013997:Time Factors; D014276:Trigeminal Nerve / Q000378:metabolism*
chemical_list: D015220:Calcium Channels; D018682:GABA Agents; D018490:Serotonin Agents; D012701:Serotonin; D001418:Baclofen; D005033:Ethylmaleimide; D002118:Calcium