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Titolo:
CHOLINERGIC CONTRIBUTION TO EXCITATION IN A SPINAL LOCOMOTOR CENTRAL PATTERN GENERATOR IN XENOPUS EMBRYOS
Autore:
PERRINS R; ROBERTS A;
Indirizzi:
UNIV BRISTOL,SCH BIOL SCI,WOODLAND RD BRISTOL BS8 1UG AVON ENGLAND
Titolo Testata:
Journal of neurophysiology
fascicolo: 3, volume: 73, anno: 1995,
pagine: 1013 - 1019
SICI:
0022-3077(1995)73:3<1013:CCTEIA>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
LEECH SWIMMING MOVEMENTS; ROHON-BEARD NEURONS; LAEVIS EMBRYOS; RENSHAW CELLS; INHIBITORY NEURONS; AXON COLLATERALS; CORD; INTERNEURONS; MECHANISMS; MOTONEURONES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Physical, Chemical & Earth Sciences
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
40
Recensione:
Indirizzi per estratti:
Citazione:
R. Perrins e A. Roberts, "CHOLINERGIC CONTRIBUTION TO EXCITATION IN A SPINAL LOCOMOTOR CENTRAL PATTERN GENERATOR IN XENOPUS EMBRYOS", Journal of neurophysiology, 73(3), 1995, pp. 1013-1019

Abstract

1. We have investigated whether in Xenopus embryos, spinal interneurons of the central pattern generator (CPG) receive cholinergic or electrical excitatory input during swimming. The functions of cholinergic excitation during swimming were also investigated. 2. Intracellular recordings were made from rhythmically active presumed premotor interneurons in the dorsal third of the spinal cord. After locally blocking inhibitory potentials with 2 mu M strychnine and 40 mu M bicuculline, thereliability of spike firing and the amplitude of fast, on-cycle, excitatory postsynaptic potentials (EPSPs) underlying the single on-cycle spikes were measured during fictive swimming. 3. The nicotinic antagonists d-tubocurarine and dihydro-beta-erythroidine (DH beta E, both 10 mu M) reversibly reduced the reliability of the spike firing during swimming and reduced the amplitude of the on-cycle EPSP by 16%. DH beta E also reduced the EPSP amplitude in spinalized embryos by 22%. These results indicate that interneurons receive rhythmic cholinergic excitation from a source within the spinal cord. 4. Combined applications ofnicotinic and excitatory amino acid (EAA) antagonists or cadmium (Cd2- 100-200 mu M) resulted in complete block of the fast EPSP, suggesting that interneurons do not receive electrical excitation. 5. The nicotinic antagonists mecamylamine and d-tubocurarine (both 5 mu M) reducedthe duration of episodes of fictive swimming recorded from the ventral roots, in spinal embryos. When applied in the middle of a long episode, d-tubocurarine decreased the swimming frequency, ruling out an effect on the initiation pathway. The cholinesterase inhibitor eserine (10 mu M) increased the duration of swimming episodes. 6. We conclude that acetylcholine(ACh) is released onto interneurons of the CPG, resulting in phasic on-cycle excitation mediated by nicotinic receptors. This excitation increases the reliability of interneuron firing thereby helping to maintain swimming. Our experiments on spinal embryos indicate that the source of ACh is one of four known classes of rhythmically active spinal neuron. We propose that motoneurons are the most likely source of this cholinergic excitation and suggest that they may be an integral part of the Xenopus CPG for swimming.

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Documento generato il 28/11/20 alle ore 21:40:08