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Gainutdinov A, Shipkov D, Sintsov M, Fabrizi L, Nasretdinov A, Khazipov R, Valeeva G. Somatosensory-Evoked Early Sharp Waves in the Neonatal Rat Hippocampus. Int J Mol Sci 2023; 24:8721. [PMID: 37240066 PMCID: PMC10217913 DOI: 10.3390/ijms24108721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 05/05/2023] [Accepted: 05/11/2023] [Indexed: 05/28/2023] Open
Abstract
The developing entorhinal-hippocampal system is embedded within a large-scale bottom-up network, where spontaneous myoclonic movements, presumably via somatosensory feedback, trigger hippocampal early sharp waves (eSPWs). The hypothesis, that somatosensory feedback links myoclonic movements with eSPWs, implies that direct somatosensory stimulation should also be capable of evoking eSPWs. In this study, we examined hippocampal responses to electrical stimulation of the somatosensory periphery in urethane-anesthetized, immobilized neonatal rat pups using silicone probe recordings. We found that somatosensory stimulation in ~33% of the trials evoked local field potential (LFP) and multiple unit activity (MUA) responses identical to spontaneous eSPWs. The somatosensory-evoked eSPWs were delayed from the stimulus, on average, by 188 ms. Both spontaneous and somatosensory-evoked eSPWs (i) had similar amplitude of ~0.5 mV and half-duration of ~40 ms, (ii) had similar current-source density (CSD) profiles, with current sinks in CA1 strata radiatum, lacunosum-moleculare and DG molecular layer and (iii) were associated with MUA increase in CA1 and DG. Our results indicate that eSPWs can be triggered by direct somatosensory stimulations and support the hypothesis that sensory feedback from movements is involved in the association of eSPWs with myoclonic movements in neonatal rats.
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Affiliation(s)
- Azat Gainutdinov
- Institut de Neurobiologie de la Méditerranée (INMED U1249), Aix-Marseille University, 13273 Marseille, France;
| | - Dmitrii Shipkov
- Laboratory of Neurobiology, Kazan Federal University, 420008 Kazan, Russia (M.S.); (L.F.); (G.V.)
| | - Mikhail Sintsov
- Laboratory of Neurobiology, Kazan Federal University, 420008 Kazan, Russia (M.S.); (L.F.); (G.V.)
| | - Lorenzo Fabrizi
- Laboratory of Neurobiology, Kazan Federal University, 420008 Kazan, Russia (M.S.); (L.F.); (G.V.)
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Azat Nasretdinov
- Laboratory of Neurobiology, Kazan Federal University, 420008 Kazan, Russia (M.S.); (L.F.); (G.V.)
| | - Roustem Khazipov
- Institut de Neurobiologie de la Méditerranée (INMED U1249), Aix-Marseille University, 13273 Marseille, France;
- Laboratory of Neurobiology, Kazan Federal University, 420008 Kazan, Russia (M.S.); (L.F.); (G.V.)
| | - Guzel Valeeva
- Laboratory of Neurobiology, Kazan Federal University, 420008 Kazan, Russia (M.S.); (L.F.); (G.V.)
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Valeeva G, Janackova S, Nasretdinov A, Rychkova V, Makarov R, Holmes GL, Khazipov R, Lenck-Santini PP. Emergence of Coordinated Activity in the Developing Entorhinal-Hippocampal Network. Cereb Cortex 2020; 29:906-920. [PMID: 30535003 PMCID: PMC6319314 DOI: 10.1093/cercor/bhy309] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 11/15/2018] [Indexed: 11/18/2022] Open
Abstract
Correlated activity in the entorhinal–hippocampal neuronal networks, supported by oscillatory and intermittent population activity patterns is critical for learning and memory. However, when and how correlated activity emerges in these networks during development remains largely unknown. Here, we found that during the first postnatal week in non-anaesthetized head-restrained rats, activity in the superficial layers of the medial entorhinal cortex (MEC) and hippocampus was highly correlated, with intermittent population bursts in the MEC followed by early sharp waves (eSPWs) in the hippocampus. Neurons in the superficial MEC layers fired before neurons in the dentate gyrus, CA3 and CA1. eSPW current-source density profiles indicated that perforant/temporoammonic entorhinal inputs and intrinsic hippocampal connections are co-activated during entorhinal–hippocampal activity bursts. Finally, a majority of the entorhinal–hippocampal bursts were triggered by spontaneous myoclonic body movements, characteristic of the neonatal period. Thus, during the neonatal period, activity in the entorhinal cortex (EC) and hippocampus is highly synchronous, with the EC leading hippocampal activation. We propose that such correlated activity is embedded into a large-scale bottom-up circuit that processes somatosensory feedback resulting from neonatal movements, and that it is likely to instruct the development of connections between neocortex and hippocampus.
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Affiliation(s)
- Guzel Valeeva
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
| | - Sona Janackova
- INMED, Aix-Marseille University, INSERM, Marseille, France
| | - Azat Nasretdinov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
| | | | - Roman Makarov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
| | - Gregory L Holmes
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, VT, USA
| | - Roustem Khazipov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.,INMED, Aix-Marseille University, INSERM, Marseille, France
| | - Pierre-Pascal Lenck-Santini
- INMED, Aix-Marseille University, INSERM, Marseille, France.,Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, VT, USA
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Valeeva G, Nasretdinov A, Rychkova V, Khazipov R. Bilateral Synchronization of Hippocampal Early Sharp Waves in Neonatal Rats. Front Cell Neurosci 2019; 13:29. [PMID: 30792630 PMCID: PMC6374346 DOI: 10.3389/fncel.2019.00029] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 01/22/2019] [Indexed: 11/17/2022] Open
Abstract
In the neonatal rodent hippocampus, the first and predominant pattern of correlated neuronal network activity is early sharp waves (eSPWs). Whether and how eSPWs are organized bilaterally remains unknown. Here, using simultaneous silicone probe recordings from the left and right hippocampus in neonatal rats in vivo we found that eSPWs are highly synchronized bilaterally with nearly zero time lag between the two sides. The amplitudes of eSPWs in the left and right hippocampi were also highly correlated. eSPWs also supported bilateral synchronization of multiple unit activity (MUA). We suggest that bilateral correlated activity supported by synchronized eSPWs participates in the formation of bilateral connections in the hippocampal system.
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Affiliation(s)
- Guzel Valeeva
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
| | - Azat Nasretdinov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
| | | | - Roustem Khazipov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.,Aix-Marseille University, INMED, Institut National de la Santé et de la Recherche Médicale (INSERM), Marseille, France
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Vinokurova D, Zakharov AV, Lebedeva J, Burkhanova GF, Chernova KA, Lotfullina N, Khazipov R, Valeeva G. Pharmacodynamics of the Glutamate Receptor Antagonists in the Rat Barrel Cortex. Front Pharmacol 2018; 9:698. [PMID: 30018551 PMCID: PMC6038834 DOI: 10.3389/fphar.2018.00698] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 06/08/2018] [Indexed: 02/01/2023] Open
Abstract
Epipial application is one of the approaches for drug delivery into the cortex. However, passive diffusion of epipially applied drugs through the cortical depth may be slow, and different drug concentrations may be achieved at different rates across the cortical depth. Here, we explored the pharmacodynamics of the inhibitory effects of epipially applied ionotropic glutamate receptor antagonists CNQX and dAPV on sensory-evoked and spontaneous activity across layers of the cortical barrel column in urethane-anesthetized rats. The inhibitory effects of CNQX and dAPV were observed at concentrations that were an order higher than in slices in vitro, and they slowly developed from the cortical surface to depth after epipial application. The level of the inhibitory effects also followed the surface-to-depth gradient, with full inhibition of sensory evoked potentials (SEPs) in the supragranular layers and L4 and only partial inhibition in L5 and L6. During epipial CNQX and dAPV application, spontaneous activity and the late component of multiple unit activity (MUA) during sensory-evoked responses were suppressed faster than the short-latency MUA component. Despite complete suppression of SEPs in L4, sensory-evoked short-latency multiunit responses in L4 persisted, and they were suppressed by further addition of lidocaine suggesting that spikes in thalamocortical axons contribute ∼20% to early multiunit responses. Epipial CNQX and dAPV also completely suppressed sensory-evoked very fast (∼500 Hz) oscillations and spontaneous slow wave activity in L2/3 and L4. However, delta oscillations persisted in L5/6. Thus, CNQX and dAPV exert inhibitory actions on cortical activity during epipial application at much higher concentrations than in vitro, and the pharmacodynamics of their inhibitory effects is characterized by the surface-to-depth gradients in the rate of development and the level of inhibition of sensory-evoked and spontaneous cortical activity.
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Affiliation(s)
- Daria Vinokurova
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.,Mediterranean Institute of Neurobiology - National Institute of Health and Medical Research, Aix-Marseille University, UMR1249, Marseille, France
| | | | - Julia Lebedeva
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
| | | | | | - Nailya Lotfullina
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.,Mediterranean Institute of Neurobiology - National Institute of Health and Medical Research, Aix-Marseille University, UMR1249, Marseille, France
| | - Rustem Khazipov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.,Mediterranean Institute of Neurobiology - National Institute of Health and Medical Research, Aix-Marseille University, UMR1249, Marseille, France
| | - Guzel Valeeva
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
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Vinokurova D, Zakharov A, Akhmetshina D, Nasretdinov A, Valeeva G, Khazipov R. The Effects of Fluoxetine on Sensory-Evoked Responses in the Neonatal Rat Barrel Cortex. BioNanoSci 2017. [DOI: 10.1007/s12668-016-0370-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Nasretdinov A, Akhmetshina D, Valeeva G, Khazipov R. Follicular Nerve Evoked Responses in the Neonatal Rat Barrel Cortex. BioNanoSci 2016. [DOI: 10.1007/s12668-016-0245-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Akhmetshina D, Zakharov A, Vinokurova D, Nasretdinov A, Valeeva G, Khazipov R. The serotonin reuptake inhibitor citalopram suppresses activity in the neonatal rat barrel cortex in vivo. Brain Res Bull 2016; 124:48-54. [PMID: 27016034 DOI: 10.1016/j.brainresbull.2016.03.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 02/10/2016] [Accepted: 03/21/2016] [Indexed: 02/02/2023]
Abstract
Inhibition of serotonin uptake, which causes an increase in extracellular serotonin levels, disrupts the development of thalamocortical barrel maps in neonatal rodents. Previous in vitro studies have suggested that the disruptive effect of excessive serotonin on barrel map formation involves a depression at thalamocortical synapses. However, the effects of serotonin uptake inhibitors on the early thalamocortical activity patterns in the developing barrel cortex in vivo remain largely unknown. Here, using extracellular recordings of the local field potentials and multiple unit activity (MUA) we explored the effects of the selective serotonin reuptake inhibitor (SSRI) citalopram (10-20mg/kg, intraperitoneally) on sensory evoked activity in the barrel cortex of neonatal (postnatal days P2-5) rats in vivo. We show that administration of citalopram suppresses the amplitude and prolongs the delay of the sensory evoked potentials, reduces the power and frequency of the early gamma oscillations, and suppresses sensory evoked and spontaneous neuronal firing. In the adolescent P21-29 animals, citalopram affected neither sensory evoked nor spontaneous activity in barrel cortex. We suggest that suppression of the early thalamocortical activity patterns contributes to the disruption of the barrel map development caused by SSRIs and other conditions elevating extracellular serotonin levels.
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Affiliation(s)
| | - Andrei Zakharov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia; Department of Physiology, Kazan State Medical University, Kazan, Russia
| | - Daria Vinokurova
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
| | - Azat Nasretdinov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
| | - Guzel Valeeva
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.
| | - Roustem Khazipov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia; INMED-INSERM U901, Marseille, France; University Aix-Marseille II, Marseille, France
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Shakirzyanova A, Valeeva G, Giniatullin A, Naumenko N, Fulle S, Akulov A, Atalay M, Nikolsky E, Giniatullin R. Age-dependent action of reactive oxygen species on transmitter release in mammalian neuromuscular junctions. Neurobiol Aging 2016; 38:73-81. [DOI: 10.1016/j.neurobiolaging.2015.10.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 10/13/2015] [Accepted: 10/26/2015] [Indexed: 01/01/2023]
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Valiullina F, Akhmetshina D, Nasretdinov A, Mukhtarov M, Valeeva G, Khazipov R, Rozov A. Developmental Changes in Electrophysiological Properties and a Transition from Electrical to Chemical Coupling between Excitatory Layer 4 Neurons in the Rat Barrel Cortex. Front Neural Circuits 2016; 10:1. [PMID: 26834567 PMCID: PMC4720737 DOI: 10.3389/fncir.2016.00001] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 01/02/2016] [Indexed: 11/22/2022] Open
Abstract
During development, sensory systems switch from an immature to an adult mode of function along with the emergence of the active cortical states. Here, we used patch-clamp recordings from neocortical slices in vitro to characterize the developmental changes in the basic electrophysiological properties of excitatory L4 neurons and their connectivity before and after the developmental switch, which occurs in the rat barrel cortex in vivo at postnatal day P8. Prior to the switch, L4 neurons had higher resting membrane potentials, higher input resistance, lower membrane capacity, as well as action potentials (APs) with smaller amplitudes, longer durations and higher AP thresholds compared to the neurons after the switch. A sustained firing pattern also emerged around the switch. Dual patch-clamp recordings from L4 neurons revealed that recurrent connections between L4 excitatory cells do not exist before and develop rapidly across the switch. In contrast, electrical coupling between these neurons waned around the switch. We suggest that maturation of electrophysiological features, particularly acquisition of a sustained firing pattern, and a transition from the immature electrical to mature chemical synaptic coupling between excitatory L4 neurons, contributes to the developmental switch in the cortical mode of function.
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Affiliation(s)
- Fliza Valiullina
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal University Kazan, Russia
| | - Dinara Akhmetshina
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal University Kazan, Russia
| | - Azat Nasretdinov
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal University Kazan, Russia
| | - Marat Mukhtarov
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal University Kazan, Russia
| | - Guzel Valeeva
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal University Kazan, Russia
| | - Roustem Khazipov
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal UniversityKazan, Russia; Institut de Neurobiologie de la Méditerranée, Institut National de la Santé et de la Recherche Médicale UMR901Marseille, France; Aix-Marseille UniversityMarseille, France
| | - Andrei Rozov
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal UniversityKazan, Russia; Department of Physiology and Pathophysiology, University of HeidelbergHeidelberg, Germany
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Khazipov R, Zaynutdinova D, Ogievetsky E, Valeeva G, Mitrukhina O, Manent JB, Represa A. Atlas of the Postnatal Rat Brain in Stereotaxic Coordinates. Front Neuroanat 2015; 9:161. [PMID: 26778970 PMCID: PMC4688355 DOI: 10.3389/fnana.2015.00161] [Citation(s) in RCA: 148] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 11/30/2015] [Indexed: 12/04/2022] Open
Affiliation(s)
- Roustem Khazipov
- Institut de Neurobiologie de la Méditerranée, Institut National de la Santé et de la Recherche Médicale U-901Marseille, France; Aix-Marseille University, UMR 901Marseille, France; Laboratory of Neurobiology, Kazan Federal UniversityKazan, Russia
| | - Dilyara Zaynutdinova
- Institut de Neurobiologie de la Méditerranée, Institut National de la Santé et de la Recherche Médicale U-901Marseille, France; Aix-Marseille University, UMR 901Marseille, France
| | - Elena Ogievetsky
- Institut de Neurobiologie de la Méditerranée, Institut National de la Santé et de la Recherche Médicale U-901Marseille, France; Aix-Marseille University, UMR 901Marseille, France
| | - Guzel Valeeva
- Laboratory of Neurobiology, Kazan Federal University Kazan, Russia
| | - Olga Mitrukhina
- Institut de Neurobiologie de la Méditerranée, Institut National de la Santé et de la Recherche Médicale U-901Marseille, France; Aix-Marseille University, UMR 901Marseille, France; Laboratory of Neurobiology, Kazan Federal UniversityKazan, Russia
| | - Jean-Bernard Manent
- Institut de Neurobiologie de la Méditerranée, Institut National de la Santé et de la Recherche Médicale U-901Marseille, France; Aix-Marseille University, UMR 901Marseille, France
| | - Alfonso Represa
- Institut de Neurobiologie de la Méditerranée, Institut National de la Santé et de la Recherche Médicale U-901Marseille, France; Aix-Marseille University, UMR 901Marseille, France
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Khazipov R, Valeeva G, Khalilov I. Depolarizing GABA and developmental epilepsies. CNS Neurosci Ther 2014; 21:83-91. [PMID: 25438879 DOI: 10.1111/cns.12353] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Revised: 10/14/2014] [Accepted: 10/20/2014] [Indexed: 12/22/2022] Open
Abstract
Early in development, GABA, which is the main inhibitory neurotransmitter in adult brain, depolarizes immature neurons and exerts dual--excitatory and shunting/inhibitory--effects in the developing neuronal networks. The present review discusses some general questions, including the properties of excitation at depolarizing GABAergic synapse and shunting inhibition by depolarizing GABA; technical issues in exploration of depolarizing GABA using various techniques and preparations, including the developmental aspects of traumatic injury and what is known (or rather unknown) on the actions of GABA in vivo; complex roles of depolarizing GABA in developmental epilepsies, including a contribution of depolarizing GABA to enhanced excitability in the immature networks, caused by repetitive seizures accumulation of intracellular chloride concentration that increases excitatory GABA power and its synchronizing proconvulsive effects, and correction of chloride homeostasis as a potential strategy to treat neonatal seizures.
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Affiliation(s)
- Roustem Khazipov
- INMED-INSERM U901, Marseille, France; Aix-Marseille University, Marseille, France; Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
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Abstract
Gamma oscillations have long been considered to emerge late in development. However, recent studies have revealed that gamma oscillations are transiently expressed in the rat barrel cortex during the first postnatal week, a "critical" period of sensory-dependent barrel map formation. The mechanisms underlying the generation and physiological roles of early gamma oscillations (EGOs) in the development of thalamocortical circuits will be discussed in this review. In contrast to adult gamma oscillations, synchronized through gamma-rhythmic perisomatic inhibition, EGOs are primarily driven through feedforward gamma-rhythmic excitatory input from the thalamus. The recruitment of cortical interneurons to EGOs and the emergence of feedforward inhibition are observed by the end of the first postnatal week. EGOs facilitate the precise synchronization of topographically aligned thalamic and cortical neurons. The multiple replay of sensory input during EGOs supports long-term potentiation at thalamocortical synapses. We suggest that this early form of gamma oscillations, which is mechanistically different from adult gamma oscillations, guides barrel map formation during the critical developmental period.
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Affiliation(s)
- R Khazipov
- INMED - INSERM U901, University Aix-Marseille II, Marseille, France; Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.
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Minlebaev M, Valeeva G, Tcheremiskine V, Coustillier G, Khazipov R. Cell-attached recordings of responses evoked by photorelease of GABA in the immature cortical neurons. Front Cell Neurosci 2013; 7:83. [PMID: 23754981 PMCID: PMC3668178 DOI: 10.3389/fncel.2013.00083] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 05/15/2013] [Indexed: 12/21/2022] Open
Abstract
We present a novel non-invasive technique to measure the polarity of GABAergic responses based on cell-attached recordings of currents activated by laser-uncaging of GABA. For these recordings, a patch pipette was filled with a solution containing RuBi-GABA, and GABA was released from this complex by a laser beam conducted to the tip of the patch pipette via an optic fiber. In cell-attached recordings from neocortical and hippocampal neurons in postnatal days P2-5 rat brain slices in vitro, we found that laser-uncaging of GABA activates integral cell-attached currents mediated by tens of GABA(A) channels. The initial response was inwardly directed, indicating a depolarizing response to GABA. The direction of the initial response was dependent on the pipette potential and analysis of its slope-voltage relationships revealed a depolarizing driving force of +11 mV for the currents through GABA channels. Initial depolarizing responses to GABA uncaging were inverted to hyperpolarizing in the presence of the NKCC1 blocker bumetanide. Current-voltage relationships of the currents evoked by RuBi-GABA uncaging using voltage-ramps at the peak of responses not only revealed a bumetanide-sensitive depolarizing reversal potential of the GABA(A) receptor mediated responses, but also showed a strong voltage-dependent hysteresis. Upon desensitization of the uncaged-GABA response, current-voltage relationships of the currents through single GABA(A) channels revealed depolarizing responses with the driving force values similar to those obtained for the initial response. Thus, cell-attached recordings of the responses evoked by local intrapipette GABA uncaging are suitable to assess the polarity of the GABA(A)-Rs mediated signals in small cell compartments.
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Affiliation(s)
- Marat Minlebaev
- Institut de Neurobiologie de la Méditerranée, Institut National de la Santé et de la Recherche Médicale U-901 Marseille, France ; Aix-Marseille University Marseille, France ; Laboratory of Neurobiology, Department of Physiology, Kazan Federal University Kazan, Russia
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Valeeva G, Valiullina F, Khazipov R. Excitatory actions of GABA in the intact neonatal rodent hippocampus in vitro. Front Cell Neurosci 2013; 7:20. [PMID: 23467988 PMCID: PMC3587803 DOI: 10.3389/fncel.2013.00020] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 02/14/2013] [Indexed: 11/27/2022] Open
Abstract
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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Affiliation(s)
- Guzel Valeeva
- Institut de Neurobiologie de la Méditerranée, INSERM U901 Marseille, France ; Aix-Marseille University Marseille, France ; Laboratory of Neurobiology, Kazan Federal University Kazan, Russia
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Valeeva G, Abdullin A, Tyzio R, Skorinkin A, Nikolski E, Ben-Ari Y, Khazipov R. Temporal coding at the immature depolarizing GABAergic synapse. Front Cell Neurosci 2010; 4. [PMID: 20725525 PMCID: PMC2914581 DOI: 10.3389/fncel.2010.00017] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Accepted: 04/27/2010] [Indexed: 11/21/2022] Open
Abstract
In the developing hippocampus, GABA exerts depolarizing and excitatory actions and contributes to the generation of neuronal network driven giant depolarizing potentials (GDPs). Here, we studied spike time coding at immature GABAergic synapses and its impact on synchronization of the neuronal network during GDPs in the neonatal (postnatal days P2–6) rat hippocampal slices. Using extracellular recordings, we found that the delays of action potentials (APs) evoked by synaptic activation of GABA(A) receptors are long (mean, 65 ms) and variable (within a time window of 10–200 ms). During patch-clamp recordings, depolarizing GABAergic responses were mainly subthreshold and their amplification by persistent sodium conductance was required to trigger APs. AP delays at GABAergic synapses shortened and their variability reduced with an increase in intracellular chloride concentration during whole-cell recordings. Negative shift of the GABA reversal potential (EGABA) with low concentrations of bumetanide, or potentiation of GABA(A) receptors with diazepam reduced GDPs amplitude, desynchronized neuronal firing during GDPs and slowed down GDPs propagation. Partial blockade of GABA(A) receptors with bicuculline increased neuronal synchronization and accelerated GDPs propagation. We propose that spike timing at depolarizing GABA synapses is determined by intracellular chloride concentration. At physiological levels of intracellular chloride GABAergic depolarization does not reach the action potential threshold and amplification of GABAergic responses by non-inactivating sodium conductance is required for postsynaptic AP initiation. Slow and variable excitation at GABAergic synapse determines the level of neuronal synchrony and the rate of GDPs propagation in the developing hippocampus.
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Affiliation(s)
- Guzel Valeeva
- Institut de Neurobiologie de la Méditerranée-Institut National de la Santé et de la Recherche Médicale U901, Universite Mediterranean Aix-Marseille II Marseille, France
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