Cells of origin of sympathetic pre- and postganglionic cardioacceleratory fibers in the pigeon.
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Animals↗
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Results for “Autonomic Fibers, Postganglionic”
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Histochemical demonstration of peripheral autonomic innervation in canine nasal mucosa by retrograde axonal transport of horseradish perioxidase.
The peripheral autonomic nervous pathways of the nasal mucosa in dogs were investigated by the horseradish peroxidase (HRP) method. HRP was applied to the nasal mucosa, caudal nasal nerve, ethmoidal nerve, vidian nerve and pterygopalatine ganglion in 20 dogs, and retrogradely labelled neurons were observed in the superior cervical ganglion (SCG) and the pterygopalatine ganglion (PPG) by the blue reaction method. It was suggested that the vidian nerve, the maxillary branch of the trigeminal nerve, the caudal nasal nerve, the pterygopalatine nerve and the ethmoidal nerve contained the postganglionic sympathetic fibres which originated in SCG and terminated in the nasal mucosa. Moreover, other sympathetic pathways, such as those around the blood vessels, were also suggested to be a main route. It was suggested that the postganglionic parasympathetic fibers originating in PPG travelled along the caudal nasal nerve and the ethmoidal nerve.
Animals↗
Autonomic dysfunction in chronic intestinal pseudo-obstruction.
Fifteen tests were used to assess adrenergic, non-vagal cholinergic, and cardiovagal functions in 11 patients with chronic intestinal pseudo-obstruction (CIP). The three aims of this study were: 1) to ascertain the presence of and spectrum of autonomic involvement; 2) to assess the level of autonomic dysfunction; and 3) to compare the results of autonomic function tests with gastrointestinal motility patterns. Gastrointestinal motility displayed a neuropathic pattern in 10 patients. Adrenergic functions were abnormal in nine patients and non-vagal cholinergic functions in 10 patients. Cardiovagal functions were abnormal in only seven patients. The autonomic dysfunction was localized mostly to the postganglionic pathways. One patient, who had a myopathic pattern and muscle degeneration on small bowel biopsy, demonstrated normal responses to autonomic function tests. The patients with neuropathic CIP demonstrated widespread, mostly postganglionic autonomic dysfunction. Neuropathic CIP can occur with or without cardiovagal involvement.
Acetylcholine↗
Effects of heterologous cross-suture between the postganglionic sympathetic and the preganglionic parasympathetic nerve trunks of submandibular glands in cats.
After sectioning the postganglionic adrenergic sympathetic nerve trunk for the submandibular gland, as close to the submandibular artery as practicable, its central end was sutured to the peripheral end of the preganglionic cholinergic parasympathetic nerve trunk for the gland, the chorda, which had been sectioned where it left the lingual nerve. The effects of this heterologous cross-sature were studied at different times, up to 1 year afterwards, by assessing the physiological and pharmacological responses of the glands and the neuro-histochemical changes in the nerve trunks and in the nerves within the glands. In all cases adrenergic sympathetic nerves grew across the site of suture and down the erstwhile cholinergic parasympathetic trunk, eventually to develop connections in the gland. In some cases the functional adrenergic reinnervation of the submandibular gland appeared to result exclusively or predominantly from the direct downgrowth of adrenergic axons to the gland, via the crossed nerves. In other cases however, in addition to a direct glandular reinnervation, there was some physiological and morphological evidence which suggested that possible heterogneous synaptic contracts may have been created between postganglionic sympathetic axons and cholinergic ganglion cells in the chorda nerve.
Animals↗
Neuroexcitatory effects of digoxin in the cat.
The effect of intravenous injections of digoxin (20 mug/kg every 15 minutes) on spontaneously occurring activity in autonomic efferent nerves, motor nerves, afferent nerves, electrocardiogram and on arterial blood pressure was evaluated in chloralose-anesthetized cats. Administration of digoxin enhanced neural activity in pre- and postganglionic cardiac synpathetic nerves and this enhancement occurred near the time the disturbances in ventricular rhym were noted. Neural activity continued to increase during ventricular tachycardia and maximum enhancement was observed just proir to ventricular fibrillation. Similar results were observed when digoxin was administered to animals in which neural activity was recorded from preganglionic splanchnic and superior cervical nerves. Digoxin administration also increased discharge frequency from vagus (efferent fibers), phrenic and carotid sinus nerves. Denervation of cardiovascular reflexogenic areas prevented the increased discharge in vagus nerves, reduced it in phrenic nerves, but did not affect nerve discharge in sympathetic nerves. These results suggest that digoxin-induced hyperactivity in synpathetic nerves was related to a central nervous system effect of the drug, whereas the mechanism for the digoxin-induced hyperactivity in vagus nerves involved a peripheral reflex effect of the drug. Both sites were involved in the digoxin-induced hyperactivity in phrenic nerves. Enhancement of cardiac sympathetic nerve activity appeared to be responsible for the ventricular arrhythmias provoked by digoxin as 1) a temporal relationship was observed between augmented nerve activity and arrhythmia development, 2) a centrally acting sympathetic nervous system depressant drug, clonidine, converted the ventricular arrhythmia to normal rhythm, and 3) removal of sympathetic influence to the heart by spinal cord transection decreased the sensitivity of the heart to the arrhythmogenic effect of digoxin. These results suggest that digoxin partially responsible for its cardiotoxic effects.
Adrenal Glands↗
Chronic idiopathic anhidrosis.
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.
Adult↗
Functional properties of lumbar preganglionic neurones.
Lumbar preganglionic neurones projecting through WRL2 and L3 to lumbar ganglia caudal to L4 were investigated for those functional properties which are typical for postganglionic vasoconstrictor neurones supplying muscle and skin and for post ganglionic sudomotor neurones. The properties tested were the cardiac rhythmicity of the activity and the reactions to systemic hypoxia, to noxious stimulation of skin and (in part of the experiments) to vibrational stimuli. Furthermore, resting activity and conduction velocities of the asons were measured. 426 neurones were investigated. 311 (73%) of them were silent and could -- as far as tested -- not be excited by the afferent stimuli used. The conduction velocities of the axons of these neurones ranged from 0.5 to about 16 m/sec. 115 neurones had resting activity of 0.1--4.6 impulses/sec. The conduction velocities of their axons ranged from 0.5 to about 12 m/sec. 80 preganglionic neurones with resting activity were classified on the basis of the reflexes in these neurones to afferent stimuli. Preganglionic neurones reacting like postganglionic vasoconstrictor neurones to muscle (excited by systemic hypoxia and/or by noxious stimulation of skin; with cardic rhythmicity) were classified as type 1 neurones (26 from 80 neurones tested). The resting activity of these neurones was 1.8 +/- 1.3 impulses/sec (mean +/- 1 S.D.). Their axons conducted with 3.9 +/- m/sec. Preganglionic neurones reacting like the majority of the postganglionic vasoconstrictor neurones to hairy and hairless skin (inhibited by systemic hypoxia and/or noxious cutaneous stimuli) were classified as type 2 neurones (48 from 80 neurones investigated). In 40% of these neurones the activity had cardiac rhythmicity. The resting activity was 0.9 +/- 0.6 impulses/sec. The distribution of the conduction velocities of the axons of these neurones was bimodal. They conducted on the average with 1.3 +/- 0.6 m/sec and 6.6 +/- 1.1 m/sec respectively. A few neurones were found (6 from 80 neurones) which were activated by vibrational stimuli (activation of Pacinian corpuscles by tapping on the hindfoot). Since this type of activation is typical for postganglionic sudomotor neurones they were classified as type 3 neurones. The activity of these neurones had no cardiac rhythmicity. Indirect measurements of the conduction velocities of pregnanglionic axons converging onto postganglionic neurones supplying skeletal muscle and hairy skin yielded values which were statistically not different from the conduction velocities of the axons of type 1 and type 2 neurones respectively. These measurements support the classification into type 1 and type 2 preganglionic neurones. The implications of this study are discussed.
Action Potentials↗
A wide field electron microscopic analysis of the fiber constituents of the major splanchnic nerve in cat.
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.
Animals↗
Effects of carotid chemoreceptor and baroreceptor stimulation upon the sympathetic preganglionic and postganglionic cardiac nerve and single fiber activity in cats.
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.
Action Potentials↗
[Functional characteristics of the conduction pathways of the caudal sympathetic mesenteric ganglion in the monkey (Macaca rhesus)].
Chronic experiments in anesthetized monkeys showed that pathways from the preganglionic branches of the ganglion (the lumbar splanchnic nerves) to the postganglionic branches were represented by fibers with different conduction velocity which ran through the ganglion without interruption. These pathways are, probably, the afferents or fibers of postganglionic sympathetic neurons. In addition, synaptically contacting pathways are present. All peripheral nerves of the ganglion are connected with each other through synaptically contacting pathways. The preganglionic branches (the lumbar splanchnic nerves, intermesenteric tract) are the independent channels without tracts connecting them. The proper reflexes related to the function of the pelvic organs are assumed to be actualized by the fibers of the reflex are closed in the ganglion. The scheme of conducting pathways of the ganglion in monkeys is presented.
Action Potentials↗
Reorganization of sympathetic preganglionic connections in cat bladder ganglia following parasympathetic denervation.
1. Experiments were undertaken to examine the mechanisms involved in the reorganization of sympathetic efferent pathways to the urinary bladder of the cat following chronic unilateral, parasympathetic preganglionic denervation of the bladder. 2. Electrical stimulation (10-30 Hz) of the hypogastric nerve in cats with an intact bladder innervation or on the normally innervated side of the bladder in unilaterally denervated preparations elicited low-amplitude (10-25 cmH2O) transient (10-30 s) bladder contractions and non-synaptic axonal volleys on bladder postganglionic nerves. However, after chronic (3-22 months) sacral preganglionic denervation, hypogastric nerve stimulation on the side of the denervation elicited large (60-80 cmH2O) and more sustained (4-5 min) bladder contractions as well as synaptically mediated firing on bladder postganglionic nerves. 3. The vesicoexcitatory effects of hypogastric nerve stimulation on the chronically denervated side were not altered selectively by the adrenergic blocking agent, phenoxybenzamine, but were blocked by atropine and hexamethonium suggesting that the responses were mediated by muscarinic and nicotinic cholinergic synapses. These drugs did not influence the responses elicited by hypogastric nerve stimulation on the normally innervated side of the bladder. 4. Following more extensive chronic unilateral denervation (transection of the pelvic and hypogastric nerves on one side of the bladder) stimulation of the contralateral intact pelvic nerve elicited postganglionic firing in vesical postganglionic nerves on the denervated side. This crossed excitatory pathway was not observed in normal animals or following sacral preganglionic denervation. 5. It is concluded that parasympathetic preganglionic denervation of the bladder ganglia leads to a reinnervation of the denervated cholinergic ganglion cells by sympathetic preganglionic pathways in the ipsilateral hypogastric nerve. This reinnervation results in the conversion of sympathetic inhibitory pathways to excitatory pathways in the denervated bladder. This change may contribute to the development of the autonomous hyperactive bladder seen under conditions of peripheral nerve or conus medullaris lesions of the spinal cord.
Action Potentials↗
Chemically distinct preganglionic inputs to iris-projecting postganglionic neurons in the rat: A light and electron microscopic study.
Individual autonomic postganglionic neurons are surrounded by pericellular baskets of preganglionic terminals that are easily identifiable with the light microscope. It has been assumed that the target cell of a pericellular basket of preganglionic terminals is the neuron at the centre of the basket. This assumption has enabled the connectivity of preganglionic neurons to be determined at the light microscopic level. However, if the preganglionic terminals in a pericellular basket make synapses with the dendrites of nearby, but functionally different, postganglionic neurons, then the conclusions of light microscopic studies are far less certain. We have used a serial section ultrastructural study to determine the target of the preganglionic pericellular basket in a situation where the apparent target cell is surrounded by neurons of dissimilar function. In the rat superior cervical ganglion, postganglionic neurons projecting to the iris were identified, using retrograde tracers, as single neurons (i.e., not in clusters). We have used immunohistochemistry to show that iris-projecting neurons are surrounded by preganglionic nerve terminals containing calcitonin gene-related peptide (CGRP). We have demonstrated that the pericellular basket of CGRP-immunoreactive preganglionic terminals provides inputs only to the soma at the centre of the basket and not to the dendrites of surrounding neurons. This suggests that, in autonomic ganglia, light microscopic identification of the preganglionic terminal baskets is likely to be a reliable method for identifying the targets of subclasses of preganglionic neurons.
Animals↗
Gustatory-salivary reflex: neural activity of sympathetic and parasympathetic fibers innervating the submandibular gland of the hamster.
Electrophysiological experiments were performed to clarify the neural control mechanisms subserving gustatory-salivary reflex in anesthetized and decerebrate hamsters. Efferent neural activities of postganglionic sympathetic and preganglionic parasympathetic fibers, innervating the submandibular gland, were recorded when taste stimuli were infused into the oral cavity. Neural activities of primary gustatory afferents were also recorded from the chorda tympani (innervating the anterior part of the tongue) and the glossopharyngeal nerve (innervating the posterior part of the tongue). The parasympathetic fibers showed a low rate of spontaneous discharges (about 0.3 Hz), and responded tonically in an excitatory manner to taste stimulation. The magnitude of parasympathetic activity was highly correlated with the magnitude of gustatory afferent responses of the chorda tympani rather than that of the glossopharyngeal nerve. On the other hand, the sympathetic fibers showed irregular burst discharges (1.5 burst/s), and the rate of burst discharges was increased in response to high concentrations of HCl (0.03 M) or NaCl (1 M) solutions. Deafferentation experiments suggest that the parasympathetic activity is mainly influenced by gustatory information via the chorda tympani, while the sympathetic activity can be evoked by both the chorda tympani and glossopharyngeal nerve.
Action Potentials↗
The effect of axotomy and denervation on calmodulin content in the superior cervical sympathetic ganglion of the rat.
Calmodulin (CaM) in the superior cervical sympathetic ganglion (SCG) of the rat and its changes after transection of the pre- or postganglionic nerves were studied biochemically and immunohistochemically. The concentration of CaM in the SCG was assayed using the extent of activation of CaM-dependent adenylate cyclase from bovine neural retina. In the SCG, CaM concentration was 4.5 micrograms/mg protein, a level similar to that in another peripheral ganglion, the nodose ganglion (4.9 micrograms/mg protein). Following denervation of the SCG, the total amount of ganglionic CaM did not change significantly within a week. On the other hand, CaM content per ganglion increased gradually 3 days after axotomy. Immunohistochemical examination revealed that CaM in unoperated SCG is present both in the neuronal fibers and in the cell soma of sympathetic neurons. But the intensity of the staining with CaM-antibody in the cytoplasmic soma varied among cells. The gross profile of the CaM immunostaining seemed to be unchanged one week after either denervation or axotomy, but the immunoelectron microscopic study showed heavy staining of the innercellular membranes of irregular shape in the axotomized SCG.
Adenylyl Cyclases↗
Segmental distribution and central projections of renal afferent fibers in the cat studied by transganglionic transport of horseradish peroxidase.
The segmental and central distributions of renal nerve afferents in adults cats and kittens were studied by using retrograde and transganglionic transport of horseradish peroxidase (HRP). Transport of HRP from the central cut ends of the left renal nerves labelled afferent axons in the ipsilateral minor splanchnic nerves and sensory perikarya in the dorsal root ganglia from T12 to L4. The majority of labeled cells (85%) were located between L1 and L3. A few neurons in the contralateral dorsal root ganglia were also labeled. Labeled cells were not confined to any particular region within a dorsal root ganglion. Some examples of bifurcation of the peripheral and central processes within the ganglion were noted. A small number of preganglionic neurons, concentrated in the intermediolateral nucleus, were also identified in some experiments. In addition, many sympathetic postganglionic neurons were labeled in the renal nerve ganglia, the superior mesenteric ganglion, and the ipsilateral paravertebral ganglia from T12 to L3. Transganglionic transport of HRP labeled renal afferent projections to the spinal cord of kittens from T11 to L6, with the greatest concentrations between L1 and L3. These afferents extended rostrocaudally in Lissauer's tract and sent collaterals into lamina I. In the transverse plane, a major lateral projection and a minor medial projection were observed along the outer and inner margins of the dorsal horn, respectively. From the lateral projection many fibers extended medially in laminae V and VI forming dorsal and ventral bundles around Clarke's nucleus. The dorsal bundle was joined by collaterals from the medial afferent projection and crossed to the contralateral side. The ventral bundle extended into lamina VII along the lateroventral border of Clarke's nucleus. Some afferents in the lateral projection could be followed ventrally into the dorsolateral portion of lamina VII in the vicinity of the intermediolateral nucleus. In the contralateral spinal cord, labeled afferent fibers were mainly seen in laminae V and VI. These results provide the first anatomical evidence for sites of central termination of renal afferent axons. Renal inputs to regions (laminae I, V, and VI) containing spinoreticular and spinothalamic tract neurons may be important in the mediation of supraspinal cardiovascular reflexes as well as in the transmission of activity from nociceptors in the kidney. In addition, the identification of a bilateral renal afferent projection in close proximity to the thoracolumbar autonomic nuclei is consistent with the demonstration in physiological experiments of a spinal pathway for the renorenal sympathetic reflexes.
Animals↗
Pre- and post-ganglionic nerve fibres of the pterygopalatine ganglion and their allocation to the eyeball of rats.
The origin, course and distribution of pre- and postganglionic neurons of the pterygopalatine ganglion (PPG) in the rat were studied using acetylcholinesterase staining, wheat germ agglutinin coupled to horseradish peroxidase (WGA-HRP) histochemistry and autoradiography. These methods were used in a selected and planned fashion to reveal details concerning the innervation of the lacrimal gland and portions of the eye. The PPG in rats consists of a rostral triangular portion and additional perikarya surrounding the distal part of the major petrosal nerve. Fibres from the superior cervical ganglion (SCG) reach the PPG via the inferior petrosal sinus. Application of WGA-HRP was made after transections: (1) rostral to the PPG; and (2) caudal to the PPG. The first of these applications labelled mainly fibres in the PPG; the second application labelled preganglionic parasympathetic brainstem neurons dorsolateral to the facial nucleus (i.e. the lacrimal nucleus), rostral cells in the SCG and trigeminal sensory fibres. WGA-HRP injections of the lacrimal gland, the conjunctiva and the anterior chamber of the eye all labelled cells in different parts of the PPG. This means that the PPG contains sensory and sympathetic nerve fibres and that the PPG has a topographical organisation along the rostrocaudal axis. Isotope injections of the PPG anterogradely labelled fibres passing through the ciliary ganglion that innervated the conjunctiva, the limbus and parts of the choroid.
Acetylcholinesterase↗
Motor innervation of the smooth muscle of the rat seminal vesicle.
Frequency-related isovolumetric contractions of the rat seminal vesicle elicited with transmural electrical stimulation were blocked by tetrodotoxin but unaffected by hexamethonium. The postganglionic motor innervation of the rat seminal vesicle is purely excitatory and contains both an adrenergic and a cholinergic component which are excited simultaneously during transmural stimulation. Contractions elicited by adrenergic nerve stimulation were mediated by norepinephrine acting via alpha adrenoceptors, i.e., 1) responses of untreated vesicles to transmural stimulation and to exogenous norepinephrine were antagonized by phentolamine and potentiated by cocaine, 2) pretreatment of animals with reserpine or 6-hydroxydopamine produced a marked depletion of tissue norepinephrine concentration and reduced the responses to transmural stimulation to a level which resembled that of untreated organs in the presence of phentolamine, 3) the residual responses of vesicles from pretreated rats were not modified by phentolamine or cocaine, and 4) responses to tyramine in untreated organs were antagonized by phentolamine but not by cocaine and were observed in organs from reserpine-pretreated rats only after repletion with exogenous norepinephrine. Responses elicited by cholinergic nerve stimulation were mediated by acetylcholine through muscarinic receptors, i.e., 1) responses of untreated vesicles to transmural stimulation and to exogenous acetylcholine were antagonized by atropine, 2) the residual responses to transmural stimulation of vesicles from animals pretreated with reserpine of 6-hydroxydopamine were nearly abolished by atropine and 3) physostigmine potentiated and prolonged the responses of organs from untreated and reserpine-pretreatd animals to transmural stimulation; these effects of physostigmine were abolished by atropine.
Animals↗
Progressive isolated segmental anhidrosis.
A patient had progressive segmental anhidrosis, which proved after extensive neurologic and autonomic workup to be an isolated abnormality. Intradermal acetylcholine produced localized sweating in areas of thermoregulatory anhidrosis five months after the onset of symptoms but failed to do so at two years. These findings are consistent with a preganglionic sympathetic lesion affecting a functionally defined subset of sympathetic cells and/or fibers. The alteration of the sudomotor response to intradermal acetylcholine during the course of the illness suggests that the diagnostic utility of pharmacologic sweat tests may be time dependent, limited to a relatively early period following onset of anhidrosis.
Acetylcholine↗