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Robert M Bradley - One of the best experts on this subject based on the ideXlab platform.
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gustatory Solitary Tract development a role for neuropilins
Neuroscience, 2013Co-Authors: Sara L Corson, Charlotte M. Mistretta, Robert M BradleyAbstract:AbsTract The rostral nucleus of the Solitary Tract (rNST) receives orosensory information from taste bud cells in the tongue and palate via cranial nerves VII and IX. These nerves enter the brainstem, form the Solitary Tract (ST) and synapse with neurons in the rNST, which then relay incoming sensory information to other brain areas to process external gustatory stimuli. Factors that direct or regulate the trajectory of the developing ST are largely unknown. We used 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI) to identify ST projections originating from cells in the geniculate ganglia of embryonic rats from embryonic day 14 through 18 (E14–E18). After identifying the ST fibers, immunolabeling for and protein expression analysis of the axon guidance molecules neuropilin-1 (Npn-1) and neuropilin-2 (Npn-2) and their binding partners, semaphorin-3A (Sema-3A) and semaphorin-3F (Sema-3F) were performed. The results detail the formation of ST projections into the gustatory brainstem and their relationship to developing rNST neurons. DiI-labeled ST fibers were present in the brainstem as early as E14. Npn-1 was expressed in the ST and in the trigeminal Tract at E14, but levels of the protein declined through E18. The expression levels of the binding partner of Npn-1, Sema-3A, increased from E14 to E18. Npn-2 was expressed in the ST and, additionally, in radially oriented, tuft-like structures within the brainstem at E14. Expression levels of Npn-2 also declined through E18, in contrast to the expression levels of its binding partner, Sema-3F, which increased during this time period. For the first time, the time course and particular molecular components involved in development of the ST have been identified. These results indicate that the neuropilin and semaphorin families of axon guidance molecules are potential molecular participants in ST formation.
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physiological and anatomical properties of intramedullary projection neurons in rat rostral nucleus of the Solitary Tract
Journal of Neurophysiology, 2013Co-Authors: James A Corson, Robert M BradleyAbstract:The rostral nucleus of the Solitary Tract (rNTS), the first-order relay of gustatory information, not only transmits sensory information to more rostral brain areas but also connects to various bra...
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pre and postnatal differences in membrane action potential and ion channel properties of rostral nucleus of the Solitary Tract neurons
Journal of Neurophysiology, 2011Co-Authors: Takeshi Suwabe, Charlotte M. Mistretta, Catherine Krull, Robert M BradleyAbstract:There is little known about the prenatal development of the rostral nucleus of the Solitary Tract (rNST) neurons in rodents or the factors that influence circuit formation. With morphological and e...
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properties of gabaergic neurons in the rostral Solitary Tract nucleus in mice
Journal of Neurophysiology, 2010Co-Authors: Min Wang, Robert M BradleyAbstract:The rostral nucleus of the Solitary Tract (rNST) plays a pivotal role in taste processing. The rNST contains projection neurons and interneurons that differ in morphology and intrinsic membrane pro...
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characteristics of rostral Solitary Tract nucleus neurons with identified afferent connections that project to the parabrachial nucleus in rats
Journal of Neurophysiology, 2009Co-Authors: Takeshi Suwabe, Robert M BradleyAbstract:Afferent information derived from oral chemoreceptors is transmitted to second-order neurons in the rostral Solitary Tract nucleus (rNST) and then relayed to other CNS locations responsible for com...
Michael Andresen - One of the best experts on this subject based on the ideXlab platform.
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convergence of cranial visceral afferents within the Solitary Tract nucleus
The Journal of Neuroscience, 2009Co-Authors: Stuart J. Mcdougall, James H Peters, Michael AndresenAbstract:Primary afferent axons within the Solitary Tract (ST) relay homeostatic information via glutamatergic synapses directly to second-order neurons within the nucleus of the Solitary Tract (NTS). These primary afferents arise from multiple organ systems and relay multiple sensory modalities. How this compact network organizes the flow of primary afferent information will shape central homeostatic control. To assess afferent convergence and divergence, we recorded ST-evoked synaptic responses in pairs of medial NTS neurons in horizontal brainstem slices. ST shocks activated EPSCs along monosynaptic or polysynaptic pathways. Gradations in shock intensity discriminated multiple inputs and stimulus recruitment profiles indicated that each EPSC was unitary. In 24 pairs, 75% were second-order neurons with 64% receiving one direct ST input with the remainder receiving additional convergent ST afferent inputs (22% two; 14% three monosynaptic ST-EPSCs). Some (34%) second-order neurons received polysynaptic EPSCs. Neurons receiving only higher-order inputs were uncommon (13%). Most ST-EPSCs were completely independent, but 4 EPSCs of a total of 81 had equal thresholds, highly correlated latencies, and synchronized synaptic failures consistent with divergence from a single source ST axon or from a common interneuron producing a pair of polysynaptic EPSCs. We conclude that ST afferent inputs are remarkably independent with little evidence of substantial shared information. Individual cells receive highly focused information from the viscera. Thus, afferent excitation of second-order NTS neurons is generally dominated by single visceral afferents and therefore focused on a single afferent modality and/or organ region.
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comparison of baroreceptive to other afferent synaptic transmission to the medial Solitary Tract nucleus
American Journal of Physiology-heart and Circulatory Physiology, 2008Co-Authors: Michael Andresen, James H PetersAbstract:Cranial nerve visceral afferents enter the brain stem to synapse on neurons within the Solitary Tract nucleus (NTS). The broad heterogeneity of both visceral afferents and NTS neurons makes underst...
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organization and properties of gabaergic neurons in Solitary Tract nucleus nts
Journal of Neurophysiology, 2008Co-Authors: Timothy W Bailey, Suzanne M Appleyard, Michael AndresenAbstract:Cranial visceral afferents enter the brain at the Solitary Tract nucleus (NTS). GABAergic neurons are scattered throughout the NTS, but their relation to Solitary Tract (ST) afferent pathways is im...
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visceral afferents directly activate catecholamine neurons in the Solitary Tract nucleus
The Journal of Neuroscience, 2007Co-Authors: Suzanne M Appleyard, Daniel L Marks, Kazuto Kobayashi, Hideyuki Okano, Michael AndresenAbstract:Brainstem A2/C2 neurons are catecholamine (CA) neurons within the Solitary Tract nucleus (NTS) that influence many homeostatic functions, including cardiovascular reflexes, food intake, and stress. Because NTS is a major interface between sensory visceral afferents and the CNS, NTS CA neurons are ideally suited to coordinate complex responses by their projections to multiple brain regions. To test how NTS CA neurons process visceral afferent information carried by Solitary Tract (ST) afferents, we identified CA neurons using transgenic mice expressing TH-EGFP (enhanced green fluorescent protein under the control of the tyrosine hydroxylase promoter) and recorded synaptic responses to ST activation in horizontal slices. ST shocks evoked large-amplitude, short-latency, glutamatergic EPSCs (ST-EPSCs) in 90% of NTS CA neurons. Within neurons, ST-EPSCs had constant latency, rarely failed, and depressed substantially at high ST frequencies, indicating that NTS CA neurons receive direct monosynaptic connections from afferent terminals. NTS CA neurons received direct ST inputs from only one or two afferent fibers, with one-half also receiving smaller amplitude indirect inputs. Up to 90% of ST shocks evoked action potentials in NTS CA neurons. However, transmission of sensory afferent information through NTS CA neurons critically depended on the expression of an A-type potassium current ( I KA), which when active attenuated ST-activated action potentials to a 37% success rate. The satiety peptide, cholecystokinin, presynaptically facilitated glutamate transmission in one-half of NTS CA neurons. Thus, NTS CA neurons are directly driven by visceral afferents with output being modulated by presynaptic peptide receptors and postsynaptic potassium channels.
James H Peters - One of the best experts on this subject based on the ideXlab platform.
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GABAB-mediated inhibition of multiple modes of glutamate release in the nucleus of the Solitary Tract
Journal of Neurophysiology, 2011Co-Authors: Jessica A. Fawley, James H Peters, Michael C. AndresenAbstract:In the caudal portions of the Solitary Tract (ST) nucleus, primary sensory afferents fall into two broad classes based on the expression of transient receptor potential vanilloid type 1 (TRPV1) rec...
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convergence of cranial visceral afferents within the Solitary Tract nucleus
The Journal of Neuroscience, 2009Co-Authors: Stuart J. Mcdougall, James H Peters, Michael AndresenAbstract:Primary afferent axons within the Solitary Tract (ST) relay homeostatic information via glutamatergic synapses directly to second-order neurons within the nucleus of the Solitary Tract (NTS). These primary afferents arise from multiple organ systems and relay multiple sensory modalities. How this compact network organizes the flow of primary afferent information will shape central homeostatic control. To assess afferent convergence and divergence, we recorded ST-evoked synaptic responses in pairs of medial NTS neurons in horizontal brainstem slices. ST shocks activated EPSCs along monosynaptic or polysynaptic pathways. Gradations in shock intensity discriminated multiple inputs and stimulus recruitment profiles indicated that each EPSC was unitary. In 24 pairs, 75% were second-order neurons with 64% receiving one direct ST input with the remainder receiving additional convergent ST afferent inputs (22% two; 14% three monosynaptic ST-EPSCs). Some (34%) second-order neurons received polysynaptic EPSCs. Neurons receiving only higher-order inputs were uncommon (13%). Most ST-EPSCs were completely independent, but 4 EPSCs of a total of 81 had equal thresholds, highly correlated latencies, and synchronized synaptic failures consistent with divergence from a single source ST axon or from a common interneuron producing a pair of polysynaptic EPSCs. We conclude that ST afferent inputs are remarkably independent with little evidence of substantial shared information. Individual cells receive highly focused information from the viscera. Thus, afferent excitation of second-order NTS neurons is generally dominated by single visceral afferents and therefore focused on a single afferent modality and/or organ region.
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comparison of baroreceptive to other afferent synaptic transmission to the medial Solitary Tract nucleus
American Journal of Physiology-heart and Circulatory Physiology, 2008Co-Authors: Michael Andresen, James H PetersAbstract:Cranial nerve visceral afferents enter the brain stem to synapse on neurons within the Solitary Tract nucleus (NTS). The broad heterogeneity of both visceral afferents and NTS neurons makes underst...
Suzanne M Appleyard - One of the best experts on this subject based on the ideXlab platform.
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Effects of acute and chronic nicotine on catecholamine neurons of the nucleus of the Solitary Tract.
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2018Co-Authors: Stephen J. Page, Suzanne M AppleyardAbstract:Nicotine is an addictive drug that has broad effects throughout the brain. One site of action is the nucleus of the Solitary Tract (NTS), where nicotine initiates a stress response and modulates ca...
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organization and properties of gabaergic neurons in Solitary Tract nucleus nts
Journal of Neurophysiology, 2008Co-Authors: Timothy W Bailey, Suzanne M Appleyard, Michael AndresenAbstract:Cranial visceral afferents enter the brain at the Solitary Tract nucleus (NTS). GABAergic neurons are scattered throughout the NTS, but their relation to Solitary Tract (ST) afferent pathways is im...
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visceral afferents directly activate catecholamine neurons in the Solitary Tract nucleus
The Journal of Neuroscience, 2007Co-Authors: Suzanne M Appleyard, Daniel L Marks, Kazuto Kobayashi, Hideyuki Okano, Michael AndresenAbstract:Brainstem A2/C2 neurons are catecholamine (CA) neurons within the Solitary Tract nucleus (NTS) that influence many homeostatic functions, including cardiovascular reflexes, food intake, and stress. Because NTS is a major interface between sensory visceral afferents and the CNS, NTS CA neurons are ideally suited to coordinate complex responses by their projections to multiple brain regions. To test how NTS CA neurons process visceral afferent information carried by Solitary Tract (ST) afferents, we identified CA neurons using transgenic mice expressing TH-EGFP (enhanced green fluorescent protein under the control of the tyrosine hydroxylase promoter) and recorded synaptic responses to ST activation in horizontal slices. ST shocks evoked large-amplitude, short-latency, glutamatergic EPSCs (ST-EPSCs) in 90% of NTS CA neurons. Within neurons, ST-EPSCs had constant latency, rarely failed, and depressed substantially at high ST frequencies, indicating that NTS CA neurons receive direct monosynaptic connections from afferent terminals. NTS CA neurons received direct ST inputs from only one or two afferent fibers, with one-half also receiving smaller amplitude indirect inputs. Up to 90% of ST shocks evoked action potentials in NTS CA neurons. However, transmission of sensory afferent information through NTS CA neurons critically depended on the expression of an A-type potassium current ( I KA), which when active attenuated ST-activated action potentials to a 37% success rate. The satiety peptide, cholecystokinin, presynaptically facilitated glutamate transmission in one-half of NTS CA neurons. Thus, NTS CA neurons are directly driven by visceral afferents with output being modulated by presynaptic peptide receptors and postsynaptic potassium channels.
Julian F R Paton - One of the best experts on this subject based on the ideXlab platform.
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Integration of cornea and cardiorespiratory afferents in the nucleus of the Solitary Tract of the rat.
American Journal of Physiology-heart and Circulatory Physiology, 2002Co-Authors: Pedro Boscan, Julian F R PatonAbstract:We determined the activity of neurons within the nucleus of the Solitary Tract (NTS) after stimulation of the cornea and assessed whether this input affected the processing of baroreceptor and peri...
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properties of Solitary Tract neurones responding to peripheral arterial chemoreceptors
Neuroscience, 2001Co-Authors: Julian F R Paton, Yuwen Li, Jim Deuchars, Sergey KasparovAbstract:AbsTract Despite the highly integrated pattern of response evoked by peripheral chemoreceptor stimulation, limited information exists regarding the neurones within the nucleus of the Solitary Tract that mediate this reflex. Using a working heart–brainstem preparation, we describe evoked synaptic response patterns, some intrinsic membrane properties, location, morphology and axonal projections of physiologically characterised ‘chemoreceptive’ neurones located in the Solitary Tract nucleus in the rat. From 172 whole cell recordings, 56 neurones were identified as chemoreceptive since they responded to aortic injections of low doses of sodium cyanide (2–5 μg). Chemoreceptive neurones had a mean resting membrane potential of −52±1 mV and input resistance was 297±15 MΩ ( n =56). Synaptic responses evoked included excitatory synaptic potentials alone, excitatory–inhibitory post-synaptic potential complexes, inhibitory synaptic potentials alone and central respiratory modulated synaptic potentials. Synaptic response latency data were obtained by stimulating electrically the Solitary Tract: the mean excitatory synaptic latency was 5.2±0.4 ms (range 2.5–8.0 ms; n =17). Chemoreceptive neurones showed a heterogeneity in their intrinsic membrane properties: neurones displayed either steady state, augmenting or adapting firing responses to depolarising current injection and, in some neurones, either delayed excitation or rebound activity following hyperpolarising pulses. Eleven chemoreceptive neurones were labelled and provided the first morphological data of these cells. Labelled somata were detected dorsomedial or medial to the Solitary Tract spanning the obex. Neurones typically had three to eight primary dendrites which often entered the Solitary Tract as well as extending across the ipsilateral region of the nucleus of the Solitary Tract. Axons were mostly unmyelinated with boutons of the en passant variety and often ramified within the Solitary Tract nucleus as well as coursed towards the ipsilateral ventral medulla. In summary, this study provides new data on the neurophysiological, anatomical and morphological properties of nucleus of the Solitary Tract neurones responding to arterial chemoreceptors in the rat.
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baroreflex inhibition of cardiac sympathetic outflow is attenuated by angiotensin ii in the nucleus of the Solitary Tract
Neuroscience, 2001Co-Authors: Pedro Boscan, Andrew M Allen, Julian F R PatonAbstract:Homeostatic regulation of arterial pressure is maintained by arterial baroreceptors. Activation of these receptors results in an inhibition of sympathetic activity to the heart. It is known that angiotensin II in the nucleus Tractus solitarii attenuates the baroreceptor reflex-evoked vagal bradycardia. Here, we determined whether the cardiac sympathetic component of the baroreceptor reflex could be modulated by angiotensin II in the nucleus of the Solitary Tract. An in situ, arterially perfused working heart–brainstem preparation of rat was employed and the sympathetic inferior cardiac nerve recorded. Increases in perfusion pressure caused a reflex bradycardia and inhibition of inferior cardiac nerve activity. Microinjection of angiotensin II (500 fmol) in the nucleus of the Solitary Tract attenuated significantly both the reflex bradycardia and inhibition of inferior cardiac nerve activity (P<0.01). The latter was reversible and sensitive to losartan, an angiotensin II type 1 receptor antagonist. In contrast, the peripheral chemoreceptor reflex evoked an increase in inferior cardiac nerve activity that was not affected by angiotensin II applied exogenously in the nucleus of the Solitary Tract. We conclude that within the nucleus of the Solitary Tract angiotensin II exerts a powerful and specific inhibitory modulation of the baroreceptor reflex control of sympathetic nerve activity destined for the heart. We suggest that our data may have clinical implications relating to hypertension, a condition when angiotensin II activity is heightened in the brain and the efficacy of the baroreflex is reduced.
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Baroreflex inhibition of cardiac sympathetic outflow is attenuated by angiotensin II in the nucleus of the Solitary Tract
Neuroscience, 2001Co-Authors: Pedro Boscan, Andrew M Allen, Julian F R PatonAbstract:Homeostatic regulation of arterial pressure is maintained by arterial baroreceptors. Activation of these receptors results in an inhibition of sympathetic activity to the heart. It is known that angiotensin II in the nucleus Tractus solitarii attenuates the baroreceptor reflex-evoked vagal bradycardia. Here, we determined whether the cardiac sympathetic component of the baroreceptor reflex could be modulated by angiotensin II in the nucleus of the Solitary Tract. An in situ, arterially perfused working heart–brainstem preparation of rat was employed and the sympathetic inferior cardiac nerve recorded. Increases in perfusion pressure caused a reflex bradycardia and inhibition of inferior cardiac nerve activity. Microinjection of angiotensin II (500 fmol) in the nucleus of the Solitary Tract attenuated significantly both the reflex bradycardia and inhibition of inferior cardiac nerve activity (P
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Properties of Solitary Tract neurons receiving inputs from the sub-diaphragmatic vagus nerve
Neuroscience, 1999Co-Authors: Julian F R Paton, Jim Deuchars, Y.-w. Li, Sergey KasparovAbstract:AbsTract Vagal afferents ascending from the gastrointestinal Tract synapse on neurons in the nucleus of the Solitary Tract. Although these neurons constitute a significant proportion of Solitary Tract cells their firing behaviour and synaptic properties are not documented. Since gastrointestinal Tract afferent termination sites overlap with regions mediating cardiorespiratory reflexes the possibility of convergence with afferents mediating cardiovascular and respiratory reflexes was proposed. Here we describe some electrophysiological and morphological properties of Solitary Tract neurons orthodromically driven from the sub-diaphragmatic vagus nerves and assess possible convergent inputs from cardiorespiratory afferents. Whole-cell recordings of Solitary Tract neurons responding to electrical stimulation of the sub-diaphragmatic vagus nerves (0.1–1 ms; 1–10 V; 2–20 Hz) were made in a working heart–brainstem preparation of rat. Baroreceptors were stimulated by raising pressure in the aorta or carotid sinus, whereas aortic injection of sodium cyanide (0.05% solution 25–50 μl) was used to activate peripheral chemoreceptors. Phrenic nerve activity and heart rate were monitored continuously. Of 88 Solitary Tract neurons tested, 39 responded with an evoked excitatory synaptic potential following stimulation of the sub-diaphragmatic vagus nerves. Resting membrane potential and input resistance of sub-diaphragmatic vagus nerve driven Solitary Tract neurons were 53.2±0.5 mV and 291+17 MΩ, respectively (mean±S.E.M.). Response latencies to sub-diaphragmatic vagus nerve stimulation were divided into two groups: n =7; mean±S.E.M.) and >20 ms (77.3±5 ms, n =32). One additional neuron displayed an evoked inhibitory postsynaptic potential (latency 175 ms). Nineteen neurons showed ongoing activity which consisted of either irregular single action potential firing (0.5–10 Hz; n =12) or burst discharge ( n =7). Of 33 neurons tested, 17 showed spike frequency adaptation during injection of positive current, whereas 19 of 38 cells displayed rebound excitation following release from hyperpolarized potentials. There was no correlation between these properties and synaptic latencies. Ninety-one per cent of neurons tested displayed synaptic depression following paired pulse stimulation of the sub-diaphragmatic vagus nerve over intervals up to 500 ms. Stimulation of either baroreceptors ( n =31) or chemoreceptors ( n =36) failed to elicit a synaptic response in all sub-diaphragmatic vagus nerve-driven Solitary Tract neurons. Neurobiotin-labelled Solitary Tract neurons ( n =10) were from both latency groups and were located medial to the Solitary Tract at the level of area postrema, −0.3 mm to +1 mm from the obex. One cell was located in commissural subnucleus at midline, seven cells dorsal to the Tractus solitarius and three ventral and medial to it. Soma sizes were 23±9.6×14±4.9 μm (range: 50×16 μm to 15×7 μm). The number of primary dendrites varied from three to five, secondary from one to eight and tertiary zero to four. Labelled axons were found in seven cells which ramified extensively in the Solitary Tract nucleus ( n =3) and/or branched extensively in the dorsal vagal motonucleus ( n =3) and/or projected towards the ventrolateral medulla ( n =3). We conclude that Solitary Tract neurons receiving signals from the sub-diaphragmatic vagus nerves (most likely from gastrointestinal Tract structures) appear to be a distinct pool of neurons. There was a heterogeneity in terms of both their ongoing activity and projection targets but despite this, there were three consistent properties. First, sub-diaphragmatic vagus nerve evoked predominantly excitatory synaptic responses in Solitary Tract neurons; second, neurons exhibited lasting paired pulse depression following activation of sub-diaphragmatic vagus nerves; and third, sub-diaphragmatic vagus nerve-driven Solitary Tract neurons were not responsive to either baroreceptor or chemoreceptor stimulation.
