Death of intermediolateral spinal cord neurons follows selective, complement-mediated destruction of peripheral preganglionic sympathetic terminals by acetylcholinesterase antibodies

Systemically injected anti-acetylcholinesterase antibodies in rats cause selective lesions of preganglionic sympathetic neurons. Adult rats were examined up to four months after a single i.v. injection of murine monoclonal acetylcholinesterase antibodies or normal immunoglobulin G (1.5 mg). Within 4 h, antibody-treated rats developed ptosis, a sign of sympathetic dysfunction that was never reversed. Persistent pupillary constriction reflected preserved and unopposed parasympathetic function. Weight gain was depressed, but locomotor activity, excitability, and sensorimotor responses were normal, and gross neuromuscular performance was near normal. These findings were supported by biochemical evidence for selective sympathetic damage. Acetylcholinesterase activity was reduced for the whole period of observation in sympathetic ganglia and adrenal glands but fell only transiently in muscle and serum. At all times, choline acetyltransferase activity (a marker of presynaptic terminals) was unaffected in muscle but grossly depleted in ganglia. Light and electron microscopy showed that preganglionic sympathetic terminals of superior cervical ganglia were severely damaged while parasympathetic ganglia were less affected and motor endplates of skeletal muscle were apparently spared. Immunocytochemistry revealed punctate deposits of murine immunoglobulin G and complement component C3 in ganglionic neuropil 12 h after antibody injection. This finding was consistent with complement-mediated lysis of preganglionic terminals. Morphometric analysis of preganglionic neurons in the intermediolateral nucleus of the spinal cord showed progressive loss of cholinergic perikarya over several months. We conclude that antibody-induced destruction of ganglionic terminals leads to death of preganglionic sympathetic neurons and, hence, permanent dysautonomia.

Neurogenic inflammation in nasal allergy: histochemical and pharmacological studies in guinea pigs. A review

The role of neuropeptides in nasal allergy was examined in guinea pigs by histochemical and pharmacological study. Intranasal application of toluene diisocyanate (TDI) induced nasal allergy-like behaviors: sneezing and watery rhinorrhea, and decreased histamine content in the nasal mucosa in guinea pigs sensitized with TDI. The immunoreactivity of substance P (SP) and calcitonin gene-related peptide (CGRP) in the nerve terminals in the nasal mucosa was increased after intranasal application of TDI. We also observed a decrease in the immunoreactivity of SP and CGRP, and an increase in their mRNA expression in the trigeminal ganglion neurons. These findings indicate that exposure to TDI enhanced the biosynthesis of both SP and CGRP in the trigeminal ganglion neurons and their axonal transportation to the terminals in the nasal mucosa. In animals pretreated with capsaicin before sensitization, TDI did not induce nasal allergy-like behaviors and histamine release in the nasal mucosa. Since capsaicin depletes SP and CGRP in the sensory nerves, this finding indicates neuropeptide-mediated histamine release in the nasal mucosa. All these findings suggest that, on exposure to TDI, the antidromic release of SP and CGRP in the nasal mucosa triggers the release of histamine, resulting in the development of symptoms of nasal allergy.

Morphologic and quantitative changes in neurotransmitters in the lumbar spinal cord after acute or chronic mechanical compression of the cauda equina

Changes in the neurotransmitters associated with pain transmission and regulation in the lumbar spinal cord were studied after acute or chronic mechanical compression of the cauda equina in rats. Using glyoxylic acid histofluorescence and immunohistochemical methods, it was morphologically apparent that substance P-containing nerve ending were decreased after chronic compression of the cauda equina. Somatostatin nerve terminals were reduced, and aminergic fibers and serotonin were enhanced after both acute and chronic mechanical compressions. In addition, quantitative analysis revealed that the levels of norepinephrine and serotonin remained elevated after mechanical compression of the cauda equina. It is suggested that pain in the lower back and extremities after mechanical compression of the cauda equina is controlled by these complicated changes of neurotransmitters in the lumbar spinal cord.

Nerve root pain secondary to posterior articular cysts: a report of 6 cases and review of the literature

The authors report 6 cases of posterior articular cysts responsible for nerve root pain, generally in the form of sciatica. Cysts of the posterior intervertebral joints are a rare cause of nerve root compression. Plain x-rays demonstrate posterior inter-apophyseal osteoarthritis. Demonstration of the posterior articular cyst requires the use of computed tomography with contrast injection and/or MRI. Arthrography of the posterior inter-apophyseal joint allows the cyst to be opacified and treated by infiltration of a corticosteroid.

Lamellated sensory corpuscles within the endoneurium

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Dose-dependent inner ear changes after i.v. administration of cisplatin

The effect on the cochlear and vestibular surface structures in the inner ear of guinea pigs receiving different doses of cisplatin was studied in three groups of animals. A semi-quantitative analysis showed that cisplatin induced outer hair cell (OHC) damage which developed over days, was dose-dependent and that repeated intraperitoneal injections of a low dose of cisplatin caused OHC changes comparable to a single intravenous injection. The range of OHC damage varied generally between the three rows of OHCs, but in the most severely damaged cochleas the changes were equally distributed between the rows in the basal turn. The inner hair cells (IHCs) and sensory cells of the vestibular end organ were unaffected up to five days after an intravenous injection of cisplatin.

Sprouting of peripherally regenerating primary sensory neurones in the adult central nervous system

We have studied the ability of primary afferent neurones to proliferate within the grey matter of the dorsal horn following the degeneration of other, nearby, afferent fibres. The peripheral branches of primary afferents have the capacity to regenerate successfully over long distances, and we have examined the possibility that when they are so doing, the neurones' status changes to facilitate greatly the sprouting of afferent fibres within the dorsal horn. "Spared root" preparations (rhizotomies of L3, L4, L6, S1, and the caudal half of L5, sparing the rostral half of the L5 dorsal root) were made in adult rats. In some animals (acute preparations) the distribution of the central terminals of the spared root was assessed by labelling the sciatic nerve with WGA-HRP at the time of the rhizotomies. In other animals (chronic preparations), symmetrical bilateral spared roots were made and the sciatic nerve on one side was concomitantly crushed to trigger regrowth of the peripheral branches of these axons. Eight to 10 weeks later the sciatic nerves on both sides were labelled with HRP-WGA. In the acute preparations the reaction product was found in a limited rostrocaudal and mediolateral region of the dorsal horn. In lamina II (the lamina of densest labelling) the labelled terminals occupied an average of 1.17 +/- 0.21 mm2. In chronic preparations, the area of labelled terminals on the side of the uncrushed sciatic nerve was 1.34 +/- 0.28 mm2 (not significantly different from acute animals). However, the labelled area on the side of the crushed sciatic nerve was significantly greater, averaging 2.17 +/- 0.14 mm2.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic maintenance of presynaptic terminals in gliotic hippocampus following ischemia

Following brief cerebral ischemia, neurons are selectively damaged and die, whereas glial cells and blood vessels survive. This phenomenon of selective vulnerability is well illustrated in the hippocampal CA1 region. Five min of forebrain ischemia in the Mongolian gerbil produced selective neuronal necrosis in the hippocampal CA1 sector. After destruction and loss of CA1 neurons, a remarkable glial reaction (gliosis) was seen. The thickness of the CA1 subfield remained unchanged until 1 month after ischemia and then gradually shrank over several months. Ultrastructural observation of this region revealed persistent maintenance of presynaptic structures. Numerous presynaptic terminals containing synaptic vesicles were scattered throughout the gliotic scar tissue. These presynaptic terminals were apposed to degenerative structures which seemed most likely to be remnants of dendrites. In another group of animals, at one month following ischemic damage in the CA1 sector, the CA3 neurons were destroyed by kainic acid injection. In these animals, numerous degenerating presynaptic boutons were seen in the CA1 sector when fixed 4 days following kainate injection. These results indicate that even in gliotic tissue, presynaptic terminals can survive and maintain their structural characteristics although neuronal cell bodies are almost absent.

Corticofugal projections to the motor nuclei of the brainstem and spinal cord in humans

We studied corticofugal projections to the motoneurons with Nauta-Gygax's technique in a patient with cerebral infarction of both hemispheres. Motoneurons in the brainstem motor nuclei and spinal anterior horns seem to receive direct cortical projections, except for the oculomotor and abducens nuclei and Onuf's nucleus in the sacral cord.

Cutaneous nerve elimination following punch biopsy

We report the first case of cutaneous nerve elimination following routine punch biopsy and primary closure. The appearance of a delicate whitish strand from a healed biopsy site, which produces lancinating pain, may represent an extruded cutaneous nerve. This case was treated successfully with simple transection of the nerve at its portal of exit.

Prolonged degeneration of muscle spindles in the masseter muscle after treatment of developing mice with the local anesthetic lidocaine hydrochloride

The effect of lidocaine-HCl on muscle spindles in the masseter muscle of developing mice was investigated. Repeated injections of mice with anesthetic in the short term decreased the diameters of primary endings, intrafusal muscle fibers and outer capsules in the equatorial regions of muscle spindles, and caused a drop in the succinic dehydrogenase activity in intrafusal muscle fibers of the muscle spindles. In addition, the diameters did not recover to the control value even after about 10 weeks following cessation of anesthetic treatment. Thus, the present results suggest that repeated use of lidocaine-HCl in developing animals may cause dysfunction of the skeletal muscles.

Sensory innervation of soft tissues of the lumbar spine in the rat

The purpose of this study was to investigate neurophysiologically and anatomically the soft tissues of the dorsal compartment of the lumbar spine in order to understand better their possible role in low back pain. The focus was primarily on the lumbar facet joint and supraspinous ligament of the Sprague-Dawley rat. Microdissection of the dorsal ramus and electrophysiological and neuroanatomical studies of the dorsal ramus and its terminations in paravertebral tissue revealed that (a) there are mechanosensitive, slowly adapting fibers in the rat lumbar facet joint capsule; (b) there are slowly adapting, mechanosensitive units in the rat supraspinous ligaments that respond to tensile loading; both types of mechanosensitive units have high threshold; (c) mechanical stimulation of these tissues sometimes elicits afterdischarges lasting several minutes; (d) many extracellular recordings from the medial branch of the dorsal ramus appear to be reflex activity to mechanical stimulation; (e) silver impregnation of the rat joint capsule reveals individual axons, very few of which were encapsulated, suggesting that they terminate in free nerve endings; and (f) the nerves of the rat facet joint capsule contain 68, 160, and 200 kdalton polypeptide subunits of neurofilament protein (NFP). These results indicate that neurons of lumbar facet joint capsules and ligaments in the back are sensitive to mechanical strain and that the higher threshold neurons may serve a nociceptive (pain) function.

Stimulation of afferent nerve endings by intragastric capsaicin protects against ethanol-induced damage of gastric mucosa

Ablation of capsaicin-sensitive afferent neurons enhances experimentally induced ulceration in the rat gastric mucosa, which suggests that these neurons are involved in gastric mucosal protection. To provide direct evidence for such a function it was investigated whether stimulation of afferent nerve endings by the intragastric administration of capsaicin could counteract the ulcerogenic effect of 25% ethanol. Capsaicin (3.2-640 microM), administered together with ethanol, inhibited the development of haemorrhagic lesions in a concentration-dependent fashion but did not alter the ethanol-induced fall in the gastric potential difference. This suggests that capsaicin does not prevent ethanol from damaging gastric epithelial cells but can counteract the vascular lesions caused by ethanol. The anti-lesion effect of intragastric capsaicin was absent in adult rats which had been treated with a high dose of systemic capsaicin as neonates in order to achieve a permanent degeneration of unmyelinated afferent neurons. It would appear, therefore, that intragastric capsaicin reduces lesion formation by an action on afferent neurons. The protective effect of intragastric capsaicin was not altered following acute subdiaphragmatic vagotomy, acute removal of the coeliac-superior mesenteric ganglion complex, acute bilateral ligation of the adrenal glands, or pretreatment of the rats with atropine or guanethidine. These findings indicate that stimulation of afferent neurons by intragastric capsaicin affords protection of the rat gastric mucosa against ethanol-induced damage. As the autonomic nervous system is not involved gastroprotection appears to represent a local effector function of sensory nerve endings in the stomach.

A direct demonstration of the perforant pathway terminal zone in Alzheimer's disease using the monoclonal antibody Alz-50

The perforant pathway links the entorhinal cortex with the hippocampal formation and provides this structure with its major cortical input. The cells of origin of the perforant pathway are destroyed in Alzheimer's disease (AD) and a marked depletion of glutamate, the putative neurotransmitter in its terminal zone, occurs. We report that the monoclonal antibody Alz-50 recognizes an antigen in the terminal zone of the perforant pathway in AD. This observation provides direct evidence for the involvement of the perforant pathway in AD, and demonstrates that Alz-50 can be used to study neural connectivity in AD brains.

[Comparative histofluorescent study of cardiac sympathetic nerves and adrenal catecholamines in rats under immobilization stress and administered a toxic dose of noradrenaline]

Changes in the adrenergic nerves of the rat heart and dynamics of adrenal catecholamines during immobilization stress and administration of a toxic dose of noradrenaline were found to be of the same type in general. They were manifested by a decrease of the number of fluorescent nerve terminals in the cardiac ventricles and an increase of catecholamine content in the adrenal glands 24 hours after the beginning of the experiment.

Mast cells in nerve end neuromas of mice

The volume density of mast cells was estimated in nerve end neuromas at various time-points after transection of the left sciatic nerve of 6-week-old mice. After an initial reduction in the amount of mast cells there was a steady increase with numerous cells in 6-month-old neuromas. The variation in amount of mast cells in the individual animals at each time-point was relatively large. Exposure of neuromas to mild trauma resulted in degranulation of mast cells. Possibly, these numerous mast cells, which can liberate their contents after very light touching, may influence the neuroma.

Neurobiological studies of transmitter systems in aging and in Alzheimer-type dementia

Dysfunction and death of specific neuronal systems are important processes occurring in aging and in Alzheimer's and in Parkinson's disease. The neuropathology and neurochemistry of some of the neuronal systems at risk in these settings are subjects of active research; the nature and consequences of these cellular pathologies have begun to be clarified. The availability of animal models (including aged monkeys, macaques with cholinergic deficiencies, and monkeys with MPTP-induced nigrostriatal pathology, all of which recapitulate certain features of human aging or disease) allow the opportunity to assess the efficacies of new pharmacotherapies, neural grafts, and trophic factors. These approaches can be monitored by behavioral testing and, in some instances, by in vivo imaging methods, which can in turn be correlated with morphologic and chemical analyses of brain. Demonstration of the efficacy of these procedures in nonhuman primates would have profound implications on the development of new therapies designed to alleviate the effects of aging and disease on the human brain.

Nerve terminal damage in cerebral ischemia: protective effect of alpha-methyl-para-tyrosine

Mongolian gerbils were treated with alpha-methyl-para-tyrosine methyl ester (AMPT, a tyrosine hydroxylase inhibitor), in order to decrease brain levels of catecholamines. Six hours later, unilateral ischemic stroke was induced by ligation of the left common carotid artery. The delayed degeneration of nerve terminals was studied sixteen hours later by measuring the high-affinity uptake of radiolabeled transmitters by isolated synaptosomes. Dopamine, serotonin and glutamate terminals were studied. AMPT-treated gerbils were compared to untreated (no AMPT) animals; 220 gerbils were studied. AMPT pretreatment (100, 250 and 400 mg/kg) produced a dose-dependent protection of all three types of nerve terminals. In the absence of AMPT pretreatment, the uptake of radiolabeled transmitters by the ischemic hemisphere, expressed as a percentage of that seen in the contralateral (unaffected) side of the brain, was as follows (mean +/- SEM): 27.3 +/- 5.2% for dopamine terminals, 49.5 +/- 6.2% for serotonin terminals, and 42.7 +/- 5.3% for glutamate terminals. Protection was essentially complete at a dose of 400 mg AMPT per kg. The number of animals with significant damage to nerve terminals was reduced from 38.5% in untreated animals to 11.1% in animals treated with AMPT 400 mg/kg. Although the nerve terminals were protected, gerbils still showed the behavioral signs of unilateral stroke due to the permanent occlusion of the left carotid. These results indicate that endogenous dopamine may play a significant role in ischemic damage to nerve terminals in the cerebrum.

Effects of repeated stripping on vocal fold mucosa in cats

Repeated stripping of the vocal folds in patients with recurrent vocal nodules may produce permanent, negative effects on voice quality. Hoarseness can be present with no evidence of structural or functional disease on indirect laryngoscopy. A common assumption is that scar tissue has formed, though the relationship between scarring and voice quality is not clear. In the study reported here, cats were subjected to four strippings of the left vocal fold at 6- to 8-week intervals. Tissues obtained were examined for changes in the composition of the mucosa and its nervous network. Alterations observed over the four strippings included 1) an increasing component of fibrous tissue and 2) apparent changes in both the number and structure of nervous elements. Implications of the findings for voice production, clinical management, and further research are discussed.

Thyroidectomy induces coated pit formation on cerebellar mossy fiber terminals

The influence that thyroid hormones have on the development of the cerebellar cortex is well known. Their absence in adults leads to important functional changes probably related to abnormalities in nerve terminal activity, although no morphological alterations have hitherto been described. Using ultrastructural morphometric methods, we have studied the effects of thyroidectomy on the cerebellar cortex mossy fiber terminals of adult rats with different survival periods. No significant changes in the volume and surface area of these terminals were found. The numbers of synaptic vesicles in groups 7, 15 and 30 days after thyroidectomy were significantly greater than in controls. A significant increase in coated pit formation was found when thyroidectomized groups were compared with controls. This increase is due to the lack of thyroxin since it can be counteracted by thyroxin administration. Whether this increased coated pit formation is a membrane retrieval mechanism or is related to the uptake of extracellular molecules remains to be determined.

Nerve terminal damage in cerebral ischemia: greater susceptibility of catecholamine nerve terminals relative to serotonin nerve terminals

The energy-dependent uptake of (3H)-dopamine (DA), (3H)-norepinephrine (NE) and (3H)-serotonin (5-HT) was measured in synaptosomes isolated from either the whole cerebral hemispheres or the striata of gerbils after cerebral ischemia. Ischemic stroke was induced in the Mongolian gerbil by left common carotid ligation. Uptake values in the affected hemisphere (expressed as a percent of the corresponding control hemisphere) were 32.6% for DA, 35.1% for NE, and 52.0% for 5-HT, 16 hours after stroke. The differential reduction in uptake of the catecholamines relative to 5-HT was significant (p less than 0.005). This differential persisted when measures were made on isolated striata from the ischemic and control hemispheres. In the latter measurements, uptake of DA was 20.7% of control and uptake of 5-HT was 44.7% of control. Uptake of both DA and NE were significantly reduced in animals exhibiting milder circling behavior, while uptake of 5-HT was not. There was no significant reduction of uptake in animals subjected to left common carotid ligation not exhibiting signs of stroke. These studies indicate a selective sensitivity of catecholamine nerve terminals to damage in ischemic stroke.

A comparative study of changes in innervation and development of supersensitivity in the rat vas deferens after various procedures

The relationship between morphological and functional changes in adrenergic nerves and the development of supersensitivity in the rat vas deferens was comparatively investigated after surgical denervation, chemical sympathectomy by 6-hydroxydopamine, daily treatment of animals with reserpine, or local application of colchicine to the hypogastric plexus. The order of ability to produce supersensitivity, as judged by the extent of the increase in the pD2 value of norepinephrine and the maximum response to norepinephrine, was as follows: denervation = colchicine greater than 6-hydroxydopamine greater than reserpine. These procedures produced alterations in morphological characteristics of the nerve ending with severeness of degeneration in the following order: denervation greater than 6-hydroxydopamine greater than colchicine greater than reserpine. Twitch contractions induced by transmural nerve stimulation were slightly reduced after colchicine or 6-hydroxydopamine treatment, markedly reduced by reserpine, and abolished by denervation. Therefore, the development of supersensitivity in the rat vas deferens is not necessarily in proportion to the morphological or functioning changes in adrenergic nerves. The results suggest that some neurofactor, e.g. trophic factor, is involved in the control of the drug sensitivity of smooth muscle in addition to the neurotransmitter itself.