The effect of Mg2+ on the synaptic depression of CA1 pyramidal neurons induced by low frequency stimulation in rat hippocampal slices

1990 ◽  
Vol 11 ◽  
pp. S51
Author(s):  
Yuko Sekino ◽  
Ikuko Koyama
Keyword(s):  
Pyramidal Neurons ◽  
Hippocampal Slices ◽  
Low Frequency ◽  
Synaptic Depression ◽  
Ca1 Pyramidal Neurons ◽  
Low Frequency Stimulation ◽  
Frequency Stimulation

Low-frequency stimulation at the troughs of theta-oscillation induces long-term depression of previously potentiated CA1 synapses

1996 ◽  
Vol 75 (2) ◽  
pp. 877-884 ◽  
Author(s):  
P. T. Huerta ◽  
J. E. Lisman
Keyword(s):  
Hippocampal Slices ◽  
Field Potential ◽  
Low Frequency ◽  
Long Term Depression ◽  
Low Frequency Stimulation ◽  
Bath Application ◽  
Stable Conditions ◽  
Theta Frequency ◽  
Frequency Stimulation

1. The induction of long-term weakening of synaptic transmission in rat hippocampal slices was examined in CA1 synapses during cholinergic modulation. 2. Bath application of the cholinergic agonist carbachol (50 microM) activated an oscillation of the local field potential in the theta-frequency range (5-12 Hz), termed theta. It was previously shown that a stimulation train of 40 single shocks (at 0.1 Hz) to the Schaffer collateral-commisural afferents, each synchronized with positive peaks of theta, caused homosynaptic long-term enhancement in CA1. Furthermore, long-term depression (LTD) was sporadically observed when the stimulation train was given at negative troughs of theta. Here we have sought to determine stable conditions for LTD induction during theta. 3. Synaptic weakening was reliably obtained, by giving 40 shocks (at 0.1 Hz) at theta-troughs, only in pathways that had been previously potentiated. This decrement, termed theta-LTD, was synapse specific because it did not occur in an independent pathway not stimulated during theta. The interval between the initial potentiating tetanus and theta-LTD induction could be as long as 90 min. 4. theta-LTD could be saturated; after consecutive episodes of theta-LTD induction, no significant further depression was obtained. Moreover, theta-LTD could be reversed by tetanic stimulation. 5. theta-LTD could prevent the induction of LTD by 600-900 pulses at 1 Hz. This suggests that the two protocols may share common mechanisms at the synaptic level. 6. We conclude that single presynaptic spikes that occur at low frequency and are properly timed to the troughs of theta may be a relevant mechanism for decreasing the strength of potentiated synapses.

scholarly journals A Comparison of the Dynamics of S100B, S100A1, and S100A6 mRNA Expression in Hippocampal CA1 Area of Rats during Long-Term Potentiation and after Low-Frequency Stimulation

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Pavel D. Lisachev ◽  
Mark B. Shtark ◽  
Olga O. Sokolova ◽  
Vladimir O. Pustylnyak ◽  
Mary Yu. Salakhutdinova ◽  
...  
Keyword(s):  
Mrna Level ◽  
Hippocampal Slices ◽  
Low Frequency ◽  
Fold Increase ◽  
Long Term Potentiation ◽  
Low Frequency Stimulation ◽  
Term Potentiation ◽  
Mrna Content ◽  
Frequency Stimulation ◽  
Ca1 Area

The interest in tissue- and cell-specific S100 proteins physiological roles in the brain remains high. However, necessary experimental data for the assessment of their dynamics in one of the most important brain activities, its plasticity, is not sufficient. We studied the expression of S100B, S100A1, and S100A6 mRNA in the subfield CA1 of rat hippocampal slices after tetanic and low-frequency stimulation by real-time PCR. Within 30 min after tetanization, a 2–4 fold increase of the S100B mRNA level was observed as compared to the control (intact slices) or to low-frequency stimulation. Subsequently, the S100B mRNA content gradually returned to baseline. The amount of S100A1 mRNA gradually increased during first hour and maintained at the achieved level in the course of second hour after tetanization. The level of S100A6 mRNA did not change following tetanization or low-frequency stimulation.

Novel Form of LTD Induced by Transient, Partial Inhibition of the Na,K-Pump in Rat Hippocampal CA1 Cells

2004 ◽  
Vol 91 (1) ◽  
pp. 239-247 ◽  
Author(s):  
Christian G. Reich ◽  
Susanne E. Mason ◽  
Bradley E. Alger
Keyword(s):  
Hippocampal Slices ◽  
Low Frequency ◽  
Bk Channels ◽  
P38 Map Kinase ◽  
Partial Inhibition ◽  
Low Frequency Stimulation ◽  
Hippocampal Ca1 ◽  
Frequency Stimulation ◽  
Selective Blocker

We tested the hypothesis that transient, partial inhibition of the Na,K-pumps could produce lasting effects on synaptic efficacy in brain tissue by applying a low concentration of the ouabain analogue, dihydroouabain (DHO), to hippocampal slices for 15 min and studying the effects on field excitatory postsynaptic potentials (fEPSPs). DHO caused a suppression of fEPSPs during the application period, but this recovered only partially, to ∼80% of control levels, after washout lasting as long as 2 h. The lasting suppression had several properties in common with low-frequency stimulation induced long-term depression (LFS-LTD), including an ability to depotentiate long-term potentiated responses. However, DHO-LTD was insensitive to blockade of N-methyl-d-aspartate or mGlu receptors or to inhibitors of protein kinase C or p38 MAP kinase. DHO-LTD did not co-occlude with LFS-LTD and therefore appears to represent a novel form of LTD. Interestingly, DHO-LTD could be prevented by pretreating slices with iberiotoxin, the selective blocker of large, Ca2+-dependent K+ channels (“big K,” BK channels), although this toxin did not affect basal fEPSPs. Certain pathological conditions, including hypoxia and ischemia, are associated with a decrease in Na,K-pump activity and hence DHO-LTD may serve as a model for the effects on neuronal function in these conditions.

scholarly journals The Cannabinoid-Like Compound, VSN16R, Acts on Large Conductance, Ca2+-Activated K+ Channels to Modulate Hippocampal CA1 Pyramidal Neuron Firing

2019 ◽  
Vol 12 (3) ◽  
pp. 104
Author(s):  
Setareh Tabatabaee ◽  
David Baker ◽  
David L. Selwood ◽  
Benjamin J. Whalley ◽  
Gary J. Stephens
Keyword(s):  
Action Potential ◽  
High Frequency ◽  
Pyramidal Neurons ◽  
Low Frequency ◽  
Firing Frequency ◽  
High Frequency Stimulation ◽  
Bkca Channel ◽  
Bkca Channels ◽  
Low Frequency Stimulation ◽  
Frequency Stimulation

Large conductance, Ca2+-activated K+ (BKCa) channels are widely expressed in the central nervous system, where they regulate action potential duration, firing frequency and consequential neurotransmitter release. Moreover, drug action on, mutations to, or changes in expression levels of BKCa can modulate neuronal hyperexcitability. Amongst other potential mechanisms of action, cannabinoid compounds have recently been reported to activate BKCa channels. Here, we examined the effects of the cannabinoid-like compound (R,Z)-3-(6-(dimethylamino)-6-oxohex-1-en-1-yl)-N-(1-hydroxypropan-2-yl) benzamide (VSN16R) at CA1 pyramidal neurons in hippocampal ex vivo brain slices using current clamp electrophysiology. We also investigated effects of the BKCa channel blockers iberiotoxin (IBTX) and the novel 7-pra-martentoxin (7-Pra-MarTx) on VSN16R action. VSN16R (100 μM) increased first and second fast after-hyperpolarization (fAHP) amplitude, decreased first and second inter spike interval (ISI) and shortened first action potential (AP) width under high frequency stimulation protocols in mouse hippocampal pyramidal neurons. IBTX (100 nM) decreased first fAHP amplitude, increased second ISI and broadened first and second AP width under high frequency stimulation protocols; IBTX also broadened first and second AP width under low frequency stimulation protocols. IBTX blocked effects of VSN16R on fAHP amplitude and ISI. 7-Pra-MarTx (100 nM) had no significant effects on fAHP amplitude and ISI but, unlike IBTX, shortened first and second AP width under high frequency stimulation protocols; 7-Pra-MarTx also shortened second AP width under low frequency stimulation protocols. However, in the presence of 7-Pra-MarTx, VSN16R retained some effects on AP waveform under high frequency stimulation protocols; moreover, VSN16R effects were revealed under low frequency stimulation protocols. These findings demonstrate that VSN16R has effects in native hippocampal neurons consistent with its causing an increase in initial firing frequency via activation of IBTX-sensitive BKCa channels. The differential pharmacological effects described suggest that VSN16R may differentially target BKCa channel subtypes.

Relative contributions of excitatory and inhibitory neuronal activity to alkaline transients evoked by stimulation of Schaffer collaterals in the rat hippocampal slice

1995 ◽  
Vol 74 (2) ◽  
pp. 643-649 ◽  
Author(s):  
T. Taira ◽  
P. Paalasmaa ◽  
J. Voipio ◽  
K. Kaila
Keyword(s):  
Hippocampal Slices ◽  
Low Frequency ◽  
Gamma Aminobutyric Acid ◽  
Schaffer Collaterals ◽  
Stratum Pyramidale ◽  
Low Frequency Stimulation ◽  
S 100 ◽  
Drug Inhibition ◽  
Frequency Stimulation ◽  
Stimulation Of

1. The neuronal basis of alkaline shifts in extracellular pH (pHo) evoked by stimulation of Schaffer collaterals was studied by means of double-barreled H(+)-selective microelectrodes in the area CA1 of rat hippocampal slices. 2. Alkaline transients in stratum pyramidale evoked by stimulation at a low frequency (5–10 Hz) were enhanced by pentobarbital sodium (100 microM). In the absence of the drug, inhibition of extracellular carbonic anhydrase (CAo) by benzolamide or by prontosildextran 5000 (PD 5000) resulted in an increase in the alkaline shifts. In contrast to this, alkaloses evoked by low-frequency stimulation in the presence of pentobarbital were attenuated by a subsequent inhibition of CAo. 3. Blockade of gamma-aminobutyric acid-A (GABAA) receptors with picrotoxin (PiTX; 100 microM) resulted in an enhancement of alkaline transients in s. pyramidale evoked by low-frequency stimulation (10 Hz) but suppressed alkaline shifts evoked by brief high-frequency (1 s, 100 Hz) trains of stimuli. 4. Application of trains of stimuli consisting of a constant number of pulses (50 or 100) revealed a striking dependence of the effect of benzolamide on stimulation frequency (10-200 Hz) in s. pyramidale: the enhancement of the alkaloses seen upon inhibition of CAo became progressively smaller with an increase in frequency, and at 100-200 Hz benzolamide produced a suppression or a complete block of the alkaline transients. However, alkaline transients evoked with the use of a constant train duration (5 s) were enhanced by benzolamide at all stimulation frequencies examined (5–200 Hz).(ABSTRACT TRUNCATED AT 250 WORDS)

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