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At least 19 recordsLinked to original sources
PubMed1996

[Neural pathways--neural networks].

During the past two decades, the introduction of several modern neuroanatomical approaches resulted in a rapidly growing body of informations about neuronal pathways in the central nervous system. Several new neuronal connections between brain areas have been discovered, and the chemical nature (neurotransmitter content) of pathways has been determined by using highly specific neurochemical and immunohistochemical techniques. On the basis of these new informations, our knowledge and attitude to the general organization of neuronal connections have been changed substantially: 1. Neuronal pathways are multi-neuronal networks rather than simple chain of neurons, wherein informations are forwarded between two brain areas bidirectionally, meanwhile several additional brain regions are inter-connected by axon-collaterals. 2. A single neuronal cell may synthesize several neuropeptides which co-localized in and released from nerve terminals, and depending on the target sites they may act as neurotransmitters or neurohormones. In certain conditions, neuropeptides may also function as nerve growth factors by supporting the survival or the restitution of neuronal cells. 3. By the introduction of molecular imaging in neuroscience (visualization of oncogenes, specific mRNA's, etc), topographical studies on neuronal pathways are more and more completed by functional informations.

Brain↗
PubMed2001

Target-dependent sexual differentiation of a limbic-hypothalamic neural pathway.

Neural pathways between sexually dimorphic forebrain regions develop under the influence of sex steroid hormones during the perinatal period, but how these hormones specify precise sex-specific patterns of connectivity is unknown. A heterochronic coculture system was used to demonstrate that sex steroid hormones direct development of a sexually dimorphic limbic-hypothalamic neural pathway through a target-dependent mechanism. Explants of the principal nucleus of the bed nuclei of the stria terminalis (BSTp) extend neurites toward explants of the anteroventral periventricular nucleus (AVPV) derived from male but not female rats. Coculture of BSTp explants from male rats with AVPV explants derived from females treated in vivo with testosterone for 9 d resulted in a high density of neurites extending from the BSTp to the AVPV explant, as was the case when the BSTp explants were derived from females and the AVPV explants were derived from males or androgen-treated females. These in vitro findings suggest that during the postnatal period testosterone induces a target-derived, diffusible chemotropic activity that results in a sexually dimorphic pattern of connectivity.

Animals↗
PubMed2000

GAL4/UAS-WGA system as a powerful tool for tracing Drosophila transsynaptic neural pathways.

Visualization of specific transsynaptic neural pathways is an indispensable technique for understanding the relationship between structure and function in the nervous system. Here, we demonstrate the application of the wheat germ agglutinin (WGA) transgene technique for tracing transsynaptic neural pathways in Drosophila. The intracellular localization of WGA was examined by immunoelectron microscopy. WGA signals were detected in granule-like structures in both the outer photoreceptor cells expressing WGA and the second-order laminar neurons. Misexpression of tetanus toxin (TNT), which inactivates N-synaptobrevin, in the outer photoreceptor cells resulted in the elimination of on/off transients in electroretinogram (ERG) recordings and in a great reduction in WGA transfer into laminar neurons, suggesting that anterograde WGA transsynaptic transfer is dependent mainly on synaptic transmission. Retrograde WGA transfer was also detected upon its forced expression in muscle cells. WGA primarily expressed in muscle cells was taken up by motoneuron axons and transported to their cell bodies in the ventral nerve cord, suggesting that WGA can trace motoneuronal pathways in combination with the muscle-specific GAL4 driver. Thus, the GAL4/UAS-WGA system should facilitate the dissection of the Drosophila neural circuit formation and/or synaptic activity in various regions and at various developmental stages.

Animals↗
PubMed1999

A review of objective methods of evaluating auditory neural pathways.

OBJECTIVES: Review physiological methods of evaluating function of the auditory neural pathways in infants, children, and adults. Present two case studies to demonstrate the usefulness of physiological measures in assessing abnormalities of the auditory neural pathways. STUDY DESIGN: Review of applications of physiological measures of auditory neural function. METHODS: Review otoacoustic emissions, auditory evoked potentials, and efferent reflexes, and discuss their use in identifying disorders of the auditory neural pathways from the cochlea to the cortex. RESULTS: Auditory disorders occur from peripheral to central areas of the neural system. Patients with disorders of the peripheral nerve and/or the input from the cochlear inner hair cells, such as the patients presently described as having auditory neuropathy, demonstrate abnormal efferent reflexes, including middle ear muscle reflexes and efferent suppression of otoacoustic emissions, as well as grossly abnormal brainstem evoked potentials. In contrast, patients with more central disorders can be differentiated by normal results on tests of the neural periphery and abnormal findings on cortical evoked potentials and other measures of central function. CONCLUSIONS: Physiological measures are sensitive, objective, and less variable in assessing neural disorders than traditional behavioral measures such as pure-tone or speech audiometry.

Adolescent↗
PubMed2006

Lack of telomerase activity in rabbit bone marrow stromal cells during differentiation along neural pathway.

OBJECTIVE: To investigate telomerase activity in rabbit bone marrow stromal cells (BMSCs) during their committed differentiation in vitro along neural pathway and the effect of glial cell line-derived neurotrophic factor (GDNF) on the expression of telomerase. METHODS: BMSCs were acquired from rabbit marrow and divided into control group, GDNF (10 ng/ml) group. Cytokine.NSCs medium (prepared by our lab, Patent No. ZL02134314. 4) supplemented with 10 percent fetal bovine serum (FBS) was used to induce BMSCs differentiation along neural pathway. Fluorescent immunocytochemistry was employed to identify the expressions of Nestin, neuron-specific endase (NSE), and gial fibrillary acidic protein (GFAP). The growth curves of the cells and the status of cell cycles were analyzed, respectively. During the differentiation, telomerase activities were detected using the telomeric repeat amplification protocol-enzyme-linked immunosorbent assay (TRAP-ELISA). RESULTS: BMSCs were successfully induced to differentiate along neural pathway and expressed specific markers of fetal neural epithelium, mature neuron and glial cells. Telomerase activities were undetectable in BMSCs during differentiation along neural pathway. Similar changes of cell growth curves, cell cycle status and telomerase expression were observed in the two groups. CONCLUSIONS: Rabbit BMSCs do not display telomerase activity during differentiation along neural pathway. GDNF shows little impact on proliferation and telomerase activity of BMSCs.

Animals↗
PubMed1998

Anaphylaxis-induced alterations in intestinal motility: role of extrinsic neural pathways.

The roles of mast cells and extrinsic and vagal neural pathways in the anaphylaxis-induced alterations in motility observed at sites remote from antigen exposure were explored. Rats were sensitized to egg albumin (EA) and prepared with 1) electrodes to monitor intestinal myoelectric activity, 2) an isolated intestinal loop, and 3) either intact vagal innervation or a subdiaphragmatic vagotomy. Fasting myoelectric activity was recorded before and after challenge of the jejunum in continuity or the isolated loop with EA or BSA. Intestinal segments and the brain stems were processed for mast cell identification (intestine) or Fos immunoreactivity (brain stem). EA but not BSA challenge of the jejunum or the isolated loop induced altered motility at both sites and diarrhea. Granulated mast cells were significantly reduced at the site local to but not remote from challenge. Vagotomy did not inhibit antigen-induced alterations in motility or diarrhea. The number of Fos-immunoreactive nuclei in vagal sensory or motor nuclei was not significantly altered by vagotomy. Thus antigen challenge of sensitized animals causes mast cell degranulation only at the site of direct challenge but alters motility at sites local and remote from challenge. The remote response requires intact extrinsic but not necessarily vagal neural pathways.

Anaphylaxis↗
PubMed1996

Influence of general anesthetics on a specific neural pathway in Drosophila melanogaster.

The neural pathway that governs an escape response of Drosophila to sudden changes in light intensity can be artificially induced by electrical stimulation of the brain and monitored by electrical recording from the effector muscles. We have refined previous work in this system to permit reliable ascertainment of two kinds of response: (i) a short-latency response that follows from direct excitation of a giant fiber neuron in the interior of the fly brain and (ii) a long-latency response in which electrical stimulation triggers neurons in the optic ganglia that ultimately impinge on the giant fiber neuron. The general anesthetic halothane is reported here to have very different potencies in inhibiting these two responses. The long-latency response is obliterated at concentrations similar to those that cause gross behavioral effects in adult flies, whereas the short-latency response is only partially inhibited at doses that are 10-fold higher. Three other volatile anesthetic agents show a similar pattern. Thus, as in higher organisms, the Drosophila nervous system is differentiated into components of high and low sensitivity to general anesthetics. Moreover, this work shows that one of the sensitive components of the nervous system lies in the optic lobe and is readily assayed by its effect on downstream systems; it should provide a focus for exploring the effects of genetic alteration of anesthetic sensitivity.

Anesthetics, General↗
PubMed2006

Alternation of substance P-containing neural pathways in a rat model of irritable bowel syndrome with rectal distension.

OBJECTIVE: Irritable bowel syndrome (IBS) is a common disorder in clinical practice, but the pathophysiology of IBS has not been completely elucidated yet. Experiments have revealed that the concentrations of some kinds of brain-gut peptides, such as substance P, were abnormal in the plasma and/or the intestinal mucosa. In order to explore further the possible role of substance P containing nerve fibers in the enteric nervous system and central nervous system, the expression of c-fos, a well-established marker of activated neural pathway, was induced to show substance P containing a neural pathway in the rat model of constipation-predominant IBS by rectal distention. METHODS: The rat model was set up by intragastric instillation of 2.0 mL water at 0-4 degrees C in 20 male Wistar rats for two weeks. Both the model group and the controls underwent rectal distention under deep anesthesia. Sections containing the anatomical areas of interest were obtained and processed for c-fos protein and substance P immunohistochemistry using the strept avidin-biotin complex (SABC) method. The staining results were analyzed semi-quantitatively, using a computerized color image analyzer with two parameters: opacity density and immunoreactive areas. The statistical difference of the opacity density and immunoreactive areas between the two groups was analyzed by a t-test. Correlation analysis was used to investigate the relationship between the expression of substance P and c-fos protein of the same region in the model group. RESULTS: The opacity density of substance P immunoreactive tissues in the ileocecal junction, colon, the posterior horn of the spinal cord and the hypothalamus of the model group were all significantly higher compared with those in the control group (176.6 vs 155.5, 172.3 vs 152.0, 182.1 vs 160.2, 128.3 vs 117.9; P < 0.05, respectively). Meanwhile in the ileocecal junction, colon, the posterior horn of the spinal cord and the hypothalamus of the model group, the opacity density of c-fos protein-positive tissue were all significantly higher than those of the same region in the controls (120.9 vs 109.0, 101.3 vs 92.2, 125.4 vs 88.7, 115.5 vs 88.6; P < 0.05, respectively). The distribution of c-fos protein-positive tissue is similar to that of the substance P and the analysis shows that there is close correlation between the expression of substance P and c-fos protein of the same region in the model group (r = 0.594-0.721, P < 0.05). CONCLUSIONS: The expression of substance P and c-fos protein in both the enteric nervous system and the central nervous system of the constipation-predominant IBS rat model is abnormal, which suggests that an abnormal change in substance P may be involved in the pathogenesis of IBS and the substance P-containing neural pathway may be one of the neural pathways that play important role in the regulation of the gastrointestinal function.

Animals↗
PubMed1984

Enteric neural pathways inhibitory to rabbit duodenal serotonin release.

Previous studies have shown that adrenergic and cholinergic neural pathways mediate duodenal serotonin (5-HT) release from the mucosal surface after a luminal acid stimulus. To examine the overall neural contribution to 5-HT release, we studied the effects of tetrodotoxin (TTX), a nerve-conduction blocker, added to mucosal and/or serosal surfaces of rabbit duodenal mucosa in a modified Ussing chamber at both neutral and acid (pH 5) luminal pH. A specific radioimmunoassay was used to measure 5-HT. TTX (2 X 10(-7) M) increased mucosal 5-HT release significantly at luminal pH 7.4 and 5 when it was added to both mucosal and serosal surfaces (2.7- and 1.9-fold at pH 7.4 and pH 5, respectively; p less than 0.05 for each) or when it was added to the serosal surface only (3.4- and 1.8-fold; p less than 0.02 and p less than 0.01, respectively). TTX added only to the mucosal surface, however, reduced 5-HT release by 48.5% at pH 5 (p less than 0.01) and had no effect at pH 7.4. Since adenosine triphosphate (ATP) and vasoactive intestinal polypeptide are the two proposed mediators of a nonadrenergic, noncholinergic inhibitory neural system, we studied the effects of each on mucosal 5-HT release. While vasoactive intestinal polypeptide had no significant effect at either pH, ATP (10(-7)M) reduced acid-stimulated 5-HT release by approximately 50% (p less than 0.02). We conclude that a nonadrenergic, noncholinergic neural pathway that is inhibitory to mucosal 5-HT release resides primarily on the basal surface of mucosal cells. ATP is the most likely neurotransmitter involved in this response.

Adenosine Triphosphate↗
PubMed2006

Topographic and functional neuroanatomical study of GABAergic disinhibitory striatum-nigral inputs and inhibitory nigrocollicular pathways: neural hodology recruiting the substantia nigra, pars reticulata, for the modulation of the neural activity in the inferior colliculus involved with panic-like emotions.

Considering the influence of the substantia nigra on mesencephalic neurons involved with fear-induced reactions organized in rostral aspects of the dorsal midbrain, the present work investigated the topographical and functional neuroanatomy of similar influence on caudal division of the corpora quadrigemina, addressing: (a) the neural hodology connecting the neostriatum, the substantia nigra, periaqueductal gray matter and inferior colliculus (IC) neural networks; (b) the influence of the inhibitory neostriatonigral-nigrocollicular GABAergic links on the control of the defensive behavior organized in the IC. The effects of the increase or decrease of activity of nigrocollicular inputs on defensive responses elicited by either electrical or chemical stimulation of the IC were also determined. Electrolytic or chemical lesions of the substantia nigra, pars reticulata (SNpr), decreased the freezing and escape behaviors thresholds elicited by electrical stimulation of the IC, and increased the behavioral responses evoked by the GABAA blockade in the same sites of the mesencephalic tectum (MT) electrically stimulated. These findings were corroborated by similar effects caused by microinjections of the GABAA-receptor agonist muscimol in the SNpr, followed by electrical and chemical stimulations of the IC. The GABAA blockade in the SNpr caused a significant increase in the defensive behavior thresholds elicited by electrical stimulation of the IC and a decrease in the mean incidence of panic-like responses induced by microinjections of bicuculline in the mesencephalic tectum (inferior colliculus). These findings suggest that the substantia nigra receives GABAergic inputs that modulate local and also inhibitory GABAergic outputs toward the IC. In fact, neurotracing experiments with fast blue and iontophoretic microinjections of biotinylated dextran amine either into the inferior colliculus or in the reticular division of the substantia nigra demonstrated a neural link between these structures, as well as between the neostriatum and SNpr.

Animals↗
PubMed2000

Neural pathways regulating Brunner's gland secretion in guinea pig duodenum in vitro.

This study examined the neural pathways innervating Brunner's glands using a novel in vitro model of acinar secretion from Brunner's glands in submucosal preparations from the guinea pig duodenum. Neural pathways were activated by focal electrical stimulation and excitatory agonists, and videomicroscopy was used to monitor dilation of acinar lumen. Electrical stimulation of perivascular nerves evoked large dilations that were blocked by TTX (1 microM) or the muscarinic receptor antagonist 4-diphenylacetoxy-N-(2-chloroethyl)-piperidine hydrochloride (1 microM). The nicotinic agonist 1,1-dimethyl-4-phenylpiperazinium iodide (100 microM) had no effect, and the nerve-evoked responses were not inhibited by hexamethonium (200 microM). Dilations were abolished in preparations from chronically vagotomized animals. Activation of submucosal ganglia significantly dilated submucosal arterioles but not Brunner's glands. Effects of electrical stimulation of perivascular and submucosal nerves were not altered by guanethidine. Capsaicin and substance P also dilated arterioles but had no effect on Brunner's glands. Cholinergic (choline acetyltransferase-immunoreactive) nerve fibers were found in Brunner's glands. These findings demonstrate that Brunner's glands are innervated by cholinergic vagal fibers but not by capsaicin-sensitive or intrinsic enteric nerves.

Animals↗
PubMed1999

Ascending neural pathways in the isolated guinea-pig ileum: effect of muscarinic M1, M2 and M3 cholinergic antagonists.

The effect of muscarinic cholinoceptor antagonists was investigated on the ascending neural pathways activated by electrical stimulation in the guinea-pig ileum. For comparison, prejunctional and postjunctional effects of muscarinic cholinoceptor antagonists were also studied on circular smooth muscle. A two-compartment (oral and anal compartments) bath was used to study the ascending neural pathways. These were activated by electrical field stimulation in the anal compartment and the resulting contraction of the intestinal circular muscle in the oral compartment was recorded isotonically. Pirenzepine (10-300 nM), a muscarinic M1 cholinoceptor antagonist, reduced the ascending neural contractions in a concentration-dependent fashion when applied either to the oral or anal compartments (11-52% and 13-55% inhibition, respectively, P < 0.05). Pirenzepine inhibited (31+/-7%, P < 0.05) the acetylcholine (100 nM)-induced contractions at a higher non-selective concentration (300 nM), while its effect on the electrically-induced contractions was biphasic (10 and 30nM: 8-15% increase, P<0.05; 100 and 300 nM: 16-28% inhibition, P<0.05). The muscarinic M2 cholinoceptor antagonist methoctramine (3-100 nM) did not modify the contractions produced by 100 nM acetylcholine, electrically-induced contractions and the ascending neural contractions (when applied to either compartment). Parafluorohexahydrosiladifenidol (3-100 nM), a muscarinic M3 cholinoceptor antagonist, inhibited the contractions produced by 100 nM acetylcholine (19-81% and 15-69%), electrically-induced contractions (11-71% and 12-72%) and the ascending neural contractions (13-76% and 866%) when applied to the oral compartment, but it was without effect when applied to the anal compartment. These studies suggest that in the enteric ascending neural pathway, muscarinic M1 receptors are involved in neuroneuronal transmission, muscle contraction is mediated by muscarinic M3 cholinergic receptors, whereas muscarinic M2 receptors do not seem to participate.

Acetylcholine↗
PubMed1998

Effect of stimulating peripheral and central neural pathways on pharyngeal muscle contraction timing during swallowing in dogs.

The effect of stimulating peripheral and central neural pathways on the electromyographic activity in the hyopharyngeal, thyropharyngeal, and cricopharyngeal muscles was studied in eight dogs during 1) eating, 2) unilateral electrical stimulation of the superior laryngeal nerve, and 3) unilateral electrical stimulation of the solitary nucleus. The duration of pharyngeal swallowing was significantly shorter during eating than during stimulation of the solitary nucleus in the anesthetized dog (mean difference 127 ms, SEM 9, n = 15). The duration of pharyngeal swallowing was significantly shorter during eating than during stimulation of the superior laryngeal nerve in the awake dog (mean difference 84 ms, SEM 13, n = 9). The duration of pharyngeal swallowing during stimulation of the superior laryngeal nerve under anesthesia was significantly shorter than during stimulation of the solitary nucleus under anesthesia (mean difference 58 ms, SEM 18, n = 9). The difference in duration of pharyngeal swallowing during stimulation of the superior laryngeal nerve between the awake state and during anesthesia was not significant (mean 19 ms, SEM 14, n = 9). It was concluded that stimulation of peripheral and central neural pathways resulted in different pharyngeal muscle contraction timing during swallowing in dogs.

Animals↗
PubMed2006

Role played by brainstem neurons in regulating testosterone secretion via a direct neural pathway between the hypothalamus and the testes.

We previously reported anatomical and functional evidence for a direct, inhibitory neural pathway that regulates testosterone (T) secretion independently of the pituitary. This pathway is activated by the intracerebroventricular (icv) administration of agents that stimulate stress responses, such as IL-1beta, corticotropin-releasing factor (CRF), and norepinephrine (NE), which results in a blunted T response to the administration of human chorionic gonadotropin (hCG). Blunting of the T response is mediated by central beta-adrenergic receptor stimulation. CRF, but not ethanol (EtOH) or IL-1beta, acts directly on the paraventricular nucleus of the hypothalamus to activate the pathway. Here we explored the role played by brain areas hypothesized to be part of this pathway, such as neurons in the dorsal pons [including the locus coeruleus (LC) of the brainstem], where NE is produced. Microinfusion of EtOH or IL-1beta, but not CRF, into these neurons activated the pathway. Electrolytic lesions of this region significantly reversed the inhibitory effect of icv-administered EtOH on hCG-induced T release, while having no effect on the ability of IL-1beta or CRF to do so. However, the icv administration of IL-1beta, EtOH, or CRF, in doses that rapidly inhibit the T response to hCG, all caused a significant depletion of NE from the LC. Collectively, these results indicate that in addition to the paraventricular nucleus, the brainstem area containing the LC is part of a neural pathway that connects the brain to the testes independently of the pituitary. We also speculate that EtOH may stimulate this pathway through NE-dependent activation of the dorsal pons.

Animals↗
PubMed1999

Neural pathways involved in the processing of concrete and abstract words.

The purpose of this study was to delineate the neural pathways involved in processing concrete and abstract words using functional magnetic resonance imaging (fMRI). Word and pseudoword stimuli were presented visually, one at a time, and the participant was required to make a lexical decision. Lexical decision epochs alternated with a resting baseline. In each lexical decision epoch, the stimuli were either concrete words and pseudowords, or abstract words and pseudowords. Behavioral data indicated that, as with previous research, concrete word stimuli were processed more efficiently than abstract word stimuli. Analysis of the fMRI data indicated that processing of word stimuli, compared to the baseline condition, was associated with neural activation in the bilateral fusiform gyrus, anterior cingulate, left middle temporal gyrus, right posterior superior temporal gyrus, and left and right inferior frontal gyrus. A direct comparison between the abstract and concrete stimuli epochs yielded a significant area of activation in the right anterior temporal cortex. The results are consistent with recent positron emission tomography work showing right hemisphere activation during processing of abstract representations of language. The results are interpreted as support for a right hemisphere neural pathway in the processing of abstract word representations.

Adult↗
PubMed1992

Pupillary constriction in response to light in rodents, which does not depend on central neural pathways.

We show here that the widely held belief that reflex constriction of the mammalian pupil in response to light depends exclusively upon neural pathways between eye and brain is in need of revision. We investigated the response of the pupil to light in dark-adapted rodents (golden hamsters; hooded rats; albino rats) subjected to a variety of surgical and pharmacological interventions designed to destroy or block all of the neural pathways and structures through which the reflex could be mediated. The interventions included bilateral intraorbital optic nerve section, or unilateral intracranial optic nerve section with enucleation of the contralateral eye, combined in some cases with bilateral removal of the superior cervical ganglia and/or pinealectomy; topical application of atropine; intraocular injection of tetrodotoxin (TTX). Golden hamsters and hooded rats, but not albino rats, retained an effective constriction of the pupil in response to light after all of these interventions, although the constriction was less and slower than in normal animals. These findings show that hamsters and hooded rats have both a neurally mediated fast light reflex that can be eliminated by severing connections between eye and brain, by blockade of cholinergic transmission to iris smooth muscle, and by blockade of action potentials by TTX; and a local, slower constriction in response to light, which remains after all these procedures. We have also confirmed previous observations of Bito and Turansky (1975) that pupillary constriction in response to light occurs in isolated in vitro anterior chamber preparations of hamster and hooded rat eyes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗