Weaker synaptic inhibition in CA1 region of ventral compared to dorsal rat hippocampal slices

Papatheodoropoulos, Costas; Asprodini, Eftihia; Nikita, Ioanna; Koutsona, Christina; Kostopoulos, George

doi:10.1016/s0006-8993(02)02958-x

Cited by 53 publications

(67 citation statements)

References 17 publications

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“…In particular, the lower a1 subunit mRNA and protein expression observed in VH compared with DH in our study might reduce the GABA A -mediated inhibitory postsynaptic potentials (IPSPs), which could contribute to the lower fast inhibition observed in VH (Papatheodoropoulos et al, 2002). It has been recently shown that the absence of a1 subunit, in knockout mice, results in a reduction of inhibitory currents' amplitude (Vicini et al, 2001), with these currents becoming slower (Vicini et al, 2001;Golstein et al, 2002).…”

Section: Discussionmentioning

confidence: 56%

“…In conclusion, the differences in the ratio of the two GABA A receptor subtypes, which were more prominent in the CA1 region, suggest a weaker inhibitory efficacy of VH GABA A receptors that may underlie the weaker GABA A -mediated inhibition in the CA1 region of VH (Papatheodoropoulos et al, 2002). Furthermore, it may explain, to some extent, the higher susceptibility of the VH for epileptiform activity (Elul, 1964;Racine et al, 1977;Gilbert et al, 1985;Bragdon et al, 1986;Borck and Jefferys, 1999).…”

Section: Discussionmentioning

confidence: 99%

“…g-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central nervous system, mediating fast synaptic inhibition (Sivilotti and Nistri, 1991), so it is a crucial factor in controlling epileptic seizures (Sloviter, 1991). Recently, we have demonstrated a weaker GABAergic inhibition in the CA1 region of ventral compared with dorsal hippocampus slices (Papatheodoropoulos et al, 2002). Previous studies in hippocampus have correlated alterations of the GABA A receptor subunits mRNA expression to epileptic activity (Kang et al, 1991;Tsunashima et al, 1997;Pirker et al, 2000).…”

mentioning

confidence: 99%

“…In the present study, we examined whether the differences in the GABA-mediated inhibition between DH and VH (Papatheodoropoulos et al, 2002) could be related to possible variations in the GABA A receptors. We therefore studied the quantitative distribution, the kinetic parameters, and the subunit composition of the GABA A receptors in the two parts of hippocampus.…”

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confidence: 99%

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Differential expression of γ‐aminobutyric acid‐A receptor subunits in rat dorsal and ventral hippocampus

Sotiriou

Papatheodoropoulos

Angelatou

2005

J of Neuroscience Research

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Recent data demonstrate weaker gamma-aminobutyric acid (GABA)-ergic inhibition in ventral (VH) compared with dorsal (DH) hippocampus. Therefore, we examined possible differences regarding the GABAA receptors between VH and DH as follows: 1) the expression of the GABAA receptor subunits (alpha1/2/4/5, beta1/2/3, gamma2, delta) mRNA and protein and 2) the quantitative distribution and kinetic parameters of [3H] muscimol (GABAA receptor agonist) binding. VH compared with DH showed: 1) lower levels for alpha1, beta2, gamma2 but higher levels for alpha2 and beta1 subunits in CA1, CA2, and CA3, the differences being more pronounced in CA1 region; in the CA1 region, the mRNA levels of alpha5 were higher, whereas those of alpha4 subunit were slightly lower; in dentate gyrus, the mRNA levels of alpha4, beta3, and delta subunits were significantly lower, presumably suggesting a lower expression of the alpha4/beta3/delta receptor subtype; and 2) lower levels of [3H]muscimol binding, with the lowest value observed in CA1, apparently resulting from weaker binding affinity, insofar as the KD values were higher in VH, whereas the Bmax values were similar between DH and VH. The differences in the subunit expression and the lower affinity of GABAA receptor binding observed predominantly in the CA1 region of VH suggest that the alpha1/beta2/gamma2 GABAA receptor subtype dominates in DH, and the alpha2/beta1/gamma2 subtype prevails in VH. This could underlie the lower GABAA-mediated inhibition observed in VH and, to some extent, explain 1) the higher liability of VH for epileptic activity and 2) the differential involvement of DH and VH in cognitive and emotional processes.

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Section: Discussionmentioning

confidence: 56%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Differential expression of γ‐aminobutyric acid‐A receptor subunits in rat dorsal and ventral hippocampus

Sotiriou

Papatheodoropoulos

Angelatou

2005

J of Neuroscience Research

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“…It was shown that ventral hippocampus (VH) is more vulnerable to the abnormal synchronization and dorsal part of hippocampus (DH) is more resistant to seizureinduced injury and neuronal death than VH [5,6,8,9]. The difference in seizure susceptibility of DH and VH could be at least partly explained by the difference in the receptor expression in different parts of hippocampus [8,10].…”

Section: Introductionmentioning

confidence: 99%

Effect of altered extracellular magnesium concentration on the neuronal activity in different hippocampal regions of immature rats

Власюк¹,

Romanov²,

Isaev³

et al. 2017

Fiziol Zh

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Model of frequent, recurrent, and spontaneous seizures in the intact mouse hippocampus

et al. 2004

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This study presents a model of chronic, recurrent, spontaneous seizures in the intact isolated hippocampal preparation from mice aged P8-P25. Field activity from the CA1 pyramidal cell layer was recorded and recurrent, spontaneous seizure-like events (SLEs) were observed in the presence of low Mg2+ (0.25 mM) artificial cerebrospinal fluid (ACSF). Hippocampi also showed interictal epileptiform discharges (IEDs) of 0.9-4.2 Hz occurring between seizures. No age-specific differences were found in SLE occurrence (2 SLEs per 10 min, on average), duration, and corresponding frequencies. After long exposure to low Mg2+ ACSF (>3 h), SLEs were completely reversible within minutes with the application of normal (2 mM Mg2+) ACSF. The AMPA antagonist, CNQX, blocked all epileptiform activity, whereas the NMDA antagonist, APV, did not. The gamma-aminobutyric acid (GABA)A antagonist, bicuculline, attenuated and fragmented SLEs, implicating interneurons in SLE generation. The L-type Ca2+ blocker, nifedipine, enhanced epileptiform activity. Analysis of dual site recordings along the septotemporal hippocampus demonstrated that epileptiform activity began first in the temporal pole of the hippocampus, as illustrated by disconnection experiments. Once an SLE had been established, however, the septal hippocampus was sometimes seen to lead the epileptiform activity. The whole hippocampus with intact local circuitry, treated with low Mg2+, provides a realistic model of recurrent spontaneous seizures, which may be used, in normal and genetically modified mice, to study the dynamics of seizures and seizure evolution, as well as the mechanisms of action of anti-epileptic drugs and other therapeutic modalities.

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Weaker synaptic inhibition in CA1 region of ventral compared to dorsal rat hippocampal slices

Cited by 53 publications

References 17 publications

Differential expression of γ‐aminobutyric acid‐A receptor subunits in rat dorsal and ventral hippocampus

Differential expression of γ‐aminobutyric acid‐A receptor subunits in rat dorsal and ventral hippocampus

Effect of altered extracellular magnesium concentration on the neuronal activity in different hippocampal regions of immature rats

Model of frequent, recurrent, and spontaneous seizures in the intact mouse hippocampus

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