Cardiac responses to the microinjections of excitatory amino acids into the intermediolateral cell column of the rat spinal cord

Sundaram, Kalyana; Murugaian, Jaya; Sapru, Hreday N.

doi:10.1016/0006-8993(89)90537-4

Cited by 51 publications

(20 citation statements)

References 26 publications

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“…Although it has been reported that microinjection of glutamate into the IML exerts an excitatory effect on cardiac functions (Sundaram et al, 1989), the effect on thermoregulatory effector organs has not yet been tested. As shown by the present PRV study, the subpopulation of SPNs sending outputs to the interscapular BAT are distributed mainly in the T2-T6 segments.…”

Section: Glutamatergic Transmission Mediates the Bat Thermogenic Pathmentioning

confidence: 99%

Identification of Sympathetic Premotor Neurons in Medullary Raphe Regions Mediating Fever and Other Thermoregulatory Functions

Nakamura

Matsumura

Hübschle

et al. 2004

Journal of Neuroscience

258

322

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Sympathetic premotor neurons directly control sympathetic preganglionic neurons (SPNs) in the intermediolateral cell column (IML) of the thoracic spinal cord, and many of these premotor neurons are localized in the medulla oblongata. The rostral ventrolateral medulla contains premotor neurons controlling the cardiovascular conditions, whereas rostral medullary raphe regions are a candidate source of sympathetic premotor neurons for thermoregulatory functions. Here, we show that these medullary raphe regions contain putative glutamatergic neurons and that these neurons directly control thermoregulatory SPNs. Neurons expressing vesicular glutamate transporter 3 (VGLUT3) were distributed in the rat medullary raphe regions, including the raphe magnus and rostral raphe pallidus nuclei, and mostly lacked serotonin immunoreactivity. These VGLUT3-positive neurons expressed Fos in response to cold exposure or to central administration of prostaglandin E 2 , a pyrogenic mediator. Transneuronal retrograde labeling after inoculation of pseudorabies virus into the interscapular brown adipose tissue (BAT) or the tail indicated that those VGLUT3-expressing medullary raphe neurons innervated these thermoregulatory effector organs multisynaptically through SPNs of specific thoracic segments, and microinjection of glutamate into the IML of the BAT-controlling segments produced BAT thermogenesis. An anterograde tracing study further showed a direct projection of those VGLUT3-expressing medullary raphe neurons to the dendrites of SPNs. Furthermore, intra-IML application of glutamate receptor antagonists blocked BAT thermogenesis triggered by disinhibition of the medullary raphe regions. The present results suggest that VGLUT3-expressing neurons in the medullary raphe regions constitute excitatory neurons that could be categorized as a novel group of sympathetic premotor neurons for thermoregulatory functions, including fever.

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Section: Glutamatergic Transmission Mediates the Bat Thermogenic Pathmentioning

confidence: 99%

Identification of Sympathetic Premotor Neurons in Medullary Raphe Regions Mediating Fever and Other Thermoregulatory Functions

Nakamura

Matsumura

Hübschle

et al. 2004

Journal of Neuroscience

258

322

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“…Two main receptor subtypes for the EAA are involved in the glutamatergic neurotransmission in the mammalian central nervous system: the N-methyl-Daspartate receptor/channel complex (NMDA) and the non NMDA receptor, AMPA/kainate (x-amino-3-hydroxy-5-methylisoxazole-4-propionic acid) (Watkins & Evans, 1981;Collingridge & Lester, 1989;Honore, 1989;Lodge & Johnson, 1990;Watkins et al, 1990). It is well known that the NMDA receptor is widely distributed throughout the brain (Cotman et al, 1987;Sundaram et al, 1989;Young & Fagg, 1990). 5,7 Dichlorokynurenic acid is a derivative of kynurenic acid (a tryptophan metabolite), an endogenous substance that has been shown to block selectively the glutamate-like neurotransmission.…”

Section: Discussionmentioning

confidence: 99%

Prevention by NMDA receptor antagonists of the centrally‐evoked increases of cardiac inotropic responses in rabbits

Monassier¹,

Tibiriçá

Roegel³

et al. 1994

British J Pharmacology

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1 The purpose of this study was to investigate further the role of the excitatory amino acid (EAA) system of neurotransmission, particularly of the NMDA receptor, in the central regulation of cardiac function. 2 Electrical stimulation of the paraventricular nucleus of the hypothalamus (PVN) in pentobarbitone anaesthetized rabbits induced a cardiovascular response mainly characterized by a positive inotropic effect, hypertension and a marked increase in the myocardial oxygen demand index. 3 The intracerebroventricular (i.c.v.) or intravenous (i.v.) injection of different EAA antagonists acting on different sites of the NMDA receptor/channel complex dose-dependently blunted the excitatory cardiovascular effects of PVN stimulation. 4 5,7 Dichlorokynurenic acid was used as a specific glycine site antagonist and 2-amino-5-phosphonovaleric acid was used to block the agonist recognition site; ketamine was used as a channel blocker site antagonist and ifenprodil as a blocker of the polyamine binding site. 5 5,7 Dichlorokynurenic acid (125 and 250 ftg kg-', i.c.v.) virtually abolished the cardiovascular responses, inducing only haemodynamic depression at the highest dose used. 2-Amino-5-phosphonovaleric acid (0.1 to 1.0 mg kg-', i.c.v.) elicited a reduction of the peak values observed during PVN stimulation which was accompanied by a decrease of the basal cardiovascular parameters. Ketamine (2.5 and 10 mg kg-') and ifenprodil (1 mg kg-'), injected intravenously, blocked the haemodynamic response induced by PVN stimulation without marked reduction of the basal haemodynamics. 6 It is concluded that glutamate neurotransmission is not only involved in vasomotor tone control but also in the central control of cardiac function and can therefore modulate the myocardial oxygen demand.

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“…In addition, glutamate receptors play important roles in the central cardiovascular regulation [3][4][5]. According to results of biochemical, pharmacological, electrophysiological, and molecular studies, glutamate receptors are classified as ionotropic and metabotropic.…”

Section: Introductionmentioning

confidence: 99%

Cardiovascular Responses to NMDA Injected into Nuclei of Hypothalamus or Amygdala in Conscious Rats

Gören

Akıcı²,

Berkman³

et al. 2000

Pharmacology

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The nuclei of hypothalamus and amygdala have been shown to be involved in the central cardiovascular homeostasis. Recent studies suggest that glutamate-containing neurons have an important role in the regulation of the central cardiovascular function. In this study, we demonstrate the roles of the central nucleus of the amygdala and the paraventricular nucleus of the amygdala and the paraventricular nucleus or the dorsomedial nucleus of the hypothalamus in N-methyl-D-aspartate (NMDA) induced blood pressure and heart rate changes in conscious Sprague-Dawley rats. Intracerebroventricular or parenchymal injections of NMDA evoke increases in arterial pressure. The NMDA-induced elevations in blood pressure are more prominent when NMDA is administered into the dorsomedial nucleus of the hypothalamus. Microinjections of NMDA into the dorsomedial hypothalamus exert significant heart rate increases, whereas NMDA when administered into the paraventricular nucleus of the hypothalamus or into the central nucleus of the amygdala has no significant effect on the heart rate. The dorsomedial nucleus of the hypothalamus is found to be the most effective site in this respect. The present study provides strong evidence for the tonic glutamatergic influence on blood pressure and heart rate via NMDA receptors located within the dorsomedial nucleus and to a lesser extent via those located within the paraventricular nucleus of the hypothalamus.

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Cardiac responses to the microinjections of excitatory amino acids into the intermediolateral cell column of the rat spinal cord

Cited by 51 publications

References 26 publications

Identification of Sympathetic Premotor Neurons in Medullary Raphe Regions Mediating Fever and Other Thermoregulatory Functions

Identification of Sympathetic Premotor Neurons in Medullary Raphe Regions Mediating Fever and Other Thermoregulatory Functions

Prevention by NMDA receptor antagonists of the centrally‐evoked increases of cardiac inotropic responses in rabbits

Cardiovascular Responses to NMDA Injected into Nuclei of Hypothalamus or Amygdala in Conscious Rats

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