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Ingram R, Volianskis R, Georgiou J, Jane DE, Michael-Titus AT, Collingridge GL, Volianskis A. Incremental induction of NMDAR-STP and NMDAR-LTP in the CA1 area of ventral hippocampal slices relies on graded activation of discrete NMDA receptors. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230239. [PMID: 38853568 PMCID: PMC11343233 DOI: 10.1098/rstb.2023.0239] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 04/12/2024] [Accepted: 04/12/2024] [Indexed: 06/11/2024] Open
Abstract
N-methyl-d-aspartate receptor (NMDAR)-dependent short- and long-term types of potentiation (STP and LTP, respectively) are frequently studied in the CA1 area of dorsal hippocampal slices (DHS). Far less is known about the NMDAR dependence of STP and LTP in ventral hippocampal slices (VHS), where both types of potentiation are smaller in magnitude than in the DHS. Here, we first briefly review our knowledge about the NMDAR dependence of STP and LTP and some other forms of synaptic plasticity. We then show in new experiments that the decay of NMDAR-STP in VHS, similar to dorsal hippocampal NMDAR-STP, is not time- but activity-dependent. We also demonstrate that the induction of submaximal levels of NMDAR-STP and NMDAR-LTP in VHS differs from the induction of saturated levels of plasticity in terms of their sensitivity to subunit-preferring NMDAR antagonists. These data suggest that activation of distinct NMDAR subtypes in a population of neurons results in an incremental increase in the induction of different phases of potentiation with changing sensitivity to pharmacological agents. Differences in pharmacological sensitivity, which arise due to differences in the levels of agonist-evoked biological response, might explain the disparity of the results concerning NMDAR subunit involvement in the induction of NMDAR-dependent plasticity.This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.
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Affiliation(s)
- Rachael Ingram
- Centre for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Rasa Volianskis
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - John Georgiou
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, Ontario, Canada
- TANZ Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
| | - David E. Jane
- Hello Bio Limited, Cabot Park, Avonmouth, Bristol, UK
| | - Adina T. Michael-Titus
- Centre for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Graham L. Collingridge
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- TANZ Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
| | - Arturas Volianskis
- Centre for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
- School of Biosciences, Cardiff University, Museum Avenue, Cardiff, UK
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Tsotsokou G, Miliou A, Trompoukis G, Leontiadis LJ, Papatheodoropoulos C. Region-Related Differences in Short-Term Synaptic Plasticity and Synaptotagmin-7 in the Male and Female Hippocampus of a Rat Model of Fragile X Syndrome. Int J Mol Sci 2024; 25:6975. [PMID: 39000085 PMCID: PMC11240911 DOI: 10.3390/ijms25136975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Revised: 06/22/2024] [Accepted: 06/24/2024] [Indexed: 07/16/2024] Open
Abstract
Fragile X syndrome (FXS) is an intellectual developmental disorder characterized, inter alia, by deficits in the short-term processing of neural information, such as sensory processing and working memory. The primary cause of FXS is the loss of fragile X messenger ribonucleoprotein (FMRP), which is profoundly involved in synaptic function and plasticity. Short-term synaptic plasticity (STSP) may play important roles in functions that are affected by FXS. Recent evidence points to the crucial involvement of the presynaptic calcium sensor synaptotagmin-7 (Syt-7) in STSP. However, how the loss of FMRP affects STSP and Syt-7 have been insufficiently studied. Furthermore, males and females are affected differently by FXS, but the underlying mechanisms remain elusive. The aim of the present study was to investigate possible changes in STSP and the expression of Syt-7 in the dorsal (DH) and ventral (VH) hippocampus of adult males and females in a Fmr1-knockout (KO) rat model of FXS. We found that the paired-pulse ratio (PPR) and frequency facilitation/depression (FF/D), two forms of STSP, as well as the expression of Syt-7, are normal in adult KO males, but the PPR is increased in the ventral hippocampus of KO females (6.4 ± 3.7 vs. 18.3 ± 4.2 at 25 ms in wild type (WT) and KO, respectively). Furthermore, we found no gender-related differences, but did find robust region-dependent difference in the STSP (e.g., the PPR at 50 ms: 50.0 ± 5.5 vs. 17.6 ± 2.9 in DH and VH of WT male rats; 53.1 ± 3.6 vs. 19.3 ± 4.6 in DH and VH of WT female rats; 48.1 ± 2.3 vs. 19.1 ± 3.3 in DH and VH of KO male rats; and 51.2 ± 3.3 vs. 24.7 ± 4.3 in DH and VH of KO female rats). AMPA receptors are similarly expressed in the two hippocampal segments of the two genotypes and in both genders. Also, basal excitatory synaptic transmission is higher in males compared to females. Interestingly, we found more than a twofold higher level of Syt-7, not synaptotagmin-1, in the dorsal compared to the ventral hippocampus in the males of both genotypes (0.43 ± 0.1 vs. 0.16 ± 0.02 in DH and VH of WT male rats, and 0.6 ± 0.13 vs. 0.23 ± 0.04 in DH and VH of KO male rats) and in the WT females (0.97 ± 0.23 vs. 0.31 ± 0.09 in DH and VH). These results point to the susceptibility of the female ventral hippocampus to FMRP loss. Importantly, the different levels of Syt-7, which parallel the higher score of the dorsal vs. ventral hippocampus on synaptic facilitation, suggest that Syt-7 may play a pivotal role in defining the striking differences in STSP along the long axis of the hippocampus.
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Affiliation(s)
| | | | | | | | - Costas Papatheodoropoulos
- Lab of Physiology-Neurophysiology, Department of Medicine, University of Patras, 265 04 Patras, Greece; (G.T.); (A.M.); (G.T.); (L.J.L.)
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Tsotsokou G, Kouri V, Papatheodoropoulos C. α7 nicotinic acetylcholine receptors induce long-term synaptic enhancement in the dorsal but not ventral hippocampus. Synapse 2024; 78:e22285. [PMID: 38287475 DOI: 10.1002/syn.22285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 11/08/2023] [Accepted: 12/04/2023] [Indexed: 01/31/2024]
Abstract
Agents that positively modulate the activity of α7nAChRs are used as cognitive enhancers and for the treatment of hippocampus-dependent functional decline. However, it is not known whether the expression and the effects of α7nAChRs apply to the entire longitudinal axis of the hippocampus equally. Given that cholinergic system-involving hippocampal functions are not equally distributed along the hippocampus, we comparatively examined the expression and the effects of α7nAChRs on excitatory synaptic transmission between the dorsal and the ventral hippocampal slices from adult rats. We found that α7nAChRs are equally expressed in the CA1 field of the two segments of the hippocampus. However, activation of α7nAChRs by their highly selective agonist PNU 282987 induced a gradually developing increase in field excitatory postsynaptic potential only in the dorsal hippocampus. This long-term potentiation was not reversed upon application of nonselective nicotinic receptor antagonist mecamylamine, but the induction of potentiation was prevented by prior blockade of α7nAChRs by their antagonist MG 624. In contrast to the long-term synaptic plasticity, we found that α7nAChRs did not modulate short-term synaptic plasticity in either the dorsal or the ventral hippocampus. These results may have implications for the role that α7nAChRs play in specifically modulating functions that depend on the normal function of the dorsal hippocampus. We propose that hippocampal functions that rely on a direct α7 nAChR-mediated persistent enhancement of glutamatergic synaptic transmission are preferably supported by dorsal but not ventral hippocampal synapses.
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Affiliation(s)
- Giota Tsotsokou
- Department of Medicine, Laboratory of Physiology, University of Patras, Rion, Greece
| | - Vasiliki Kouri
- Department of Medicine, Laboratory of Physiology, University of Patras, Rion, Greece
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Li SS, Fang SM, Chen J, Zhang Z, Yu QY. Effects of short-term exposure to volatile pesticide dichlorvos on the olfactory systems in Spodoptera litura: Calcium homeostasis, synaptic plasticity and apoptosis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 864:161050. [PMID: 36549522 DOI: 10.1016/j.scitotenv.2022.161050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/30/2022] [Accepted: 12/15/2022] [Indexed: 06/17/2023]
Abstract
Volatile pesticides are a growing environmental and public health concern. However, little attention has been paid to its olfactory neurotoxic effect on pests and non-target organisms. Dichlorvos is a widely used organophosphorus fumigant that is ubiquitous in the environment. This study aims to explore the mode of action of the volatile dichlorvos-mediated olfactory impairment using a lepidopteran insect Spodoptera litura as a model. It was indicated that electroantennogram amplitudes of the male moths' response to sex pheromones and phenylacetaldehyde were reduced by approximately 20 % after 12-h fumigation exposure. RNA-Sequencing analysis revealed that down-regulation of trypsin and CLIC2 might be responsible for inhibition of odor recognition in the antenna, the peripheral olfactory tissue. In the head, 822 (84.05 %) of the 978 differentially expressed genes (DEGs) were up-regulated, of which seven DEGs encoding transcription factors may mainly modulate the stress-regulatory networks. Combining transcriptome with brain calcium imaging and Annexin V-mCherry staining experiments showed that volatile dichlorvos mainly disrupts Ca2+ homeostasis and synaptic plasticity, induces apoptosis in the central nervous system, and further leads to olfactory dysfunction. Overall, this study highlighted a comprehensive work model for dichlorvos-induced olfactory impairment in S. litura and may provide insights into toxic effects of airborne organophosphates on non-target organisms.
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Affiliation(s)
- Shu-Shang Li
- School of Life Sciences, Chongqing University, Chongqing 400044, China
| | - Shou-Min Fang
- College of Life Science, China West Normal University, Nanchong 637002, Sichuan, China
| | - Jie Chen
- School of Life Sciences, Chongqing University, Chongqing 400044, China
| | - Ze Zhang
- School of Life Sciences, Chongqing University, Chongqing 400044, China
| | - Quan-You Yu
- School of Life Sciences, Chongqing University, Chongqing 400044, China.
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