Copyright © 2004, European Society of Cardiology
Functional interaction between nucleus tractus solitarius NK1 and 5-HT3 receptors in the inhibition of baroreflex in rats
Inserm U.288, Faculté de Médecine Pitié-Salpêtrière, 91 Boulevard de l–Hôpital, 75634 Paris Cedex 13, France
* Corresponding author. Tel.: +33 1 40 77 97 14; fax: +33 1 40 77 97 90. Email address: sevoz{at}ext.jussieu.fr
Objective: Previous data showed that in the nucleus tractus solitarius (NTS), 5-HT3 receptors are critically involved in the inhibition of cardiac baroreceptor reflex response occurring during the defense reaction. Since stimulation of NTS NK1 receptors has been found to inhibit the baroreflex bradycardia, we examined in this study whether this reflex response is inhibited during the defense reaction via an interaction between NK1 and 5-HT3 receptors.
Methods: For this purpose, we analyzed in urethane-anaesthetized rats the effects of intra-NTS GR205171, a selective NK1 receptor antagonist, on the baroreflex bradycardia inhibition observed either during the defense reaction triggered by electrical stimulation of the dorsal periaqueductal grey matter (dPAG) or after NTS 5-HT3 receptor activation.
Results: Intra-NTS GR205171, reversed, in dose-dependent manner, the inhibitory effect of dPAG stimulation on baroreflex bradycardia. This reversion was of 49% when both sinus carotid and aortic baroreceptors were stimulated by phenylephrine, and of 84% when aortic depressor nerve was stimulated. Similarly, intra-NTS GR205171 reversed partially or almost totally the inhibitory effect of local microinjections of phenylbiguanide, a 5-HT3 receptor agonist, on baroreflex bradycardia induced either by phenylephrine administration or aortic nerve stimulation, respectively.
Conclusion: These results strongly suggest that NK1 receptors contribute downstream to the 5-HT3 receptor-mediated inhibition of the aortic but not carotid cardiac baroreflex response occurring during the defense reaction, therefore implying that baroreceptor afferent inputs may be differentially modulated depending on their origin. This differentiation may be useful for a better understanding of baroreflex dysfunction in disease-induced conditions.
KEYWORDS Baroreflex; Serotonin; NK1; Nucleus tractus solitarius; Autonomic nervous system
Time for primary review 23 days
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  R. L. Khan, R. Vadigepalli, M. K. McDonald, R. F. Rogers, G. R. Gao, and J. S. Schwaber Dynamic transcriptomic response to acute hypertension in the nucleus tractus solitarius Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2008; 295(1): R15 - R27. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. V. Dzurik, A. Diedrich, B. Black, S. Y. Paranjape, S. R. Raj, D. W. Byrne, and D. Robertson Endogenous substance P modulates human cardiovascular regulation at rest and during orthostatic load J Appl Physiol, June 1, 2007; 102(6): 2092 - 2097. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Sevoz-Couche, M. A. Comet, J. F. Bernard, M. Hamon, and R. Laguzzi Cardiac baroreflex facilitation evoked by hypothalamus and prefrontal cortex stimulation: role of the nucleus tractus solitarius 5-HT2A receptors Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2006; 291(4): R1007 - R1015. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. M. Degtyarenko and M. P. Kaufman MLR-induced inhibition of barosensory cells in the NTS Am J Physiol Heart Circ Physiol, December 1, 2005; 289(6): H2575 - H2584. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Solt, R. J. Stevens, P. A. Davies, and D. E. Raines General Anesthetic-Induced Channel Gating Enhancement of 5-Hydroxytryptamine Type 3 Receptors Depends on Receptor Subunit Composition J. Pharmacol. Exp. Ther., November 1, 2005; 315(2): 771 - 776. [Abstract] [Full Text] [PDF]
|
|