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Fei F, Wang X, Wang Y, Chen Z. Dissecting the role of subiculum in epilepsy: Research update and translational potential. Prog Neurobiol 2021; 201:102029. [PMID: 33636224 DOI: 10.1016/j.pneurobio.2021.102029] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 01/12/2021] [Accepted: 02/21/2021] [Indexed: 11/25/2022]
Abstract
The subiculum serves as the strategic core output of the hippocampus, through which neural activity exits the hippocampal proper and targets the entorhinal cortex and other more distant subcortical and cortical areas. The past decade has witnessed a growing interest in the subiculum, owing to discoveries revealing its critical role in regulating many physiological and pathophysiological processes. Notably, accumulating evidence from both clinical and experimental studies suggests that the subiculum plays a vital role in seizure initiation and propagation, in epilepsy. In this review, we briefly describe the structure and connectivity of the subiculum and then summarize the molecular and cellular mechanisms in the subiculum underlying the epileptic brain, in both epilepsy patients and animal models. Next, we review some translational approaches targeting the malfunctioned subiculum to treat epilepsy. Finally, we pose open questions for future research in the subiculum and their clinical translation challenges.
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Affiliation(s)
- Fan Fei
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Xia Wang
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Yi Wang
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China; Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China
| | - Zhong Chen
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China; Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China; Epilepsy Center, Department of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
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Jorwal P, Sikdar SK. Lactate reduces epileptiform activity through HCA1 and GIRK channel activation in rat subicular neurons in an in vitro model. Epilepsia 2019; 60:2370-2385. [DOI: 10.1111/epi.16389] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 10/24/2019] [Accepted: 10/24/2019] [Indexed: 12/13/2022]
Affiliation(s)
- Pooja Jorwal
- Molecular Biophysics Unit Indian Institute of Science Bangalore India
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Castañeda MS, Tonini R, Richards CD, Stocker M, Pedarzani P. Benzamil inhibits neuronal and heterologously expressed small conductance Ca2+-activated K+ channels. Neuropharmacology 2019; 158:107738. [DOI: 10.1016/j.neuropharm.2019.107738] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 07/10/2019] [Accepted: 08/07/2019] [Indexed: 10/26/2022]
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Lv X, Guo F, Xu X, Chen Z, Sun X, Min D, Cao Y, Shi X, Wang L, Chen T, Shaw C, Gao H, Hao L, Cai J. Abnormal alterations in the Ca²⁺/CaV1.2/calmodulin/caMKII signaling pathway in a tremor rat model and in cultured hippocampal neurons exposed to Mg²⁺-free solution. Mol Med Rep 2015; 12:6663-71. [PMID: 26299765 PMCID: PMC4626152 DOI: 10.3892/mmr.2015.4227] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 07/21/2015] [Indexed: 11/05/2022] Open
Abstract
Voltage-dependent calcium channels (VDCCs) are key elements in epileptogenesis. There are several binding-sites linked to calmodulin (CaM) and several potential CaM-dependent protein kinase II (CaMKII)-mediated phosphorylation sites in CaV1.2. The tremor rat model (TRM) exhibits absence‑like seizures from 8 weeks of age. The present study was performed to detect changes in the Ca2+/CaV1.2/CaM/CaMKII pathway in TRMs and in cultured hippocampal neurons exposed to Mg2+‑free solution. The expression levels of CaV1.2, CaM and phosphorylated CaMKII (p‑CaMKII; Thr‑286) in these two models were examined using immunofluorescence and western blotting. Compared with Wistar rats, the expression levels of CaV1.2 and CaM were increased, and the expression of p‑CaMKII was decreased in the TRM hippocampus. However, the expression of the targeted proteins was reversed in the TRM temporal cortex. A significant increase in the expression of CaM and decrease in the expression of CaV1.2 were observed in the TRM cerebellum. In the cultured neuron model, p‑CaMKII and CaV1.2 were markedly decreased. In addition, neurons exhibiting co‑localized expression of CaV1.2 and CaM immunoreactivities were detected. Furthermore, intracellular calcium concentrations were increased in these two models. For the first time, o the best of our knowledge, the data of the present study suggested that abnormal alterations in the Ca2+/CaV1.2/CaM/CaMKII pathway may be involved in epileptogenesis and in the phenotypes of TRMs and cultured hippocampal neurons exposed to Mg2+‑free solution.
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Affiliation(s)
- Xintong Lv
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Feng Guo
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Xiaoxue Xu
- Department of Neurology, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Zaixing Chen
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Xuefei Sun
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Dongyu Min
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Yonggang Cao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Xianbao Shi
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Lei Wang
- Molecular Therapeutics Research Group, School of Pharmacy, Queen's University, Belfast BT7 1NN, United Kingdom
| | - Tianbao Chen
- Molecular Therapeutics Research Group, School of Pharmacy, Queen's University, Belfast BT7 1NN, United Kingdom
| | - Chris Shaw
- Molecular Therapeutics Research Group, School of Pharmacy, Queen's University, Belfast BT7 1NN, United Kingdom
| | - Huiling Gao
- College of Life and Health Sciences, Northeastern University, Shenyang, Liaoning 110001, P.R. China
| | - Liying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Jiqun Cai
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, Liaoning 110001, P.R. China
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Sah N, Sikdar SK. Tonic current through GABAA receptors and hyperpolarization-activated cyclic nucleotide-gated channels modulate resonance properties of rat subicular pyramidal neurons. Eur J Neurosci 2014; 40:2241-54. [PMID: 24720274 DOI: 10.1111/ejn.12581] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 02/10/2014] [Accepted: 03/05/2014] [Indexed: 11/26/2022]
Abstract
The subiculum, considered to be the output structure of the hippocampus, modulates information flow from the hippocampus to various cortical and sub-cortical areas such as the nucleus accumbens, lateral septal region, thalamus, nucleus gelatinosus, medial nucleus and mammillary nuclei. Tonic inhibitory current plays an important role in neuronal physiology and pathophysiology by modulating the electrophysiological properties of neurons. While the alterations of various electrical properties due to tonic inhibition have been studied in neurons from different regions, its influence on intrinsic subthreshold resonance in pyramidal excitatory neurons expressing hyperpolarization-activated cyclic nucleotide-gated (HCN) channels is not known. Using pharmacological agents, we show the involvement of α5βγ GABAA receptors in the picrotoxin-sensitive tonic current in subicular pyramidal neurons. We further investigated the contribution of tonic conductance in regulating subthreshold electrophysiological properties using current clamp and dynamic clamp experiments. We demonstrate that tonic GABAergic inhibition can actively modulate subthreshold properties, including resonance due to HCN channels, which can potentially alter the response dynamics of subicular pyramidal neurons in an oscillating neuronal network.
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Affiliation(s)
- Nirnath Sah
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560 012, India
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Sah N, Sikdar SK. Transition in subicular burst firing neurons from epileptiform activity to suppressed state by feedforward inhibition. Eur J Neurosci 2013; 38:2542-56. [DOI: 10.1111/ejn.12262] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 04/21/2013] [Accepted: 04/23/2013] [Indexed: 01/03/2023]
Affiliation(s)
- Nirnath Sah
- Molecular Biophysics Unit; Indian Institute of Science; Bangalore; India
| | - Sujit K. Sikdar
- Molecular Biophysics Unit; Indian Institute of Science; Bangalore; India
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Kim Y, Spruston N. Target-specific output patterns are predicted by the distribution of regular-spiking and bursting pyramidal neurons in the subiculum. Hippocampus 2012; 22:693-706. [PMID: 21538658 PMCID: PMC3209495 DOI: 10.1002/hipo.20931] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/06/2010] [Indexed: 11/06/2022]
Abstract
Pyramidal neurons in the subiculum project to a variety of cortical and subcortical areas in the brain to convey information processed in the hippocampus. Previous studies have shown that two groups of subicular pyramidal neurons--regular-spiking and bursting neurons--are distributed in an organized fashion along the proximal-distal axis, with more regular-spiking neurons close to CA1 (proximal) and more bursting neurons close to presubiculum (distal). Anatomically, neurons projecting to some targets are located more proximally along this axis, while others are located more distally. However, the relationship between the firing properties and the targets of subicular pyramidal neurons is not known. To study this relationship, we used in vivo injections of retrogradely transported fluorescent beads into each of nine different regions and conducted whole-cell current-clamp recordings from the bead-containing subicular neurons in acute brain slices. We found that subicular projections to each area were composed of a mixture of regular-spiking and bursting neurons. Neurons projecting to amygdala, lateral entorhinal cortex, nucleus accumbens, and medial/ventral orbitofrontal cortex were located primarily in the proximal subiculum and consisted mostly of regular-spiking neurons (∼80%). By contrast, neurons projecting to medial EC, presubiculum, retrosplenial cortex, and ventromedial hypothalamus were located primarily in the distal subiculum and consisted mostly of bursting neurons (∼80%). Neurons projecting to a thalamic nucleus were located in the middle portion of subiculum, and their probability of bursting was close to 50%. Thus, the fraction of bursting neurons projecting to each target region was consistent with the known distribution of regular-spiking and bursting neurons along the proximal-distal axis of the subiculum. Variation in the distribution of regular-spiking and bursting neurons suggests that different types of information are conveyed from the subiculum to its various targets.
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Affiliation(s)
- Yujin Kim
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208, USA
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Sah N, Rajput S, Singh J, Meena C, Jain R, Sikdar S, Sharma S. l-pGlu-(2-propyl)-l-His-l-ProNH2 attenuates 4-aminopyridine-induced epileptiform activity and sodium current: a possible action of new thyrotropin-releasing hormone analog for its anticonvulsant potential. Neuroscience 2011; 199:74-85. [DOI: 10.1016/j.neuroscience.2011.10.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 09/30/2011] [Accepted: 10/04/2011] [Indexed: 12/11/2022]
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