Gamma‐aminobutyric acid uptake and the termination of inhibitory synaptic potentials in the rat hippocampal slice.

Dingledine, Raymond; Korn, Stephen J.

doi:10.1113/jphysiol.1985.sp015804

Cited by 128 publications

(97 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The attenuation and even loss of IPSPs in the presence of nipecotic acid is similar to previous reports from crayfish stretch receptor (Aickin & Deisz, 1981) and hippocampal neurones (Dingledine & Korn, 1985). In order to test whether the depression of both inhibitory synaptic potentials was an unspecific effect as proposed for hippocampal neurones (Dingledine & Korn, 1985) or related to a decrease in GABA uptake, we determined the frequency dependence of the IPSP in the presence of nipecotic acid.…”

Section: Effects Of Nipecotic Acidmentioning

confidence: 56%

“…Inhibitory transmission, however, was either little affected (Curtis et al 1976) or prolonged (Matthews, McCafferty & Setler, 1981) by reduction of GABA uptake. Intracellular recordings from hippocampal pyramidal cells confirmed a prolongation of IPSPs by nipecotic acid (Dingledine & Korn, 1985), attributable to enhancement of a late component of the synaptic current (HIablitz & Lebeda, 1985). But, nipecotic acid severely reduced IPSP amplitudes in the majority of neurones (Dingledine & Korn, 1985).…”

Section: Introductionmentioning

confidence: 95%

“…A. DEIS"-;Z AND D. A. PRINCE Dingledine & Korn, 1985;Hablitz & Lebeda, 1985) suggests that the saturable GABA uptake system limits diffusion. Therefore, access of exogenous GABA to postsynaptic sites is probably neither unrestricted nor constant.…”

Section: Frequency-dependent Decline Of Ionic Gradienltsmentioning

confidence: 99%

“…Intracellular recordings from hippocampal pyramidal cells confirmed a prolongation of IPSPs by nipecotic acid (Dingledine & Korn, 1985), attributable to enhancement of a late component of the synaptic current (HIablitz & Lebeda, 1985). But, nipecotic acid severely reduced IPSP amplitudes in the majority of neurones (Dingledine & Korn, 1985). The latter observation is remarkably similar to that in the crayfish stretch receptor where synaptic efficacy declined after blockade of GABA uptake by nipecotic acid (Aickin & Deisz, 1981).…”

Section: Introductionmentioning

confidence: 99%

“…In order to test whether the depression of both inhibitory synaptic potentials was an unspecific effect as proposed for hippocampal neurones (Dingledine & Korn, 1985) or related to a decrease in GABA uptake, we determined the frequency dependence of the IPSP in the presence of nipecotic acid. If the effects of nipecotic acid were unspecific, a constant depression at all frequencies would be anticipated, while an effect of nipecotic acid due to a prolongation of the GABA transient in the cleft would be expected to produce an altered frequency dependence.…”

Section: Effects Of Nipecotic Acidmentioning

confidence: 99%

See 4 more Smart Citations

Frequency‐dependent depression of inhibition in guinea‐pig neocortex in vitro by GABAB receptor feed‐back on GABA release.

Deisz

Prince

1989

The Journal of Physiology

330

208

View full text Add to dashboard Cite

SUMMARY1. The mechanisms involved in the lability of inhibition at higher frequencies of stimulation were investigated in the guinea-pig in vitro neocortical slice preparation by intracellular recording techniques. We attempted to test the possibility of a feedback depression of GABA on subsequent release.2. At resting membrane potential (Em, -75-8 + 5-2 mV) stimulation of either the pial surface or subcortical white matter evoked a sequence of depolarizing and hyperpolarizing synaptic components in most neurones. An early hyperpolarizing component (IPSPA) was usually only obvious as a pronounced termination of the EPSP. followed by a later hyperpolarizing event (IPSPB). Current-voltage relationships revealed two different conductances of about 200 and 20 nS and reversal potentials of -73-0+444 and -88-6+6 1 mV for the early and late component. respectively.3. The conductances of IPSPA and IPSPB were fairly stable at a stimulus frequency of 0-1 Hz. At frequencies between 0-5 and 2 Hz both IPSPs were attenuated with the second stimulus and after about five stimuli a steady state was reached. Concomitantly IPSPs were shortened. The average decrease in synaptic conductance between 0-1 and 1 Hz was 80% for the IPSPA and 60% for the IPSPB. At these frequencies the reversal potentials decreased by 5 and 2 mV, respectively; Em and input resistance (Rin) were not consistently affected.4. The amplitudes of field potentials, action potentials and EPSPs of pyramidal cells were attenuated less than 10% at stimulus frequencies up to 1 Hz, suggesting that alterations in local circuits between the stimulation site and excitatory input onto inhibitory interneurones may play only a minor role in the frequency-dependent decav of IPSPs.5. Localized application of GABA produced multiphasic responses. With low concentrations and application near the soma an early hyperpolarization prevailed followed by a depolarizing late component. Brief application of GABA at low frequencies induced constant responses; at higher frequencies, the responses sometimes declined. were similar to each other and to the early IPSP. An apparently fivefold higher conductance was estimated at lower Ems, suggesting that the GABA response had a voltage sensitivity. The slope conductance of IPSPs was decreased by up to 50 % for tens of seconds after postsynaptically detectable effects of GABA had dissipated. 6. Application of the GABA uptake inhibitor nipecotic acid (50-500 JLM) reduced the conductance of both components of orthodromically evoked inhibition and shortened the IPSP at low frequencies, but had no additional effects at higher stimulation rates. Em and Rin were not consistently affected. Application of nipecotic acid usually decreased the latency and increased the slope conductance of GABA responses. Depression of IPSPs by nipecotic acid at low frequencies, in the face of enhanced GABA responses, is probably presynaptically mediated. The prolonged time course of synaptically liberated GABA by nipecotic acid may cause extended presynaptic effects.7. ...

show abstract

Section: Effects Of Nipecotic Acidmentioning

confidence: 56%