Most neurons in the nucleus tractus solitarii do not send collateral projections to multiple autonomic targets in the rat brain

Hermes, Sam M.; Mitchell, Jennifer; Aicher, Sue A.

doi:10.1016/j.expneurol.2005.12.028

Cited by 61 publications

(83 citation statements)

References 35 publications

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“…Rats (230 -270 g) were anesthetized with isoflurane (4% for induction, 2% for maintenance), and tracers were pressure injected (Picospritzer II; General Valve, Fairfield, NJ) as described previously (Hermes et al, 2006). Stereotaxic coordinates were 1.0 mm rostral, 1.9 -2.0 mm lateral, and 1.9 -2.0 mm ventral from calamus scriptorius.…”

Section: Methodsmentioning

confidence: 99%

“…Such results are consistent with substantially different afferent processing along the pathways reaching neurons within CVLM compared with those in PVN. Because CVLM-and PVN-projecting NTS neurons are distinct populations of neurons (Hermes et al, 2006), we hypothesized that the pathway from cranial visceral afferents through NTS have target-specific characteristics.…”

Section: Introductionmentioning

confidence: 99%

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Cranial Visceral Afferent Pathways through the Nucleus of the Solitary Tract to Caudal Ventrolateral Medulla or Paraventricular Hypothalamus: Target-Specific Synaptic Reliability and Convergence Patterns

Bailey

Hermes

Andresen³

et al. 2006

J. Neurosci.

128

141

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Cranial visceral afferents activate central pathways that mediate systemic homeostatic processes. Afferent information arrives in the brainstem nucleus of the solitary tract (NTS) and is relayed to other CNS sites for integration into autonomic responses and complex behaviors. Little is known about the organization or nature of processing within NTS. We injected fluorescent retrograde tracers into two nuclei to identify neurons that project to sites involved in autonomic regulation: the caudal ventrolateral medulla (CVLM) or paraventricular nucleus of the hypothalamus (PVN). We found distinct differences in synaptic connections and performance in the afferent path through NTS to these neurons. Anatomical studies using confocal and electron microscopy found prominent, primary afferent synapses directly on somata and dendrites of CVLM-projecting NTS neurons identifying them as second-order neurons. In brainstem slices, afferent activation evoked large, constant latency EPSCs in CVLM-projecting NTS neurons that were consistent with the precise timing and rare failures of monosynaptic contacts on second-order neurons. In contrast, most PVN-projecting NTS neurons lacked direct afferent input and responded to afferent stimuli with highly variable, intermittently failing synaptic responses, indicating polysynaptic pathways to higher-order neurons. The afferent-evoked EPSCs in most PVN-projecting NTS neurons were smaller and unreliable but also often included multiple, convergent polysynaptic responses not observed in CVLM-projecting neurons. A few PVN-projecting NTS neurons had monosynaptic EPSC characteristics. Together, we found that cranial visceral afferent pathways are structured distinctly within NTS depending on the projection target. Such, intra-NTS pathway architecture will substantially impact performance of autonomic or neuroendocrine reflex arcs.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cranial Visceral Afferent Pathways through the Nucleus of the Solitary Tract to Caudal Ventrolateral Medulla or Paraventricular Hypothalamus: Target-Specific Synaptic Reliability and Convergence Patterns

Bailey

Hermes

Andresen³

et al. 2006

J. Neurosci.

128

141

View full text Add to dashboard Cite

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“…The NTS receives the first central synapse of glutamatergic mechano-and chemoreceptor (2), as well as afferents from the caudal-most circumventricular organ the area postrema (45). The NTS also has extensive reciprocal connections with other areas of the brainstem-forebrain autonomic system, including the ventrolateral medulla (20), hypothalamus (20), and amygdala (52).…”

Section: Introductionmentioning

confidence: 99%

Changes in the subcellular distribution of NADPH oxidase subunit p47phox in dendrites of rat dorsomedial nucleus tractus solitarius neurons in response to chronic administration of hypertensive agents

Glass

Chan

Frys

et al. 2007

Experimental Neurology

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NADPH oxidase-generated superoxide can modulate crucial intracellular signaling cascades in neurons of the nucleus tractus solitarius (NTS), a brain region that plays an important role in cardiovascular processes. Modulation of NTS signaling by superoxide may be linked to the subcellular location of the mobile NADPH oxidase p47 phox subunit, which is known to be present in dendrites of NTS neurons. It is not known, however, if hypertension can produce changes in the trafficking of p47 phox in defined NTS subregions, particularly the preferentially barosensitive dorsomedial NTS (dmNTS), or preferentially gastrointestinal medial NTS (mNTS). We used immunogold electron microscopy to determine if p47 phox localization was differentially affected in dendritic profiles of neurons from these NTS subregions of the rat in response to distinct models of hypertension, namely chronic seven-day subcutaneous administration of angiotensin II (AngII), or phenylephrine. In small (<1 μm) dendritic processes, both AngII and phenylephrine produced a decrease in intracellular p47 phox labeling selectively in dmNTS neurons. In intermediate-size (1-2 μm) dendritic profiles in the dmNTS region only, there was an increase in p47 phox labeling in response to each hypertensive agent, although these changes occurred in different subcellular compartments. There was an increase in non-vesicular labeling in response to AngII, but an increase in surface labeling with phenylephrine. Moreover, each of the changes in p47 phox targeting mentioned above occurred in dendritic profiles with, or without immunoperoxidase labeling for the AngII AT-1A receptor subtype (AT-1A). These results indicate that chronic administration of agents that induce hypertension can also produce changes in the subcellular localization in p47 phox in dmNTS neurons. Thus, systemic hypertension may produce alterations in the trafficking of proteins associated with superoxide production in central autonomic neurons, thus revealing a potentially important neurogenic component of free radical production and systemic blood pressure elevation.

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“…5A). Estimates indicate that of THϩ neurons in the NTS, 51% project to PVN and 17% to PBN, with little overlap between the two populations (Petrov et al, 1993;Hermes et al, 2006). Of functional significance is that the THϩ NTS¡PVN neurons are directly involved in cardiovascular responses (Kannan and Yamashita, 1985;Krukoff et al, 1995;Hermes et al, 2006).…”

Section: Functions and Projections Of Th؉ Neurons In Nts And Vlmmentioning

confidence: 99%

“…Estimates indicate that of THϩ neurons in the NTS, 51% project to PVN and 17% to PBN, with little overlap between the two populations (Petrov et al, 1993;Hermes et al, 2006). Of functional significance is that the THϩ NTS¡PVN neurons are directly involved in cardiovascular responses (Kannan and Yamashita, 1985;Krukoff et al, 1995;Hermes et al, 2006). A large proportion (78%) of THϩ neurons in the medial, intermediate, and commissural subnuclei of the NTS projects to the vlPAG, a structure involved in cardiovascular adjustments associated with fear and anxiety related behaviors (Chen et al, 1995).…”

Section: Functions and Projections Of Th؉ Neurons In Nts And Vlmmentioning

confidence: 99%

Medial Prefrontal Cortex

2015

Encyclopedia of Psychopharmacology

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Abstract-The infralimbic (IL) 'visceromotor' area of the rat medial prefrontal cortex projects to strategic subcortical nuclei involved in autonomic functions. Central among these targets are the nucleus tractus solitarius (NTS) and the rostral ventrolateral medulla (rVLM). By combining tract-tracing using the anterograde tracer biotinylated dextran amine (BDA) with immunolabeling for tyrosine hydroxylase (TH; an enzyme marker of catecholaminergic neurons), a limited proportion of BDA-labeled IL axonal boutons in the NTS and rVLM was found to be closely associated with TH immunopositive (؉) target structures. Such structural appositions were mainly located proximally over the labeled dendritic arbors of identified TH؉ neurons.Quantitative ultrastructural examination revealed that in NTS, TH؉ dendritic shafts comprised 7.0% of the overall post-synaptic target population innervated by BDA-labeled IL boutons, whereas TH؉ dendritic spines represented 1.25% of targets. In rVLM, TH؉ shafts represented 9.0% and TH؉ spines 2.5% of IL targets. Labeled IL boutons established exclusively asymmetric Gray Type 1 (presumed excitatory) synaptic junctions.The results indicate that subpopulations of catecholaminergic neurons in the NTS and rVLM are among the spectrum of post-synaptic neurons monosynaptically innervated by descending 'excitatory' input from IL cortex. Such connectivity, albeit restricted, identifies the potential direct influence of IL cortex on the processing and distribution of cardiovascular, respiratory and related autonomic information by catecholaminergic neurons in the NTS and VLM of the rat. The medial prefrontal cortex (mPFC) is directly involved in the integration of cognitive and autonomic functions underlying flexible goal-directed behavior (Cechetto and Saper, 1990;Neafsey et al., 1993;Loewy, 1991;Owens et al., 1999;Van Eden and Buijs, 2000;Drevets, 2000;Heidbreder and Groenewegen, 2003). In the rat, the mPFC is composed of the anterior cingulate (ACd, Brodmann area 24b), prelimbic (PL, area 32), infralimbic (IL, area 25), and peduncular (P) cortices (Neafsey et al., 1993;Gabbott et al., 2005;Resstel and Corrêa, 2006b).Anatomical and physiological evidence indicates that areas of dorsal (d) mPFC (ACd and dPL cortices) process cognitive information, whereas regions of ventromedial prefrontal cortex (vmPFC) (vPL, IL and P cortices) are also involved in autonomic and visceral functions, especially, cardiovascular and respiratory activities (Hardy and Mack, 1990;Neafsey, 1990;Loewy, 1991;Neafsey et al., 1993;Spyer, 1994;Fisk and Wyss, 2000;Uylings et al., 2003;Heidbreder and Groenewegen, 2003). Descending efferent projections from vmPFC, in particular IL cortex, innervate a wide range of subcortical autonomic centers, including the nucleus tractus solitarius (NTS) and ventrolateral medulla (VLM), brain stem nuclei strategically involved in cardiopulmonary activities (Agarwal and Calarescu, 1992;Van Giersbergen et al., 1992;Dampney, 1994;Owens and Verberne, 1996, 2000Owens et al., 1999). Indeed, stimulati...

show abstract

Most neurons in the nucleus tractus solitarii do not send collateral projections to multiple autonomic targets in the rat brain

Cited by 61 publications

References 35 publications

Cranial Visceral Afferent Pathways through the Nucleus of the Solitary Tract to Caudal Ventrolateral Medulla or Paraventricular Hypothalamus: Target-Specific Synaptic Reliability and Convergence Patterns

Cranial Visceral Afferent Pathways through the Nucleus of the Solitary Tract to Caudal Ventrolateral Medulla or Paraventricular Hypothalamus: Target-Specific Synaptic Reliability and Convergence Patterns

Changes in the subcellular distribution of NADPH oxidase subunit p47phox in dendrites of rat dorsomedial nucleus tractus solitarius neurons in response to chronic administration of hypertensive agents

Medial Prefrontal Cortex

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