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European Journal of Clinical... Dec 2000Based on recent evidence from in vitro and gene knockout/insertion studies, this short review summarizes the molecular scenario underlying the development of adrenal... (Review)
Review
Based on recent evidence from in vitro and gene knockout/insertion studies, this short review summarizes the molecular scenario underlying the development of adrenal chromaffin cells and their preganglionic innervation. During migration of neural crest cells from the dorsal surface of the neural tube to their destinations in the sympathetic primordia and adrenal glands, precursors of the so-called sympathoadrenal (SA) cell lineage are exposed to signals from the notochord and ventral neural tube probably including the protein, Sonic hedgehog. These, and signals in the region of the dorsal aorta (members of the family of bone morphogentic proteins), where SA progenitor cells subsequently assemble, are essential for the induction of the adrenergic phenotype. SA progenitor cells subsequently differentiate into paravertebral and prevertebral sympathetic neurones, intra- and extra-adrenal chromaffin cells and intermediate SIF (small intensely fluorescent) cells. Based on in vitro studies with isolated SA and chromaffin progenitor cells, glucocortiocids have been claimed as essential for suppressing neuronal commitment and for channelling SA cells towards the chromaffin phenotype. However, mice deficient for a functional glucocorticoid receptor possess the full complement of adrenal chromaffin cells at birth, suggesting that signals other than glucocorticoid hormones may be important in triggering chromaffin cell differentiation. The cholinergic neurones that are preganglionic to adrenal chromaffin cells have their cell bodies located in the intermediolateral column (IML) of the spinal cord. For their normal development, these neurones require signals from the adrenal medulla, which include neurotrophin-4, a major neurotrophic factor of adrenal chromaffin cells. Taken together, these data provide a more complete picture of molecular signalling in the development of one of the most important neuroendocrine tissues in vertebrates.
Topics: Animals; Autonomic Fibers, Preganglionic; Chromaffin Cells; Glucocorticoids; Humans; Neural Crest; Spinal Cord; Stem Cells; Sympathetic Nervous System
PubMed: 11281376
DOI: 10.1046/j.1365-2362.2000.0300s3087.x -
Progress in Brain Research 2006Spinal cord injuries above mid-thoracic levels can lead to a potentially life-threatening hypertensive condition termed autonomic dysreflexia that is often triggered by... (Review)
Review
Spinal cord injuries above mid-thoracic levels can lead to a potentially life-threatening hypertensive condition termed autonomic dysreflexia that is often triggered by distension of pelvic viscera (bladder or bowel). This syndrome is characterized by episodic hypertension due to sudden, massive discharge of sympathetic preganglionic neurons in the thoracolumbar spinal cord. This hypertension is usually accompanied by bradycardia, particularly if the injury is caudal to the 2nd to 4th thoracic spinal segments. The development of autonomic dysreflexia is correlated with aberrant sprouting of peptidergic afferent fibers into the spinal cord below the injury. In particular, sprouting of nerve growth factor-responsive afferent fibers has been shown to have a major influence on dysreflexia, perhaps by amplifying the activation of disinhibited sympathetic neurons. Using a model of noxious bowel distension after complete thoracic spinal transection at the 4th thoracic segment in rats, we selectively altered C-fiber sprouting, at specified spinal levels caudal to the injury, with microinjections of adenovirus encoding the growth-promoting nerve growth factor or the growth-inhibitory semaphorin 3A. This was followed by assessment of physiological responses to colorectal distension and subsequent histology. Additionally, anterograde tract tracers were injected into the lumbosacral region to compare the extent of labeled propriospinal rostral projections in uninjured cords to those in cords after complete 4th thoracic transection. In summary, overexpression of chemorepulsive semaphorin 3A impeded C-fiber sprouting in lumbosacral segments and mitigated hypertensive autonomic dysreflexia, whereas the opposite results were obtained with nerve growth factor overexpression. Furthermore, compared to naïve rats, there were significantly more labeled lumbosacral propriospinal projections rostrally after thoracic injury. Collectively, our findings suggest that distension of pelvic viscera increases the excitation of expanded afferent terminals in the disinhibited lumbosacral spinal cord. This, in turn, triggers excitation and sprouting of local propriospinal neurons to relay visceral sensory stimuli and amplify the activation of sympathetic preganglionic neurons in the thoracolumbar cord, to enhance transmission in the spinal viscero-sympathetic reflex pathway. These responses are manifested as autonomic dysreflexia.
Topics: Adrenergic Fibers; Animals; Autonomic Dysreflexia; Autonomic Fibers, Preganglionic; Calcitonin Gene-Related Peptide; Humans; Hypertension; Nerve Growth Factor; Neurons; Reflex; Spinal Cord; Spinal Cord Injuries; Thoracic Vertebrae; Viscera
PubMed: 16198706
DOI: 10.1016/S0079-6123(05)52017-X -
Brain Research Nov 1996The muskrat, and aquatic rodent with a brisk and reliable diving response, shows a remarkable bradycardia after nasal stimulation. However, the medullary origin of...
The muskrat, and aquatic rodent with a brisk and reliable diving response, shows a remarkable bradycardia after nasal stimulation. However, the medullary origin of cardiac preganglionic motoneurons is unknown in this species. We injected fat pads near the base of the heart of muskrats with a WGA-HRP solution to label retrogradely preganglionic parasympathetic neurons that project to the cardiac plexi. Results showed that the preponderance of labeled neurons was in ventrolateral parts of the medulla from 1.5 mm caudal to the obex to 2.0 mm rostral. Eighty-nine percent of the labeled neurons were located bilaterally in the external formation of the nucleus ambiguus, 5.6% were in the lateral extreme of the dorsal motor nucleus of the vagus nerve and 5.3% were found in the intermediate area in between these two nuclei. Although controversy still exists concerning the medullary origin of preganglionic cardiac motoneurons, our results from muskrats agree with those from most other species where preganglionic cardiac motoneurons were located just ventral to the nucleus ambiguus.
Topics: Animals; Arvicolinae; Autonomic Fibers, Preganglionic; Brain Stem; Female; Heart; Male; Medulla Oblongata; Motor Neurons; Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
PubMed: 8955533
DOI: 10.1016/s0006-8993(96)01048-7 -
Journal of Neuropathology and... 1978The myelinated fiber (MF) composition of T6-T8 Rami Communicantes were obtained in 9 healthy persons of various ages. The textbook picture that distal rami (DR) contain...
The myelinated fiber (MF) composition of T6-T8 Rami Communicantes were obtained in 9 healthy persons of various ages. The textbook picture that distal rami (DR) contain all of the myelinated fibers and therefore are white, while proximal rami (PR) contain none of them and therefore are grey must be modified. We found that DR usually contained abundant MFs and that PR concordance was found between segmental numbers of intermediolateral nuclei cytons, ventral root small myelinated fibers (SMFs), and rami total small MFs to suggest that both rami probably contain the distal myelinated axons of preganglionic autonomic fibers. Finally, there was an attrition of total MFs of rami with age, similar to what we had previously found for ILC cytons and for root SMFs. The decrease in number of pre-ganglionic autonomic neurons with age is thought to be of sufficient magnitude to account for the dysautonomia of the elderly.
Topics: Adult; Aged; Aging; Autonomic Fibers, Preganglionic; Autonomic Nervous System; Child, Preschool; Female; Humans; Male; Middle Aged; Nerve Fibers, Myelinated; Spinal Nerve Roots
PubMed: 739274
DOI: 10.1097/00005072-197811000-00002 -
Experimental Eye Research Oct 2013
Topics: Accommodation, Ocular; Animals; Autonomic Fibers, Preganglionic; Female; Humans; Male; Neurons; Oculomotor Nerve
PubMed: 24099063
DOI: 10.1016/j.exer.2013.06.021 -
Acta Neurobiologiae Experimentalis 1996The activity of preganglionic sympathetic neurones largely depends on synaptic excitation from antecedent reticulospinal neurones located in the rostral ventrolateral... (Review)
Review
The activity of preganglionic sympathetic neurones largely depends on synaptic excitation from antecedent reticulospinal neurones located in the rostral ventrolateral medulla (RVLM). Our study, conducted in anaesthetized rats, showed that all RVLM pre-sympathetic neurones display a substantial synaptic noise and their action potentials are usually preceded by fast EPSPs. No evidence was found for presence of gradual depolarizations (autodepolarizations) between individual spikes. Therefore our results are consistent with the "network" hypothesis for the generation of sympathetic vasomotor tone. Axons of some pre-sympathetic neurones intracellularly labelled with Neurobiotin or Lucifer Yellow had collaterals arborizing in several medullary regions. Thus these neurones have synaptic inputs not only to preganglionic sympathetic neurones, but also to other, yet unidentified cells in the brainstem. Finally, our results show that anatomically adjacent RVLM pre-sympathetic and Bötzinger respiratory neurones from two functionally distinct neuronal subpopulations, and that some pre-sympathetic neurones have an adrenergic phenotype.
Topics: Animals; Autonomic Fibers, Preganglionic; Electrophysiology; Medulla Oblongata; Neurons; Rats; Sympathetic Nervous System
PubMed: 8787198
DOI: 10.55782/ane-1996-1141 -
European Neurology 1993Two cases of pure progressive autonomic failure (PAF) are presented. A postmortem study of one case (case 2) showed a pathology resembling that of Parkinson's disease.... (Review)
Review
Two cases of pure progressive autonomic failure (PAF) are presented. A postmortem study of one case (case 2) showed a pathology resembling that of Parkinson's disease. Marked cell loss was noted in the substantia nigra, nucleus ceruleus, and intermediolateral column of the spinal cord, while cell loss in the sympathetic ganglion was not remarkable. This case may be an exceptionally rare case of late-onset PAF in which autonomic failure was mainly ascribed to preganglionic (and central) pathology, although autonomic function tests suggested postganglionic sympathetic disorder in both cases.
Topics: Aged; Aged, 80 and over; Autonomic Fibers, Postganglionic; Autonomic Fibers, Preganglionic; Autonomic Nervous System Diseases; Biopsy; Brain; Diagnosis, Differential; Ganglia, Sympathetic; Humans; Male; Nerve Degeneration; Neurologic Examination; Parkinson Disease; Sural Nerve
PubMed: 8307061
DOI: 10.1159/000116985 -
Advances in Experimental Medicine and... 2002
Topics: Animals; Autonomic Fibers, Preganglionic; Denervation; Dry Eye Syndromes; Lacrimal Apparatus; Male; Parasympathetic Nervous System; Rabbits; Tears; Time Factors
PubMed: 12613912
DOI: 10.1007/978-1-4615-0717-8_30 -
Acta Neurobiologiae Experimentalis 1977The stimulation of arterial baroreceptors (blind sack technique) inhibited the preganglionic and postganglionic cardiac sympathetic activity. There were found three...
The stimulation of arterial baroreceptors (blind sack technique) inhibited the preganglionic and postganglionic cardiac sympathetic activity. There were found three populations of single sympathetic preganglionic fibers (Th3) responding in a different way to the stimulation of arterial baroreceptors and arterial chemoreceptors (infusion of the small volume of saline bubbled with CO2 into the carotid sinus): (i) inhibited by carotid baroreceptors and excited by carotid chemoreceptors stimulation, (ii) inhibited by carotid baroreceptors and by carotid chemoreceptors stimulation, (iii) some fibers inhibited by baroreceptors did not change activity during stimulation of chemoreceptors. A functional role of each particular group of preganglionic sympathetic fibers is discussed.
Topics: Action Potentials; Animals; Autonomic Fibers, Postganglionic; Autonomic Fibers, Preganglionic; Carotid Sinus; Cats; Chemoreceptor Cells; Ganglia, Autonomic; Heart; Heart Rate; Pressoreceptors; Sympathetic Nervous System
PubMed: 855684
DOI: No ID Found -
The Journal of Comparative Neurology Sep 1982The fiber composition of the left major splanchnic nerve was studied in cats by electron microscopy. Comparisons were made between normal and partially degenerated nerve...
The fiber composition of the left major splanchnic nerve was studied in cats by electron microscopy. Comparisons were made between normal and partially degenerated nerve specimens following ventral rhizotomy (T3-L1), or spinal nerve division (T3-L1). Normal, major splanchnic nerves contained 2,500-4,000 myelinated and 10,000-15,000 unmyelinated fibers. Preganglionic fibers included approximately 90% of the finely myelinated (1-7 micrometers) and over 50% of the unmyelinated fibers. Removal of the sensory and preganglionic components by spinal nerve division revealed a third postganglionic fiber category. This included 13-38 small myelinated (1-5 micrometers) and 1,645-7,619 unmyelinated fibers. Finally, a comparison of normal and partially degenerated nerve specimens of both groups (ventral rhizotomy and spinal nerve cut) indicated that splanchnic afferents are made up of virtually all of the 120-350 large myelinated (8-14 micrometers) and 10% of the small myelinated (1-7 micrometers) fibers. A preliminary estimate indicated that about 10-20% of the unmyelinated fibers were sensory. The implications of these findings are discussed.
Topics: Animals; Autonomic Fibers, Postganglionic; Autonomic Fibers, Preganglionic; Cats; Cell Count; Microscopy, Electron; Nerve Fibers, Myelinated; Neurons, Afferent; Spinal Nerve Roots; Splanchnic Nerves
PubMed: 7130470
DOI: 10.1002/cne.902100106