Article

Endogenous 5-HT(1/2) systems and the newborn rat respiratory control. A comparative in vivo and in vitro study.

Dysrégulations métaboliques acquises et génétiques, EA 2088-2629, Faculté de Médecine, Université de Picardie Jules Verne, 3 rue des Louvels, 80036 Amiens cedex 1, France.
Respiratory Physiology & Neurobiology (impact factor: 2.24). 08/2004; 141(1):47-57. DOI:10.1016/j.resp.2004.03.007 pp.47-57
Source: PubMed

ABSTRACT Consequences of 5-HT(1/2) systems blockade by methysergide on newborn rats respiratory drive were evaluated in vivo with unrestrained animals and in vitro using brainstem-spinal cord preparations. A decrease in respiratory frequency until a plateau level was observed under both in vivo (82.8 +/- 0.6% of control values) and in vitro (76.8 +/- 0.8% of control values) conditions whereas an increase in inspiratory amplitude (135.1 +/- 2.1% of control values) was only retrieved in vivo. By the use of the c-fos expression analysis, we correlated these effects with neuronal activity changes, particularly, in vivo in two key structures between the respiratory ponto-medullary network and the peripheral or suprapontine afferences, namely the commissural subnucleus of the nucleus of the solitary tract and the lateral parabrachial nucleus. Thus, peripheral and suprapontine inputs seem to be of a primeval importance in the respiratory influence of endogenous 5-HT. Besides, as 5-HT is involved in the respiratory perturbations that occur in sudden infant death syndrome (SIDS), our results suggest a participation of peripheral and suprapontine inputs in these disorders.

0 0
 · 
0 Bookmarks
 · 
30 Views
  • Source
    Article: Intracerebroventricular serotonin reduces the degree of acute hypoxic ventilatory depression in peripherally chemodenervated rabbits.
    Ibrahim Guner, Gulderen Sahin, Nermin Karaturan Yelmen, Ugur Aksu, Tulin Oruc, Zeynep Yildirim
    [show abstract] [hide abstract]
    ABSTRACT: Hypoxia causes changes in the rate of synthesis or release of neurotransmitters in the brain. The accumulation of serotonin (5-HT) in the central nervous system might cause hypoxic respiratory depression. In the present study, we aimed to examine the role of central 5-HT on normoxic and acute hypoxic ventilatory depression (AHVD) in peripheral chemoreceptors denervated rabbits. All experiments were performed in peripherally chemodenervated rabbits anesthetized with intravenous injection of urethane (400 mg/kg) and alpha-chloralose (40 mg/kg). For intracerebroventricular (ICV) administration of 5-HT (20 microg/kg) and ketanserin (10 microg/kg), a cannula was placed in left lateral ventricle by stereotaxic method. Respiratory frequency (fR), tidal volume (VT), ventilation minute volume (VE) and systemic arterial bood pressure (BP) were recorded in each experimental phases and mean arterial pressure was calculated (MAP). Heart rate (HR) was also determined from the pulsation of BP. The effects of ICV serotonin and ICV ketanserin on the indicated parameters during air breathing (normoxia) and breathing of hypoxia (8% O2--92% N2) were investigated. During hypoxia, fR, VT, VE, MAP and HR decreased, and AHVD was thus obtained. ICV injection of 5-HT during normoxia caused significant increases in VT (P < 0.001) and in VE (P < 0.01). On the other hand, ICV 5-HT injection reduced the degree of AHVD in peripherally chemodenervated rabbits during hypoxia (fR; P < 0.05, VT; P < 0.05 and VE; P < 0.01). After ICV injection of ketanserin, the enhancement of 5-HT on VE was prevented during normoxia. On the breathing of hypoxic gas after ICV ketanserin, the degree of AHVD was augmented. In conclusion, our findings suggested that central 5-HT increases normoxic ventilation and reduces the degree of AHVD during hypoxia and that ICV ketanserin prevents the stimulatory effect of 5-HT on respiration and augments AHVD.
    The Chinese journal of physiology 06/2008; 51(3):136-45. · 0.56 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

brainstem-spinal cord preparations
 
c-fos expression analysis
 
commissural subnucleus
 
endogenous 5-HT
 
inspiratory amplitude
 
key structures
 
lateral parabrachial nucleus
 
neuronal activity changes
 
newborn rats respiratory drive
 
nucleus
 
plateau level
 
respiratory frequency
 
respiratory influence
 
respiratory perturbations
 
respiratory ponto-medullary network
 
sudden infant death syndrome
 
suprapontine afferences
 
unrestrained animals
 
vitro
 
vivo