Electrical Stimulation of the Stratum Radiatum Increases the Release and Neosynthesis of Aspartate, Glutamate, and ?-Aminobutyric Acid in Rat Hippocampal Slices

Ion-selective microelectrode recordings were made to assess a possible contribution of extracellular γ-aminobutyric acid (GABA) accumulation to early responses evoked in the brain by anoxia and ischemia. Changes evoked by GABA or N2 in [K+]o, [Cl-]o, [Na+]o, and [TMA+]o were recorded in the cell body and dendritic regions of the stratum pyramidale (SP) and stratum radiatum (SR), respectively, of pyramidal neurons in CA1 of guinea pig hippocampal slices. Bath application of GABA (1-10 mM) for approximately 5 min evoked changes in [K+]o and [Cl-]o with respective EC50 levels of 3.8 and 4.1 mM in SP, and 4.7 and 5.6 mM in SR. In SP 5 mM GABA reversibly increased [K+]o and [Cl-]o and decreased [Na+]o; replacement of 95% O2 -5% CO2 by 95% N2 -5% CO2 for a similar period of time evoked changes which were for each ion in the same direction as those with GABA. In SR both GABA and N2 caused increases in [K+]o and decreases in [Cl-]o and [Na+]o. The reduction of extracellular space, estimated from levels of [TMA+]o during exposures to GABA and N2, was 5-6% and insufficient to cause the observed changes in ion concentration. Ion changes induced by GABA and N2 were reversibly attenuated by the GABAA receptor antagonist bicuculline methiodide (BMI, 100 µM). GABA-evoked changes in [K+]o in SP and SR and [Cl-]o in SP were depressed by >=90%, and of [Cl-]o in SR by 50%; N2-evoked changes in [K+]o in SP and SR were decreased by 70% and those of [Cl-]o by 50%. BMI blocked Δ [Na+]o with both GABA and N2 by 20-30%. It is concluded that during early anoxia: (i) accumulation of GABA and activation of GABAA receptors may contribute to the ion changes and play a significant role, and (ii) responses in the dendritic (SR) regions are greater than and (or) differ from those in the somal (SP) layers. A large component of the [K+]o increase may involve a GABA-evoked Ca2+-activated gk, secondary to [Ca2+]i increase. A major part of [Cl-]o changes may arise from GABA-induced gCl and glial efflux, with strong stimulation of active outward transport and anion exchange at SP, and inward Na+/K+/2Cl- co-transport at SR. Na+ influx is attributable mainly to Na+-dependent transmitter uptake, with only a small amount related to GABAA receptor activation. Although the release and (or) accumulation of GABA during anoxia might be viewed as potentially protectant, the ultimate role may more likely be an important contribution to toxicity and delayed neuronal death. Key words: brain slices, ion-selective microelectrodes, stratum pyramidale, stratum radiatum, bicuculline methiodide, extracellular space shrinkage.

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2-Deoxyglucose–Induced Long-Term Potentiation in CA1 Is Not Prevented by Intraneuronal Chelator

Journal of Neurophysiology ◽

10.1152/jn.2000.83.1.177 ◽

2000 ◽

Vol 83 (1) ◽

pp. 177-180 ◽

Cited By ~ 6

Author(s):

Yong-Tao Zhao ◽

Krešimir Krnjević

Keyword(s):

Ethylene Glycol ◽

Hippocampal Slices ◽

Long Term Potentiation ◽

Stratum Radiatum ◽

Tetanic Stimulation ◽

Tetraacetic Acid ◽

Ca1 Neurons ◽

Term Potentiation ◽

Stimulation Of

In hippocampal slices, temporary (10–20 min) replacement of glucose with 10 mM 2-deoxyglucose is followed by marked and very sustained potentiation of EPSPs (2-DG LTP). To investigate its mechanism, we examined 2-DG's effect in CA1 neurons recorded with sharp 3 M KCl electrodes containing a strong chelator, 50 or 100 mM ethylene glycol-bis(β-aminoethyl ether)- N, N, N′, N′-tetraacetic acid (EGTA). In most cases, field EPSPs were simultaneously recorded and conventional LTP was also elicited in some cells by tetanic stimulation of stratum radiatum. 2-DG potentiated intracellular EPSP slopes by 48 ± 5.1% (SE) in nine cells recorded with plain KCl electrodes and by 52 ± 6.2% in seven cells recorded with EGTA-containing electrodes. In four of the latter cells, tetanic stimulation (twice 100 Hz for 1 s) failed to evoke LTP (2 ± 1.1%), although field EPSPs were clearly potentiated (by 28 ± 6.9%). Thus unlike tetanic LTP, 2-DG LTP is not readily prevented by postsynaptic intraneuronal injection of EGTA. These findings agree with other evidence that the rise in postsynaptic (somatic) [Ca2+]i caused by 2-DG is not the principal trigger for the subsequent 2-DG LTP and that it may be a purely presynaptic phenomenon.

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Spinal glycinergic and gamma‐aminobutyric acid‐ergic neurons inhibit the micturition reflex after electrical stimulation of the perineum in rats with pelvic venous congestion

International Journal of Urology ◽

10.1111/iju.14116 ◽

2019 ◽

Vol 26 (12) ◽

pp. 1149-1155 ◽

Cited By ~ 1

Author(s):

Kimio Sugaya ◽

Saori Nishijima ◽

Katsumi Kadekawa ◽

Katsuhiko Noguchi ◽

Tomoyuki Ueda ◽

...

Keyword(s):

Electrical Stimulation ◽

Venous Congestion ◽

Aminobutyric Acid ◽

Gamma Aminobutyric Acid ◽

Micturition Reflex ◽

Stimulation Of

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The involvement of nonspiking cells in long-term potentiation of synaptic transmission in the hippocampus

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y88-135 ◽

1988 ◽

Vol 66 (6) ◽

pp. 841-844 ◽

Cited By ~ 14

Author(s):

B. R. Sastry ◽

J. W. Goh ◽

P. B. Y. May ◽

S. S. Chirwa

Keyword(s):

Pyramidal Neurons ◽

Hippocampal Slices ◽

Long Term Potentiation ◽

Stratum Radiatum ◽

Ca1 Pyramidal Neurons ◽

Term Potentiation ◽

Ca1 Area ◽

Glial Depolarization ◽

Stimulation Of

In guinea pig hippocampal slices, stimulation of stratum radiatum during depolarization (with intracellular current injections) of nonspiking cells (presumed to be glia) in the apical dendritic area of CA1 pyramidal neurons resulted in a subsequent long-term potentiation of intracellularly recorded excitatory postsynaptic potentials as well as extracellularly recorded population spikes in the CA1 area. Tetanic stimulation of stratum radiatum resulted in a subsequent prolonged depolarization of the presumed glial cells, and this depolarization was smaller when the tetanus was given during the presence of 2-amino-5-phosphonovalerate or when the slices were exposed to Ca2+-free medium containing Mn2+ and Mg2+. These results suggest that glial depolarization is involved as one of the steps in generating long-term potentiation.

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Temporal resolution of activity-dependent pH shifts in rat hippocampal slices

Journal of Neurophysiology ◽

10.1152/jn.1996.76.4.2804 ◽

1996 ◽

Vol 76 (4) ◽

pp. 2804-2807 ◽

Cited By ~ 16

Author(s):

J. A. Gottfried ◽

M. Chesler

Keyword(s):

Rise Time ◽

Hippocampal Slices ◽

Time Frame ◽

Stratum Radiatum ◽

Optical Data ◽

Excitatory Postsynaptic Currents ◽

Microelectrode Recordings ◽

The Mean ◽

Activity Dependent ◽

Stimulation Of

1. The rise time of activity-dependent extracellular pH shifts was measured in the CA1 stratum radiatum of rat hippocampal slices by recording pH-sensitive fluorescence of a fluorescein-conjugated dextran. Optical data were compared with simultaneous pH microelectrode recordings. 2. The pH shifts generated by CO2 or by stimulation of the Schaffer collaterals were paralleled by shifts in fluorescence emissions at 535 nm when the probe was excited with 490-nm light (delta F490). Emissions at 535 nm induced by 440-nm light were unchanged in these paradigms. 3. A train of three stimuli at 100 Hz was repeated at 30-s intervals and the stimulus-triggered delta F490 was averaged. The mean rise time of the delta F490 was 69 +/- 24 (SE) ms (range 20-200 ms, n = 6). The mean increase in emission was 0.75 +/- 0.22% of baseline, associated with a pH microelectrode response of +0.06 +/- 0.02 unit pH. 4. These data demonstrate that synaptically evoked alkaline transients develop within tens of milliseconds. The occurrence of the alkalinization in the same time frame as excitatory postsynaptic currents indicates that these pH shifts arise with sufficient speed to modulate synaptic transmission.

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Editorial Comment to Spinal glycinergic and gamma‐aminobutyric acid‐ergic neurons inhibit the micturition reflex after electrical stimulation of the perineum in rats with pelvic venous congestion

International Journal of Urology ◽

10.1111/iju.14128 ◽

2019 ◽

Vol 26 (12) ◽

pp. 1156-1156

Author(s):

Motoaki Saito

Keyword(s):

Electrical Stimulation ◽

Editorial Comment ◽

Venous Congestion ◽

Aminobutyric Acid ◽

Gamma Aminobutyric Acid ◽

Micturition Reflex ◽

Stimulation Of

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Picrotoxin-induced epileptiform activity in hippocampus: role of endogenous versus synaptic factors

Journal of Neurophysiology ◽

10.1152/jn.1984.51.5.1011 ◽

1984 ◽

Vol 51 (5) ◽

pp. 1011-1027 ◽

Cited By ~ 151

Author(s):

J. J. Hablitz

Keyword(s):

Refractory Period ◽

Mossy Fiber ◽

Epileptiform Activity ◽

Hippocampal Slices ◽

Extracellular Recording ◽

Synaptic Activity ◽

Stratum Radiatum ◽

Resting Membrane Potential ◽

Stimulation Of

Picrotoxin-(PTX) induced epileptiform activity was studied in guinea pig hippocampal slices maintained in vitro, using intra- and extracellular recording techniques. The observed pattern of spontaneous and evoked epileptiform activity was quite complex. Spontaneous epileptiform events originated in the CA3 region and subsequently spread or propagated to CA1. Activation of CA1 could then reactivate CA3. This reverberation of activity was seen also following stimulation of the mossy fiber afferents from the dentate gyrus to CA3. Stimulation of fibers in the stratum radiatum of the CA1 region could trigger, at short latency, epileptiform activity that either was localized in CA1 or also occurred in CA3, with a late secondary discharge in CA1. This is attributed to a backfiring of the Schaffer collaterals and illustrates the ability of a variety of CA3 inputs to trigger epileptiform activity. Bath-applied PTX, at concentrations of 50-200 microM, had no apparent effect on the resting membrane potential or input resistance of the CA3 cells tested. Depolarizing current pulses elicited characteristic endogenous-burst responses that were not altered by PTX. Synaptic activity evoked by mossy fiber stimulation was altered markedly by PTX. The pattern of observed changes indicated that PTX reduced inhibitory postsynaptic potential (IPSP) amplitudes, resulting in the appearance of repetitive (presumably recurrent) excitatory inputs. Paroxysmal depolarizing shifts ( PDSs ) were generated by the coalescence of these excitatory inputs. Two types of spontaneous bursting were observed after PTX application. The first type was nonepileptiform , all or none in nature, and its frequency was voltage dependent. The second type of spontaneous burst was the PDS. It was epileptiform in character because it was associated with the synchronous discharge of many neurons. It was graded in nature, and its frequency was voltage independent. The graded nature of the PDS was demonstrated by varying the duration and intensity of the orthodromic stimulation. Trains of stimulation could produce PDSs that lasted 500-800 ms. A refractory period was observed following a PDS. By varying the strength of the orthodromic stimulation, it was possible to demonstrate that for the intervals tested this was a relative, not absolute, refractory period. Intracellular recordings in CA3 neurons indicated that each spontaneous PDS was followed by an afterhyperpolarization (AHP).

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