Glutamate and GABA mediate suprachiasmatic nucleus inputs to spinal-projecting paraventricular neurons

2001 ◽  
Vol 281 (4) ◽  
pp. R1283-R1289 ◽  
Author(s):  
Lu-Ning Cui ◽  
Elaine Coderre ◽  
Leo P. Renaud
Keyword(s):  
Electrical Stimulation ◽  
Suprachiasmatic Nucleus ◽  
Input Resistance ◽  
Inward Rectification ◽  
Sprague Dawley ◽  
Postsynaptic Potentials ◽  
Glutamatergic Neurons ◽  
Inhibitory Postsynaptic Potentials ◽  
Sprague Dawley Rats ◽  
Low Threshold

We used patch-clamp recordings in slice preparations from Sprague-Dawley rats to evaluate responses of 20 spinal-projecting neurons in the dorsal paraventricular nucleus (PVN) to electrical stimulation in suprachiasmatic nucleus (SCN). Neurons containing a retrograde label transported from the thoracic (T1-T4) intermediolateral column displayed three intrinsic properties that collectively allowed distinction from neighboring parvocellular or magnocellular cells: a low-input resistance, a hyperpolarization-activated time-dependent inward rectification, and a low-threshold calcium conductance. Twelve of fifteen cells tested responded to electrical stimulation in SCN. All of 10 cells tested in media containing 2,3,-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide disodium (5 μM) andd(−)-2-amino-5-phosphonopentanoic acid (20 μM) responded with constant latency (11.4 ± 0.7 ms) inhibitory postsynaptic potentials, able to follow 20- to 50-Hz stimulation and blockable with bicuculline (20 μM). By contrast, all eight cells tested in the presence of bicuculline demonstrated constant latency (9.8 ± 0.6 ms) excitatory postsynaptic potentials that followed at 20–50 Hz and featured both non- N-methyl-d-aspartate (NMDA) and NMDA receptor-mediated components. We conclude that both GABAergic and glutamatergic neurons in SCN project directly to spinal-projecting neurons in the dorsal PVN.

Anoxia produces smaller changes in synaptic transmission, membrane potential, and input resistance in immature rat hippocampus

1989 ◽  
Vol 62 (4) ◽  
pp. 882-895 ◽  
Author(s):  
E. Cherubini ◽  
Y. Ben-Ari ◽  
K. Krnjevic
Keyword(s):  
Synaptic Transmission ◽  
Hippocampal Slices ◽  
Mossy Fibers ◽  
Input Resistance ◽  
Resting Potential ◽  
Inward Rectification ◽  
Adult Rats ◽  
Ca1 Neurons ◽  
Postsynaptic Potentials ◽  
Ca3 Neurons

1. The reversible blocking effect of brief anoxia (2-4 min) on synaptic transmission was studied in submerged hippocampal slices (kept mostly at 34 degrees), obtained from adult (greater than 120 g) and very young (6-50 g) Wistar rats. Excitatory postsynaptic potentials (EPSPs) were recorded with extra- and intracellular electrodes, sometimes simultaneously: in CA1, they were evoked by stratum radiation stimulation, in CA3 by hilar stimulation. 2. In slices from adults, EPSPs in CA1 were depressed by 90% after 2 min of anoxia, and postanoxic recovery was relatively slow (one-half recovery times 4.0 +/- 0.23 min, mean +/- SE). EPSPs in CA3 were consistently more resistant, especially those generated by mossy fibers; after 2 min of anoxia, these were reduced by only 14.7 +/- 5.4%. 3. In newborn animals (PN1-4), both intra- and extracellular EPSPs (but no population spikes) could be recorded in CA1. Although smaller and more fatigable than in the adult, they were much more resistant to anoxia, after 2 min being reduced by only 44.1 +/- 8.8%; and they were not abolished even after 6-7 min. On the other hand, postanoxic recovery was very rapid, being one-half complete in 2.4 +/- 0.48 min. Only large and very prolonged (giant) depolarizing PSPs [probably inhibitory postsynaptic potentials (IPSPs)] could be recorded in CA3 neurons; they were rapidly blocked by anoxia. 4. In older pups (PN6-21), the CA1 EPSPs became progressively more sensitive to anoxia. At the end of the second week, they were as rapidly blocked as in slices from adults; but postanoxic recovery remained quicker throughout this period. In CA3, EPSPs could now be evoked that were as resistant to anoxia as in adult slices. 5. In both CA1 and CA3 neurons from adult rats, anoxia (for 2-3 min) reduced the input resistance (RN) by 45.7 +/- 6.25%. In CA1 neurons, there was most often some hyperpolarization (-7.2 +/- 1.8 mV), which was less consistent in CA3 cells. The return of O2 typically led to a second (postanoxic) phase of hyperpolarization (-7.9 +/- 1.93 mV). 6. At PN1-4, the resting potential (Vm) of most cells had to be maintained by current injection; the input resistance (RN) of CA1 neurons was 70% higher than in mature cells, and there was little time-dependent inward rectification. Anoxia produced no regular changes in Vm, and reductions in RN were very small (by only 9.6 +/- 5.0%). A postanoxic hyperpolarization was seen in only 2 neurons out of 11.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects on Peroneal Motoneurons of Cutaneous Afferents Activated by Mechanical or Electrical Stimulations

2000 ◽  
Vol 83 (6) ◽  
pp. 3209-3216 ◽  
Author(s):  
Jean-François Perrier ◽  
Boris Lamotte D'Incamps ◽  
Nezha Kouchtir-Devanne ◽  
Léna Jami ◽  
Daniel Zytnicki
Keyword(s):  
Electrical Stimulation ◽  
Mechanical Stimulation ◽  
Cutaneous Afferents ◽  
Postsynaptic Potentials ◽  
Electric Pulses ◽  
Plantar Surface ◽  
Cutaneous Reflex ◽  
Inhibitory Postsynaptic Potentials ◽  
Mixed Pattern ◽  
Stimulation Of

The postsynaptic potentials elicited in peroneal motoneurons by either mechanical stimulation of cutaneous areas innervated by the superficial peroneal nerve (SP) or repetitive electrical stimulation of SP were compared in anesthetized cats. After denervation of the foot sparing only the territory of SP terminal branches, reproducible mechanical stimulations were applied by pressure on the plantar surface of the toes via a plastic disk attached to a servo-length device, causing a mild compression of toes. This stimulus evoked small but consistent postsynaptic potentials in every peroneal motoneuron. Weak stimuli elicited only excitatory postsynaptic potentials (EPSPs), whereas increase in stimulation strength allowed distinction of three patterns of response. In about one half of the sample, mechanical stimulation or trains of 20/s electric pulses at strengths up to six times the threshold of the most excitable fibers in the nerve evoked only EPSPs. Responses to electrical stimulation appeared with 3–7 ms central latencies, suggesting oligosynaptic pathways. In another, smaller fraction of the sample, inhibitory postsynaptic potentials (IPSPs) appeared with an increase of stimulation strength, and the last fraction showed a mixed pattern of excitation and inhibition. In 24 of 32 motoneurons where electrical and mechanical effects could be compared, the responses were similar, and in 6 others, they changed from pure excitation on mechanical stimulation to mixed on electrical stimulation. With both kinds of stimulation, stronger stimulations were required to evoke inhibitory postsynaptic potentials (IPSPs), which appeared at longer central latencies than EPSPs, indicating longer interneuronal pathways. The similarity of responses to mechanical and electrical stimulation in a majority of peroneal motoneurons suggests that the effects of commonly used electrical stimulation are good predictors of the responses of peroneal motoneurons to natural skin stimulation. The different types of responses to cutaneous afferents from SP territory reflect a complex connectivity allowing modulations of cutaneous reflex responses in various postures and gaits.

Localization of components of the renin–angiotensin system in the suprachiasmatic nucleus of normotensive Sprague–Dawley rats

2004 ◽  
Vol 1008 (2) ◽  
pp. 212-223 ◽  
Author(s):  
Martin Alexander Thomas ◽  
Gerta Fleissner ◽  
Marion Stöhr ◽  
Stefan Hauptfleisch ◽  
Björn Lemmer
Keyword(s):  
Suprachiasmatic Nucleus ◽  
Renin Angiotensin System ◽  
Sprague Dawley ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Sprague Dawley Rats

A New Fibrin Seal: Functional Evaluation of Sensory Regeneration Following Primary Repair of Peripheral Nerves

1994 ◽  
Vol 19 (2) ◽  
pp. 250-254 ◽  
Author(s):  
B. POVLSEN
Keyword(s):  
Peripheral Nerves ◽  
Primary Repair ◽  
Functional Results ◽  
Relevant Information ◽  
Functional Evaluation ◽  
Sprague Dawley ◽  
Morphological Examination ◽  
Sprague Dawley Rats ◽  
Low Threshold ◽  
Fibrin Seal

A new fibrin seal has recently been evaluated in terms of axonal regeneration; however morphological examination of the fibre composition of regenerated nerves may not necessarily provide functionally relevant information. This study therefore aims to evaluate the functional regenerated sensation, following peripheral nerve transection treated with fibrin seal (Tisseel-Duo, Immuno; Austria). The sural nerve-innervated skin of the rat hindfoot served as the target organ. Previously published results from animals following transection and suture served as controls. Ten 3-month-old female Sprague-Dawley rats were used. The sciatic nerve was divided and rejoined with fibrin seal. The rats were allowed unrestricted movement directly after surgery and allowed to survive for 3 months. Our observations show that the functional results of regenerated polymodal nociceptors and low-threshold mecanoreceptors show no statistical difference when compared with microsuture. This strengthens the early positive morphological impression of this new product. Further prospective studies in man are anticipated.

scholarly journals Canal-Specific Excitation and Inhibition of Frog Second-Order Vestibular Neurons

1997 ◽  
Vol 78 (3) ◽  
pp. 1363-1372 ◽  
Author(s):  
H. Straka ◽  
S. Biesdorf ◽  
N. Dieringer
Keyword(s):  
Electrical Stimulation ◽  
Semicircular Canal ◽  
Second Order ◽  
Projection Neurons ◽  
Postsynaptic Potentials ◽  
Vestibular Neurons ◽  
Inhibitory Postsynaptic Potentials ◽  
Monosynaptic Epsp ◽  
Stimulation Of ◽  
Monosynaptic Excitation

Straka, H., S. Biesdorf, and N. Dieringer. Canal-specific excitation and inhibition of frog second-order vestibular neurons. J. Neurophysiol. 78: 1363–1372, 1997. Second-order vestibular neurons (2°VNs) were identified in the in vitro frog brain by their monosynaptic excitation following electrical stimulation of the ipsilateral VIIIth nerve. Ipsilateral disynaptic inhibitory postsynaptic potentials were revealed by bath application of the glycine antagonist strychnine or of the γ-aminobutyric acid-A (GABAA) antagonist bicuculline. Ipsilateral disynaptic excitatory postsynaptic potentials (EPSPs) were analyzed as well. The functional organization of convergent monosynaptic and disynaptic excitatory and inhibitory inputs onto 2°VNs was studied by separate electrical stimulation of individual semicircular canal nerves on the ipsilateral side. Most 2°VNs (88%) received a monosynaptic EPSP exclusively from one of the three semicircular canal nerves; fewer 2°VNs (10%) were monosynaptically excited from two semicircular canal nerves; and even fewer 2°VNs (2%) were monosynaptically excited from each of the three semicircular canal nerves. Disynaptic EPSPs were present in the majority of 2°VNs (68%) and originated from the same (homonymous) semicircular canal nerve that activated a monosynaptic EPSP in a given neuron (22%), from one or both of the other two (heteronymous) canal nerves (18%), or from all three canal nerves (28%). Homonymous activation of disynaptic EPSPs prevailed (74%) among those 2°VNs that exhibited disynaptic EPSPs. Disynaptic inhibitory postsynaptic potentials (IPSPs) were mediated in 90% of the tested 2°VNs by glycine, in 76% by GABA, and in 62% by GABA as well as by glycine. These IPSPs were activated almost exclusively from the same semicircular canal nerve that evoked the monosynaptic EPSP in a given 2°VN. Our results demonstrate a canal-specific, modular organization of vestibular nerve afferent fiber inputs onto 2°VNs that consists of a monosynaptic excitation from one semicircular canal nerve followed by disynaptic excitatory and inhibitory inputs originating from the homonymous canal nerve. Excitatory and inhibitory second-order (2°) vestibular interneurons are envisaged to form side loops that mediate spatially similar but dynamically different signals to 2° vestibular projection neurons. These feedforward side loops are suited to adjust the dynamic response properties of 2° vestibular projection neurons by facilitating or disfacilitating phasic and tonic input components.

scholarly journals EPSPs in rat neocortical neurons in vitro. II. Involvement of N-methyl-D-aspartate receptors in the generation of EPSPs

1989 ◽  
Vol 61 (3) ◽  
pp. 621-634 ◽  
Author(s):  
B. Sutor ◽  
J. J. Hablitz
Keyword(s):  
Electrical Stimulation ◽  
Membrane Potential ◽  
Action Potentials ◽  
Voltage Dependence ◽  
Negative Slope ◽  
Inward Rectification ◽  
Potential Range ◽  
Bathing Solution ◽  
Postsynaptic Potentials ◽  
Neocortical Neurons

1. Intracellular recordings were obtained from neurons in layer II/III of rat frontal cortex. Single-electrode current- and voltage-clamp techniques were employed to compare the sensitivity of excitatory postsynaptic potentials (EPSPs) and iontophoretically evoked responses to N-methyl-D-aspartate (NMDA) to the selective NMDA antagonist D-2-amino-5-phosphonovaleric acid (D-2-APV). The voltage dependence of the amplitudes of the EPSPs before and after pharmacologic changes in the neuron's current-voltage relationship was also examined. 2. NMDA depolarized the membrane potential, increased the neuron's apparent input resistance (RN), and evoked bursts of action potentials. The NMDA-induced membrane current (INMDA) gradually increased with depolarization from -80 to -40 mV. The relationship between INMDA and membrane potential displayed a region of negative slope conductance in the potential range between -70 and -40 mV which was sufficient to explain the apparent increase in RN and the burst discharges during the NMDA-induced depolarization. 3. Short-latency EPSPs (eEPSPs) were evoked by low-intensity electrical stimulation of cortical layer IV. Changes in the eEPSP waveform following membrane depolarization and hyperpolarization resembled those of NMDA-mediated responses. However, the eEPSP was insensitive to D-2-APV applied at concentrations (up to 20 microM) that blocked NMDA responses. 4. EPSPs with latencies between 10 and 40 ms [late EPSPs (lEPSPs)] were evoked by electrical stimulation using intensities just subthreshold to the activation of IPSPs. The amplitude of the lEPSP increased with hyperpolarization and decreased with depolarization. 5. The lidocaine derivative QX-314, injected intracellularly, suppressed sodium-dependent action potentials and depolarizing inward rectification. Simultaneously, the amplitude of the eEPSP significantly decreased with depolarization. Neither the amplitude of a long-latency EPSP nor the amplitude of inhibitory postsynaptic potentials (IPSPs) was significantly affected by QX-314. 6. Cesium ions (0.5-2.0 mM) added to the bathing solution reduced or blocked hyperpolarizing inward rectification. Under these conditions, the amplitude of the eEPSP increased with hyperpolarization. The amplitude of the lEPSP was unaltered or enhanced. 7. The lEPSP was reversibly blocked by D-2-APV (5-20 microM), although the voltage-dependence of its amplitude did not resemble the action of NMDA on neocortical neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Subfornical organ stimulation excites paraventricular neurons projecting to dorsal medulla

1984 ◽  
Vol 247 (6) ◽  
pp. R1088-R1092 ◽  
Author(s):  
A. V. Ferguson ◽  
T. A. Day ◽  
L. P. Renaud
Keyword(s):  
Electrical Stimulation ◽  
Functional Connectivity ◽  
Subfornical Organ ◽  
Sprague Dawley ◽  
Extracellular Recordings ◽  
Long Latency ◽  
Sprague Dawley Rats ◽  
Pressor Responses ◽  
Increased Activity ◽  
Dorsal Medulla

Electrical stimulation in the subfornical organ (SFO) of pentobarbital-anesthetized Sprague-Dawley rats was noted to influence the excitability of paraventricular nucleus (PVN) neurons antidromically identified as projecting to the dorsomedial medulla. Extracellular recordings indicated that 60% (n = 34) of these caudally projecting PVN neurons increased activity in response to single shock stimuli delivered to the SFO. Short-latency [30.0 +/- 2.7 (SE) ms] and long-latency (162.5 +/- 32.5 ms) responses were observed. The remaining neurons were either unaffected (38%) or inhibited (2%) by SFO stimulation. These data suggest functional connectivity between the SFO and the dorsomedial medulla. It is proposed that such a pathway may mediate pressor responses observed to follow electrical stimulation in the SFO.

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