HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 90/4/2521    most recent 00275.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (14) Citing Articles via Google Scholar Google Scholar Articles by Sévoz-Couche, C. Articles by Laguzzi, R. Search for Related Content PubMed PubMed Citation Articles by Sévoz-Couche, C. Articles by Laguzzi, R.

Role of Nucleus Tractus Solitarius 5-HT₃ Receptors in the Defense Reaction–Induced Inhibition of the Aortic Baroreflex in Rats

Institut National de la Santé et de la Recherche Médicale, Unité 288, Faculté de Médecine Pitié-Salpêtrière, 75634 Paris Cedex 13, France

Submitted 21 March 2003; accepted in final form 23 May 2003

Different stressful conditions elicit a typical behavior called the defense reaction. Our aim was to determine whether 5-HT₃ receptors in the nucleus tractus solitarius (NTS) are involved in 1) the inhibition of the baroreflex bradycardia and 2) the rise in blood pressure, which are known to occur during the defense reaction. In urethane-anesthetized rats, the defense reaction was elicited by electrical stimulation of the dorsomedial nucleus of the hypothalamus (DMH) or the dorsal part of the periaqueductal gray (dPAG). Direct electrical stimulation of the aortic depressor nerve was used to trigger the typical baroreflex responses. Aortic stimulation at high (100–150 µA) and low (50–90 µA) intensity produced a decrease in heart rate of –39 to –44% (relative to baseline, Group 1 responses, n = 113) and –19 to –24% (Group 2 responses, n = 43), respectively. In spontaneously breathing rats, Group 1 and Group 2 bradycardiac responses were inhibited during DMH (–75 ± 4% and –96 ± 4%, n = 38 and n = 11, respectively), as well as dPAG (–81 ± 3% and –95 ± 4%, n = 36 and n = 10, respectively) stimulation. The aortic baroreflex bradycardia was hardly affected by DMH or dPAG stimulation when bicuculline (5 pmol), a specific GABA_A receptor antagonist, had previously been microinjected into the NTS. Likewise, NTS microinjections of granisetron, a specific 5-HT₃ receptor antagonist, prevented, in a dose-dependent manner, the baroreflex bradycardia inhibition. In addition, intra-NTS granisetron did not affect the rise in blood pressure induced by either site stimulation. These data show that 5-HT₃ receptors in the NTS are involved in the GABAergic inhibition of the aortic baroreflex bradycardia, but not in the rise in blood pressure, occurring during the defense reaction elicited by DMH or dPAG stimulation.

This article has been cited by other articles:

				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]

				W. Zhang, T. Sakurai, Y. Fukuda, and T. Kuwaki Orexin neuron-mediated skeletal muscle vasodilation and shift of baroreflex during defense response in mice Am J Physiol Regulatory Integrative Comp Physiol, June 1, 2006; 290(6): R1654 - R1663. [Abstract] [Full Text] [PDF]

				L. M. McDowall, J. Horiuchi, S. Killinger, and R. A. L. Dampney Modulation of the baroreceptor reflex by the dorsomedial hypothalamic nucleus and perifornical area Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2006; 290(4): R1020 - R1026. [Abstract] [Full Text] [PDF]

				M.-A. Comet, R. Laguzzi, M. Hamon, and C. Sevoz-Couche Functional interaction between nucleus tractus solitarius NK1 and 5-HT3 receptors in the inhibition of baroreflex in rats Cardiovasc Res, March 1, 2005; 65(4): 930 - 939. [Abstract] [Full Text] [PDF]

				M.-A. Comet, C. Sevoz-Couche, N. Hanoun, M. Hamon, and R. Laguzzi 5-HT-mediated inhibition of cardiovagal baroreceptor reflex response during defense reaction in the rat Am J Physiol Heart Circ Physiol, October 1, 2004; 287(4): H1641 - H1649. [Abstract] [Full Text] [PDF]

				A. Bhattacharya, H. Dang, Q.-M. Zhu, B. Schnegelsberg, N. Rozengurt, G. Cain, R. Prantil, D. A. Vorp, N. Guy, D. Julius, et al. Uropathic Observations in Mice Expressing a Constitutively Active Point Mutation in the 5-HT3A Receptor Subunit J. Neurosci., June 16, 2004; 24(24): 5537 - 5548. [Abstract] [Full Text] [PDF]