Biophysical properties of hypoglossal neurons in vitro: intracellular studies in adult and neonatal rats

1990 ◽  
Vol 69 (4) ◽  
pp. 1509-1517 ◽  
Author(s):  
G. G. Haddad ◽  
D. F. Donnelly ◽  
P. A. Getting
Keyword(s):  
Brain Stem ◽  
Nucleus Tractus Solitarius ◽  
Outward Current ◽  
Input Resistance ◽  
Membrane Properties ◽  
Resting Membrane Potential ◽  
Single Action ◽  
Soma Size ◽  
Newborn Neurons

A brain stem slice preparation from adult and neonatal (less than or equal to 12 days old) rats and intracellular recordings were used to examine the cellular properties of neurons within the hypoglossal (HYP) nucleus. Resting membrane potential (Vm) for adult hypoglossal neurons was -80 +/- 2 (SE) mV. Rheobase was 2.1 +/- 0.4 nA, and input resistance (RN) was 20.8 +/- 1.5 M omega and decreased during the hyperpolarizing period ("sag"). Compared with adult HYP cells, newborn HYP neurons had significantly lower resting potentials (Vm = -73 +/- 2 mV), lower rheobase (0.7 +/- 0.2 nA), and higher RN (27.6 +/- 3.9 M omega). Single action potentials, elicited by short depolarizing-current pulses, were followed by a slow afterhyperpolarization in adult [6.4 +/- 0.3 mV, time constant (tc) 31.0 +/- 1.2 ms] and newborn cells (7.4 +/- 0.2 mV, tc 37.2 +/- 8.2 ms). Prolonged outward current (2 s) produced little spike frequency adaptation in either adult or newborn neurons. Onset of spike activity was not delayed by hyperpolarizing pulses preceding depolarizations. In addition, pharmacological experiments showed that HYP neurons have a tetrodotoxin-sensitive Na+ current and a delayed and an inward rectifier current but no major Ca2+ current. We conclude the following. 1) Electrophysiological membrane properties mature postnatally in HYP neurons; some of these developmental changes can be ascribed to an increase in soma size and dendritic outgrowth but others cannot. 2) Adult HYP neurons, compared with other brain stem neurons (i.e., vagal cells or cells in the nucleus tractus solitarius), are not endowed with major Ca2+ currents or K+ currents such as the A current and the Ca2(+)-activated K+ current.

Dorsal and Ventral Distribution of Excitable and Synaptic Properties of Neurons of the Bed Nucleus of the Stria Terminalis

2003 ◽  
Vol 90 (1) ◽  
pp. 405-414 ◽  
Author(s):  
Regula E. Egli ◽  
Danny G. Winder
Keyword(s):  
Receptor Antagonist ◽  
Drugs Of Abuse ◽  
Input Resistance ◽  
Membrane Properties ◽  
Resting Membrane Potential ◽  
Stria Terminalis ◽  
Bed Nucleus ◽  
Adult Mice ◽  
Dependent Potential

The bed nucleus of the stria terminalis (BNST) is a structure uniquely positioned to integrate stress information and regulate both stress and reward systems. Consistent with this arrangement, evidence suggests that the BNST, and in particular the noradrenergic input to this structure, is a key component of affective responses to drugs of abuse. We have utilized an in vitro slice preparation from adult mice to determine synaptic and membrane properties of these cells, focusing on the dorsal and ventral subdivisions of the anterolateral BNST (dBNST and vBNST) because of the differential noradrenergic input to these two regions. We find that while resting membrane potential and input resistance are comparable between these subdivisions, excitable properties, including a low-threshold spike (LTS) likely mediated by T-type calcium channels and an Ih-dependent potential, are differentially distributed. Inhibitory and excitatory postsynaptic potentials (IPSPs and EPSPs, respectively) are readily evoked in both dBNST and vBNST. The fast IPSP is predominantly GABAA-receptor mediated and is partially blocked by the AMPA/kainate-receptor antagonist CNQX. In the presence of the GABAA-receptor antagonist picrotoxin, cells in dBNST but not vBNST are more depolarized and have a higher input resistance, suggesting tonic GABAergic inhibition of these cells. The EPSPs elicited in BNST are monosynaptic, exhibit paired pulse facilitation, and contain both an AMPA- and an N-methyl-d-aspartate (NMDA) receptor-mediated component. These data support the hypothesis that neurons of the dorsal and ventral BNST differentially integrate synaptic input, which is likely of behavioral significance. The data also suggest mechanisms by which information may flow through stress and reward circuits.

Postnatal Changes in Membrane Properties of Mice Trigeminal Ganglion Neurons

2002 ◽  
Vol 87 (5) ◽  
pp. 2398-2407 ◽  
Author(s):  
Carmen Cabanes ◽  
Mikel López de Armentia ◽  
Félix Viana ◽  
Carlos Belmonte
Keyword(s):  
Postnatal Development ◽  
Trigeminal Ganglion ◽  
Input Resistance ◽  
Membrane Capacitance ◽  
Membrane Properties ◽  
Inward Rectification ◽  
Resting Membrane Potential ◽  
Depolarization Rate ◽  
Ganglion Neurons

Intracellular recordings from neurons in the mouse trigeminal ganglion (TG) in vitro were used to characterize changes in membrane properties that take place from early postnatal stages (P0–P7) to adulthood (>P21). All neonatal TG neurons had uniformly slow conduction velocities, whereas adult neurons could be separated according to their conduction velocity into Aδ and C neurons. Based on the presence or absence of a marked inflection or hump in the repolarization phase of the action potential (AP), neonatal neurons were divided into S- (slow) and F-type (fast) neurons. Their passive and subthreshold properties (resting membrane potential, input resistance, membrane capacitance, and inward rectification) were nearly identical, but they showed marked differences in AP amplitude, AP overshoot, AP duration, rate of AP depolarization, rate of AP repolarization, and afterhyperpolarization (AHP) duration. Adult TG neurons also segregated into S- and F-type groups. Differences in their mean AP amplitude, AP overshoot, AP duration, rate of AP depolarization, rate of AP repolarization, and AHP duration were also prominent. In addition, axons of 90% of F-type neurons and 60% of S-type neurons became faster conducting in their central and peripheral branch, suggestive of axonal myelination. The proportion of S- and F-type neurons did not vary during postnatal development, suggesting that these phenotypes were established early in development. Membrane properties of both types of TG neurons evolved differently during postnatal development. The nature of many of these changes was linked to the process of myelination. Thus myelination was accompanied by a decrease in AP duration, input resistance ( R in), and increase in membrane capacitance (C). These properties remained constant in unmyelinated neurons (both F- and S-type). In adult TG, all F-type neurons with inward rectification were also fast-conducting Aδ, suggesting that those F-type neurons showing inward rectification at birth will evolve to F-type Aδ neurons with age. The percentage of F-type neurons showing inward rectification also increased with age. Both F- and S-type neurons displayed changes in the sensitivity of the AP to reductions in extracellular Ca2+ or substitution with Co2+ during the process of maturation.

Effects of norepinephrine upon superficial layer neurons in the superior colliculus of the hamster: In vitro studies

1999 ◽  
Vol 16 (3) ◽  
pp. 557-570 ◽  
Author(s):  
HONGJING TAN ◽  
RICHARD D. MOONEY ◽  
ROBERT W. RHOADES
Keyword(s):  
Superior Colliculus ◽  
Optic Tract ◽  
Reversal Potential ◽  
Outward Current ◽  
Input Resistance ◽  
Superficial Layer ◽  
Membrane Properties ◽  
Induced Response

Intracellular recording techniques were used to evaluate the effects of norepinephrine (NE) on the membrane properties of superficial layer (stratum griseum superficiale and stratum opticum) superior colliculus (SC) cells. Of the 207 cells tested, 44.4% (N = 92) were hyperpolarized by ≥3 mV and 8.7% (N = 18) were depolarized by ≥3 mV by application of NE. Hyperpolarization induced by NE was dose dependent (EC50 = 8.1 μM) and was associated with decreased input resistance and outward current which had a reversal potential of −94.0 mV. Depolarization was associated with a very slight rise in input resistance and had a reversal potential of −93.1 mV for the single cell tested. Pharmacologic experiments demonstrated that isoproterenol, dobutamine, and p-aminoclonidine all hyperpolarized SC cells. These results are consistent with the conclusion that NE-induced hyperpolarization of SC cells is mediated by both α2 and β1 adrenoceptors. The α1 adrenoceptor agonists, methoxamine and phenylephrine, depolarized 35% (6 of 17) of the SC cells tested by ≥3 mV. Most of the SC cells tested exhibited responses indicative of expression of more than one adrenoceptor. Application of p-aminoclonidine or dobutamine inhibited transsynaptic responses in SC cells evoked by electrical stimulation of optic tract axons. Inhibition of evoked responses by these agents was usually, but not invariably, associated with a hyperpolarization of the cell membrane and a reduction in depolarizing potentials evoked by application of glutamate. The present in vitro results are consistent with those of the companion in vivo study which suggested that NE-induced response suppression in superficial layer SC neurons was primarily postsynaptic and chiefly mediated by both α2 and β1 adrenoceptors.

Effects of aging on the intrinsic membrane properties of medial NTS neurons of Fischer-344 rats

1993 ◽  
Vol 70 (5) ◽  
pp. 1975-1987 ◽  
Author(s):  
S. M. Johnson ◽  
R. B. Felder
Keyword(s):  
Action Potential ◽  
Nucleus Tractus Solitarius ◽  
Input Resistance ◽  
Membrane Properties ◽  
Repetitive Firing ◽  
Resting Membrane Potential ◽  
Fischer 344 Rats ◽  
Fischer 344 ◽  
Steady State Current ◽  
Intrinsic Membrane Properties

1. Recent studies have demonstrated that the arterial baroreflex is imparied with aging and have implicated central components of the baroreflex arc in this autonomic dysfunction. Neurons in the medial portion of the nucleus tractus solitarius (mNTS) receive a major input from the arterial baroreceptors. The present study was undertaken to characterize the intrinsic membrane properties of mNTS neurons in young rats and to test the hypothesis that these properties are altered with aging. An in vitro brain stem slice preparation was used to record intracellularly from mNTS neurons; passive membrane properties, action potential characteristics, and repetitive firing properties were examined and compared. 2. Neurons in the mNTS of young (3-5 mo old) Fischer-344 rats (F-344; n = 35) had a resting membrane potential of -57 +/- 6.9 mV (mean +/- SD), a membrane time constant of 18 +/- 9.0 ms, and an input resistance of 110 +/- 60 m omega. Action potential amplitude was 81 +/- 7.5 mV with a duration at half-height of 0.83 +/- 0.15 ms. The spontaneous firing rate in 24 cells was 4.3 +/- 2.9 Hz. The amplitude and duration of the action potential afterhyperpolarization (AHP) were 6.6 +/- 3.0 mV and 64 +/- 34 ms, respectively. All neurons expressed spike frequency adaptation, action potential AHP, and posttetanic hyperpolarization. Delayed excitation and postinhibitory rebound were present in 34 and 14% of neurons tested, respectively. Neurons from adult (10-12 mo old) F-344 rats (n = 34) were similar to the young F-344 rats with respect to all of these variables. 3. Neurons from aged (21-24 mo old) F-344 (n = 32) were similar to those from young and adult rats, but there were two potentially important differences: the mean input resistance of the aged neurons was higher (170 +/- 150 M omega), with a larger proportion (46% of aged neurons vs. 20% of young neurons and 21% of adult neurons) having input resistances > 150 M omega; and there was a tendency for a smaller percentage of aged neurons (16% of aged neurons vs. 34% of young neurons and 29% of adult neurons) to express delayed excitation. 4. The potential significance of a high input resistance was tested by comparing the steady-state current-voltage (I-V) relationships and the frequency-current (f-I) relationships among low-resistance (1-100 M omega), medium-resistance (101-200 M omega).(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Membrane properties of rat subicular neurons in vitro

1993 ◽  
Vol 70 (3) ◽  
pp. 1244-1248 ◽  
Author(s):  
D. Mattia ◽  
G. G. Hwa ◽  
M. Avoli
Keyword(s):  
Hippocampal Slices ◽  
Rhythmic Activity ◽  
Input Resistance ◽  
Membrane Properties ◽  
Inward Rectification ◽  
Resting Membrane Potential ◽  
Channel Blockers ◽  
Electrophysiological Properties ◽  
Low Threshold

1. Conventional intracellular recordings were performed in rat hippocampal slices to investigate the electrophysiological properties of subicular neurons. These cells had a resting membrane potential (RMP) of -66 +/- 7.2 mV (mean +/- SD; n = 50), input resistance of 23.6 +/- 8.2 M omega (n = 51), time constant of 7.1 +/- 1.9 ms (n = 51), action potential amplitude of 85.8 +/- 13.8 mV (n = 50), and duration of 2.9 +/- 1.2 ms (n = 48). Analysis of the current-voltage relationship revealed membrane inward rectification in both depolarizing and hyperpolarizing direction. The latter type was readily abolished by Cs+ (3 mM; n = 6 cells). 2. Injection of depolarizing current pulses of threshold intensity induced in all subicular neurons (n = 51) recorded at RMP a burst of two to three fast action potentials (frequency = 212.7 +/- 90 Hz, n = 13 cells). This burst rode on a slow depolarizing envelope and was followed by an afterhyperpolarization and later by regular spiking mode once the pulse was prolonged. Similar bursts were also generated upon termination of a hyperpolarizing current pulse. 3. The slow depolarization underlying the burst resembled a low-threshold response, which in thalamic cells is caused by a Ca2+ conductance and is contributed by the Cs(+)-sensitive inward rectifier. However, bursts in subicular cells persisted in medium containing the Ca(2+)-channel blockers Co2+ (2 mM) and Cd2+ (1 mM) (n = 5 cells) but disappeared during application of TTX (1 microM; n = 3 cells). Hence they were mediated by Na+. Blockade of the hyperpolarizing inward rectification by Cs+ did not prevent the rebound response (n = 3 cells). 4. Our findings demonstrate that intrinsic bursts, presumably related to a "low-threshold" Na+ conductance are present in rat subicular neurons. Similar intrinsic characteristics have been suggested to underlie the rhythmic activity described in other neuronal networks, although in most cases the low-threshold electrogenesis was caused by Ca2+. We propose that the bursting mechanism might play a role in modulating incoming signals from the classical hippocampal circuit within the limbic system.

Structural and functional alterations in rat corticospinal neurons after axotomy

1996 ◽  
Vol 75 (1) ◽  
pp. 248-267 ◽  
Author(s):  
G. F. Tseng ◽  
D. A. Prince
Keyword(s):  
Steady State ◽  
Cervical Spinal Cord ◽  
Input Resistance ◽  
Membrane Properties ◽  
Resting Membrane Potential ◽  
Survival Group ◽  
Double Labeling ◽  
Postsynaptic Potentials ◽  
Electrophysiological Properties

1. The electrophysiological properties of rat corticospinal neurons (CSNs) were studied 3, 9, and 12 mo after axotomy in the cervical spinal cord, with the use of a combination of the in vitro neocortical slice technique, intracellular recordings, and a double-labeling method that allowed identification of CSNs studied in vitro. 2. CSNs retained the rhodamine-labeled microspheres employed as a retrograde marker and were functionally active in the longest survival group (1 yr). 3. The somatic area of axotomized CSNs became progressively smaller, a reduction that amounted to 37% for all cells at 1 yr. There were no obvious differences between normal and axotomized cells in terms of apical dendritic widths, numbers of apical dendritic branches, or basal dendritic arbors. Intracortical axonal arborizations of axotomized neurons were in general similar to those of normal CSNs in that most axons ended in layers V and VI with only occasional collaterals reaching supragranular layers. 4. Axotomized CSNs were grouped according to their spike firing patterns during depolarizing current pulses so that their electrophysiological behavior could be compared with that of regular spiking and adapting groups of normal CSNs. No significant differences were found in resting membrane potential, or spike parameters between axotomized neurons in any survival group and normal controls. Neurons surviving 1 yr after axotomy had a higher input resistance (RN) than normal CSNs. There was a reduction in the percentage of CSNs that generated prominent spike depolarizing afterpotentials in the axotomized group. 5. The steady-state relationship between spike frequency and applied current (f-I slope) became steeper over time and was significantly greater 9 mo after axotomy in regular spiking (RS) and adapting neurons than in normal CSNs in the same groups. The increase in steady-state f-I slope was in part related to increases in the RN of axotomized neurons. 6. There was a significant decrease in the generation of slow afterhyperpolarizations following trains of spikes in axotomized versus normal RS neurons, first detected at 3 mo and also present in 9 mo and 1 yr survival groups. 7. Biphasic inhibitory postsynaptic potentials (IPSPs) were evoked in only 1 of 11 axotomized neurons in the 3-mo group, 2 of 12 cells examined at 9 mo, and 3 of 15 neurons 1 yr after axotomy. The proportions of neurons generating IPSPs were significantly smaller than in comparable groups of control CSNs. As a consequence, longer duration evoked excitatory postsynaptic potentials were generated by axotomized CSNs. 8. Results show that axotomized CSNs undergo alterations in intrinsic membrane properties and inhibitory synaptic electrogenesis that would tend to make them more responsive to excitatory inputs.

Zinc enhances GABAergic transmission in rat neocortical neurons

1993 ◽  
Vol 70 (3) ◽  
pp. 1264-1269 ◽  
Author(s):  
F. M. Zhou ◽  
J. J. Hablitz
Keyword(s):  
Action Potentials ◽  
Excitatory Amino Acid ◽  
Input Resistance ◽  
Synaptic Activity ◽  
Membrane Properties ◽  
Repetitive Firing ◽  
Resting Membrane Potential ◽  
Gamma Aminobutyric Acid ◽  
Postsynaptic Potentials

1. Intracellular recordings were made in layer II-III neurons of rat neocortical slices maintained in vitro. The effect of bath application of zinc (50-300 microM) on evoked synaptic activity and passive membrane properties was examined. 2. Excitatory postsynaptic potentials (EPSPs) mediated by N-methyl-D-aspartate (NMDA) and non-NMDA receptors were recorded in response to electrical stimulation. Zinc did not affect either type of EPSP. Resting membrane potential, repetitive firing properties, and input resistance were not altered by zinc. 3. Inhibitory postsynaptic potentials (IPSPs) were enhanced after zinc application. Zinc also induced generation of large amplitude spontaneous gamma-aminobutyric acid-A (GABAA)- and GABAB-mediated IPSPs. Postsynaptic responses to iontophoretically applied GABA were unaffected. In the presence of zinc, GABAergic synaptic potentials could result in generation of action potentials. 4. Directly evoked IPSPs recorded in the presence of the excitatory amino acid receptor blockers 6-cyano-7-nitroquinoxaline-2,3-dione and 2-amino-5-phosphonovaleric acid were enhanced by zinc. Under these conditions spontaneous IPSPs with superimposed action potentials were present. Baclofen, in the presence of zinc, reduced the amplitude of evoked IPSPs. 5. These results indicate that zinc may be an endogenously occurring neuromodulator. Zinc appears to enhance GABAergic IPSPs by increasing the excitability of inhibitory interneurons, thus resulting in increased GABA release.

Hyperpolarization-Activated Current (Ih) in the Inferior Colliculus: Distribution and Contribution to Temporal Processing

2003 ◽  
Vol 90 (6) ◽  
pp. 3679-3687 ◽  
Author(s):  
Ursula Koch ◽  
Benedikt Grothe
Keyword(s):  
Brain Stem ◽  
Inferior Colliculus ◽  
Temporal Processing ◽  
Auditory Processing ◽  
Input Resistance ◽  
Temporal Analysis ◽  
Membrane Properties ◽  
Resting Membrane Potential ◽  
Auditory Brain Stem ◽  
Hyperpolarization Activated Current

Neurons in the inferior colliculus (IC) process acoustic information converging from inputs from almost all nuclei of the auditory brain stem. Despite its importance in auditory processing, little is known about the distribution of ion currents in IC neurons, namely the hyperpolarization-activated current Ih. This current, as shown in neurons of the auditory brain stem, contributes to the precise analysis of temporal information. Distribution and properties of the Ih current and its contribution to membrane properties and synaptic integration were examined by current- and voltage-clamp recordings obtained from IC neurons in acute slices of rats (P17-P19). Based on firing patterns to positive current injection, three basic response types were distinguished: onset, adapting, and sustained firing neurons. Onset and adapting cells showed an Ih-dependent depolarizing sag and had a more depolarized resting membrane potential and lower input resistance than sustained neurons. Ih amplitudes were largest in onset, medium in adapting, and small in sustained neurons. Ih activation kinetics was voltage dependent in all neurons and faster in onset and adapting compared with sustained neurons. Injecting trains of simulated synaptic currents into the neurons or evoking inhibitory postsynaptic potentials (IPSPs) by stimulating the lemniscal tract showed that Ih reduced temporal summation of excitatory and inhibitory potentials in onset but not in sustained neurons. Blocking Ih also abolished afterhyperpolarization and rebound spiking. These results suggest that, in a large proportion of IC cells, namely the onset and adapting neurons, Ih improves precise temporal processing and contributes to the temporal analysis of input patterns.

Secretin depolarizes nucleus tractus solitarius neurons through activation of a nonselective cationic conductance

2004 ◽  
Vol 286 (5) ◽  
pp. R927-R934 ◽  
Author(s):  
Bo Yang ◽  
Martin Goulet ◽  
Richard Boismenu ◽  
Alastair V. Ferguson
Keyword(s):  
Binding Sites ◽  
Nucleus Tractus Solitarius ◽  
Input Resistance ◽  
Resting Membrane Potential ◽  
Whole Cell ◽  
Whole Cell Patch Clamp ◽  
Bath Application ◽  
The Central Nervous System ◽  
The Mean

The recent suggestion that secretin may be useful in treating autism and schizophrenia has begun to focus attention on the mechanisms underlying this gut-brain peptide's actions in the central nervous system (CNS). In vitro autoradiographic localization of 125I-secretin binding sites in rat brain shows the highest binding density in the nucleus tractus solitarius (NTS). Recent evidence suggests that intravenous infusion of secretin causes fos activation in NTS, a relay station playing important roles in the central regulation of autonomic functions. In this study, whole cell patch-clamp recordings were obtained from 127 NTS neurons in rat medullary slices. The mean resting membrane potential of these neurons was -54.7 ± 0.3 mV, the mean input resistance was 3.7 ± 0.2 GΩ, and the action potential amplitude of these neurons was always >70 mV. Current-clamp studies showed that bath application of secretin depolarized the majority (80.8%; 42/52) of NTS neurons tested, whereas the remaining cells were either unaffected (17.3%; 9/52) or hyperpolarized (1.9%; 1/52). These depolarizing effects were maintained in the presence of 5 μM TTX and found to be concentration dependent from 10-12 to 10-7 M. Using voltage-clamp techniques, we also identified modulatory actions of secretin on specific ion channels. Our results demonstrate that while secretin is without effect on net whole cell potassium currents, it activates a nonselective cationic conductance (NSCC). These results show that NTS neurons are activated by secretin as a consequence of activation of a NSCC and support the emerging view that secretin can act as a neuropeptide within the CNS.

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