IV. Current concepts of vagal efferent projections to the gut

2003 ◽  
Vol 284 (3) ◽  
pp. G357-G366 ◽  
Author(s):  
Howard Y. Chang ◽  
Hiroshi Mashimo ◽  
Raj K. Goyal
Keyword(s):  
Motor Neurons ◽  
Nucleus Ambiguus ◽  
Inhibitory Neurons ◽  
Cholinergic Innervation ◽  
Motor Nucleus ◽  
Striated Muscles ◽  
Preganglionic Neurons ◽  
Excitatory Neurotransmitters ◽  
Efferent Projections ◽  
Motor Effects

Vagal efferents, consisting of distinct lower motor and preganglionic parasympathetic fibers, constitute the motor limb of vagally mediated reflexes. Arising from the nucleus ambiguus, vagal lower motor neurons (LMN) mediate reflexes involving striated muscles of the orad gut. LMNs provide cholinergic innervation to motor end plates that are inhibited by myenteric nitrergic neurons. Preganglionic neurons from the dorsal motor nucleus implement parasympathetic motor and secretory functions. Cholinergic preganglionic neurons form parallel inhibitory and excitatory vagal pathways to smooth muscle viscera and stimulate postganglionic neurons via nicotinic and muscarinic receptors. In turn, the postganglionic inhibitory neurons release ATP, VIP, and NO, whereas the excitatory neurons release ACh and substance P. Vagal motor effects are dependent on the viscera's intrinsic motor activity and the interaction between the inhibitory and excitatory vagal influences. These interactions help to explain the physiology of esophageal peristalsis, gastric motility, lower esophageal sphincter, and pyloric sphincter. Vagal secretory pathways are predominantly excitatory and involve ACh and VIP as the postganglionic excitatory neurotransmitters. Vagal effects on secretory functions are exerted either directly or via release of local mediators or circulating hormones.

Medullary pathways mediating depressor responses from Na(+)-sensitive sites in nucleus of the solitary tract

1997 ◽  
Vol 272 (1) ◽  
pp. R126-R133 ◽  
Author(s):  
S. L. Hochstenbach ◽  
J. Ciriello
Keyword(s):  
Area Postrema ◽  
Cardiovascular Response ◽  
Nucleus Ambiguus ◽  
Ventrolateral Medulla ◽  
Cell Group ◽  
Motor Nucleus ◽  
Solitary Tract ◽  
Male Wistar Rats ◽  
Efferent Projections ◽  
Series Of Experiments

Two series of experiments were done in male Wistar rats to investigate the medullary pathways that mediate the depressor responses from sodium-sensitive sites in the nucleus of the solitary tract (NTS). In the first series, the anterograde tract tracer Phaseolus vulgaris leucoagglutinin (PHA-L) was iontophoresed unilaterally at sites in the NTS at which microinjections (20 nl) of a 154-175 mM NaCl solution elicited depressor responses. PHA-L injection sites were found to be localized within the medial subnucleus of the NTS (Sm). In the medulla, PHA-L-labeled fibers and presumptive terminal boutons were observed bilaterally, but with an ipsilateral predominance, throughout the rostrocaudal extent of the NTS the dorsal motor nucleus of the vagus, area postrema, the ventrolateral medulla (VLM), and nucleus ambiguus. The pontine region, containing the A5 catecholaminergic cell group and the parabrachial nucleus, also received projections from Sm. In the second series of experiments, the effect of blocking synaptic transmission in VLM with cobalt chloride (CoCl2; 5 mM, 100 nl) on the cardiovascular response elicited by microinjection (20 nl) of hypertonic saline (154-175 mM) into the ipsilateral Sm was investigated in the alpha-chloralose-anesthetized, paralyzed, and artificially ventilated rat. Microinjection of CoCl2 into VLM, at sites shown in the previous study to receive efferent projections from Sm, significantly attenuated the depressor (60%) and bradycardic (80%) responses to stimulation of Sm. These data indicate that the sodium-sensitive region of the caudal Sm innervates VLM neurons and suggest that these VLM neurons are involved in mediating the depressor and bradycardic responses elicited by changes in the extracellular concentration of sodium.

Differential control over postganglionic neurons in rat cardiac ganglia by NA and DmnX neurons: anatomical evidence

2004 ◽  
Vol 286 (4) ◽  
pp. R625-R633 ◽  
Author(s):  
Zixi (Jack) Cheng ◽  
Hong Zhang ◽  
Shang Z. Guo ◽  
Robert Wurster ◽  
David Gozal
Keyword(s):  
Brain Stem ◽  
Motor Neurons ◽  
Nucleus Ambiguus ◽  
Motor Nucleus ◽  
Sprague Dawley ◽  
Tracer Injection ◽  
Cardiac Ganglia ◽  
Dorsal Motor Nucleus ◽  
Differential Control ◽  
The Brain

In previous single-labeling experiments, we showed that neurons in the nucleus ambiguus (NA) and the dorsal motor nucleus of the vagus (DmnX) project to intrinsic cardiac ganglia. Neurons in these two motor nuclei differ significantly in the size of their projection fields, axon caliber, and endings in cardiac ganglia. These differences in NA and DmnX axon cardiac projections raise the question as to whether they target the same, distinct, or overlapping populations of cardiac principal neurons. To address this issue, we examined vagal terminals in cardiac ganglia and tracer injection sites in the brain stem using two different anterograde tracers {1,1′-dioleyl-3,3,3′,3′-tetramethylindocarbocyanine methanesulfonate and 4-[4-(dihexadecylamino)-styryl]- N-methylpyridinium iodide} and confocal microscopy in male Sprague-Dawley rats. We found that 1) NA and DmnX neurons innervate the same cardiac ganglia, but these axons target separate subpopulations of principal neurons and 2) axons arising from neurons in the NA and DmnX in the contralateral sides of the brain stem enter the cardiac ganglionic plexus through separate bundles and preferentially innervate principal neurons near their entry regions, providing topographic mapping of vagal motor neurons in left and right brain stem vagal nuclei. Because the NA and DmnX project to distinct populations of cardiac principal neurons, we propose that they may play different roles in controlling cardiac function.

scholarly journals MET Receptor Tyrosine Kinase Regulates Vagal Laryngeal Motor Neuron Development and Lifespan Ultrasonic Vocal Communication

2020 ◽  
Author(s):  
Anna K. Kamitakahara ◽  
Ramin Ali Marandi Ghoddousi ◽  
Alexandra L. Lanjewar ◽  
Valerie M. Magalong ◽  
Hsiao-Huei Wu ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Motor Neurons ◽  
Receptor Tyrosine Kinase ◽  
Ultrasonic Vocalization ◽  
Nucleus Ambiguus ◽  
Postnatal Life ◽  
Motor Nucleus ◽  
Met Receptor ◽  
Met Receptor Tyrosine Kinase ◽  
Specific Subset

SummaryThe vagal motor nucleus ambiguus (nAmb) innervates the intrinsic muscles of the larynx, providing direct motor control over vocal production in humans and rodents. Here, we demonstrate that early developmental signaling through the MET receptor tyrosine kinase (MET) is required for proper formation of the nAmb. Embryonic deletion of Met in the developing brainstem resulted in a loss of one-third of motor neurons in the nAmb. While the remaining neurons were able to establish connections with target muscles in the larynx, advanced signal processing analyses revealed severe deficits in ultrasonic vocalization in early postnatal life. Abnormal vocalization patterns persisted into adulthood in the majority of mice tested. Interestingly, 28% of adult mice recovered the ability to vocalize demonstrating heterogeneity in circuit restitution. Together, the data establish MET as a factor necessary for development of a specific subset of neurons in the nAmb required for normal ultrasonic vocalization.

Vagal cardiac preganglionic neurons: distribution, cell types, and reflex discharges

1982 ◽  
Vol 243 (1) ◽  
pp. R92-R98 ◽  
Author(s):  
S. Nosaka ◽  
K. Yasunaga ◽  
S. Tamai
Keyword(s):  
Vagus Nerve ◽  
Cell Types ◽  
Nucleus Ambiguus ◽  
Motor Nucleus ◽  
Preganglionic Neurons ◽  
Antidromic Responses ◽  
Group 2 ◽  
Group B ◽  
The Right ◽  
Stimulation Of

In chloralose- and urethan-anesthetized rats, the cardiac branch (CB) of the vagus nerve was electrically stimulated, and antidromic responses of medullary cells were recorded. The cells identified as the vagal cardiac preganglionic neurons (VCPN) were localized in the dorsal motor nucleus (ND group, 8 cells), a region in and around the nucleus ambiguus (NA group, 7 cells) and an intermediary zone (IM group, 2 cells) lying in between. Latencies of the antidromic responses were distinctly different among the three groups, and calculated conduction velocities indicated that the VCPN of the ND group possess C-fiber axons whereas those of the NA group and probably of the IM group, B-fiber axons. In another series of experiments, the right carotid sinus nerve (CSN) or the left cervical vagus nerve was stimulated, and efferent fiber group(s) mediating reflexly evoked discharges to the CB was determined by means of two-point recordings. Among reflex discharges evoked by stimulation of the CSN the shortest latency reflex was proved to be mediated by B-efferent fibers. In contrast, among reflex discharges evoked by stimulation of the vagus nerve, the greatest reflex component was found to be conveyed by C-efferent fibers. It was concluded that the VCPN consist of two types of cells, each located in a different region of the medulla oblongata and contributing to vagal cardiac reflex mechanisms in a different manner.

Central Control of the Cardiovascular and Respiratory Systems and Their Interactions in Vertebrates

1999 ◽  
Vol 79 (3) ◽  
pp. 855-916 ◽  
Author(s):  
Edwin W. Taylor ◽  
David Jordan ◽  
John H. Coote
Keyword(s):  
Respiratory Rhythm ◽  
Nucleus Ambiguus ◽  
Motor Nucleus ◽  
Cardiorespiratory System ◽  
Preganglionic Neurons ◽  
Larval Amphibians ◽  
Dorsal Motor Nucleus ◽  
Changing Roles ◽  
Productive Research ◽  
And Control

This review explores the fundamental neuranatomical and functional bases for integration of the respiratory and cardiovascular systems in vertebrates and traces their evolution through the vertebrate groups, from primarily water-breathing fish and larval amphibians to facultative air-breathers such as lungfish and some adult amphibians and finally obligate air-breathers among the reptiles, birds, and mammals. A comparative account of respiratory rhythm generation leads to consideration of the changing roles in cardiorespiratory integration for central and peripheral chemoreceptors and mechanoreceptors and their central projections. We review evidence of a developing role in the control of cardiorespiratory interactions for the partial relocation from the dorsal motor nucleus of the vagus into the nucleus ambiguus of vagal preganglionic neurons, and in particular those innervating the heart, and for the existence of a functional topography of specific groups of sympathetic preganglionic neurons in the spinal cord. Finally, we consider the mechanisms generating temporal modulation of heart rate, vasomotor tone, and control of the airways in mammals; cardiorespiratory synchrony in fish; and integration of the cardiorespiratory system during intermittent breathing in amphibians, reptiles, and diving birds. Concluding comments suggest areas for further productive research.

Differential Ca2+ signaling characteristics of inhibitory and excitatory myenteric motor neurons in culture

2000 ◽  
Vol 279 (5) ◽  
pp. G1121-G1127 ◽  
Author(s):  
Pieter Vanden Berghe ◽  
Sander Molhoek ◽  
Ludwig Missiaen ◽  
Jan Tack ◽  
Jozef Janssens
Keyword(s):  
Substance P ◽  
Motor Neurons ◽  
Circular Muscle ◽  
Receptor Expression ◽  
Inhibitory Neurons ◽  
Excitatory Neurotransmitter ◽  
Retrograde Labeling ◽  
Transient Rise ◽  
Excitatory Neurotransmitters ◽  
Intracellular Ca

Physiological studies on functionally identified myenteric neurons are scarce because of technical limitations. We combined retrograde labeling, cell culturing, and fluorescent intracellular Ca2+ concentration ([Ca2+]i) signaling to study excitatory neurotransmitter responsiveness of myenteric motor neurons. 1,1-Didodecyl-3,3,3′,3′-tetramethyl indocarbocyanine (DiI) was used to label circular muscle motor neurons of the guinea pig ileum. DiI-labeled neurons were easily detectable in cultures prepared from these segments. The excitatory neurotransmitters (10−5 M) acetylcholine, substance P, and serotonin induced a transient rise in [Ca2+]i in subsets of DiI-labeled neurons (66.7, 56.5, and 84.3%, respectively). DiI-labeled motor neurons were either inhibitory (23.8%) or excitatory (76.2%) as assessed by staining for nitric oxide synthase or choline acetyltransferase. Compared with excitatory motor neurons, significantly fewer inhibitory neurons in culture responded to acetylcholine (0 vs. 69%) and substance P (12.5 vs. 69.2%). We conclude that combining retrograde labeling and Ca2+ imaging allows identification of differential receptor expression in functionally identified neurons in culture.

Attenuation of baroreflex sensitivity after domoic acid lesion of the nucleus ambiguus of rats

2004 ◽  
Vol 96 (3) ◽  
pp. 1137-1145 ◽  
Author(s):  
Zixi (Jack) Cheng ◽  
Hong Zhang ◽  
Jerry Yu ◽  
Robert D. Wurster ◽  
David Gozal
Keyword(s):  
Electrical Stimulation ◽  
Motor Neurons ◽  
Domoic Acid ◽  
Baroreflex Sensitivity ◽  
Neuronal Loss ◽  
Nucleus Ambiguus ◽  
Motor Nucleus ◽  
Sprague Dawley ◽  
Baroreflex Control ◽  
Stimulation Of

The nucleus ambiguus (NA) and the dorsal motor nucleus of the vagus (DmnX) innervate distinct populations of cardiac ganglionic principal neurons. This anatomic evidence suggests that these two nuclei play different roles (Cheng Z and Powley TL, Soc Neurosci Abstr 26: 1189, 2000). However, lesion of the DmnX does not attenuate baroreflex sensitivity (Cheng Z, Guo SZ, Lipton AJ, and Gozal D, J Neurosci 22: 3215–3226, 2002). The present study tested the functional role of the NA in baroreflex control of heart rate (HR). Domoic acid (DA) was injected into the left NA of Sprague-Dawley rats to lesion the NA. The neuronal loss was assessed using retrograde labeling and confocal microscopy. HR changes induced by phenylephrine and sodium nitroprusside administration and after electrical stimulation of the left vagal trunk were measured at 15 days, and HR responses to left NA microinjection of l-glutamate were determined at 180 days postlesion. Compared with vehicle injections, DA lesions significantly reduced the population of NA motor neurons by ∼68% ( P < 0.01) and attenuated baroreflex sensitivity by ∼83% ( P < 0.01) at 15 days. Similarly, electrical stimulation of the vagal trunk of DA-lesioned animals led to attenuated decreases in HR responses. NA neuronal counts were reduced by ∼81% ( P < 0.01) and mean HR responses to l-glutamate injection into the lesioned NA were attenuated by ∼65% ( P < 0.01) at 180 days. Therefore, the NA plays a major role in baroreflex control of HR, and the integrity of the NA is critically important for the normal baroreflex control. In addition, NA lesions produce long-term anatomic and functional dysfunction of the nucleus, and thus it may provide an useful model for functional assessment of respective roles of the NA and DmnX.

Potential of Motor Neurons in the Nucleus Ambiguus ∼ Utilizing Nestin-EGFP Transgenic Rats

2007 ◽  
Vol 58 (2) ◽  
pp. 193-193
Author(s):  
T. Takaoka ◽  
A. Shiotani ◽  
K. Saito ◽  
M. Tomifuji ◽  
Y. Mori ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Nucleus Ambiguus ◽  
Transgenic Rats

scholarly journals Catecholaminergic Fiber Innervation of the Vocal Motor System Is Intrasexually Dimorphic in a Teleost with Alternative Reproductive Tactics

2015 ◽  
Vol 86 (2) ◽  
pp. 131-144 ◽  
Author(s):  
Zachary N. Ghahramani ◽  
Miky Timothy ◽  
Gurpreet Kaur ◽  
Michelle Gorbonosov ◽  
Alena Chernenko ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Motor System ◽  
Advertisement Call ◽  
Motor Nucleus ◽  
Type I ◽  
Type Ii ◽  
Fiber Density ◽  
Reproductive Tactics ◽  
Long Duration ◽  
Behavioral Divergence

Catecholamines, which include the neurotransmitters dopamine and noradrenaline, are known modulators of sensorimotor function, reproduction, and sexually motivated behaviors across vertebrates, including vocal-acoustic communication. Recently, we demonstrated robust catecholaminergic (CA) innervation throughout the vocal motor system in the plainfin midshipman fish Porichthys notatus, a seasonal breeding marine teleost that produces vocal signals for social communication. There are 2 distinct male reproductive morphs in this species: type I males establish nests and court females with a long-duration advertisement call, while type II males sneak spawn to steal fertilizations from type I males. Like females, type II males can only produce brief, agonistic, grunt type vocalizations. Here, we tested the hypothesis that intrasexual differences in the number of CA neurons and their fiber innervation patterns throughout the vocal motor pathway may provide neural substrates underlying divergence in reproductive behavior between morphs. We employed immunofluorescence (-ir) histochemistry to measure tyrosine hydroxylase (TH; a rate-limiting enzyme in catecholamine synthesis) neuron numbers in several forebrain and hindbrain nuclei as well as TH-ir fiber innervation throughout the vocal pathway in type I and type II males collected from nests during the summer reproductive season. After controlling for differences in body size, only one group of CA neurons displayed an unequivocal difference between male morphs: the extraventricular vagal-associated TH-ir neurons, located just lateral to the dimorphic vocal motor nucleus (VMN), were significantly greater in number in type II males. In addition, type II males exhibited greater TH-ir fiber density within the VMN and greater numbers of TH-ir varicosities with putative contacts on vocal motor neurons. This strong inverse relationship between the predominant vocal morphotype and the CA innervation of vocal motor neurons suggests that catecholamines may function to inhibit vocal output in midshipman. These findings support catecholamines as direct modulators of vocal behavior, and differential CA input appears reflective of social and reproductive behavioral divergence between male midshipman morphs.

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