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The Journal of Neuroscience : the... Sep 2010Cocaine and amphetamine-regulated transcript peptide (CART) is present in a subset of sympathetic preganglionic neurons in the rat. We examined the distribution of... (Comparative Study)
Comparative Study
Cocaine and amphetamine-regulated transcript peptide (CART) is present in a subset of sympathetic preganglionic neurons in the rat. We examined the distribution of CART-immunoreactive terminals in rat stellate and superior cervical ganglia and adrenal gland and found that they surround neuropeptide Y-immunoreactive postganglionic neurons and noradrenergic chromaffin cells. The targets of CART-immunoreactive preganglionic neurons in the stellate and superior cervical ganglia were shown to be vasoconstrictor neurons supplying muscle and skin and cardiac-projecting postganglionic neurons: they did not target non-vasoconstrictor neurons innervating salivary glands, piloerector muscle, brown fat, or adrenergic chromaffin cells. Transneuronal tracing using pseudorabies virus demonstrated that many, but not all, preganglionic neurons in the vasoconstrictor pathway to forelimb skeletal muscle were CART immunoreactive. Similarly, analysis with the confocal microscope confirmed that 70% of boutons in contact with vasoconstrictor ganglion cells contained CART, whereas 30% did not. Finally, we show that CART-immunoreactive cells represented 69% of the preganglionic neuron population expressing c-Fos after systemic hypoxia. We conclude that CART is present in most, although not all, cardiovascular preganglionic neurons but not thoracic preganglionic neurons with non-cardiovascular targets. We suggest that CART immunoreactivity may identify the postulated "accessory" preganglionic neurons, whose actions may amplify vasomotor ganglionic transmission.
Topics: Adrenergic Fibers; Animals; Autonomic Fibers, Preganglionic; Cardiovascular System; Female; Immunohistochemistry; Male; Nerve Tissue Proteins; Neurons; Rats; Rats, Sprague-Dawley; Superior Cervical Ganglion; Sympathetic Fibers, Postganglionic; Vasoconstriction
PubMed: 20810898
DOI: 10.1523/JNEUROSCI.0796-10.2010 -
Progress in Neurobiology 1988
Review
Topics: Animals; Autonomic Fibers, Preganglionic; Sympathetic Nervous System; Synapses
PubMed: 3287455
DOI: 10.1016/0301-0082(88)90022-6 -
The Journal of Comparative Neurology Apr 1997The patterns and extent of vagal preganglionic divergence and convergence within the gastrointestinal tract of the rat were characterized with the anterograde tracer...
The patterns and extent of vagal preganglionic divergence and convergence within the gastrointestinal tract of the rat were characterized with the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHA-L). Three weeks after tracer was iontophoretically injected into two to four sites within the dorsal motor nucleus of the vagus, wholemounts of perfused gut organs (stomach, duodenum, cecum) were prepared, counterstained with Cuprolinic blue, and processed for PHA-L using the avidin biotin complex with diaminobenzidine. Controls included animals injected with PHA-L after intracranial deafferentations. Well-positioned injections labeled an extremely dense and intricate network of varicose efferent axons throughout the gastric myenteric plexus (including that of the fundus). Individual fibers collateralized extensively, forming a variety of pericellular arborizations and terminal complexes made up of both en passant and end swellings. Single axons frequently innervated subsets of neurons within ganglia. Most enteric neurons were contacted by varicosities of more than one vagal fiber. The patterns of vagal preganglionic fibers in the duodenal and cecal myenteric plexuses resembled the organization in the stomach in many aspects, but the projections in each organ had distinctive characteristics, and label was less dense in the intestines than in the stomach. Vagal preganglionic fibers directly innervated submucosal ganglia, although sparsely. Brainstem injections of PHA-L retrogradely labeled a few myenteric neurons in the corpus, fundus, and duodenum: These "gastrobulbar" and "duodenobulbar" neurons received reciprocal vagal preganglionic innervation. Finally, the PHA-L that spread to the nucleus of the solitary tract occasionally produced transganglionic labeling of afferent intramuscular arrays (gastric fundus). The results of this paper provide strong evidence that the traditional "command neuron" or "mother cell" hypotheses of vagal-enteric organization should be abandoned for an integrative neural network model.
Topics: Animals; Autonomic Fibers, Preganglionic; Cecum; Duodenum; Efferent Pathways; Male; Microinjections; Myenteric Plexus; Phytohemagglutinins; Rats; Rats, Sprague-Dawley; Stomach; Submucous Plexus; Vagus Nerve
PubMed: 9087421
DOI: 10.1002/(sici)1096-9861(19970428)381:1<81::aid-cne7>3.0.co;2-g -
Autonomic Neuroscience : Basic &... Aug 2010The dorsal motor nucleus of the vagus (DMV) is the main source of the vagal innervation of the pancreas. Several studies in vitro have demonstrated that the DMV consists... (Comparative Study)
Comparative Study
The dorsal motor nucleus of the vagus (DMV) is the main source of the vagal innervation of the pancreas. Several studies in vitro have demonstrated that the DMV consists of a heterogeneous population of preganglionic neurons but little is known about their electrophysiological characteristics in vivo. The aims of this study were to (i) identify DMV preganglionic neurons in vivo with axons in the pancreatic vagus and (ii) characterize their responses to stimulation of cholecystokinin (CCK(1)) and serotonin (5-HT(3)) receptors which are major regulators of pancreatic secretion. Male Sprague Dawley rats anaesthetised with isoflurane (1.5%/100% O(2)) were used throughout. Dorsal vagal preganglionic neurons were identified by antidromic activation in response to stimulation of the pancreatic vagus. Dorsal vagal preganglionic neurons had axonal conduction velocities in the C-fibre range (0.7+/-0.03 m/s). Forty-four neurons were identified within the rostral, intermediate and caudal DMV and thirty-eight were tested for responsiveness to CCK-8S (CCK(1) agonist) and phenylbiguanide (PBG; 5-HT(3) receptor agonist). CCK-8S and PBG (0.1-10 microg/kg, i.v.) produced three types of response: (i) preganglionic neurons in the intermediate DMV were inhibited by CCK-8S (n=18) and PBG (n=10), (ii) neurons in the caudal DMV were activated by CCK (n=5) and PBG (n=2) and (iii) CCK-8S (n=9) and PBG (n=7) had no effect on preganglionic neurons in the rostral DMV. CCK-8S and PBG have complex actions on preganglionic neurons in the DMV that may be related to their effects on pancreatic secretion.
Topics: Animals; Autonomic Fibers, Preganglionic; Chemokines, CC; Electric Stimulation; Male; Neural Inhibition; Rats; Rats, Sprague-Dawley; Receptors, Serotonin, 5-HT3; Serotonin 5-HT3 Receptor Agonists; Sincalide; Vagus Nerve
PubMed: 20346737
DOI: 10.1016/j.autneu.2010.03.001 -
Clinical and Experimental Pharmacology... Dec 20061. The idea is introduced that cardiac rate, contractility or atrioventricular (A-V) conduction spread may be controlled independently by the brain. Limited data from... (Review)
Review
1. The idea is introduced that cardiac rate, contractility or atrioventricular (A-V) conduction spread may be controlled independently by the brain. Limited data from reflex studies are cited to support this view. 2. Evidence is presented that individual autonomic post- and preganglionic neurons have quite specific actions on the heart. Premotor and other central neurons can have preferential actions on heart rate, contractility or A-V conduction. 3. The functional implications of selective cardiac control are discussed.
Topics: Animals; Autonomic Fibers, Postganglionic; Autonomic Fibers, Preganglionic; Brain; Brain Stem; Heart; Humans; Neural Pathways; Neurons
PubMed: 17184511
DOI: 10.1111/j.1440-1681.2006.04520.x -
The American Journal of Gastroenterology Jun 1977
Review
Topics: Acetylcholine; Adrenergic Fibers; Adrenergic alpha-Antagonists; Adrenergic beta-Antagonists; Animals; Autonomic Fibers, Postganglionic; Autonomic Fibers, Preganglionic; Celiac Plexus; Cholecystokinin; Cholinergic Fibers; Dogs; Ganglia; Humans; Islets of Langerhans; Nerve Endings; Pancreas; Parasympathetic Nervous System; Splanchnic Nerves; Vagus Nerve
PubMed: 20775
DOI: No ID Found -
The Journal of Comparative Neurology Apr 1981Previously reported preganglionic-postganglionic ratios for the sympathetic system are a major part of the evidence for the widely accepted idea that the sympathetic...
Previously reported preganglionic-postganglionic ratios for the sympathetic system are a major part of the evidence for the widely accepted idea that the sympathetic innervation of the viscera is diffuse. Unfortunately, the previous reports did not assess the non-preganglionic fibers in the nerves examined, and the limitations of light microscopy precluded accurate unmyelinated fiber counts. Thus, a recalculation of these ratios is necessary. The present study recalculates these ratios for the cervical sympathetic system of the rat. All fiber counts are done with the electron microscope which has the resolution necessary for accurately determining axon numbers. Selective surgical procedures establish that 84% of the axons in the cervical sympathetic trunk are preganglionic, 11% are postganglionic, and 5% are sensory. Thus, the numbers of preganglionic fibers can now be accurately assessed and compared to the number of postganglionic neurons in the superior cervical ganglion. When this is done, a preganglionic/postganglionic ratio of approximately 1:4 is obtained. This ratio differs considerably from those previously published.
Topics: Animals; Autonomic Fibers, Postganglionic; Autonomic Fibers, Preganglionic; Axons; Female; Ganglia, Spinal; Ganglia, Sympathetic; Male; Microscopy, Electron; Nerve Fibers, Myelinated; Rats; Sympathetic Nervous System
PubMed: 7276232
DOI: 10.1002/cne.901970204 -
Neuroscience Letters Dec 1979In anaesthetised cats the response of the soma dendritic region of sympathetic preganglionic neurones (SPN) recorded intracellularly in T3 spinal segment was studied...
In anaesthetised cats the response of the soma dendritic region of sympathetic preganglionic neurones (SPN) recorded intracellularly in T3 spinal segment was studied following excitation of third thoracic white ramus and following orthodromic inputs. Most cells had action potentials of short duration. Many cells were active. Decreases in membrane potential were relatively short lasting, less than 40 msec and a change of 5 mV was sufficient to discharge the cell. Increases in membrane potential were also evident.
Topics: Animals; Autonomic Fibers, Preganglionic; Cats; Female; Intercostal Nerves; Male; Membrane Potentials; Neural Conduction; Reflex; Sympathetic Nervous System
PubMed: 530526
DOI: 10.1016/0304-3940(79)96108-1 -
Journal of the Autonomic Nervous System Jan 1982Two types of preganglionic neurons have been identified in the sacral parasympathetic nucleus (SPN) of the cat. These neurons could be differentiated by various...
Two types of preganglionic neurons have been identified in the sacral parasympathetic nucleus (SPN) of the cat. These neurons could be differentiated by various characteristics including axonal conduction velocities, morphology, location in the nucleus, organ of innervation and central reflex mechanisms controlling their activity. Neurons having myelinated axons (B-PGNs) with conduction velocities between 3.3 and 13 m/s were located in the lateral band of the SPN and innervated the urinary bladder. Neurons with unmyelinated axons (C-PGNs) with conduction velocities of 0.5-1.4 m/s were located in the dorsal band of the nucleus and innervated the large intestine. B-PGNs were excited by distention of the bladder and inhibited by distension or mechanical stimulation of the intestine, whereas C-PGNs exhibited the opposite responses to these stimuli. C-PGNs often exhibited a low level of spontaneous discharge in absence of stimulation but exhibited marked firing (3.5-10 spikes/s) during a defecation reflex elicited by mechanical stimulation of the rectum-anal canal. The excitatory responses were elicited by C-fiber afferents via a spinal reflex pathway. B-PGNs were inactive when intravesical pressure was below the threshold for inducing micturition (5 cm H2O) but raising the pressure above the threshold induced firing consisting of repetitive bursts of action potentials occurring at relatively high frequencies (15-60 spikes/s). These bursts coincided with rhythmic bladder contractions. The frequency of bladder contractions and associated bursts of PGN-firing and the mean PGN-firing rate (2-8 spikes/s) increased as intravesical pressure was increased in steps between 5 and 30 cm H2O. However, as indicated by interspike interval histograms, the frequency of firing within a burst of action potentials was unchanged. It is concluded that the micturition reflex pathway is organized as a simple on-off switching circuit and that B-PGNs receive a maximal synaptic input when intravesical pressure exceeds the micturition threshold. This circuit was triggered by vesical A delta afferents via a spinobulbospinal pathway. Transection of the spinal cord interrupted the reflex pathway and blocked micturition. However, in chronic spinal animals a spinal reflex mechanisms emerged which contributed to the recovery of bladder function. This mechanism, which was weak or non-existent in animals with an intact neuraxis, exhibited a number of important differences from the normal micturition reflex, most notably being activated by a C-fiber afferent rather than a A delta afferent limb. The mechanism underlying the emergence of C-fiber evoked bladder reflexes in spinal animals is uncertain.
Topics: Action Potentials; Afferent Pathways; Animals; Autonomic Fibers, Preganglionic; Axons; Cats; Electric Stimulation; Ganglia, Parasympathetic; Intestines; Neurons; Spinal Cord; Synapses; Urinary Bladder; Urination
PubMed: 7056993
DOI: 10.1016/0165-1838(82)90087-x -
Clinical and Experimental Pharmacology... Dec 20061. Mental disorders associated with chronic stressors are established risk factors for cardiac morbidity and mortality, but there is no satisfactory explanation of the... (Review)
Review
1. Mental disorders associated with chronic stressors are established risk factors for cardiac morbidity and mortality, but there is no satisfactory explanation of the mechanistic link between mental and cardiac disorders. 2. The present article presents the hypothesis suggesting that abnormal functioning of serotonin 5-HT(1A) receptors in the lower brain stem may represent this missing link. Currently available data suggest that there may be a global downregulation of 5-HT(1A) receptors in depressive and panic patients. 3. Recent animal results indicate that 5-HT(1A) receptors, located in the medullary raphe, possibly on the raphe-spinal presympathetic cardiomotor neurons, reduce stress-elicited activation of these neurons. 4. Decreased density/function of 5-H(1A) receptors in the raphe area (possibly occurring during chronic stress/depression) may lead to increased sympathetic outflow to the heart and, consequently, to the increase in noradrenalin release from the cardiac sympathetic nerve terminals.
Topics: Animals; Autonomic Fibers, Postganglionic; Autonomic Fibers, Preganglionic; Brain; Brain Stem; Heart; Humans; Neural Pathways; Neurons
PubMed: 17184512
DOI: 10.1111/j.1440-1681.2006.04521.x