Evidence for L-glutamate as the Neurotransmitter of Baroreceptor Afferent Nerve Fibers

Talman, William T.; Perrone, Mark H.; Reis, Donald J.

doi:10.1126/science.6105709

Cited by 423 publications

(200 citation statements)

References 17 publications

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“…The role of the NTS, including the commNTS, in the control of the cardiovascular reflexes has been extensively studied (18)(19)(20)27). The new finding of the present study is that the commNTS also contributes to water intake control and may represent an essential step in the neural pathways involved in the regulation of water intake induced by sc isoproterenol.…”

Section: Discussionmentioning

confidence: 49%

“…The medial NTS (mNTS) and the commissural NTS (commNTS) subnuclei project to the forebrain areas involved in the control of hydroelectrolyte balance, such as the paraventricular nucleus and the anteroventral third ventricle region and to hindbrain areas such as the LPBN (14)(15)(16) and receive projections from the AP (17). Besides playing a well-established role in cardiovascular regulation (18)(19)(20), the NTS may also be involved in the control of fluid balance. Lesions of the mNTS increase the ingestion of water in response to intravenous ANG II and this effect has been attributed to the impairment of the baroreflex or to a loss of an inhibitory signal produced by water consumption (21).…”

Section: Introductionmentioning

confidence: 99%

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Lesions of the commissural subnucleus of the nucleus of the solitary tract increase isoproterenol-induced water intake

Blanch

Freiria-Oliveira

Colombari

et al. 2007

Braz J Med Biol Res

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The nucleus of the solitary tract (NTS) is the primary site of the cardiovascular afferent information about arterial blood pressure and volume. The NTS projects to areas in the central nervous system involved in cardiovascular regulation and hydroelectrolyte balance, such as the anteroventral third ventricle region and the lateral parabrachial nucleus. The aim of the present study was to investigate the effects of electrolytic lesion of the commissural NTS on water and 0.3 M NaCl intake and the cardiovascular responses to subcutaneous injection of isoproterenol. Male Holtzman rats weighing 280 to 320 g were submitted to sham lesion or electrolytic lesion of the commissural NTS (N = 6-15/group). The sham-lesioned rats had the electrode placed along the same coordinates, except that no current was passed. Water intake induced by subcutaneous isoproterenol (30 µg/kg body weight) significantly increased in chronic (15 days) commissural NTS-lesioned rats (to 2.4 ± 0.2 vs sham: 1.9 ± 0.2 mL 100 g body weight -1 60 min -1 ). Isoproterenol did not induce any sodium intake in sham or in commissural NTS-lesioned rats. The isoproterenol-induced hypotension (sham: -27 ± 4 vs commissural NTS-lesioned rats: -22 ± 4 mmHg/20 min) and tachycardia (sham: 168 ± 10 vs commissural NTS: 144 ± 24 bpm/20 min) were not different between groups. The present results suggest that the commissural NTS is part of an inhibitory neural pathway involved in the control of water intake induced by subcutaneous isoproterenol, and that the overdrinking observed in lesioned rats is not the result of a cardiovascular imbalance in these animals.

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Section: Discussionmentioning

confidence: 49%

Section: Introductionmentioning

confidence: 99%

Lesions of the commissural subnucleus of the nucleus of the solitary tract increase isoproterenol-induced water intake

Blanch

Freiria-Oliveira

Colombari

et al. 2007

Braz J Med Biol Res

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“…Moreover, glutamate has been demonstrated to be the main neurotransmitter of baroreceptor afferents terminating in the NTS (Talman et al, 1980;Reis et al, 1981). However, microinjections of nicotine into the NTS elicited hypotension and bradycardia similar to that elicited by activation of baroreceptors (Kubo and Misu, 1981;Talman and Lewis, 1991).…”

Section: Introductionmentioning

confidence: 99%

Heterogeneity of nicotinic acetylcholine receptor expression in the caudal nucleus of the solitary tract

Smith

Uteshev

2008

Neuropharmacology

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The nucleus of the solitary tract (NTS) is the principal integrating relay in the processing of visceral sensory and gustatory information. In the present study, patch-clamp electrophysiological experiments were conducted using rat horizontal brainstem sections. Pre-synaptic and somatic/ dendritic nicotinic acetylcholine receptors (nAChRs) expressed in neurons of the caudal NTS (cNTS) were found to be randomly distributed between pre-synaptic and somatic/dendritic sites (χ 2 =0.72, df =3, p>0.87, n=200). Pre-synaptic nAChRs were detected by their facilitating effects on glutamatergic neurotransmission of a sub-population of cNTS neurons (categorized as "effectpositive") upon brief picospritzer applications of 0.1-0.5 mM nicotine. These effects were resistant to inhibition by 20 nM methyllycaconitine (MLA) and 4 μM dihydro-β-erythroidine (DHβE), and were replicated by brief picospritzer applications of 0.2-1 mM cytisine. Picospritzer applications of 0.2 mM RJR-2403, a potent agonist of α4β2 nAChRs, did not facilitate synaptic release of glutamate in effect-positive cNTS neurons. The population of somatic/dendritic nAChRs has been found to be heterogeneous and included nAChRs that were activated by RJR-2403 and/or cytisine; or insensitive to cytisine; or inhibited by MLA. The presented results are consistent with the expression of β4-containing (i.e., β4*) nAChRs, likely α3β4*, in presynaptic terminals of effectpositive cNTS neurons. Somatic/dendritic nAChRs appear to involve both α7 and non-α7 subunits. Heterogeneity in the subunit composition of pre-synaptic and somatic/dendritic nAChRs may underlie diverse roles that these receptors play in regulation of behavioral and visceral reflexes, and may reflect specific targeting by endogenous nicotinic agents and nicotine.

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“…However these opiate receptors do not appear to be an integral part of the baroreflex pathway, but may be involved in a neuromodulator system. This seems likely since administration of naloxone into the n. tractus solitarii did not affect the depressor response induced by L-glutamate, which has been proposed to be a neurotransmitter of baroreceptor afferent nerve fibres in the n. tractus solitarii (Talman, Perrone and Reis, 1980). The change in arterial pressure induced by L-glutamate (1 pg) being -19 + 4 and -17 f 9 mmHg after pretreatment with saline and naloxone (10 ng) respectively.…”

Section: Discussionmentioning

confidence: 97%

Endorphins and the hypotensive response to stimulation of alpha-receptors in the brainstem by alpha-methylnoradrenaline

Petty

Jong

1984

Neuropharmacology

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Summary-Opioid peptide involvement in the fall in blood pressure resulting from stimulation of alpha-receptors in the brainstem has been investigated in the urethane-anaesthetised rat. Unilateral microinjection of alpha-methylnoradrenahne into the nucleus tractus sohtarii (NTS) induced a doserelated fall in blood pressure and heart rate. The depressor response induced by the amine was prevented by pretreatment with naloxone, administered either subcutaneously or directly into the nucleus. Pretreatment with antiserum to beta-endorphin, applied locally, also blocked the depressor response, however a similar dilution of antiserum to met-enkephalin was ineffective in this respect. The local application of phentolamine into the n. tractus solitarii caused an initial fall in both blood pressure and heart rate, and blocked the cardiovascular changes induced by alpha-methylnoradrenaline for at least 90 min. Pretreatment with the alpha-receptor antagonist attenuated the fall in blood pressure produced by microinjection of beta-endorphin. These results suggest that the fall in blood pressure observed after administration of alpha-methylnoradrenaline involves a beta-endorphin-like peptide, a probable site of this interaction being the n. tractus solitarii.

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Evidence for L-glutamate as the Neurotransmitter of Baroreceptor Afferent Nerve Fibers

Cited by 423 publications

References 17 publications

Lesions of the commissural subnucleus of the nucleus of the solitary tract increase isoproterenol-induced water intake

Lesions of the commissural subnucleus of the nucleus of the solitary tract increase isoproterenol-induced water intake

Heterogeneity of nicotinic acetylcholine receptor expression in the caudal nucleus of the solitary tract

Endorphins and the hypotensive response to stimulation of alpha-receptors in the brainstem by alpha-methylnoradrenaline

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