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Autonomic Neuroscience : Basic &... Aug 2016The autonomic nervous system controls the heart by dynamic recruitment and withdrawal of cardiac parasympathetic and sympathetic activities. These activities are... (Review)
Review
The autonomic nervous system controls the heart by dynamic recruitment and withdrawal of cardiac parasympathetic and sympathetic activities. These activities are generated by groups of sympathoexcitatory and vagal preganglionic neurones residing in a close proximity to each other within well-defined structures of the brainstem. This short essay provides a general overview and an update on the latest developments in our understanding of the central nervous origins and functional significance of cardiac vagal tone. Significant experimental evidence suggests that distinct groups of cardiac vagal preganglionic neurones with different patterns of activity control nodal tissue (controlling the heart rate and atrioventricular conductance) and the ventricular myocardium (modulating its contractility and excitability).
Topics: Animals; Autonomic Fibers, Preganglionic; Heart; Heart Rate; Humans; Medulla Oblongata; Neurons; Vagus Nerve
PubMed: 27396874
DOI: 10.1016/j.autneu.2016.06.003 -
Comprehensive Physiology Apr 2015The sympathetic nervous system comprises one half of the autonomic nervous system and participates in maintaining homeostasis and enabling organisms to respond in an... (Review)
Review
The sympathetic nervous system comprises one half of the autonomic nervous system and participates in maintaining homeostasis and enabling organisms to respond in an appropriate manner to perturbations in their environment, either internal or external. The sympathetic preganglionic neurons (SPNs) lie within the spinal cord and their axons traverse the ventral horn to exit in ventral roots where they form synapses onto postganglionic neurons. Thus, these neurons are the last point at which the central nervous system can exert an effect to enable changes in sympathetic outflow. This review considers the degree of complexity of sympathetic control occurring at the level of the spinal cord. The morphology and targets of SPNs illustrate the diversity within this group, as do their diverse intrinsic properties which reveal some functional significance of these properties. SPNs show high degrees of coupled activity, mediated through gap junctions, that enables rapid and coordinated responses; these gap junctions contribute to the rhythmic activity so critical to sympathetic outflow. The main inputs onto SPNs are considered; these comprise afferent, descending, and interneuronal influences that themselves enable functionally appropriate changes in SPN activity. The complexity of inputs is further demonstrated by the plethora of receptors that mediate the different responses in SPNs; their origins and effects are plentiful and diverse. Together these different inputs and the intrinsic and coupled activity of SPNs result in the rhythmic nature of sympathetic outflow from the spinal cord, which has a variety of frequencies that can be altered in different conditions.
Topics: Animals; Autonomic Fibers, Preganglionic; Central Pattern Generators; Gap Junctions; Humans; Models, Neurological; Spinal Cord; Sympathetic Nervous System; Synapses
PubMed: 25880515
DOI: 10.1002/cphy.c140020 -
Neurourology and Urodynamics 2005
Topics: Autonomic Fibers, Preganglionic; Electric Stimulation Therapy; Electrodes, Implanted; Female; Humans; Perineum; Peripheral Nerves; Urinary Bladder
PubMed: 15977257
DOI: 10.1002/nau.20119 -
Cardiovascular Research Oct 2023The brain controls the heart by dynamic recruitment and withdrawal of cardiac parasympathetic (vagal) and sympathetic activity. Autonomic control is essential for the...
AIMS
The brain controls the heart by dynamic recruitment and withdrawal of cardiac parasympathetic (vagal) and sympathetic activity. Autonomic control is essential for the development of cardiovascular responses during exercise, however, the patterns of changes in the activity of the two autonomic limbs, and their functional interactions in orchestrating physiological responses during exercise, are not fully understood. The aim of this study was to characterize changes in vagal parasympathetic drive in response to exercise and exercise training by directly recording the electrical activity of vagal preganglionic neurons in experimental animals (rats).
METHODS AND RESULTS
Single unit recordings were made using carbon-fibre microelectrodes from the populations of vagal preganglionic neurons of the nucleus ambiguus (NA) and the dorsal vagal motor nucleus of the brainstem. It was found that (i) vagal preganglionic neurons of the NA and the dorsal vagal motor nucleus are strongly activated during bouts of acute exercise, and (ii) exercise training markedly increases the resting activity of both populations of vagal preganglionic neurons and augments the excitatory responses of NA neurons during exercise.
CONCLUSIONS
These data show that central vagal drive increases during exercise and provide the first direct neurophysiological evidence that exercise training increases vagal tone. The data argue against the notion of exercise-induced central vagal withdrawal during exercise. We propose that robust increases in the activity of vagal preganglionic neurons during bouts of exercise underlie activity-dependent plasticity, leading to higher resting vagal tone that confers multiple health benefits associated with regular exercise.
Topics: Rats; Animals; Autonomic Fibers, Preganglionic; Vagus Nerve; Heart; Neurons; Medulla Oblongata
PubMed: 37516977
DOI: 10.1093/cvr/cvad115 -
Clinical and Experimental Pharmacology... 20021. Amino acid neurotransmitters are critical for controlling the activity of most central neurons, including sympathetic preganglionic neurons (SPN), the spinal cord... (Review)
Review
1. Amino acid neurotransmitters are critical for controlling the activity of most central neurons, including sympathetic preganglionic neurons (SPN), the spinal cord neurons involved in controlling blood pressure and other autonomic functions. 2. In studies reviewed here, SPN were identified either by retrograde tracing from a peripheral target (superior cervical ganglion or adrenal medulla) or by detection of immunoreactivity for choline acetyltransferase (ChAT), the acetylcholine-synthesizing enzyme that is a marker for all SPN, in intact or completely transected rat spinal cord. 3. Postembedding immunogold labelling on ultrathin sections was then used to detect GABA and sometimes glutamate in nerve terminals on SPN or near them in the neuropil of the lateral horn. 4. In some cases, the terminals were prelabelled to show an anterograde tracer or immunoreactivity for ChAT or neuropeptide Y. 5. This anatomical work has provided information that is helpful in understanding how SPN are influenced by their GABAergic innervation. 6. Immunogold studies showed that the proportion of input provided by GABAergic terminals varies between different groups of SPN. For some groups, this input may be preferentially targeted to cell bodies. 7. Anterograde tracing demonstrated that supraspinal as well as intraspinal GABAergic neurons innervate SPN and investigations on completely transected cord suggested that supraspinal neurons may provide a surprisingly large proportion of the GABAergic terminals that contact SPN. 8. The double-labelling studies in which other amino acids, ChAT or neuropeptide Y were localized along with GABA indicate that GABAergic terminals contain other neurochemicals that could modulate the actions of GABA, depending on the complement of receptors that are present pre- and post-synaptically. 9. Taken together, these data indicate that GABAergic transmission to SPN may be much more complicated than suggested by the currently available electrophysiological studies.
Topics: Animals; Autonomic Fibers, Preganglionic; Dendrites; Glutamic Acid; Glycine; Immunohistochemistry; Neurons; Neuropeptide Y; Rats; Spinal Cord; gamma-Aminobutyric Acid
PubMed: 12010200
DOI: 10.1046/j.1440-1681.2002.03664.x -
Progress in Brain Research 1996
Review
Topics: Animals; Autonomic Fibers, Preganglionic; Efferent Pathways; Humans; Spinal Cord; Sympathetic Nervous System
PubMed: 8782512
DOI: 10.1016/s0079-6123(08)61857-9 -
Progress in Brain Research 1996
Review
Topics: Animals; Autonomic Fibers, Preganglionic; Interneurons; Neurons; Reflex; Sacrococcygeal Region; Spinal Cord
PubMed: 8782515
DOI: 10.1016/s0079-6123(08)61860-9 -
Annals of Neurology Sep 1985We describe the cases of eight patients with chronic idiopathic anhidrosis. These patients were heat intolerant and became hot, flushed, dizzy, dyspneic, and weak but...
We describe the cases of eight patients with chronic idiopathic anhidrosis. These patients were heat intolerant and became hot, flushed, dizzy, dyspneic, and weak but did not sweat when the ambient temperature was high or when they exercised. Four patients had preganglionic sudomotor lesions and in the remaining 4 the lesion appeared to be postganglionic. The patients did not have orthostatic hypotension, other evidence of generalized autonomic failure, or symptomatic somatic neuropathy. One patient regained thermoregulatory sweat function and no patient's condition progressed to generalized autonomic failure. Chronic idiopathic anhidrosis appears to be distinctly different from other autonomic neuropathies that tend to carry much poorer prognoses.
Topics: Adult; Autonomic Fibers, Postganglionic; Autonomic Fibers, Preganglionic; Autonomic Nervous System; Blood Pressure; Body Temperature Regulation; Chronic Disease; Female; Heart Rate; Humans; Hypohidrosis; Male; Middle Aged; Prognosis; Reflex, Pupillary; Sweating
PubMed: 4051460
DOI: 10.1002/ana.410180312 -
Canadian Journal of Physiology and... 1992Intracellular recordings from sympathetic preganglionic neurons (SPNs) in adult cat and neonatal rat spinal cord slices reveal four types of synaptic potentials, namely,... (Review)
Review
Intracellular recordings from sympathetic preganglionic neurons (SPNs) in adult cat and neonatal rat spinal cord slices reveal four types of synaptic potentials, namely, excitatory postsynaptic potentials (EPSPs), inhibitory postsynaptic potentials (IPSPs), and slow EPSPs in both preparations, and a slow IPSP in cat SPNs. Pharmacological studies show that glutamate or a related excitatory amino acid and glycine are the probable mediators of EPSPs and IPSPs. There may be heterogenous mediators of slow EPSPs; substance P, serotonin, norepinephrine, and epinephrine are all probable mediators of slow EPSPs in subpopulations of SPNs. In the case of slow IPSPs, norepinephrine appears to be the likely transmitter. Finally, stimulation of ventral roots elicits a synaptic potential that appears to be caused by glutamate released from afferent fibers in the ventral roots. Our results indicate that a multitude of synaptic mechanisms exist in the rat SPNs by means of which inputs arising from sensory and supraspinal neurons are processed in a timely and orderly manner, thus ensuring highly organized but differentiated outputs to multiple peripheral target cells.
Topics: Animals; Autonomic Fibers, Preganglionic; Cats; Electrophysiology; In Vitro Techniques; Rats; Spinal Cord; Synapses
PubMed: 1295689
DOI: 10.1139/y92-248 -
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