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Titolo:
DUAL-COMPONENT EXCITATORY AMINO ACID-MEDIATED RESPONSES IN TRIGEMINALMOTONEURONS AND THEIR MODULATION BY SEROTONIN IN-VITRO
Autore:
TRUEBLOOD PR; LEVINE MS; CHANDLER SH;
Indirizzi:
UNIV CALIF LOS ANGELES,DEPT PHYSIOL SCI,2851 SLICHTER HALL LOS ANGELES CA 90095 UNIV CALIF LOS ANGELES,DEPT PHYSIOL SCI LOS ANGELES CA 90095 UNIV CALIF LOS ANGELES,MENTAL RETARDAT RES CTR LOS ANGELES CA 90095
Titolo Testata:
Journal of neurophysiology
fascicolo: 4, volume: 76, anno: 1996,
pagine: 2461 - 2473
SICI:
0022-3077(1996)76:4<2461:DEAARI>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
METHYL-D-ASPARTATE; RHYTHMICAL JAW MOVEMENTS; DEPENDENT PROTEIN-KINASE; GUINEA-PIG; SPINAL-CORD; IONTOPHORETIC ANALYSIS; NEOCORTICAL NEURONS; FACIAL MOTONEURONS; CEREBELLAR SLICES; IN-VITRO;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
59
Recensione:
Indirizzi per estratti:
Citazione:
P.R. Trueblood et al., "DUAL-COMPONENT EXCITATORY AMINO ACID-MEDIATED RESPONSES IN TRIGEMINALMOTONEURONS AND THEIR MODULATION BY SEROTONIN IN-VITRO", Journal of neurophysiology, 76(4), 1996, pp. 2461-2473

Abstract

1. Intracellular recordings were made from guinea pig trigeminal motoneurons in brain stem slices. Monosynaptic excitatory postsynaptic potentials (EPSPs) were evoked in trigeminal motoneurons by focal stimulation of the mesencephalic nucleus of V (Mes V), a region containing cell bodies of primary afferent fibers of jaw muscle spindle and periodontal receptor origin. 2. The presence of N-methyl-D,L-aspartate (NMDA)and non-NMDA excitatory amino acid receptors (EAAs) was determined byiontophoretic application of NMDA and lpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) from multibarreled micropipettes. Application of either agonist in normal Mg2+-containing extracellular solutions produced a membrane depolarization or inward current from resting potential in current- or voltage-clamp modes, respectively. However,the voltage and current responses to NMDA and AMPA differed in their dependence on initial membrane potential. In voltage clamp between -70and -50 mV, the peak current response to NMDA application increased whereas the response to AMPA application decreased as a function of holding potential. 3. Mes-V-induced synaptic potentials were examined forthe presence of NMDA and non-NMDA components in extracellular solutions devoid of Mg2+. In the presence of DL-2-amino-5-phosphonopentanoic acid (30 mu M), the peak amplitude and half-amplitude duration were decreased 52 and 36% (n = 2), respectively, compared with control. In the presence of 6-cyano-7-nitroquinoxaline-2,3-dione( (CNQX, 10-15 mu M), a specific non-NMDA antagonist, the mean decrease in evoked synapticpotential amplitude was 55% (n = 5), but the half-amplitude duration increased by a mean of 63% (n = 5). 4. The non-NMDA component of the evoked EPSP obtained in the presence of DL-2-amino-5-phosphonovaleric acid showed a linear decrease in peak amplitude as a function of holding potential. In contrast, the NMDA EPSP component obtained in the presence of CNQX increased in peak amplitude as a function of holding potential between -70 and -40 mV. The increase in EPSP peak amplitude was abolished by removal of Mg2+ from the extracellular media. 5. Bath application of serotonin (5-HT) (50-100 mu M) increased the peak NMDA andnon-NMDA EPSP components by 31% (n = 10) and 23% (n = 8), respectively, while producing a mean increase in half-amplitude duration of 67 and 88%, respectively. Concomitantly, 5-HT increased input resistance bysimilar to 40% and produced a membrane depolarization. 6. In the presence of tetrodotoxin, 5-HT enhanced both iontophoretic NMDA and AMPA voltage responses. In cells voltage clamped between -60 and -70 mV in Mg2+-free solutions, iontophoretic NMDA and AMPA peak currents were enhanced 27 and 32%, respectively, by 5-HT. 7. The enhancement of the iontophoretic NMDA and non-NMDA responses was mimicked by /-)-1-(2,5-dimethyoxy-4-iodophenyl)-2-aminopropane HCL and blocked by 1-piperdinyl]-2,4(1H,3H)-quinazolinedione-tartrate and )-1,6-dimethylergolin-8-yl]-N,N-dimethyl-sulfamide hydrochloride, suggesting 5-HT2 receptor involvement. 8. The results demonstrate that trigeminal motoneurons possess both NMDA and non-NMDA receptors that are activated during Mes-V-inducedsynaptic transmission. The data suggest that EAA-mediated responses in trigeminal motoneurons are substrates for modulation by 5-HT via changes in membrane resistance and modulation of the EAA-induced synapticcurrent.

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Documento generato il 05/12/20 alle ore 01:25:13