Characterization of pancreas-projecting rat dorsal motor nucleus of vagus neurons

2005 ◽  
Vol 288 (5) ◽  
pp. G950-G955 ◽  
Author(s):  
Kirsteen N. Browning ◽  
F. Holly Coleman ◽  
R. Alberto Travagli
Keyword(s):  
Morphological Characteristics ◽  
Input Resistance ◽  
The Body ◽  
Morphological Properties ◽  
Motor Nucleus ◽  
Electrophysiological Properties ◽  
Dorsal Motor Nucleus ◽  
Whole Cell Patch Clamp ◽  
Brain Stem Slices

The electrophysiological and morphological properties of rat dorsal motor nucleus of the vagus (DMV) neurons innervating the pancreas were examined by using whole cell patch clamp recordings from brain stem slices and postfixation morphological reconstructions of Neurobiotin-filled neurons. Recordings were made from 178 DMV neurons whose projections had been identified by previous apposition of the fluorescent neuronal tracer DiI to the body of the pancreas. DMV neurons projecting to the pancreas had an input resistance of 434 ± 14 MΩ, an action potential duration of 3 ± 0.1 ms, and an afterhyperpolarization of 18 ± 0.4 mV amplitude and 108 ± 7 ms time constant of decay; these electrophysiological properties resembled those of gastric-projecting neurons but were significantly different from those of intestinal-projecting neurons. Interestingly, 14 of 178 pancreas-projecting neurons showed the presence of a slowly developing afterhyperpolarization whose presence was not reported in DMV neurons projecting to any other gastrointestinal area. The morphological characteristics of pancreas-projecting neurons (soma area 274 ± 12 μm2; soma diameter of 25 ± 0.7 μm; soma form factor 0.74 ± 0.01; segments 9.7 ± 0.41), however, were similar to those of intestinal- but differed from those of gastric-projecting neurons. In summary, these results suggest that pancreas-projecting rat DMV neurons are heterogeneous with respect to some electrophysiological and morphological properties. These differences might underlie functional differences in the vagal modulation of pancreatic functions.

scholarly journals Brain stem as a target site for the metabolic side effects of olanzapine

2016 ◽  
Vol 115 (3) ◽  
pp. 1389-1398 ◽  
Author(s):  
Imran J. Anwar ◽  
Kayoko Miyata ◽  
Andrea Zsombok
Keyword(s):  
Side Effects ◽  
Neuronal Excitability ◽  
Input Resistance ◽  
Experimental Models ◽  
Motor Nucleus ◽  
Metabolic Side Effects ◽  
Dorsal Motor Nucleus ◽  
Whole Cell Patch Clamp ◽  
Electrophysiological Recordings ◽  
Underlying Mechanisms

Olanzapine, an atypical antipsychotic, is widely prescribed for the treatment of schizophrenia and bipolar disorder despite causing undesirable metabolic side effects. A variety of mechanisms and brain sites have been proposed as contributors to the side effects; however, the role of the dorsal motor nucleus of the vagus nerve (DMV), which plays a crucial role in the regulation of subdiaphragmatic organs and thus governs energy and glucose homeostasis, is largely unknown. Identifying the effect of olanzapine on the excitability of DMV neurons in both sexes is thus crucial to understanding possible underlying mechanisms. Whole cell patch-clamp electrophysiological recordings were conducted in stomach- and liver-related DMV neurons identified with retrograde viral tracers and in random DMV neurons. The effect of olanzapine on the neuronal excitability of DMV neurons both in male and female mice was established. Our data demonstrate that olanzapine hyperpolarizes the DMV neurons in both sexes and this effect is reversible. The hyperpolarization is associated with decreased firing rate and input resistance. Olanzapine also decreases the excitability of a subset of stomach- and liver-related DMV neurons. Our study demonstrates that olanzapine has a powerful effect on DMV neurons in both sexes, indicating its ability to reduce vagal output to the subdiaphragmatic organs, which likely contributes to the metabolic side effects observed in both humans and experimental models. These findings suggest that the metabolic side effects of olanzapine may partially originate in the DMV.

scholarly journals A Characterization of the Electrophysiological and Morphological Properties of Vasoactive Intestinal Peptide (VIP) Interneurons in the Medial Entorhinal Cortex (MEC)

2021 ◽  
Vol 15 ◽  
Author(s):  
Saishree Badrinarayanan ◽  
Frédéric Manseau ◽  
Sylvain Williams ◽  
Mark P. Brandon
Keyword(s):  
Vasoactive Intestinal Peptide ◽  
Entorhinal Cortex ◽  
Spatial Location ◽  
Inhibitory Neurons ◽  
Morphological Properties ◽  
Medial Entorhinal Cortex ◽  
Electrophysiological Properties ◽  
Whole Cell Patch Clamp

Circuit interactions within the medial entorhinal cortex (MEC) translate movement into a coherent code for spatial location. Entorhinal principal cells are subject to strong lateral inhibition, suggesting that a disinhibitory mechanism may drive their activation. Cortical Vasoactive Intestinal Peptide (VIP) expressing inhibitory neurons are known to contact other interneurons and excitatory cells and are thus capable of providing a local disinhibitory mechanism, yet little is known about this cell type in the MEC. To investigate the electrophysiological and morphological properties of VIP cells in the MEC, we use in vitro whole-cell patch-clamp recordings in VIPcre/tdTom mice. We report several gradients in electrophysiological properties of VIP cells that differ across laminae and along the dorsal-ventral MEC axis. We additionally show that VIP cells have distinct morphological features across laminae. Together, these results characterize the cellular and morphological properties of VIP cells in the MEC.

scholarly journals Rapid Inhibition of Neurons in the Dorsal Motor Nucleus of the Vagus by Leptin

Endocrinology ◽  
2007 ◽  
Vol 148 (4) ◽  
pp. 1868-1881 ◽  
Author(s):  
K. W. Williams ◽  
A. Zsombok ◽  
B. N. Smith
Keyword(s):  
Input Resistance ◽  
Synaptic Activity ◽  
K Channel ◽  
Motor Nucleus ◽  
Membrane Hyperpolarization ◽  
Postsynaptic Currents ◽  
Dorsal Motor Nucleus ◽  
Whole Cell Patch Clamp ◽  
Cellular Responsiveness ◽  
Phosphoinositide 3 Kinase

The peptide leptin conveys the availability of adipose energy stores to the brain. Increasing evidence implicates a significant role for extrahypothalamic sites of leptin action, including the dorsal vagal complex, a region critical for regulating visceral parasympathetic function. The hypothesis that leptin suppresses cellular activity in the dorsal motor nucleus of the vagus nerve (DMV) was tested using whole-cell patch-clamp recordings in brainstem slices. Leptin caused a rapid membrane hyperpolarization in 50% of rat DMV neurons. Leptin also hyperpolarized a subset of gastric-related neurons (62%), identified after gastric inoculation with a transneuronal retrograde viral tracer. The hyperpolarization was associated with a decrease in input resistance and cellular responsiveness and displayed characteristics consistent with an increased K+ conductance. Perfusion of tolbutamide (200 μm) reversed the leptin-induced hyperpolarization, and tolbutamide or wortmannin (10–100 nm) prevented the hyperpolarization, indicating that leptin activated an ATP-sensitive K+ channel via a phosphoinositide-3-kinase-dependent mechanism. Leptin reduced the frequency of spontaneous and miniature excitatory postsynaptic currents (EPSCs), whereas inhibitory postsynaptic currents (IPSCs) were largely unaffected. Electrical stimulation of the nucleus tractus solitarii (NTS) resulted in constant-latency EPSCs, which were decreased in amplitude by leptin. The paired-pulse ratio was increased, suggesting leptin effects involved activation of receptors presynaptic to the recorded neuron. A leptin-induced suppression of EPSCs, but not IPSCs, evoked by focal photolytic uncaging of glutamate within the NTS was also observed, supportive of leptin effects on the glutamatergic NTS projection to the DMV. Therefore, leptin directly hyperpolarized and indirectly suppressed excitatory synaptic activity to DMV neurons involved in visceral regulation, including gastric-related neurons.

scholarly journals Effects of substance P on identified neurons of the rat dorsal motor nucleus of the vagus

2001 ◽  
Vol 281 (1) ◽  
pp. G164-G172 ◽  
Author(s):  
Mark W. Lewis ◽  
R. Alberto Travagli
Keyword(s):  
Substance P ◽  
Response Curve ◽  
Target Organ ◽  
Motor Nucleus ◽  
Peripheral Target ◽  
Previous Evidence ◽  
Dorsal Motor Nucleus ◽  
Whole Cell Patch Clamp ◽  
Neuronal Groups ◽  
Concentration Response Curve

Previous evidence suggests that substance P (SP) activates subpopulations of neurons within the dorsal motor nucleus of the vagus (DMV). In this study we aimed at identifying these subpopulations in relation to their gastrointestinal projection organs or vagal branches and characterizing pharmacologically the SP response. Using whole cell patch-clamp recordings from identified gastrointestinal-projecting vagal motoneurons, we found that SP induced an inward current in all neuronal groups except for cecum-projecting cells. The lowest percentage of SP-responding neurons was found in fundus-projecting cells, where SP also had a concentration-response curve that was shifted to the left ( P < 0.05). Independently from the projections, the SP response was reduced by sendide and MEN 10,376 and mimicked by a combination of [Sar9-Met(O2)11]SP and α-neurokinin. SP and α-neurokinin also increased the frequency, but not the amplitude, of postsynaptic currents. In conclusion, we demonstrated that SP induces both pre- and postsynaptic effects on DMV neurons via activation of neurokinin NK1 and NK2 receptors. The magnitude of the SP response was correlated to the peripheral target organ.

Three types of postsynaptic glutamatergic receptors are activated in DMNX neurons upon stimulation of NTS

1996 ◽  
Vol 271 (6) ◽  
pp. R1614-R1619 ◽  
Author(s):  
A. Willis ◽  
M. Mihalevich ◽  
R. A. Neff ◽  
D. Mendelowitz
Keyword(s):  
Concanavalin A ◽  
High Frequency ◽  
Kainate Receptors ◽  
Motor Nucleus ◽  
Postsynaptic Receptors ◽  
Dorsal Motor Nucleus ◽  
Synaptic Control ◽  
Perforated Patch Clamp ◽  
Brain Stem Slices ◽  
Stimulation Of

While it is widely accepted that parasympathetic activity plays a significant role in cardiovascular, bronchomotor, and gastrointestinal function, little is known about the synaptic control of parasympathetic vagal neurons. In this study, we identified the neurotransmitter(s) and postsynaptic responses in dorsal motor nucleus of the vagus (DMNX) neurons upon stimulation of the nucleus of the solitary tract (NTS). Neurons were visualized in rat brain stem slices, and perforated patch-clamp techniques were used to record postsynaptic currents. NTS stimulation activated glutamatergic currents in DMNX that were separated into N-methyl-D-aspartate (NMDA) and non-NMDA components using D-2-amino-5-phosphonovalerate and 6-cyano-7-nitroquinoxaline-2,3-dione, respectively. The non-NMDA component was further characterized using cyclothiazide and concanavalin A to block desensitization of DL-alpha-amino-3-hydroxy-5-methylisoxazole-propionic acid (AMPA) and kainate receptors, respectively. Cyclothiazide increased the postsynaptic amplitude, whereas concanavalin A augmented duration, suggesting kainate, but not AMPA, currents are curtailed by desensitization. High frequency stimulations did not alter synaptic efficacy. In conclusion, this study demonstrates the existence of a monosynaptic glutamatergic pathway from NTS that activates NMDA, kainate, and AMPA postsynaptic receptors in DMNX neurons.

Inhibitory effect of somatostatin on vagal motoneurons in the rat brain stem in vitro

1989 ◽  
Vol 256 (1) ◽  
pp. C155-C159 ◽  
Author(s):  
J. Nabekura ◽  
Y. Mizuno ◽  
Y. Oomura
Keyword(s):  
Brain Stem ◽  
Rat Brain ◽  
Reversal Potential ◽  
Input Resistance ◽  
Inhibitory Effect ◽  
Hill Coefficient ◽  
Resting Membrane Potential ◽  
Motor Nucleus ◽  
Dorsal Motor Nucleus

Effects of somatostatin-14 (SRIF) on membrane electrical properties were studied in rat brain stem slice preparations maintained in vitro. SRIF hyperpolarized the resting membrane potential and decreased the input resistance of more than two-thirds of the 85 vagal motoneurons tested in the dorsal motor nucleus of the vagus. These effects persisted under synaptic blockade caused by perfusion with a solution containing tetrodotoxin or a Ca2+-free/high-Mg2+ solution and were dependent on the extracellular SRIF concentration (5 X 10(-8) to 1 X 10(-8) M). The Hill coefficient was estimated to be 2. The reversal potential of SRIF-induced hyperpolarization was affected by changing external K+ concentration. The results suggest that, in addition to its well-known peripheral action, SRIF may inhibit secretomotor functions of visceral organs by reducing vagal output in the central nervous system.

Abstract 414: Intrinsic Osmosensitivity of Neurons in the Organum Vasculosum of the Lamina Termialis is Mediated by Benzamil-Sensitive Channels

Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Kirsteen N Browning ◽  
Sean D Stocker
Keyword(s):  
Blood Pressure ◽  
Hormone Secretion ◽  
Cardiovascular Responses ◽  
Input Resistance ◽  
Physiological Changes ◽  
Sprague Dawley ◽  
Electrophysiological Properties ◽  
Whole Cell Patch Clamp ◽  
Organum Vasculosum ◽  
Salt Sensitive Hypertension

Neurons of the Organum Vasculosum of the Lamina Terminalis (OVLT) play a pivotal role in body fluid homeostasis and blood pressure regulation. Lesion of OVLT neurons severely disrupts drinking, antidiuretic hormone secretion, and sympathetic-cardiovascular responses to acute sodium loads. Importantly, OVLT lesions also lower blood pressure in several models of salt-sensitive hypertension. Similarly, intracerebroventricular administration of the non-voltage dependent channel blocker benzamil attenuates sympathetic-cardiovascular responses to acute sodium loads and salt-sensitive hypertension. Therefore, the purpose of the present study was two-fold: 1) to establish OVLT neurons are sensitive to physiological changes in osmolality, and 2) to identify whether benzamil-sensitive channels mediate the osmosensitivity of OVLT neurons. Whole-cell patch-clamp recordings were performed in OVLT neuronal slices of male Sprague-Dawley rats (250-350g). 71% (17/24) of OVLT neurons responded to increased bath osmolality by addition of mannitol (5-20 mOsm/L). There were no differences in basic electrophysiological properties (ie, input resistance, membrane capacitance, etc) between responsive and non-responsive neurons. Increases in bath osmoality produced dose-dependent decreases in membrane potential (5 mOsm: 5.0±0.63 mV, 10 mOsm: 6.1±1.24 mV, 15 mOsm: 12.4±2.1; n=5, P<0.05) and increases in firing rates (5 mOsm: 208±32%, 10 mOsm: 246±55%, 15 mOsm: 274±101%, 20 mOsm: 496±53%; n=5, P<0.05). Bath application of benzamil (0.5 uM) significantly attenuated the membrane depolarization (0.2±0.7 vs 5.3±0.4 mV) and increased firing rate (98±6% vs 219±20%) during a 10mOsm/L increase in bath osmolality. These findings suggest OVLT neurons are sensitive to physiological changes in osmolality, and the intrinsic sensitivity of OVLT neurons are mediated by benzamil-sensitive channels.

Mechanism of action of baclofen in rat dorsal motor nucleus of the vagus

2001 ◽  
Vol 280 (6) ◽  
pp. G1106-G1113 ◽  
Author(s):  
K. N. Browning ◽  
R. A. Travagli
Keyword(s):  
Mechanism Of Action ◽  
Receptor Agonist ◽  
Outward Current ◽  
Calcium Currents ◽  
Motor Nucleus ◽  
Channel Blockers ◽  
Calcium Dependent ◽  
Ion Channel Blockers ◽  
Dorsal Motor Nucleus ◽  
Whole Cell Patch Clamp

Using whole cell patch-clamp recordings, we investigated the effects of the GABAB receptor agonist baclofen in thin slices of rat brain stem containing identified gastric- or intestinal-projecting dorsal motor nucleus of the vagus (DMV) neurons. Perfusion with baclofen (0.1–100 μM) induced a concentration-dependent outward current (EC50, 3 μM) in 54% of DMV neurons with no apparent differences between gastric- and intestinal-projecting neurons. The outward current was attenuated by pretreatment with the selective GABAB antagonists saclofen and 2-hydroxysaclofen, but not by the synaptic blocker TTX, indicating a direct effect at GABAB receptors on DMV neurons. Using the selective ion channel blockers barium, nifedipine, and apamin, we showed that the outward current was due to effects on potassium and calcium currents as well as calcium-dependent potassium currents. The calcium-mediated components of the outward current were more prominent in intestinal-projecting neurons than in gastric-projecting neurons. These data indicate that although baclofen inhibits both intestinal- and gastric-projecting neurons in the rat DMV, its mechanism of action differs among the neuronal subpopulations.

Physiological and Morphological Characterization of Local Interneurons in the Drosophila Antennal Lobe

2010 ◽  
Vol 104 (2) ◽  
pp. 1007-1019 ◽  
Author(s):  
Yoichi Seki ◽  
Jürgen Rybak ◽  
Dieter Wicher ◽  
Silke Sachse ◽  
Bill S. Hansson
Keyword(s):  
Antennal Lobe ◽  
Neural Circuit ◽  
Three Dimensional ◽  
Morphological Characterization ◽  
Morphological Properties ◽  
Electrophysiological Properties ◽  
Local Interneurons ◽  
Enhancer Trap Line ◽  
Almost All

The Drosophila antennal lobe (AL) has become an excellent model for studying early olfactory processing mechanisms. Local interneurons (LNs) connect a large number of glomeruli and are ideally positioned to increase computational capabilities of odor information processing in the AL. Although the neural circuit of the Drosophila AL has been intensively studied at both the input and the output level, the internal circuit is not yet well understood. An unambiguous characterization of LNs is essential to remedy this lack of knowledge. We used whole cell patch-clamp recordings and characterized four classes of LNs in detail using electrophysiological and morphological properties at the single neuron level. Each class of LN displayed unique characteristics in intrinsic electrophysiological properties, showing differences in firing patterns, degree of spike adaptation, and amplitude of spike afterhyperpolarization. Notably, one class of LNs had characteristic burst firing properties, whereas the others were tonically active. Morphologically, neurons from three classes innervated almost all glomeruli, while LNs from one class innervated a specific subpopulation of glomeruli. Three-dimensional reconstruction analyses revealed general characteristics of LN morphology and further differences in dendritic density and distribution within specific glomeruli between the different classes of LNs. Additionally, we found that LNs labeled by a specific enhancer trap line (GAL4-Krasavietz), which had previously been reported as cholinergic LNs, were mostly GABAergic. The current study provides a systematic characterization of olfactory LNs in Drosophila and demonstrates that a variety of inhibitory LNs, characterized by class-specific electrophysiological and morphological properties, construct the neural circuit of the AL.

scholarly journals Pedological Characteristics of Soils under Different Cultivation Periods in Harrad Center and Al-Kharj, Kingdom of Saudi Arabia

2020 ◽  
pp. 55-69
Author(s):  
Meshal Abdullah Otian Al-Harbi ◽  
Mohamed S. Al-Sewailem ◽  
Abdelazeem Sh. Sallam
Keyword(s):  
Saudi Arabia ◽  
Land Use Planning ◽  
Rating Scale ◽  
Soil Depth ◽  
Morphological Characteristics ◽  
Morphological Properties ◽  
Soil Profiles ◽  
Kingdom Of Saudi Arabia ◽  
Transfer Of Technology

A detailed pedological characterization of soils earmarked as benchmark soils of Harrad Center and Al-Kharj region, Saudi Arabia, was carried out to provide data required for planning and execution of soil fertility studies and transfer of technology in the regions. The present study aims to study the effect of cultivation periods on the morphological properties of soil profiles represented by a number of farms in the Haradh center and Al-Kharj governorate. The field morphology rating scale was used to compare adjacent horizons to calculate a relative profile development in soils. Soil samples representative of the benchmark soil profiles were described and analyzed for their pedological characteristics. The results indicated that, the relative horizon distinctness (RHD) values ​​of the Haradh center profiles showed the highest values (10-17) ​​in the surface layers only, and it decreased with soil depth, except for profile No.9. The results data did not show a uniform distribution of RHD values ​​in the deeper layers. The most morphological characteristics affected by soils cultivation and contributing to the RHD values ​​are color in dry and moist state followed by decaying organic matter, and soil consistence. Other morphological characteristics have a limited contribution on RHD values, such as structure and soil mottles, with various contributions to some other morphological properties such as textures and boundaries between layers in soil profiles. The boundaries between layers show converging contribution to RHD values ​​in Harrad and Al-Kharj profiles. The data obtained through this study presents a substantial base for sound land use planning and will facilitate transfer of technology from one area to another with similar ecological conditions.

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