An electrophysiological and morphological study of esophageal motoneurons in rats

1994 ◽  
Vol 266 (2) ◽  
pp. R622-R632 ◽  
Author(s):  
B. Kruszewska ◽  
J. Lipski ◽  
R. Kanjhan
Keyword(s):  
Lucifer Yellow ◽  
Nucleus Ambiguus ◽  
Upper Airways ◽  
Dendritic Trees ◽  
Antidromic Stimulation ◽  
Respiratory Modulation ◽  
Intracellular Labelling ◽  
Rostral Portion ◽  
Dorsal Medulla

Previous anatomic studies have shown that motoneurons supplying the striated musculature of the esophagus form a tightly grouped cluster in the rostral portion of the nucleus ambiguus, known as the compact formation. This study, conducted in anesthetized rats, presents the first in vivo intracellular and extracellular recordings from this group of motoneurons, which were identified by antidromic stimulation directly from the esophagus (latency 7-68 ms). The motoneurons were silent at rest, and those impaled intracellularly (n = 44) showed no respiratory modulation of their membrane potential. Intracellular labelling with Lucifer Yellow (n = 3) or Neurobiotin (n = 15) revealed multipolar somas with longitudinally oriented dendritic trees mainly confined to the compact formation. No axon collaterals were found. When swallowing-like activity was induced by muscarine applied to the dorsal medullary surface, the motoneurons displayed bursting activity, with the majority of bursts occurring during expiration. These results show that antidromic stimulation of esophageal motoneurons with an electrode inserted into the esophagus provides a simple way of identifying these motoneurons. In the absence of pharmacological stimulation, these motoneurons receive no respiratory-modulated synaptic input, in contrast to adjacent motoneurons in the semicompact formation (supplying the upper airways), which are known to display respiratory activity. However, some synchronization of respiratory and swallowing-like activity was observed after pharmacological activation of the swallowing pattern generator in the dorsal medulla.

Distribution of vagal cardioinhibitory neurons in the medulla of the cat

1980 ◽  
Vol 238 (1) ◽  
pp. R57-R64 ◽  
Author(s):  
J. Ciriello ◽  
F. R. Calaresu
Keyword(s):  
Nucleus Tractus Solitarius ◽  
Border Region ◽  
Nucleus Ambiguus ◽  
Motor Nucleus ◽  
Dorsal Motor Nucleus ◽  
Antidromic Stimulation ◽  
Low Threshold ◽  
Vagal Bradycardia ◽  
Medullary Nuclei ◽  
Stimulation Of

Experiments were done in cats anesthetized with chloralose, paralyzed and artificially ventilated cats to obtain electrophysiological evidence on the medullary site of origin of vagal cardioinhibitory fibers. The regions of the nucleus ambiguus (AMB), dorsal motor nucleus of the vagus (DMV), nucleus tractus solitarius (NTS), and external cuneate nucleus (ECN) were systematically explored for units responding both to antidromic stimulation of the cardiac branches of the vagus (CBV) and to orthodromic stimulation of the carotid sinus and aortic depressor nerves. Eighty-six single units conforming to these criteria were found in the medulla: 30 in the AMB, 26 in the DMV, 12 in the NTS, 8 in the NTS-DMV border region, and 10 in the ECN. Antidromically evoked spikes had durations of 0.5--2.5 ms and followed stimulation frequencies of 20--500 Hz. The axons of these units conducted at velocities of 3.3--20.8 m/s. The specificity of activation of medullary units by cardioinhibitory fibers was tested in 11 units, which were found to respond consistently with an antidromic spike to stimulation of CBV but not to stimulation of the thoracic vagus. In eight spinal animals low threshold (less than 15 microA) sites eliciting vagal bradycardia were found in the same medullary nuclei where cardioinhibitory units had been located. These results indicate that vagal cardioinhibitory axons, originate in at least three medullary nuclei, the AMB, DMV, and NTS. Unit activity from the ECN may have been recorded from carioinhibitory fibers because of the short duration of the spike potentials.

scholarly journals Chinese hamster ovary cell lysosomes rapidly exchange contents.

1987 ◽  
Vol 105 (6) ◽  
pp. 2703-2712 ◽  
Author(s):  
A L Ferris ◽  
J C Brown ◽  
R D Park ◽  
B Storrie
Keyword(s):  
Cell Fusion ◽  
Lucifer Yellow ◽  
Recipient Cell ◽  
Chinese Hamster ◽  
Donor Cell ◽  
Fluid Phase ◽  
Ovary Cell ◽  
Priming Process

We have used cell fusion to address the question of whether macromolecules are rapidly exchanged between lysosomes. Donor cell lysosomes were labeled by the long-term internalization of the fluid-phase pinocytic markers, invertase (sucrase), Lucifer Yellow, FITC-conjugated dextran, or Texas red-conjugated dextran. Recipient cells contained lysosomes swollen by long-term internalization of dilute sucrose or marked by an overnight FITC-dextran uptake. Cells were incubated for 1 or 2 h in marker-free media before cell fusion to clear any marker from an endosomal compartment. Recipient cells were infected with vesicular stomatitis virus as a fusogen. Donor and recipient cells were co-cultured for 1 or 2 h and then fused by a brief exposure to pH 5. In all cases, extensive exchange of content between donor and recipient cell lysosomes was observed at 37 degrees C. Incubation of cell syncytia at 17 degrees C blocked lysosome/lysosome exchange, although a "priming" process(es) appeared to occur at 17 degrees C. The kinetics of lysosome/lysosome exchange in fusions between cells containing invertase-positive lysosomes and sucrose-positive lysosomes indicated that lysosome/lysosome exchange was as rapid, if not more rapid, than endosome/lysosome exchange. These experiments suggest that in vivo the lysosome is a rapidly intermixing organellar compartment.

Cyclic Adenosine Monophosphate Stimulation of Mucociliary Activity in the Upper Airways in Vivo

1995 ◽  
Vol 104 (5) ◽  
pp. 388-393 ◽  
Author(s):  
Anders Cervin ◽  
Sven Lindberg ◽  
Jan Dolata ◽  
Ulf Mercke
Keyword(s):  
Upper Airway ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Airway Disease ◽  
Maxillary Artery ◽  
Dibutyryl Camp ◽  
Upper Airways ◽  
Maximum Increase ◽  
Xanthine Derivatives

Xanthine derivatives are known to accelerate mucociliary transport in the lower airways, probably by preventing degradation of cyclic adenosine monophosphate (cAMP) and thereby increasing its intracellular concentration. The purpose of this study was to investigate the effects of cAMP on mucociliary activity in the upper airways. The effect on the mucociliary activity in the rabbit maxillary sinus of the xanthine derivatives theophylline and enprophylline was compared to that of the cAMP analog dibutyryl cAMP. The compounds were administered into the maxillary artery, and the response was recorded with a photoelectric technique. Infusions of theophylline (1.0 and 10 mg/kg) increased mucociliary activity (22.8% ± 5.9%, n = 6, and 21.6% ± 4.9%, n = 7, p < .05, respectively). Infusions of enprophylline (1.0 and 10.0 mg/kg) accelerated mucociliary activity (at the highest dosage tested, 24.3% ± 4.1%). Infusions of dibutyryl cAMP (0.1 and 1.0 mg/kg) stimulated mucociliary activity, with the maximum increase (20.1% ± 3.0%, n = 13, p < .05) being observed at a dosage of 0.1 mg/kg. The infused substances increased mucociliary activity within 1 minute after the start of the infusion, the duration of the response being approximately 20 minutes for theophylline, 22 minutes for enprophylline, and 12 minutes for dibutyryl cAMP. The present results support the view that cAMP is involved in regulating mucociliary activity in the upper airways. It remains to be elucidated whether xanthines such as theophylline and enprophylline are beneficial in upper airway disease in which mucociliary function is impaired (eg, chronic sinusitis).

Spatial distribution of excitatory and inhibitory synapses on a Purkinje cell in a rat cerebellar culture

1993 ◽  
Vol 70 (4) ◽  
pp. 1316-1325 ◽  
Author(s):  
T. Hirano ◽  
K. Kasono
Keyword(s):  
Spatial Distribution ◽  
Purkinje Cell ◽  
Purkinje Cells ◽  
Spatial Organization ◽  
Lucifer Yellow ◽  
Inhibitory Synapses ◽  
Presynaptic Neuron ◽  
Presynaptic Terminals ◽  
Excitatory And Inhibitory Synapses

1. The spatial distribution of excitatory and inhibitory synapses on cultured Purkinje cells was studied with fluorescence, scanning electron microscopy (SEM), and electrophysiological techniques. 2. Presynaptic terminals were identified with immunohistochemical staining of synaptophysin and the results were correlated with SEM micrographs. 3. Excitatory and inhibitory inputs onto the Purkinje cell were identified from the direction and pharmacology of the postsynaptic current. 4. The localization of the presynaptic terminals on the Purkinje cell was observed after electrophysiological identification by filling the presynaptic neuron with Lucifer yellow and the Purkinje cell with Texas red. 5. The axon and presynaptic terminals of excitatory and inhibitory inputs had a different spatial organization. Excitatory inputs from granule cells were exclusively localized on the dendrites of Purkinje cells, whereas inhibitory contacts were found on both the soma and dendrites. This result is similar to that described in vivo.

scholarly journals HIV-1-Tat excites cardiac parasympathetic neurons of nucleus ambiguus and triggers prolonged bradycardia in conscious rats

2014 ◽  
Vol 306 (11) ◽  
pp. R814-R822 ◽  
Author(s):  
Eugen Brailoiu ◽  
Elena Deliu ◽  
Romeo A. Sporici ◽  
Khalid Benamar ◽  
G. Cristina Brailoiu
Keyword(s):  
Transient Receptor Potential ◽  
Nucleus Ambiguus ◽  
Neuronal Membrane ◽  
Transient Receptor Potential Vanilloid ◽  
Viral Load Suppression ◽  
Conscious Rats ◽  
Qt Interval Prolongation ◽  
Parasympathetic Neurons ◽  
Hiv 1

The mechanisms of autonomic imbalance and subsequent cardiovascular manifestations in HIV-1-infected patients are poorly understood. We report here that HIV-1 transactivator of transcription (Tat, fragment 1–86) produced a concentration-dependent increase in cytosolic Ca2+ in cardiac-projecting parasympathetic neurons of nucleus ambiguus retrogradely labeled with rhodamine. Using store-specific pharmacological agents, we identified several mechanisms of the Tat-induced Ca2+ elevation: 1) lysosomal Ca2+ mobilization, 2) Ca2+ release via inositol 1,4,5-trisphosphate-sensitive endoplasmic reticulum pools, and 3) Ca2+ influx via transient receptor potential vanilloid type 2 (TRPV2) channels. Activation of TRPV2, nonselective cation channels, induced a robust and prolonged neuronal membrane depolarization, thus triggering an additional P/Q-mediated Ca2+ entry. In vivo microinjection studies indicate a dose-dependent, prolonged bradycardic effect of Tat administration into the nucleus ambiguus of conscious rats, in which neuronal TRPV2 played a major role. Our results support previous studies, indicating that Tat promotes bradycardia and, consequently, may be involved in the QT interval prolongation reported in HIV-infected patients. In the context of an overall HIV-dependent autonomic dysfunction, these Tat-mediated mechanisms may account for the higher prevalence of sudden cardiac death in HIV-1-infected patients compared with general population with similar risk factors. Our results may be particularly relevant in view of the recent findings that significant Tat levels can still be identified in the cerebrospinal fluid of HIV-infected patients with viral load suppression due to efficient antiretroviral therapy.

Preparation and In Vivo Imaging of Lucifer Yellow Tagged Hydrogels

2011 ◽  
Vol 309-310 (1) ◽  
pp. 222-228 ◽  
Author(s):  
Lena Möller ◽  
Andreas Krause ◽  
Ivonne Bartsch ◽  
Andreas Kirschning ◽  
Frank Witte ◽  
...  
Keyword(s):  
In Vivo Imaging ◽  
Lucifer Yellow

scholarly journals Diverse processing underlying frequency integration in midbrain neurons of barn owls

2021 ◽  
Vol 17 (11) ◽  
pp. e1009569
Author(s):  
Julia C. Gorman ◽  
Oliver L. Tufte ◽  
Anna V. R. Miller ◽  
William M. DeBello ◽  
José L. Peña ◽  
...  
Keyword(s):  
Sound Localization ◽  
Frequency Tuning ◽  
Interaural Time Difference ◽  
Sound Sources ◽  
Dendritic Trees ◽  
Midbrain Neurons ◽  
Dendritic Processing ◽  
Barn Owls ◽  
Nonlinear Integration

Emergent response properties of sensory neurons depend on circuit connectivity and somatodendritic processing. Neurons of the barn owl’s external nucleus of the inferior colliculus (ICx) display emergence of spatial selectivity. These neurons use interaural time difference (ITD) as a cue for the horizontal direction of sound sources. ITD is detected by upstream brainstem neurons with narrow frequency tuning, resulting in spatially ambiguous responses. This spatial ambiguity is resolved by ICx neurons integrating inputs over frequency, a relevant processing in sound localization across species. Previous models have predicted that ICx neurons function as point neurons that linearly integrate inputs across frequency. However, the complex dendritic trees and spines of ICx neurons raises the question of whether this prediction is accurate. Data from in vivo intracellular recordings of ICx neurons were used to address this question. Results revealed diverse frequency integration properties, where some ICx neurons showed responses consistent with the point neuron hypothesis and others with nonlinear dendritic integration. Modeling showed that varied connectivity patterns and forms of dendritic processing may underlie observed ICx neurons’ frequency integration processing. These results corroborate the ability of neurons with complex dendritic trees to implement diverse linear and nonlinear integration of synaptic inputs, of relevance for adaptive coding and learning, and supporting a fundamental mechanism in sound localization.

scholarly journals REGN-COV2 antibodies prevent and treat SARS-CoV-2 infection in rhesus macaques and hamsters

Science ◽  
2020 ◽  
Vol 370 (6520) ◽  
pp. 1110-1115 ◽  
Author(s):  
Alina Baum ◽  
Dharani Ajithdoss ◽  
Richard Copin ◽  
Anbo Zhou ◽  
Kathryn Lanza ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Therapeutic Potential ◽  
Rhesus Macaques ◽  
Severe Disease ◽  
Spike Protein ◽  
Upper Airways ◽  
In Vivo Efficacy ◽  
Mild Disease ◽  
Antibody Cocktail

An urgent global quest for effective therapies to prevent and treat coronavirus disease 2019 (COVID-19) is ongoing. We previously described REGN-COV2, a cocktail of two potent neutralizing antibodies (REGN10987 and REGN10933) that targets nonoverlapping epitopes on the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein. In this report, we evaluate the in vivo efficacy of this antibody cocktail in both rhesus macaques, which may model mild disease, and golden hamsters, which may model more severe disease. We demonstrate that REGN-COV-2 can greatly reduce virus load in the lower and upper airways and decrease virus-induced pathological sequelae when administered prophylactically or therapeutically in rhesus macaques. Similarly, administration in hamsters limits weight loss and decreases lung titers and evidence of pneumonia in the lungs. Our results provide evidence of the therapeutic potential of this antibody cocktail.

scholarly journals Reassortment between Avian H5N1 and Human H3N2 Influenza Viruses in Ferrets: a Public Health Risk Assessment

2009 ◽  
Vol 83 (16) ◽  
pp. 8131-8140 ◽  
Author(s):  
Sara Jackson ◽  
Neal Van Hoeven ◽  
Li-Mei Chen ◽  
Taronna R. Maines ◽  
Nancy J. Cox ◽  
...  
Keyword(s):  
Upper Airway ◽  
Influenza Viruses ◽  
Upper Respiratory Tract ◽  
Upper Airways ◽  
Nasal Secretions ◽  
H5 Subtype ◽  
H3n2 Influenza ◽  
Human Viruses ◽  
Reassortant Viruses

ABSTRACT This study investigated whether transmissible H5 subtype human-avian reassortant viruses could be generated in vivo. To this end, ferrets were coinfected with recent avian H5N1 (A/Thailand/16/04) and human H3N2 (A/Wyoming/3/03) viruses. Genotype analyses of plaque-purified viruses from nasal secretions of coinfected ferrets revealed that approximately 9% of recovered viruses contained genes from both progenitor viruses. H5 and H3 subtype viruses, including reassortants, were found in airways extending toward and in the upper respiratory tract of ferrets. However, only parental H5N1 genotype viruses were found in lung tissue. Approximately 34% of the recovered reassortant viruses possessed the H5 hemagglutinin (HA) gene, with five unique H5 subtypes recovered. These H5 reassortants were selected for further studies to examine their growth and transmissibility characteristics. Five H5 viruses with representative reassortant genotypes showed reduced titers in nasal secretions of infected ferrets compared to the parental H5N1 virus. No transmission by direct contact between infected and naïve ferrets was observed. These studies indicate that reassortment between H5N1 avian influenza and H3N2 human viruses occurred readily in vivo and furthermore that reassortment between these two viral subtypes is likely to occur in ferret upper airways. Given the relatively high incidence of reassortant viruses from tissues of the ferret upper airway, it is reasonable to conclude that continued exposure of humans and animals to H5N1 alongside seasonal influenza viruses increases the risk of generating H5 subtype reassortant viruses that may be shed from upper airway secretions.

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