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Titolo:
MODULATION OF RESPIRATORY RHYTHM BY 5-HT IN THE BRAIN-STEM-SPINAL CORD PREPARATION FROM NEWBORN RAT
Autore:
ONIMARU H; SHAMOTO A; HOMMA I;
Indirizzi:
SHOWA UNIV,SCH MED,DEPT PHYSIOL,SHINAGAWA KU,1-5-8 HATANODAI TOKYO 142 JAPAN
Titolo Testata:
Pflugers Archiv
fascicolo: 4, volume: 435, anno: 1998,
pagine: 485 - 494
SICI:
0031-6768(1998)435:4<485:MORRB5>2.0.ZU;2-3
Fonte:
ISI
Lingua:
ENG
Soggetto:
NEONATAL RAT; PREINSPIRATORY NEURONS; INSPIRATORY NEURONS; PHRENIC MOTONEURONS; INVITRO; SEROTONIN; MEDULLA; 5-HYDROXYTRYPTAMINE; GENERATION; RECEPTORS;
Keywords:
SEROTONIN; RESPIRATORY RHYTHM; MEDULLA; IN VITRO; NEONATAL RAT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
39
Recensione:
Indirizzi per estratti:
Citazione:
H. Onimaru et al., "MODULATION OF RESPIRATORY RHYTHM BY 5-HT IN THE BRAIN-STEM-SPINAL CORD PREPARATION FROM NEWBORN RAT", Pflugers Archiv, 435(4), 1998, pp. 485-494

Abstract

Effects of 5-hydroxytryptamine (5-HT) on inspiration-related nerve activity and membrane potential of respiratory neurons in the ventrolateral medulla were studied in brainstem-spinal cord preparations isolated from newborn rats. Bath application of 5-100 mu M 5-HT induced a biphasic response in inspiratory nerve activity: a transient increase in respiratory frequency followed by a decrease in the rate of discharge. The excitatory effect of 5-HT was particularly prominent in preparations with a respiratory rate of less than 3 min(-1), whereas the inhibitory effect was more pronounced in preparations with a higher respiratory rate. In pre-inspiratory (Pre-I) and inspiratory (Insp) neurons, 20 mu M 5-HT induced a membrane depolarization of up to 10 mV accompanied by a significant decrease in the input resistance. Membrane depolarization by 5-HT was also evident in the presence of tetrodotoxin. In Pre-I neurons, 5-HT caused an increase in the burst rate, which was followed by a decrease in the intraburst firing frequency and burst amplitude, although the burst rate remained high. The burst rate in Insp neurons first increased and subsequently decreased without significant change in the intraburst firing frequency. Simultaneous intra-and extracellular recordings (in the contralateral medulla) of Pre-I/Pre-I neuron or Pre-I/Insp neuron pairs revealed that 5-HT disturbed the correlation between these neuron bursts. Increase in the respiratory rate induced by 20 mu M 5-HT was completely blocked by pretreatment (5-15 min)with 5 mu M ketanserin or 1 mu M methysergide, but not by 10 mu M propranolol. None of these antagonists blocked the inhibitory effects of 5-HT. A 5-HT2 agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI, 10-100 mu M) increased the respiratory rate. Perfusion with a 5-HT1A agonist, 8-hydroxy-dipropylaminotetralin hydrobromide (8-OH-DPAT, 20-100 mu M) induced an increase or a decrease in the respiratory rate. A 5-HT2C agonist, 1-(3-chlorophenyl)piperazine (m-CPP 2-10 mu M) induced an initial decrease in the respiratory rate followed by a furtherlong-lasting decrease. Burst activity of Pre-I neurons was suppressedupon administration of 10 mu M m-CPP and enhanced with 20 mu M DOI. The results suggest that changes in the bursting properties of Pre-I and Insp neurons induced by 5-HT lead to modulation of the respiratory network, thus causing biphasic modulation of the respiratory rhythm. Inaddition to effects via 5-HT1A receptors, activation of 5-HT2A and 5-HT2C receptor subtypes might be involved in excitatory effects and inhibitory effects of 5-HT respectively.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 03/12/20 alle ore 12:34:15