Three-Independent-Compartment Chamber to Study In Vitro Commissural Synapses

Khazipov, Roustem; Desfreres, Luc; Khalilov, Ilgam; Ben‐Ari, Yehezkel

doi:10.1152/jn.1999.81.2.921

Cited by 27 publications

(21 citation statements)

References 4 publications

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“…Furthermore, these studies cannot rule out field effects that may be involved in seizure reduction by DBS. Other bilateral in vitro preparations have been developed but include the entire hippocampus (Khalilov et al , 1997; Khazipov et al , 1999; Khalilov et al , 2003). To our knowledge, this is first in-vitro slice preparation of bilaterally coupled hippocampi in rats.…”

Section: Discussionmentioning

confidence: 99%

Fiber tract stimulation can reduce epileptiform activity in an in-vitro bilateral hippocampal slice preparation

Toprani

Durand

2013

Experimental Neurology

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Mesial temporal lobe epilepsy (MTLE) is a common medically refractory neurological disease that has been treated with electrical stimulation of gray matter with limited success. However, stimulation of a white matter tract connecting the hippocampi could maximize treatment efficacy and extent. We tested low-frequency stimulation (LFS) of a novel target that enables simultaneous targeting of bilateral hippocampi: the ventral hippocampal commissure (VHC) with a novel in-vitro slice preparation containing bilateral hippocampi connected by the VHC. The goal of this study is to understand the role of hippocampal interplay in seizure propagation and reduction by commissural fiber tract stimulation. LFS is applied to the VHC as extracellular and intracellular recording techniques are combined with signal processing to estimate several metrics of epilepsy including: (1) total time occupied by seizure activity (%); (2) seizure duration (s); (3) seizures per minute (#); and (4) power in the ictal (V2Hz−1); as well as (5) interictal spectra (V2Hz−1). Bilateral epileptiform activity in this preparation is highly correlated between hippocampi. Application of LFS to the VHC reduces all metrics of epilepsy during treatment in an amplitude and frequency dependent manner. This study lends several insights into the mechanisms of bilateral seizure reduction by LFS of the VHC, including that depolarization blocking, LTD/LTP and GABAA are not involved. Importantly, enhanced post-stimulation 1-Hz spiking correlates with long-lasting seizure reduction and both are heightened by targeting bilateral hippocampi via the VHC. Therefore, stimulating bilateral hippocampi via a single electrode in the VHC may provide an effective MTLE treatment.

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Section: Discussionmentioning

confidence: 99%

Fiber tract stimulation can reduce epileptiform activity in an in-vitro bilateral hippocampal slice preparation

Toprani

Durand

2013

Experimental Neurology

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“…Intact hippocampal formations were prepared from P1–7 Swiss mice and Wistar rat pups of both sexes as described earlier (Khalilov et al, 1997a; Khazipov et al, 1999). The animals were either cryoanesthetized (P1–4 animals) or anesthetized with chloral hydrate (P5–7) 350 mg/kg, intraperitoneally.…”

Section: Methodsmentioning

confidence: 99%

Excitatory actions of GABA in the intact neonatal rodent hippocampus in vitro

Valeeva¹,

Valiullina²,

Khazipov³

2013

Front. Cell. Neurosci.

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The excitatory action of gamma-aminobutyric acid (GABA) is considered to be a hallmark of the developing nervous system. However, in immature brain slices, excitatory GABA actions may be secondary to neuronal injury during slice preparation. Here, we explored GABA actions in the rodent intact hippocampal preparations and at different depths of hippocampal slices during the early post-natal period [post-natal days (P) 1–7]. We found that in the intact hippocampus at P1–3: (i) GABA exerts depolarizing action as seen in cell-attached single GABA(A) channel recordings; (ii) GABA(A) receptor (GABA(A)-R) agonist isoguvacine and synaptic activation of the GABA(A)-Rs increase the frequency of multiple unit activity and the frequency of the network-driven giant depolarizing potentials (GDPs); and that (iii) Na+–K+–2Cl- cotransporter (NKCC1) antagonist bumetanide suppresses GDPs and the excitatory actions of isoguvacine. In the hippocampal slices at P2–5, isoguvacine and synaptic activation of GABA(A)-Rs-evoked excitatory responses at all slice depths, including surface and core. Thus, GABA exerts excitatory actions in the intact hippocampus (P1–3) and at all depths of hippocampal slices (P2–5). Therefore, the excitatory actions of GABA in hippocampal slices during the first post-natal days are not due to neuronal injury during slice preparation, and the trauma-related excitatory GABA actions at the slice surface are a fundamentally different phenomenon observed during the second post-natal week.

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“…Because of a better preservation of intrinsic connections, this generates readily network-driven oscillations including ictal high-frequency oscillations and other patterns that are seldom recorded in slices. This preparation can be placed in a three-independent compartment chamber that enables the perfusion of the two hippocampi and the commissures with different liquids (322). It is thus possible to apply a convulsive agent to one hippocampus and determine the consequences of the propagation of recurrent seizures in the naive hippocampus relying on field and patch-clamp recordings in both hippocampi.…”

Section: B Seizures Beget Seizures: Gaba and High-frequency Oscillatmentioning

confidence: 99%

GABA: A Pioneer Transmitter That Excites Immature Neurons and Generates Primitive Oscillations

Ben-Ari

Gaı̈arsa

Tyzio

et al. 2007

Physiological Reviews

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1,136

1,123

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Developing networks follow common rules to shift from silent cells to coactive networks that operate via thousands of synapses. This review deals with some of these rules and in particular those concerning the crucial role of the neurotransmitter γ-aminobuytric acid (GABA), which operates primarily via chloride-permeable GABAAreceptor channels. In all developing animal species and brain structures investigated, neurons have a higher intracellular chloride concentration at an early stage leading to an efflux of chloride and excitatory actions of GABA in immature neurons. This triggers sodium spikes, activates voltage-gated calcium channels, and acts in synergy with NMDA channels by removing the voltage-dependent magnesium block. GABA signaling is also established before glutamatergic transmission, suggesting that GABA is the principal excitatory transmitter during early development. In fact, even before synapse formation, GABA signaling can modulate the cell cycle and migration. The consequence of these rules is that developing networks generate primitive patterns of network activity, notably the giant depolarizing potentials (GDPs), largely through the excitatory actions of GABA and its synergistic interactions with glutamate signaling. These early types of network activity are likely required for neurons to fire together and thus to “wire together” so that functional units within cortical networks are formed. In addition, depolarizing GABA has a strong impact on synaptic plasticity and pathological insults, notably seizures of the immature brain. In conclusion, it is suggested that an evolutionary preserved role for excitatory GABA in immature cells provides an important mechanism in the formation of synapses and activity in neuronal networks.

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Three-Independent-Compartment Chamber to Study In Vitro Commissural Synapses

Cited by 27 publications

References 4 publications

Fiber tract stimulation can reduce epileptiform activity in an in-vitro bilateral hippocampal slice preparation

Fiber tract stimulation can reduce epileptiform activity in an in-vitro bilateral hippocampal slice preparation

Excitatory actions of GABA in the intact neonatal rodent hippocampus in vitro

GABA: A Pioneer Transmitter That Excites Immature Neurons and Generates Primitive Oscillations

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