Organization of GABA and GABA-transaminase containing neurons in the gustatory zone of the nucleus of the solitary tract

Lasiter, Phillip S.; Kachele, Diane L.

doi:10.1016/0361-9230(88)90202-x

Cited by 108 publications

(57 citation statements)

References 27 publications

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“…Previous estimates of the proportion of rNST neurons that are GABAergic have been based on GABA immunoreactivity in the chorda tympani (CT) terminal field of rats (18%; Lasiter and Kachele 1988) or on counts of GFP-expressing neurons in the ventral subdivision in the "GIN" mouse (24%; Wang and Bradley 2010a). We report a proportion of ϳ36% throughout the nucleus in the GAD67-EGFP knockin mouse, which is notably higher than previous studies.…”

Section: Discussionmentioning

confidence: 99%

The μ-opioid receptor agonist DAMGO presynaptically suppresses solitary tract-evoked input to neurons in the rostral solitary nucleus

Boxwell

Yanagawa

Travers

et al. 2013

Journal of Neurophysiology

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Boxwell AJ, Yanagawa Y, Travers SP, Travers JB. The -opioid receptor agonist DAMGO presynaptically suppresses solitary tract-evoked input to neurons in the rostral solitary nucleus. J Neurophysiol 109: 2815-2826, 2013. First published March 13, 2013 doi:10.1152/jn.00711.2012.-Taste processing in the rostral nucleus of the solitary tract (rNST) is subject to modulatory influences including opioid peptides. Behavioral pharmacological studies suggest an influence of -opioid receptors in rNST, but the underlying mechanism is unknown. To determine the cellular site of action, we tested the effects of the -opioid receptor agonist DAMGO in vitro. Whole cell patch-clamp recordings were made in brain stem slices from GAD67-GFP knockin mice expressing enhanced green fluorescent protein (EGFP) under the control of the endogenous promoter for GAD67, a synthetic enzyme for GABA. Neuron counts showed that ϳ36% of rNST neurons express GABA. We recorded monosynaptic solitary tract (ST)-evoked currents (jitter Յ 300 s) in both GAD67-EGFP-positive (GAD67ϩ) and GAD67-EGFP-negative (GAD67Ϫ) neurons with equal frequency (25/31; 22/28), but the inputs to the GAD67ϩ neurons had significantly smaller paired-pulse ratios compared with GAD67Ϫ neurons. DAMGO (0.3 M) significantly suppressed ST-evoked currents in both cell types (mean suppression ϭ 46 Ϯ 3.3% SE), significantly increased the paired-pulse ratio of these currents, and reduced the frequency of spontaneous miniature excitatory postsynaptic currents but did not diminish their amplitude, indicating a presynaptic site of action. Under inhibitory amino acid receptor blockade, DAMGO was significantly more suppressive in GAD67ϩ neurons (59% reduction) compared with GAD67Ϫ neurons (35% reduction), while the reverse was true in normal artificial cerebrospinal fluid (GAD67ϩ: 35% reduction; GAD67Ϫ: 57% reduction). These findings suggest that DAMGO suppresses activity in rNST neurons predominantly via a presynaptic mechanism, and that this effect may interact significantly with tonic or evoked inhibitory activity.

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Section: Discussionmentioning

confidence: 99%

The μ-opioid receptor agonist DAMGO presynaptically suppresses solitary tract-evoked input to neurons in the rostral solitary nucleus

Boxwell

Yanagawa

Travers

et al. 2013

Journal of Neurophysiology

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“…It is plausible that the inhibitory influence may be mediated by interneurons in the rNST. Both in vitro and in vivo, it has been reported that taste afferent nerve terminals released glutamate (Li and Smith 1997;Wang and Bradley 1995), and GABA-immunoreactive neurons were observed in the CT terminal field in the rNST (Lasiter and Kachele 1988).…”

Section: Implications Of Umami Tastants or Artificial Salivamentioning

confidence: 99%

Topographical representations of taste response characteristics in the rostral nucleus of the solitary tract in the rat

Yokota

Eguchi

Hiraba

2014

Journal of Neurophysiology

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Yokota T, Eguchi K, Hiraba K. Topographical representations of taste response characteristics in the rostral nucleus of the solitary tract in the rat. J Neurophysiol 111: 182-196, 2014. First published October 16, 2013 doi:10.1152/jn.01031.2012.-The rostral nucleus of the solitary tract (rNST) is the first-order taste relay in rats. This study constructed topographical distributions of taste response characteristics (best-stimulus, response magnitude, and taste-tuning) from spike discharges of single neurons in the rNST. The rNST is divided into four subregions along the rostrocaudal (RC) axis, which include r1-r4. We explored single-neuron activity in r1-r3, using multibarreled glass microelectrodes. NaCl (N)-best neurons were localized to the rostral half of r1-r3, while HCl (H)-best and sucrose (S)-best neurons showed a tendency toward more caudal locations. NaCl and HCl (NH)-best neurons were distributed across r2-r3. The mean RC values and Mahalanobis distance indicated a significant difference between the distributions of N-best and NH-best neurons in which N-best neurons were located more rostrally. The region of large responses to NaCl (net response Ͼ5 spikes/s) overlapped with the distribution of N-best neurons. The region of large responses to HCl extended widely over r1-r3. The region of large responses to sucrose was in the medial part of r2. The excitatory region (Ͼ1 spike/s) for quinine overlapped with that for HCl. Neurons with sharp to moderate tuning were located primarily in r1-r2, while those with broad tuning were located in r2-r3. The robust responses to NaCl in r1-r2 primarily contributed to sharp to moderate taste-tuning. Neurons in r3 tended to have broad tuning, apparently due to small responses to both NaCl and HCl. Therefore, the rNST is spatially organized by neurons with distinct taste response characteristics, suggesting that these neurons serve different functional roles.best-stimulus; response magnitude; taste-tuning; Mahalanobis distance; medulla oblongata THE ROSTRAL NUCLEUS of the solitary tract (rNST), the first-order taste relay, has been reported to receive spatially organized projections on the rostrocaudal (RC) axis from four taste afferents [the chorda tympani (CT), the great superficial petrosal nerve (GSP), the glossopharyngeal nerve (IX), and the superior laryngeal nerves (SL)] in the rat (Contreras et al. 1982;Hamilton and Norgren 1984;Rhoton 1968;Torvik 1956) and the hamster (Whitehead and Frank 1983). However, recent studies have reported overlapping terminal projections from these afferent nerves (Corson et al. 2012;May and Hill 2006). In studies examining the oral receptive field properties of taste-sensitive neurons in the rNST, oral receptive field configurations in the horizontal plane were associated with afferent projections along the RC axis in the rNST (Halpern and Nelson 1965;Sweazey and Smith 1987;Travers and Norgren 1995). Of individual neurons, one-third actually received convergent inputs from the different receptive fields, primarily the anterior ton...

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“…The baroreceptive region of the NTS contains a high density of GABA-containing nerve terminals (2,11,16,20,24,25) and a high density of both GABA A and GABA B receptors (4,10,25). Previous studies (3,9,22,29,31) demonstrated that stimulation of GABA B receptors in this region of the NTS elicits a marked pressor response in anesthetized rats.…”

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confidence: 99%

Cardiovascular mechanisms activated by microinjection of baclofen into NTS of conscious rats

Landulpho

Dias

Colombari

2003

American Journal of Physiology-Heart and Circulatory Physiology

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The peripheral mechanisms responsible for pressor response produced by microinjections of baclofen (GABAB agonist) into the nucleus tractus solitarii (NTS) of conscious rats were studied. Bilateral microinjections of baclofen (10-1,000 pmol/100 nl) produced a dose-related increase in mean arterial pressure (MAP) and heart rate. The maximal response was observed after 15 min. Intravenous injection of prazosin decreased MAP to control levels. Subsequent treatment with Manning compound (vasopressin receptor antagonist; iv) produced an additional decrease in MAP. In a different group of rats, vasopressin antagonist was injected first and MAP was significantly decreased; however, it remained elevated compared with prebaclofen injection levels. Subsequent treatment with prazosin abolished the baclofen-induced pressor response. Reductions in baclofen-induced pressor response with prazosin treatment were followed by a reflex tachycardia in animals that received a 100 pmol/100 nl dose of baclofen. The tachycardia was not observed with a dose of 1,000 pmol/100 nl. The pressor response induced by microinjection of baclofen into the NTS of conscious rats may be produced by both increases in sympathetic tonus and vasopressin release. GABAB agonist; prazosin; blood pressure; vasopressin; cardiovascular control; baroreflex THE MAJORITY OF CARDIOVASCULAR and respiratory afferents relay to the central nervous system (CNS) via the vagus and glossopharyngeal nerves and terminate in the nucleus tractus solitarii (NTS) (12,17). The NTS is a major site of reflex integration, and it is also richly innervated from regions of the CNS concerned directly or indirectly with cardiorespiratory control (17), changing both the activity of the sympathetic nervous system (SNS) and vasopressin (VP) release (27).The role of GABA in the NTS has been investigated in the last decade. The baroreceptive region of the NTS contains a high density of GABA-containing nerve terminals (2,11,16,20,24,25) and a high density of both GABA A and GABA B receptors (4,10,25). Previous studies (3,9,22,29,31) demonstrated that stimulation of GABA B receptors in this region of the NTS elicits a marked pressor response in anesthetized rats. In conscious rats, systemic administration of baclofen causes a sustained hypertension and tachycardia (23).Anatomic studies showed projections from the NTS to neurons of the paraventricular nucleus of the hypothalamus to and from the NTS to the spinal cord (6,18,32). Previous results showed an important participation of VP in the pressor response produced by microinjection of muscimol (GABA A agonist) and nipecotic acid (inhibitor of GABA uptake) into the NTS of anesthetized rats (7). Moreover, extensive chemical or electrolytic lesions of the NTS demonstrated that, in addition to VP, the SNS is involved in the pressor response (1).The mechanisms related to the hypertension observed after baclofen injection into the NTS are not yet clear. Several mechanisms can be considered for this hypertension, the possibility of an increase in s...

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Organization of GABA and GABA-transaminase containing neurons in the gustatory zone of the nucleus of the solitary tract

Cited by 108 publications

References 27 publications

The μ-opioid receptor agonist DAMGO presynaptically suppresses solitary tract-evoked input to neurons in the rostral solitary nucleus

The μ-opioid receptor agonist DAMGO presynaptically suppresses solitary tract-evoked input to neurons in the rostral solitary nucleus

Topographical representations of taste response characteristics in the rostral nucleus of the solitary tract in the rat

Cardiovascular mechanisms activated by microinjection of baclofen into NTS of conscious rats

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