1
|
Waris A, Ullah A, Asim M, Ullah R, Rajdoula MR, Bello ST, Alhumaydhi FA. Phytotherapeutic options for the treatment of epilepsy: pharmacology, targets, and mechanism of action. Front Pharmacol 2024; 15:1403232. [PMID: 38855752 PMCID: PMC11160429 DOI: 10.3389/fphar.2024.1403232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 05/09/2024] [Indexed: 06/11/2024] Open
Abstract
Epilepsy is one of the most common, severe, chronic, potentially life-shortening neurological disorders, characterized by a persisting predisposition to generate seizures. It affects more than 60 million individuals globally, which is one of the major burdens in seizure-related mortality, comorbidities, disabilities, and cost. Different treatment options have been used for the management of epilepsy. More than 30 drugs have been approved by the US FDA against epilepsy. However, one-quarter of epileptic individuals still show resistance to the current medications. About 90% of individuals in low and middle-income countries do not have access to the current medication. In these countries, plant extracts have been used to treat various diseases, including epilepsy. These medicinal plants have high therapeutic value and contain valuable phytochemicals with diverse biomedical applications. Epilepsy is a multifactorial disease, and therefore, multitarget approaches such as plant extracts or extracted phytochemicals are needed, which can target multiple pathways. Numerous plant extracts and phytochemicals have been shown to treat epilepsy in various animal models by targeting various receptors, enzymes, and metabolic pathways. These extracts and phytochemicals could be used for the treatment of epilepsy in humans in the future; however, further research is needed to study the exact mechanism of action, toxicity, and dosage to reduce their side effects. In this narrative review, we comprehensively summarized the extracts of various plant species and purified phytochemicals isolated from plants, their targets and mechanism of action, and dosage used in various animal models against epilepsy.
Collapse
Affiliation(s)
- Abdul Waris
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR, China
| | - Ata Ullah
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR, China
| | - Muhammad Asim
- Department of Neurosciences, City University of Hong Kong, Kowloon, Hong Kong SAR, China
- Centre for Regenerative Medicine and Health (CRMH), Hong Kong, Hong Kong SAR, China
| | - Rafi Ullah
- Department of Botany, Bacha Khan University Charsadda, Charsadda, Pakistan
| | - Md. Rafe Rajdoula
- Department of Neurosciences, City University of Hong Kong, Kowloon, Hong Kong SAR, China
| | - Stephen Temitayo Bello
- Department of Neurosciences, City University of Hong Kong, Kowloon, Hong Kong SAR, China
- Centre for Regenerative Medicine and Health (CRMH), Hong Kong, Hong Kong SAR, China
| | - Fahad A. Alhumaydhi
- Department of Medical Laboratories, College of Applied Medical Sciences, Qassim University, Buraydah, Saudi Arabia
| |
Collapse
|
2
|
Vasu SO, Kaphzan H. Direct Current Stimulation Modulates Synaptic Facilitation via Distinct Presynaptic Calcium Channels. Int J Mol Sci 2023; 24:16866. [PMID: 38069188 PMCID: PMC10706473 DOI: 10.3390/ijms242316866] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 11/23/2023] [Accepted: 11/23/2023] [Indexed: 12/18/2023] Open
Abstract
Transcranial direct current stimulation (tDCS) is a subthreshold neurostimulation technique known for ameliorating neuropsychiatric conditions. The principal mechanism of tDCS is the differential polarization of subcellular neuronal compartments, particularly the axon terminals that are sensitive to external electrical fields. Yet, the underlying mechanism of tDCS is not fully clear. Here, we hypothesized that direct current stimulation (DCS)-induced modulation of presynaptic calcium channel conductance alters axon terminal dynamics with regard to synaptic vesicle release. To examine the involvement of calcium-channel subtypes in tDCS, we recorded spontaneous excitatory postsynaptic currents (sEPSCs) from cortical layer-V pyramidal neurons under DCS while selectively inhibiting distinct subtypes of voltage-dependent calcium channels. Blocking P/Q or N-type calcium channels occluded the effects of DCS on sEPSCs, demonstrating their critical role in the process of DCS-induced modulation of spontaneous vesicle release. However, inhibiting T-type calcium channels did not occlude DCS-induced modulation of sEPSCs, suggesting that despite being active in the subthreshold range, T-type calcium channels are not involved in the axonal effects of DCS. DCS modulates synaptic facilitation by regulating calcium channels in axon terminals, primarily via controlling P/Q and N-type calcium channels, while T-type calcium channels are not involved in this mechanism.
Collapse
Affiliation(s)
| | - Hanoch Kaphzan
- Sagol Department of Neurobiology, University of Haifa, Haifa 3103301, Israel
| |
Collapse
|
3
|
Wang X, Sela-Donenfeld D, Wang Y. Axonal and presynaptic FMRP: Localization, signal, and functional implications. Hear Res 2023; 430:108720. [PMID: 36809742 PMCID: PMC9998378 DOI: 10.1016/j.heares.2023.108720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 01/22/2023] [Accepted: 02/09/2023] [Indexed: 02/12/2023]
Abstract
Fragile X mental retardation protein (FMRP) binds a selected set of mRNAs and proteins to guide neural circuit assembly and regulate synaptic plasticity. Loss of FMRP is responsible for Fragile X syndrome, a neuropsychiatric disorder characterized with auditory processing problems and social difficulty. FMRP actions in synaptic formation, maturation, and plasticity are site-specific among the four compartments of a synapse: presynaptic and postsynaptic neurons, astrocytes, and extracellular matrix. This review summarizes advancements in understanding FMRP localization, signals, and functional roles in axons and presynaptic terminals.
Collapse
Affiliation(s)
- Xiaoyu Wang
- Division of Histology & Embryology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Medical College, Jinan University, Guangzhou 510632, China
| | - Dalit Sela-Donenfeld
- Koret School of Veterinary Medicine, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | - Yuan Wang
- Department of Biomedical Sciences, Program in Neuroscience, Florida State University College of Medicine, Tallahassee, FL 32306, USA.
| |
Collapse
|
4
|
Heuser JE. The Structural Basis of Long-Term Potentiation in Hippocampal Synapses, Revealed by Electron Microscopy Imaging of Lanthanum-Induced Synaptic Vesicle Recycling. Front Cell Neurosci 2022; 16:920360. [PMID: 35978856 PMCID: PMC9376242 DOI: 10.3389/fncel.2022.920360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 05/05/2022] [Indexed: 11/29/2022] Open
Abstract
Hippocampal neurons in dissociated cell cultures were exposed to the trivalent cation lanthanum for short periods (15–30 min) and prepared for electron microscopy (EM), to evaluate the stimulatory effects of this cation on synaptic ultrastructure. Not only were characteristic ultrastructural changes of exaggerated synaptic vesicle turnover seen within the presynapses of these cultures—including synaptic vesicle depletion and proliferation of vesicle-recycling structures—but the overall architecture of a large proportion of the synapses in the cultures was dramatically altered, due to large postsynaptic “bulges” or herniations into the presynapses. Moreover, in most cases, these postsynaptic herniations or protrusions produced by lanthanum were seen by EM to distort or break or “perforate” the so-called postsynaptic densities (PSDs) that harbor receptors and recognition molecules essential for synaptic function. These dramatic EM observations lead us to postulate that such PSD breakages or “perforations” could very possibly create essential substrates or “tags” for synaptic growth, simply by creating fragmented free edges around the PSDs, into which new receptors and recognition molecules could be recruited more easily, and thus, they could represent the physical substrate for the important synaptic growth process known as “long-term potentiation” (LTP). All of this was created simply in hippocampal dissociated cell cultures, and simply by pushing synaptic vesicle recycling way beyond its normal limits with the trivalent cation lanthanum, but we argued in this report that such fundamental changes in synaptic architecture—given that they can occur at all—could also occur at the extremes of normal neuronal activity, which are presumed to lead to learning and memory.
Collapse
|
5
|
Bogacheva PO, Molchanova AI, Pravdivceva ES, Miteva AS, Balezina OP, Gaydukov AE. ProBDNF and Brain-Derived Neurotrophic Factor Prodomain Differently Modulate Acetylcholine Release in Regenerating and Mature Mouse Motor Synapses. Front Cell Neurosci 2022; 16:866802. [PMID: 35591942 PMCID: PMC9110780 DOI: 10.3389/fncel.2022.866802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/18/2022] [Indexed: 11/30/2022] Open
Abstract
The effects of brain-derived neurotrophic factor (BDNF) processing by-products (proBDNF and BDNF prodomain) on the activity of mouse neuromuscular junctions (NMJs) were studied in synapses formed during the reinnervation of extensor digitorum longus muscle (m. EDL) and mature synapses of the diaphragm. The parameters of spontaneous miniature endplate potentials (MEPPs) and evoked endplate potentials (EPPs) were analyzed in presence of each of the BDNF maturation products (both – 1 nM). In newly formed NMJs, proBDNF caused an increase in the resting membrane potential of muscle fibers and a decrease in the frequency of MEPPs, which was prevented by tertiapin-Q, a G-protein-coupled inwardly rectifying potassium channels (GIRK) blocker but not by p75 receptor signaling inhibitor TAT-Pep5. proBDNF had no effect on the parameters of EPPs. BDNF prodomain in newly formed synapses had effects different from those of proBDNF: it increased the amplitude of MEPPs, which was prevented by vesamicol, an inhibitor of vesicular acetylcholine (ACh) transporter; and reduced the quantal content of EPPs. In mature NMJs, proBDNF did not influence MEPPs parameters, but BDNF prodomain suppressed both spontaneous and evoked ACh release: decreased the frequency and amplitude of MEPPs, and the amplitude and quantal content of EPPs. This effect of the BDNF prodomain was prevented by blocking GIRK channels, by TAT-Pep5 or by Rho-associated protein kinase (ROCK) inhibitor Y-27632. At the same time, the BDNF prodomain did not show any inhibitory effects in diaphragm motor synapses of pannexin 1 knockout mice, which have impaired purinergic regulation of neuromuscular transmission. The data obtained suggest that there is a previously unknown mechanism for the acute suppression of spontaneous and evoked ACh release in mature motor synapses, which involves the activation of p75 receptors, ROCK and GIRK channels by BDNF prodomain and requires interaction with metabotropic purinoreceptors. In general, our results show that both the precursor of BDNF and the product of its maturation have predominantly inhibitory effects on spontaneous and evoked ACh release in newly formed or functionally mature neuromuscular junctions, which are mainly opposite to the effects of BDNF. The inhibitory influences of both proteins related to brain neurotrophin are mediated via GIRK channels of mouse NMJs.
Collapse
|
6
|
The role of axonal voltage-gated potassium channels in tDCS. Brain Stimul 2022; 15:861-869. [DOI: 10.1016/j.brs.2022.05.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 05/17/2022] [Accepted: 05/26/2022] [Indexed: 11/17/2022] Open
|
7
|
Li M, Danyeli LV, Colic L, Wagner G, Smesny S, Chand T, Di X, Biswal BB, Kaufmann J, Reichenbach JR, Speck O, Walter M, Sen ZD. The differential association between local neurotransmitter levels and whole-brain resting-state functional connectivity in two distinct cingulate cortex subregions. Hum Brain Mapp 2022; 43:2833-2844. [PMID: 35234321 PMCID: PMC9120566 DOI: 10.1002/hbm.25819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 12/21/2021] [Accepted: 02/10/2022] [Indexed: 11/16/2022] Open
Affiliation(s)
- Meng Li
- Department of Psychiatry and Psychotherapy, Jena University Hospital, Jena, Germany.,Center for Intervention and Research on Adaptive and Maladaptive Brain Circuits Underlying Mental Health, DZP, Germany.,Clinical Affective Neuroimaging Laboratory (CANLAB), Magdeburg, Germany
| | - Lena Vera Danyeli
- Department of Psychiatry and Psychotherapy, Jena University Hospital, Jena, Germany.,Clinical Affective Neuroimaging Laboratory (CANLAB), Magdeburg, Germany.,Department of Psychiatry and Psychotherapy, University Tübingen, Tübingen, Germany
| | - Lejla Colic
- Department of Psychiatry and Psychotherapy, Jena University Hospital, Jena, Germany.,Center for Intervention and Research on Adaptive and Maladaptive Brain Circuits Underlying Mental Health, DZP, Germany.,Clinical Affective Neuroimaging Laboratory (CANLAB), Magdeburg, Germany
| | - Gerd Wagner
- Department of Psychiatry and Psychotherapy, Jena University Hospital, Jena, Germany.,Center for Intervention and Research on Adaptive and Maladaptive Brain Circuits Underlying Mental Health, DZP, Germany
| | - Stefan Smesny
- Department of Psychiatry and Psychotherapy, Jena University Hospital, Jena, Germany
| | - Tara Chand
- Department of Psychiatry and Psychotherapy, Jena University Hospital, Jena, Germany.,Clinical Affective Neuroimaging Laboratory (CANLAB), Magdeburg, Germany.,Department of Psychiatry and Psychotherapy, University Tübingen, Tübingen, Germany.,Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Xin Di
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, New Jersey, USA
| | - Bharat B Biswal
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, New Jersey, USA
| | - Jörn Kaufmann
- Department of Neurology, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Jürgen R Reichenbach
- Center for Intervention and Research on Adaptive and Maladaptive Brain Circuits Underlying Mental Health, DZP, Germany.,Medical Physics Group, Department of Diagnostic and Interventional Radiology, Jena University Hospital, Jena, Germany.,Michael Stifel Center Jena for Data-Driven & Simulation Science (MSCJ), Jena, Germany.,Center of Medical Optics and Photonics (CeMOP), Jena, Germany
| | - Oliver Speck
- Center for Intervention and Research on Adaptive and Maladaptive Brain Circuits Underlying Mental Health, DZP, Germany.,Department of Biomedical Magnetic Resonance, Otto von Guericke University, Magdeburg, Germany.,Center for Behavioral Brain Sciences, Magdeburg, Germany.,German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany.,Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Martin Walter
- Department of Psychiatry and Psychotherapy, Jena University Hospital, Jena, Germany.,Center for Intervention and Research on Adaptive and Maladaptive Brain Circuits Underlying Mental Health, DZP, Germany.,Clinical Affective Neuroimaging Laboratory (CANLAB), Magdeburg, Germany.,Department of Psychiatry and Psychotherapy, University Tübingen, Tübingen, Germany.,Max Planck Institute for Biological Cybernetics, Tübingen, Germany.,Center for Behavioral Brain Sciences, Magdeburg, Germany
| | - Zümrüt Duygu Sen
- Department of Psychiatry and Psychotherapy, Jena University Hospital, Jena, Germany.,Center for Intervention and Research on Adaptive and Maladaptive Brain Circuits Underlying Mental Health, DZP, Germany.,Clinical Affective Neuroimaging Laboratory (CANLAB), Magdeburg, Germany.,Department of Psychiatry and Psychotherapy, University Tübingen, Tübingen, Germany
| |
Collapse
|
8
|
Khairullin AE, Valiullin VV, Teplov AY, Shaihutdinova AR, Kashtanova NM, Grishin SN. The Effect of Cesium Ions on the Inhibitory Action of Purines in the Neuromuscular Synapse. Biophysics (Nagoya-shi) 2021. [DOI: 10.1134/s0006350921060051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
|
9
|
Acetaldehyde Excitation of Lateral Habenular Neurons via Multiple Cellular Mechanisms. J Neurosci 2021; 41:7532-7545. [PMID: 34326141 DOI: 10.1523/jneurosci.2913-20.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 06/26/2021] [Accepted: 07/25/2021] [Indexed: 11/21/2022] Open
Abstract
Acetaldehyde (ACD), the first metabolite of ethanol, is implicated in several of ethanol's actions, including the reinforcing and aversive effects. The neuronal mechanisms underlying ACD's aversive effect, however, are poorly understood. The lateral habenula (LHb), a regulator of midbrain monoaminergic centers, is activated by negative valence events. Although the LHb has been linked to the aversive responses of several abused drugs, including ethanol, little is known about ACD. We, therefore, assessed ACD's action on LHb neurons in rats. The results showed that intraperitoneal injection of ACD increased cFos protein expression within the LHb and that intra-LHb infusion of ACD induced conditioned place aversion in male rats. Furthermore, electrophysiological recording in brain slices of male and female rats showed that bath application of ACD facilitated spontaneous firing and glutamatergic transmission. This effect of ACD was potentiated by an aldehyde dehydrogenase (ALDH) inhibitor, disulfiram (DS), but attenuated by the antagonists of dopamine (DA) receptor (DAR) subtype 1 (SCH23390) and subtype 2 (raclopride), and partly abolished by the pretreatment of DA or DA reuptake blocker (GBR12935; GBR). Moreover, application of ACD initiated a depolarizing inward current (I ACD) and enhanced the hyperpolarizing-activated currents in LHb neurons. Bath application of Rp-cAMPs, a selective cAMP-PKA inhibitor, attenuated ACD-induced potentiation of EPSCs and I ACD Finally, bath application of ZD7288, a selective blocker of hyperpolarization-activated cyclic nucleotide-gated channels, attenuated ACD-induced potentiation of firing, EPSCs, and I ACD These results show that ACD exerts its aversive property by exciting LHb neurons via multiple cellular mechanisms, and new treatments targeting the LHb may be beneficial for alcoholism.SIGNIFICANCE STATEMENT Acetaldehyde (ACD) has been considered aversive peripherally and rewarding centrally. However, whether ACD has a central aversive property is unclear. Here, we report that ACD excites the lateral habenula (LHb), a brain region associated with aversion and negative valence, through multiple cellular and molecular mechanisms. Intra-LHb ACD produces significant conditioned place aversion. These results suggest that ACD's actions on the LHb neurons might contribute to its central aversive property and new treatments targeting the LHb may be beneficial for alcoholism.
Collapse
|
10
|
Zhang Y, Garcia E, Sack AS, Snutch TP. L-type calcium channel contributions to intrinsic excitability and synaptic activity during basolateral amygdala postnatal development. J Neurophysiol 2020; 123:1216-1235. [PMID: 31967931 DOI: 10.1152/jn.00606.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The amygdala contributes toward emotional processes such as fear, anxiety, and social cognition. Furthermore, evidence suggests that increased excitability of basolateral amygdala (BLA) principal neurons underlie certain neuropsychiatric disorders. Gain-of-function mutations in neuronal L-type calcium channels (LTCCs) are linked to neurodevelopmental diseases, including autism spectrum disorders (ASDs). While LTCCs are expressed throughout the BLA, direct evidence for increased LTCC activity affecting BLA excitability and potentially contributing to disease pathophysiology is lacking. In this study, we utilized a pharmacological approach to examine the contributions of LTCCs to BLA principal cell excitability and synaptic activity at immature (postnatal day 7, P7) and juvenile (P21) developmental stages. Acute upregulation of LTCC activity in brain slices by application of the agonist (S)-Bay K 8644 resulted in increased intrinsic excitability properties including firing frequency response, plateau potential, and spike-frequency adaptation selectively in P7 neurons. Contrastingly, for P21 neurons, the main effect of (S)-Bay K 8644 was to enhance burst firing. (S)-Bay K 8644 increased spontaneous inhibitory synaptic currents at both P7 and P21 but did not affect evoked synaptic currents at either stage. (S)-Bay K 8644 did not alter P7 spontaneous excitatory synaptic currents, although it increased current amplitude in P21 neurons. Overall, the results provide support for the notion that alteration of LTCC activity at specific periods of early brain development may lead to functional alterations to neuronal network activity and subsequently contribute to underlying mechanisms of amygdala-related neurological disorders.NEW & NOTEWORTHY The role of L-type calcium channels (LTCCs) in regulating neuronal electrophysiological properties during development remains unclear. We show that in basolateral amygdala principal neurons, an increase of LTCC activity alters both neuronal excitability and synaptic activity. The results also provide evidence for the distinct contributions of LTCCs at different stages of neurodevelopment and shed insight into our understanding of LTCC dysfunction in amygdala-related neurological disorders.
Collapse
Affiliation(s)
- Yiming Zhang
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Esperanza Garcia
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Anne-Sophie Sack
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Terrance P Snutch
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| |
Collapse
|
11
|
Sasaoka M, Ota T, Kageyama M. Rotenone-induced inner retinal degeneration via presynaptic activation of voltage-dependent sodium and L-type calcium channels in rats. Sci Rep 2020; 10:969. [PMID: 31969611 PMCID: PMC6976703 DOI: 10.1038/s41598-020-57638-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 12/31/2019] [Indexed: 01/11/2023] Open
Abstract
Rotenone, a mitochondrial complex I inhibitor, causes retinal degeneration via unknown mechanisms. To elucidate the molecular mechanisms of its action, we further characterized a rat model of rotenone-induced retinal degeneration. Intravitreal injection of rotenone (2 nmol/eye) damaged mainly the inner retinal layers, including cell loss in the ganglion cell and inner nuclear layers, which were very similar to those induced by 10 nmol/eye N-methyl-D-aspartate (NMDA). These morphological changes were accompanied by the reduced b-wave amplitude of electroretinogram, and increased immunostaining of 2,4-dinitrophenyl, an oxidative stress marker. Rotenone also downregulated expression of neurofilament light-chain gene (Nfl) as a retinal ganglion cell (RGC) marker. This effect was prevented by simultaneous injection of rotenone with antioxidants or NMDA receptor antagonists. More importantly, voltage-dependent sodium and L-type calcium channel blockers and intracellular calcium signaling modulators remarkably suppressed rotenone-induced Nfl downregulation, whereas none of these agents modified NMDA-induced Nfl downregulation. These results suggest that rotenone-induced inner retinal degeneration stems from indirect postsynaptic NMDA stimulation that is triggered by oxidative stress-mediated presynaptic intracellular calcium signaling via activation of voltage-dependent sodium and L-type calcium channels.
Collapse
Affiliation(s)
- Masaaki Sasaoka
- Global Alliances and External Research, Santen Pharmaceutical Co., Ltd., Ikoma-shi, Nara, 630-0101, Japan
| | - Takashi Ota
- Global Alliances and External Research, Santen Pharmaceutical Co., Ltd., Ikoma-shi, Nara, 630-0101, Japan
| | - Masaaki Kageyama
- Global Alliances and External Research, Santen Pharmaceutical Co., Ltd., Ikoma-shi, Nara, 630-0101, Japan.
| |
Collapse
|
12
|
Isoflurane Inhibits Dopaminergic Synaptic Vesicle Exocytosis Coupled to Ca V2.1 and Ca V2.2 in Rat Midbrain Neurons. eNeuro 2019; 6:eN-NWR-0278-18. [PMID: 30680310 PMCID: PMC6345200 DOI: 10.1523/eneuro.0278-18.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 12/18/2018] [Accepted: 12/21/2018] [Indexed: 11/21/2022] Open
Abstract
Volatile anesthetics affect neuronal signaling by poorly understood mechanisms. Activation of central dopaminergic pathways has been implicated in emergence from general anesthesia. The volatile anesthetic isoflurane differentially inhibits glutamatergic and GABAergic synaptic vesicle (SV) exocytosis by reducing presynaptic Ca2+ influx without affecting the Ca2+-exocytosis relationship, but its effects on dopaminergic exocytosis are unclear. We tested the hypothesis that isoflurane inhibits exocytosis in dopaminergic neurons. We used electrical stimulation or depolarization by elevated extracellular KCl to evoke exocytosis measured by quantitative live-cell fluorescence imaging in cultured rat ventral tegmental area neurons. Using trains of electrically evoked action potentials (APs), isoflurane inhibited exocytosis in dopaminergic neurons to a greater extent (30 ± 4% inhibition; p < 0.0001) than in non-dopaminergic neurons (15 ± 5% inhibition; p = 0.014). Isoflurane also inhibited exocytosis evoked by elevated KCl in dopaminergic neurons (35 ± 6% inhibition; p = 0.0007), but not in non-dopaminergic neurons (2 ± 4% inhibition). Pharmacological isolation of presynaptic Ca2+ channel subtypes showed that isoflurane inhibited KCl-evoked exocytosis mediated exclusively by either CaV2.1 (P/Q-type Ca2+ channels; 30 ± 5% inhibition; p = 0.0002) or by CaV2.2 (N-type Ca2+ channels; 35 ± 11% inhibition; p = 0.015). Additionally, isoflurane inhibited single AP-evoked Ca2+ influx by 41 ± 3% and single AP-evoked exocytosis by 34 ± 6%. Comparable reductions in exocytosis and Ca2+ influx were produced by lowering extracellular [Ca2+]. Thus, isoflurane inhibits exocytosis from dopaminergic neurons by a mechanism distinct from that in non-dopaminergic neurons involving reduced Ca2+ entry through CaV2.1 and/or CaV2.2.
Collapse
|
13
|
Neurobiology and therapeutic applications of neurotoxins targeting transmitter release. Pharmacol Ther 2019; 193:135-155. [DOI: 10.1016/j.pharmthera.2018.08.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
|
14
|
Sánchez-Zavaleta R, Cortés H, Avalos-Fuentes JA, García U, Segovia Vila J, Erlij D, Florán B. Presynaptic cannabinoid CB2 receptors modulate [ 3 H]-Glutamate release at subthalamo-nigral terminals of the rat. Synapse 2018; 72:e22061. [PMID: 30022523 DOI: 10.1002/syn.22061] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 07/12/2018] [Accepted: 07/13/2018] [Indexed: 11/08/2022]
Abstract
Recent studies suggested the expression of CB2 receptors in neurons of the CNS, however, most of these studies have only explored one aspect of the receptors, i.e., expression of protein, messenger RNA, or functional response, and more complete studies appear to be needed to establish adequately their role in the neuronal function. Electron microscopy studies showed the presence of CB2r in asymmetric terminals of the substantia nigra pars reticulata (SNr), and its mRNA appeared is expressed in the subthalamic nucleus. Here, we explore the expression, source, and functional effects of such receptors by different experimental approaches. Through PCR and immunochemistry, we showed mRNA and protein for CB2rs in slices and primary neuronal cultures from subthalamus. GW833972A, GW405833, and JHW 133, three CB2r agonists dose-dependent inhibited K+ -induced [3 H]-Glutamate release in slices of SNr, and the two antagonist/inverse agonists, JTE-907 and AM630, but not AM281, a CB1r antagonist, prevented GW833972A effect. Subthalamus lesions with kainic acid prevented GW833972A inhibition on release and decreased CB2r protein in nigral synaptosomes, thus nigral CB2rs originate in subthalamus. Inhibition of [3 H]-Glutamate release was PTX- and gallein-sensitive, suggesting a Giβγ -mediated effect. P/Q Ca2+ -type channel blocker, ω-Agatoxin-TK, also inhibited the [3 H]-Glutamate release, this effect was occluded with GW833972A inhibition, indicating that the βγ subunit effect is exerted on Ca2+ channel activity. Finally, microinjections of GW833972A in SNr induced contralateral turning. Our data showed that presynaptic CB2rs inhibit [3 H]-Glutamate release in subthalamo-nigral terminals by P/Q-channels modulation through the Giβγ subunit and suggested their participation in motor behavior.
Collapse
Affiliation(s)
- Rodolfo Sánchez-Zavaleta
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - Hernán Cortés
- Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra, Ciudad de México, México
| | - José Arturo Avalos-Fuentes
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - Ubaldo García
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - José Segovia Vila
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - David Erlij
- Department of Physiology, SUNY Downstate Medical Center, Brooklyn, New York
| | - Benjamín Florán
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| |
Collapse
|
15
|
Mumtaz F, Khan MI, Zubair M, Dehpour AR. Neurobiology and consequences of social isolation stress in animal model-A comprehensive review. Biomed Pharmacother 2018; 105:1205-1222. [PMID: 30021357 DOI: 10.1016/j.biopha.2018.05.086] [Citation(s) in RCA: 200] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 05/10/2018] [Accepted: 05/18/2018] [Indexed: 12/09/2022] Open
Abstract
The brain is a vital organ, susceptible to alterations under genetic influences and environmental experiences. Social isolation (SI) acts as a stressor which results in alterations in reactivity to stress, social behavior, function of neurochemical and neuroendocrine system, physiological, anatomical and behavioral changes in both animal and humans. During early stages of life, acute or chronic SIS has been proposed to show signs and symptoms of psychiatric and neurological disorders such as anxiety, depression, schizophrenia, epilepsy and memory loss. Exposure to social isolation stress induces a variety of endocrinological changes including the activation of hypothalamic-pituitary-adrenal (HPA) axis, culminating in the release of glucocorticoids (GCs), release of catecholamines, activation of the sympatho-adrenomedullary system, release of Oxytocin and vasopressin. In several regions of the central nervous system (CNS), SIS alters the level of neurotransmitter such as dopamine, serotonin, gamma aminobutyric acid (GABA), glutamate, nitrergic system and adrenaline as well as leads to alteration in receptor sensitivity of N-methyl-D-aspartate (NMDA) and opioid system. A change in the function of oxidative and nitrosative stress (O&NS) mediated mitochondrial dysfunction, inflammatory factors, neurotrophins and neurotrophicfactors (NTFs), early growth response transcription factor genes (Egr) and C-Fos expression are also involved as a pathophysiological consequences of SIS which induce neurological and psychiatric disorders.
Collapse
Affiliation(s)
- Faiza Mumtaz
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Muhammad Imran Khan
- Department of Pharmacy, Kohat University of Science and Technology, 26000 Kohat, KPK, Pakistan; Drug Detoxification Health Welfare Research Center, Bannu, KPK, Pakistan
| | - Muhammad Zubair
- Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agriculture University, Nanjing, 210095, PR China
| | - Ahmad Reza Dehpour
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran.
| |
Collapse
|
16
|
Jijón-Lorenzo R, Caballero-Florán IH, Recillas-Morales S, Cortés H, Avalos-Fuentes JA, Paz-Bermúdez FJ, Erlij D, Florán B. Presynaptic Dopamine D2 Receptors Modulate [ 3H]GABA Release at StriatoPallidal Terminals via Activation of PLC → IP3 → Calcineurin and Inhibition of AC → cAMP → PKA Signaling Cascades. Neuroscience 2017; 372:74-86. [PMID: 29292080 DOI: 10.1016/j.neuroscience.2017.12.041] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 12/14/2017] [Accepted: 12/23/2017] [Indexed: 01/11/2023]
Abstract
Striatal dopamine D2 receptors activate the PLC → IP3 → Calcineurin-signaling pathway to modulate the neural excitability of En+ Medium-sized Spiny GABAergic neurons (MSN) through the regulation of L-type Ca2+ channels. Presynaptic dopaminergic D2 receptors modulate GABA release at striatopallidal terminals through L-type Ca2+ channels as well, but their signaling pathway is still undetermined. Since D2 receptors are Gi/o-coupled and negatively modulate adenylyl cyclase (AC), we investigated whether presynaptic D2 receptors modulate GABA release through the same signaling cascade that controls excitability in the striatum or by the inhibition of AC and decreased PKA activity. Activation of D2 receptors stimulated formation of [3H]IP1 and decreased Forskolin-stimulated [3H]cAMP accumulation in synaptosomes from rat Globus Pallidus. D2 receptor activation with Quinpirole in the presence of L 745,870 decreased, in a dose-dependent manner, K+-induced [3H]GABA release in pallidal slices. The effect was prevented by the pharmacological blockade of Gi/o βγ subunit effects with Gallein, PLC with U 73122, IP3 receptor activation with 4-APB, Calcineurin with FK506. In addition, when release was stimulated with Forskolin to activate AC, D2 receptors also decreased K+-induced [3H]GABA release, an effect occluded with the effect of the blockade of PKA with H89 or stimulation of release with the cAMP analog 8-Br-cAMP. These data indicate that D2 receptors modulate [3H]GABA release at striatopallidal terminals by activating the PLC → IP3 → Calcineurin-signaling cascade, the same one that modulates excitability in soma. Additionally, D2 receptors inhibit release when AC is active. Both mechanisms appear to converge to regulate the activity of presynaptic L-type Ca2+ channels.
Collapse
Affiliation(s)
- Rafael Jijón-Lorenzo
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico
| | - Isaac Hiram Caballero-Florán
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico
| | | | - Hernán Cortés
- Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra, Ciudad de México, Mexico
| | - José Arturo Avalos-Fuentes
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico
| | - Francisco Javier Paz-Bermúdez
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico
| | - David Erlij
- Department of Physiology, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA
| | - Benjamín Florán
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico.
| |
Collapse
|
17
|
Macias-Medri AE, Liendo JA, Silva RJ. An electrostatic and probabilistic simulation model to describe neurosecretion at the synaptic scale. NETWORK (BRISTOL, ENGLAND) 2017; 28:53-73. [PMID: 29120672 DOI: 10.1080/0954898x.2017.1386806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A hybrid simulation model (macro-molecular dynamics and Monte Carlo method) is proposed to reproduce neurosecretion and exocytosis. A theory has been developed for vesicular dynamics based on quasi-static electric interactions and a simple transition-state model for the vesicular fusion. Under the non-equilibrium electric conditions in an electrolytic fluid, it is considered that the motion of each synaptic vesicle is influenced by electrostatic forces exerted by the membranes of the synaptic bouton, other vesicles, the intracellular and intravesicular fluids, and external elements to the neuron. In addition, friction between each vesicle and its surrounding intracellular fluid is included in the theory, resulting in a drift type movement. To validate the vesicle equations of motion, a molecular dynamics method has been implemented, where the synaptic pool was replaced by a straight angle parallelepiped, the vesicles were represented by spheres and the fusion between each vesicle and the presynaptic membrane was simulated by a Monte Carlo type probabilistic change of state. Density profiles showing clusters of preferential activity as well as fusion distributions similar to the Poisson distributions associated with miniature end-plate potentials were obtained in the simulations.
Collapse
Affiliation(s)
- A E Macias-Medri
- a Departamento de Física , Universidade Federal do Paraná , Curitiba , Brazil
| | - Jacinto A Liendo
- b Physics Department , Simón Bolívar University , Baruta , Venezuela
| | - Ricardo J Silva
- c Instituto Montenegro para la Investigación y Desarrollo de las Neurociencias Cognitivas , Unidad Médica I de la Clínica San Francisco , Guayaquil , Ecuador
| |
Collapse
|
18
|
Neurotransmitter Release Can Be Stabilized by a Mechanism That Prevents Voltage Changes Near the End of Action Potentials from Affecting Calcium Currents. J Neurosci 2017; 36:11559-11572. [PMID: 27911759 DOI: 10.1523/jneurosci.0066-16.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 08/29/2016] [Accepted: 09/14/2016] [Indexed: 11/21/2022] Open
Abstract
At chemical synapses, presynaptic action potentials (APs) activate voltage-gated calcium channels, allowing calcium to enter and trigger neurotransmitter release. The duration, peak amplitude, and shape of the AP falling phase alter calcium entry, which can affect neurotransmitter release significantly. In many neurons, APs do not immediately return to the resting potential, but instead exhibit a period of depolarization or hyperpolarization referred to as an afterpotential. We hypothesized that presynaptic afterpotentials should alter neurotransmitter release by affecting the electrical driving force for calcium entry and calcium channel gating. In support of this, presynaptic calcium entry is affected by afterpotentials after standard instant voltage jumps. Here, we used the mouse calyx of Held synapse, which allows simultaneous presynaptic and postsynaptic patch-clamp recording, to show that the postsynaptic response is affected significantly by presynaptic afterpotentials after voltage jumps. We therefore tested the effects of presynaptic afterpotentials using simultaneous presynaptic and postsynaptic recordings and AP waveforms or real APs. Surprisingly, presynaptic afterpotentials after AP stimuli did not alter calcium channel responses or neurotransmitter release appreciably. We show that the AP repolarization time course causes afterpotential-induced changes in calcium driving force and changes in calcium channel gating to effectively cancel each other out. This mechanism, in which electrical driving force is balanced by channel gating, prevents changes in calcium influx from occurring at the end of the AP and therefore acts to stabilize synaptic transmission. In addition, this mechanism can act to stabilize neurotransmitter release when the presynaptic resting potential changes. SIGNIFICANCE STATEMENT The shape of presynaptic action potentials (APs), particularly the falling phase, affects calcium entry and small changes in calcium influx can produce large changes in postsynaptic responses. We hypothesized that afterpotentials, which often follow APs, affect calcium entry and neurotransmitter release. We tested this in calyx of Held nerve terminals, which allow simultaneous recording of presynaptic calcium currents and postsynaptic responses. Surprisingly, presynaptic afterpotentials did not alter calcium current or neurotransmitter release. We show that the AP falling phase causes afterpotential-induced changes in electrical driving force and calcium channel gating to cancel each other out. This mechanism regulates calcium entry at the end of APs and therefore stabilizes synaptic transmission. This also stabilizes responses when the presynaptic resting potential changes.
Collapse
|
19
|
Yin H, Wang H, Zhang H, Gao N, Zhang T, Yang Z. Resveratrol Attenuates Aβ-Induced Early Hippocampal Neuron Excitability Impairment via Recovery of Function of Potassium Channels. Neurotox Res 2017; 32:311-324. [PMID: 28361268 DOI: 10.1007/s12640-017-9726-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 03/08/2017] [Accepted: 03/13/2017] [Indexed: 12/20/2022]
Abstract
Alzheimer's disease (AD) is an age-related neurodegenerative disease. Amyloid-β (Aβ) is not only the morphological hallmark but also the initiator of the pathology process of AD. As a natural compound found in grapes, resveratrol shows a protective effect on the pathophysiology of AD, but the underlying mechanism is not very clear. This study was to investigate whether resveratrol could attenuate Aβ-induced early impairment in hippocampal neuron excitability and the underlying mechanism. The excitability and voltage-gated potassium currents were examined in rat hippocampal CA1 pyramidal neurons by using whole-cell patch-clamp technique. It was found that Aβ25-35 increased the excitability of neurons. Resveratrol could reverse the Aβ25-35-induced increase in the frequency of repetitive firing and the spike half-width of action potential (AP). Moreover, resveratrol can attenuate Aβ25-35-induced decreases in transient potassium channel (I A ) and delay rectifier potassium channel (I K(DR)) of neurons. It was also found that resveratrol could decline the increase of protein kinase A (PKA) and inhibit the activation of PI3K/Akt signaling pathway induced by Aβ25-35. The results suggest that resveratrol alleviates Aβ25-35-induced dysfunction in hippocampal CA1 pyramidal neurons via recovery of the function of I A and I K(DR) by inhibiting the increase of PKA and the activation of PI3K/Akt signaling pathway.
Collapse
Affiliation(s)
- Hongqiang Yin
- School of Medicine, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, 300071, People's Republic of China
| | - Hui Wang
- College of Life Sciences and Key Laboratory of Bioactive Materials Ministry of Education, Nankai University, Tianjin, 300071, People's Republic of China
| | - Hui Zhang
- College of Life Sciences and Key Laboratory of Bioactive Materials Ministry of Education, Nankai University, Tianjin, 300071, People's Republic of China
| | - Na Gao
- School of Medicine, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, 300071, People's Republic of China.,Tianjin Medical University Cancer Institute and Hospital, Tianjin, 300200, People's Republic of China
| | - Tao Zhang
- College of Life Sciences and Key Laboratory of Bioactive Materials Ministry of Education, Nankai University, Tianjin, 300071, People's Republic of China
| | - Zhuo Yang
- School of Medicine, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, 300071, People's Republic of China.
| |
Collapse
|
20
|
The Molecular Basis of Toxins' Interactions with Intracellular Signaling via Discrete Portals. Toxins (Basel) 2017; 9:toxins9030107. [PMID: 28300784 PMCID: PMC5371862 DOI: 10.3390/toxins9030107] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 03/02/2017] [Accepted: 03/04/2017] [Indexed: 12/20/2022] Open
Abstract
An understanding of the molecular mechanisms by which microbial, plant or animal-secreted toxins exert their action provides the most important element for assessment of human health risks and opens new insights into therapies addressing a plethora of pathologies, ranging from neurological disorders to cancer, using toxinomimetic agents. Recently, molecular and cellular biology dissecting tools have provided a wealth of information on the action of these diverse toxins, yet, an integrated framework to explain their selective toxicity is still lacking. In this review, specific examples of different toxins are emphasized to illustrate the fundamental mechanisms of toxicity at different biochemical, molecular and cellular- levels with particular consideration for the nervous system. The target of primary action has been highlighted and operationally classified into 13 sub-categories. Selected examples of toxins were assigned to each target category, denominated as portal, and the modulation of the different portal’s signaling was featured. The first portal encompasses the plasma membrane lipid domains, which give rise to pores when challenged for example with pardaxin, a fish toxin, or is subject to degradation when enzymes of lipid metabolism such as phospholipases A2 (PLA2) or phospholipase C (PLC) act upon it. Several major portals consist of ion channels, pumps, transporters and ligand gated ionotropic receptors which many toxins act on, disturbing the intracellular ion homeostasis. Another group of portals consists of G-protein-coupled and tyrosine kinase receptors that, upon interaction with discrete toxins, alter second messengers towards pathological levels. Lastly, subcellular organelles such as mitochondria, nucleus, protein- and RNA-synthesis machineries, cytoskeletal networks and exocytic vesicles are also portals targeted and deregulated by other diverse group of toxins. A fundamental concept can be drawn from these seemingly different toxins with respect to the site of action and the secondary messengers and signaling cascades they trigger in the host. While the interaction with the initial portal is largely determined by the chemical nature of the toxin, once inside the cell, several ubiquitous second messengers and protein kinases/ phosphatases pathways are impaired, to attain toxicity. Therefore, toxins represent one of the most promising natural molecules for developing novel therapeutics that selectively target the major cellular portals involved in human physiology and diseases.
Collapse
|
21
|
Mukunda CL, Narayanan R. Degeneracy in the regulation of short-term plasticity and synaptic filtering by presynaptic mechanisms. J Physiol 2017; 595:2611-2637. [PMID: 28026868 DOI: 10.1113/jp273482] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 12/13/2016] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS We develop a new biophysically rooted, physiologically constrained conductance-based synaptic model to mechanistically account for short-term facilitation and depression, respectively through residual calcium and transmitter depletion kinetics. We address the specific question of how presynaptic components (including voltage-gated ion channels, pumps, buffers and release-handling mechanisms) and interactions among them define synaptic filtering and short-term plasticity profiles. Employing global sensitivity analyses (GSAs), we show that near-identical synaptic filters and short-term plasticity profiles could emerge from disparate presynaptic parametric combinations with weak pairwise correlations. Using virtual knockout models, a technique to address the question of channel-specific contributions within the GSA framework, we unveil the differential and variable impact of each ion channel on synaptic physiology. Our conclusions strengthen the argument that parametric and interactional complexity in biological systems should not be viewed from the limited curse-of-dimensionality standpoint, but from the evolutionarily advantageous perspective of providing functional robustness through degeneracy. ABSTRACT Information processing in neurons is known to emerge as a gestalt of pre- and post-synaptic filtering. However, the impact of presynaptic mechanisms on synaptic filters has not been quantitatively assessed. Here, we developed a biophysically rooted, conductance-based model synapse that was endowed with six different voltage-gated ion channels, calcium pumps, calcium buffer and neurotransmitter-replenishment mechanisms in the presynaptic terminal. We tuned our model to match the short-term plasticity profile and band-pass structure of Schaffer collateral synapses, and performed sensitivity analyses to demonstrate that presynaptic voltage-gated ion channels regulated synaptic filters through changes in excitability and associated calcium influx. These sensitivity analyses also revealed that calcium- and release-control mechanisms were effective regulators of synaptic filters, but accomplished this without changes in terminal excitability or calcium influx. Next, to perform global sensitivity analysis, we generated 7000 randomized models spanning 15 presynaptic parameters, and computed eight different physiological measurements in each of these models. We validated these models by applying experimentally obtained bounds on their measurements, and found 104 (∼1.5%) models to match the validation criteria for all eight measurements. Analysing these valid models, we demonstrate that analogous synaptic filters emerge from disparate combinations of presynaptic parameters exhibiting weak pairwise correlations. Finally, using virtual knockout models, we establish the variable and differential impact of different presynaptic channels on synaptic filters, underlining the critical importance of interactions among different presynaptic components in defining synaptic physiology. Our results have significant implications for protein-localization strategies required for physiological robustness and for degeneracy in long-term synaptic plasticity profiles.
Collapse
Affiliation(s)
- Chinmayee L Mukunda
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Rishikesh Narayanan
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| |
Collapse
|
22
|
KV1 and KV3 Potassium Channels Identified at Presynaptic Terminals of the Corticostriatal Synapses in Rat. Neural Plast 2016; 2016:8782518. [PMID: 27379187 PMCID: PMC4917754 DOI: 10.1155/2016/8782518] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 04/12/2016] [Accepted: 05/16/2016] [Indexed: 12/19/2022] Open
Abstract
In the last years it has been increasingly clear that KV-channel activity modulates neurotransmitter release. The subcellular localization and composition of potassium channels are crucial to understanding its influence on neurotransmitter release. To investigate the role of KV in corticostriatal synapses modulation, we combined extracellular recording of population-spike and pharmacological blockage with specific and nonspecific blockers to identify several families of KV channels. We induced paired-pulse facilitation (PPF) and studied the changes in paired-pulse ratio (PPR) before and after the addition of specific KV blockers to determine whether particular KV subtypes were located pre- or postsynaptically. Initially, the presence of KV channels was tested by exposing brain slices to tetraethylammonium or 4-aminopyridine; in both cases we observed a decrease in PPR that was dose dependent. Further experiments with tityustoxin, margatoxin, hongotoxin, agitoxin, dendrotoxin, and BDS-I toxins all rendered a reduction in PPR. In contrast heteropodatoxin and phrixotoxin had no effect. Our results reveal that corticostriatal presynaptic KV channels have a complex stoichiometry, including heterologous combinations KV1.1, KV1.2, KV1.3, and KV1.6 isoforms, as well as KV3.4, but not KV4 channels. The variety of KV channels offers a wide spectrum of possibilities to regulate neurotransmitter release, providing fine-tuning mechanisms to modulate synaptic strength.
Collapse
|
23
|
Aviner B, Gradwohl G, Bliznyuk A, Grossman Y. Selective pressure modulation of synaptic voltage-dependent calcium channels-involvement in HPNS mechanism. J Cell Mol Med 2016; 20:1872-88. [PMID: 27273194 PMCID: PMC5020619 DOI: 10.1111/jcmm.12877] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 03/21/2016] [Indexed: 11/28/2022] Open
Abstract
Exposure to hyperbaric pressure (HP) exceeding 100 msw (1.1 MPa) is known to cause a constellation of motor and cognitive impairments named high-pressure neurological syndrome (HPNS), considered to be the result of synaptic transmission alteration. Long periods of repetitive HP exposure could be an occupational risk for professional deep-sea divers. Previous studies have indicated the modulation of presynaptic Ca(2+) currents based on synaptic activity modified by HP. We have recently demonstrated that currents in genetically identified cellular voltage-dependent Ca(2+) channels (VDCCs), CaV 1.2 and CaV 3.2 are selectively affected by HP. This work further elucidates the HPNS mechanism by examining HP effect on Ca(2+) currents in neuronal VDCCs, CaV 2.2 and CaV 2.1, which are prevalent in presynaptic terminals, expressed in Xenopus oocytes. HP augmented the CaV 2.2 current amplitude, much less so in a channel variation containing an additional modulatory subunit, and had almost no effect on the CaV 2.1 currents. HP differentially affected the channels' kinetics. It is, therefore, suggested that HPNS signs and symptoms arise, at least in part, from pressure modulation of various VDCCs.
Collapse
Affiliation(s)
- Ben Aviner
- Department of Physiology and Neurobiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.
| | - Gideon Gradwohl
- Department of Physics, Jerusalem College of Technology, Jerusalem, Israel
| | - Alice Bliznyuk
- Department of Physiology and Neurobiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Yoram Grossman
- Department of Physiology and Neurobiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| |
Collapse
|
24
|
Ostadhadi S, Khan MI, Norouzi-Javidan A, Chamanara M, Jazaeri F, Zolfaghari S, Dehpour AR. Involvement of NMDA receptors and L-arginine/nitric oxide/cyclic guanosine monophosphate pathway in the antidepressant-like effects of topiramate in mice forced swimming test. Brain Res Bull 2016; 122:62-70. [PMID: 26988103 DOI: 10.1016/j.brainresbull.2016.03.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 03/06/2016] [Accepted: 03/11/2016] [Indexed: 11/26/2022]
Abstract
Topiramate (TPM) is an agent primarily used in the treatment of epilepsy. Using mice model of forced swimming test (FST) the current study was basically aimed to investigate the influence of TPM on depression by inhibiting NMDA receptor and nitric oxide-cGMP production. When TPM was administered in a dose of 20 and 30 mg/kg by i.p. route it reduced the immobility time during FST. However this effect of TPM (30 mg/kg, i.p.) in the FST was abolished when the mice were pretreated either with NMDA (75 mg/kg, i.p.), or l-arginine (750 mg/kg, i.p. NO precursor), or sildenafil (5mg/kg, i.p. Phosphodiesterase 5 inhibitor). The immobility time in the FST was reduced after administration of L-NAME (10mg/kg, i.p, a non-specific NOS inhibitor), 7-nitoinidazol (30 mg/kg, i.p. a nNOS inhibitor) or MK-801 (0.05 mg/kg, i.p, a NMDA receptor antagonist) in combination with a subeffective dose of TPM (10mg/kg, i.p.) as compared with single use of either drug. Co-administrated of lower doses of MK-801 (0.01 mg/kg) or L-NAME (1mg/kg) failed to effect immobility time. However, simultaneous administration of these two agents in the same doses with subeffective dose of TPM (10mg/kg, i.p.), reduced the immobility time during FST. None of these drugs were found to have a profound effect on the locomotor activity per se during the open field test. Taken together, our data demonstrates that TPM exhibit antidepressant-like effect which is accomplished either due to inhibition of NMDA receptors or NO-cGMP production.
Collapse
Affiliation(s)
- Sattar Ostadhadi
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Brain and Spinal Cord Injury Research Center, Neuroscience Institute Tehran University of Medical Sciences, Tehran, Iran
| | - Muhammad Imran Khan
- Department of Pharmacology, School of Medicine, International Campus, Tehran University of Medical Sciences, Tehran, Iran
| | - Abbas Norouzi-Javidan
- Brain and Spinal Cord Injury Research Center, Neuroscience Institute Tehran University of Medical Sciences, Tehran, Iran
| | - Mohsen Chamanara
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Farahnaz Jazaeri
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Samira Zolfaghari
- Department of Tissue Engineering and Applied Cell Sciences Iran University of Medical Sciences, Tehran, Iran
| | - Ahmad-Reza Dehpour
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Brain and Spinal Cord Injury Research Center, Neuroscience Institute Tehran University of Medical Sciences, Tehran, Iran; Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran.
| |
Collapse
|
25
|
Pennock RL, Hentges ST. Desensitization-resistant and -sensitive GPCR-mediated inhibition of GABA release occurs by Ca2+-dependent and -independent mechanisms at a hypothalamic synapse. J Neurophysiol 2016; 115:2376-88. [PMID: 26912590 DOI: 10.1152/jn.00535.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 02/19/2016] [Indexed: 11/22/2022] Open
Abstract
Whereas the activation of Gαi/o-coupled receptors commonly results in postsynaptic responses that show acute desensitization, the presynaptic inhibition of transmitter release caused by many Gαi/o-coupled receptors is maintained during agonist exposure. However, an exception has been noted where GABAB receptor (GABABR)-mediated inhibition of inhibitory postsynaptic currents (IPSCs) recorded in mouse proopiomelanocortin (POMC) neurons exhibit acute desensitization in ∼25% of experiments. To determine whether differential effector coupling confers sensitivity to desensitization, voltage-clamp recordings were made from POMC neurons to compare the mechanism by which μ-opioid receptors (MORs) and GABABRs inhibit transmitter release. Neither MOR- nor GABABR-mediated inhibition of release relied on the activation of presynaptic K(+) channels. Both receptors maintained the ability to inhibit release in the absence of external Ca(2+) or in the presence of ionomycin-induced Ca(2+) influx, indicating that inhibition of release can occur through a Ca(2+)-independent mechanism. Replacing Ca(2+) with Sr(2+) to disrupt G-protein-mediated inhibition of release occurring directly at the release machinery did not alter MOR- or GABAB -mediated inhibition of IPSCs, suggesting that reductions in evoked release can occur through the inhibition of Ca(2+) channels. Additionally, both receptors inhibited evoked IPSCs in the presence of selective blockers of N- or P/Q-type Ca(2+) channels. Altogether, the results show that MORs and GABABRs can inhibit transmitter release through the inhibition of calcium influx and by direct actions at the release machinery. Furthermore, since both the desensitizing and nondesensitizing presynaptic receptors are similarly coupled, differential effector coupling is unlikely responsible for differential desensitization of the inhibition of release.
Collapse
Affiliation(s)
- Reagan L Pennock
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Shane T Hentges
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| |
Collapse
|
26
|
Jankowska M, Pawlowska-Mainville A, Stankiewicz M, Rogalska J, Wyszkowska J. Exposure to 50 Hz electromagnetic field changes the efficiency of the scorpion alpha toxin. J Venom Anim Toxins Incl Trop Dis 2015; 21:38. [PMID: 26430395 PMCID: PMC4589959 DOI: 10.1186/s40409-015-0040-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 09/24/2015] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Extremely low-frequency (50 Hz) electromagnetic field (ELF-EMF) is produced by electric power transmission lines and electronic devices of everyday use. Some phenomena are proposed as "first effects" of ELF-EMF: the discrete changes in the membrane potential and the increase of the calcium channel activity as well as the intracellular concentration of Ca(2+). Interaction of the scorpion alpha toxin with the sodium channel depends on the orientation of the charges and may be perturbed by changes in the membrane polarization. The toxin induces overexcitability in the nervous system and an increase in the neurotransmitters released with different consequences, mainly the paralysis of muscles. We assumed that the exposure to ELF-EMF 0.7 mT will change the effects of the insect selective scorpion alpha toxin (recombinant LqhαIT from Leiurus quinquestriatus hebraeus) at the level of the cercal nerve function, the synaptic transmission and on the level of entire insect organism. Taking into account the compensatory mechanisms in organisms, we tested in addition ten times higher ELF-EMF on whole insects. METHODS Experiments were performed in vivo on cockroaches (Periplaneta americana) and in vitro - on isolated cockroach abdominal nerve cord with cerci. In biotests, the effects of LqhαIT (10(-8) M) were estimated on the basis of the insect ability to turn back from dorsal to ventral side. Three groups were compared: the control one and the two exposed to ELF-EMF - 0.7 and 7 mT. Bioelectrical activity of the cercal nerve and of the connective nerve that leaves the terminal abdominal ganglion was recorded using extracellular electrodes. LqhαIT (5 × 10(-8) M) induced modifications of neuronal activity that were observed in the control cockroach preparations and in the ones exposed to ELF-EMF (0.7 mT). The exposure to ELF-EMF was carried out using coils with a size appropriate to the examined objects. RESULTS The exposure to ELF-EMF (0.7 mT) modified the effects of LqhαIT (5 × 10(-8) M) on activity of the cercal nerve and of the connective nerve. We observed a decrease of the toxin effect on the cercal nerve activity, but the toxic effect of LqhαIT on the connective nerve was increased. Biotests showed that toxicity of LqhαIT (10(-8) M) on cockroaches was reduced by the exposure to ELF-EMF (0.7 and 7 mT). CONCLUSIONS The exposure to 50 Hz ELF-EMF modified the mode of action of the anti-insect scorpion alpha toxin LqhαIT at cellular level of the cockroach nervous system and in biotests. Toxin appeared as a usefull tool in distinguishing between the primary and the secondary effects of ELF-EMF.
Collapse
Affiliation(s)
- Milena Jankowska
- />Nicolaus Copernicus University, Faculty of Biology and Environmental Protection, Torun, Poland
| | | | - Maria Stankiewicz
- />Nicolaus Copernicus University, Faculty of Biology and Environmental Protection, Torun, Poland
| | - Justyna Rogalska
- />Nicolaus Copernicus University, Faculty of Biology and Environmental Protection, Torun, Poland
| | - Joanna Wyszkowska
- />Nicolaus Copernicus University, Faculty of Biology and Environmental Protection, Torun, Poland
| |
Collapse
|
27
|
Isoflurane inhibits synaptic vesicle exocytosis through reduced Ca2+ influx, not Ca2+-exocytosis coupling. Proc Natl Acad Sci U S A 2015; 112:11959-64. [PMID: 26351670 DOI: 10.1073/pnas.1500525112] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Identifying presynaptic mechanisms of general anesthetics is critical to understanding their effects on synaptic transmission. We show that the volatile anesthetic isoflurane inhibits synaptic vesicle (SV) exocytosis at nerve terminals in dissociated rat hippocampal neurons through inhibition of presynaptic Ca(2+) influx without significantly altering the Ca(2+) sensitivity of SV exocytosis. A clinically relevant concentration of isoflurane (0.7 mM) inhibited changes in [Ca(2+)]i driven by single action potentials (APs) by 25 ± 3%, which in turn led to 62 ± 3% inhibition of single AP-triggered exocytosis at 4 mM extracellular Ca(2+) ([Ca(2+)]e). Lowering external Ca(2+) to match the isoflurane-induced reduction in Ca(2+) entry led to an equivalent reduction in exocytosis. These data thus indicate that anesthetic inhibition of neurotransmitter release from small SVs occurs primarily through reduced axon terminal Ca(2+) entry without significant direct effects on Ca(2+)-exocytosis coupling or on the SV fusion machinery. Isoflurane inhibition of exocytosis and Ca(2+) influx was greater in glutamatergic compared with GABAergic nerve terminals, consistent with selective inhibition of excitatory synaptic transmission. Such alteration in the balance of excitatory to inhibitory transmission could mediate reduced neuronal interactions and network-selective effects observed in the anesthetized central nervous system.
Collapse
|
28
|
Meneses D, Mateos V, Islas G, Barral J. G-protein-coupled inward rectifier potassium channels involved in corticostriatal presynaptic modulation. Synapse 2015; 69:446-52. [DOI: 10.1002/syn.21833] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 06/01/2015] [Accepted: 06/16/2015] [Indexed: 01/13/2023]
|
29
|
Takada Y, Hirano M, Kiyonaka S, Ueda Y, Yamaguchi K, Nakahara K, Mori MX, Mori Y. Rab3 interacting molecule 3 mutations associated with autism alter regulation of voltage-dependent Ca²⁺ channels. Cell Calcium 2015; 58:296-306. [PMID: 26142343 DOI: 10.1016/j.ceca.2015.06.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 06/16/2015] [Accepted: 06/16/2015] [Indexed: 10/23/2022]
Abstract
Autism is a neurodevelopmental psychiatric disorder characterized by impaired reciprocal social interaction, disrupted communication, and restricted and stereotyped patterns of interests. Autism is known to have a strong genetic component. Although mutations in several genes account for only a small proportion of individuals with autism, they provide insight into potential biological mechanisms that underlie autism, such as dysfunction in Ca(2+) signaling, synaptic dysfunction, and abnormal brain connectivity. In autism patients, two mutations have been reported in the Rab3 interacting molecule 3 (RIM3) gene. We have previously demonstrated that RIM3 physically and functionally interacts with voltage-dependent Ca(2+) channels (VDCCs) expressed in neurons via the β subunits, and increases neurotransmitter release. Here, by introducing corresponding autism-associated mutations that replace glutamic acid residue 176 with alanine (E176A) and methionine residue 259 with valine (M259V) into the C2B domain of mouse RIM3, we demonstrate that both mutations partly cancel the suppressive RIM3 effect on voltage-dependent inactivation of Ba(2+) currents through P/Q-type CaV2.1 recombinantly expressed in HEK293 cells. In recombinant N-type CaV2.2 VDCCs, the attenuation of the suppressive RIM3 effect on voltage-dependent inactivation is conserved for M259V but not E176A. Slowing of activation speed of P/Q-type CaV2.1 currents by RIM3 is abolished in E176A, while the physical interaction between RIM3 and β subunits is significantly attenuated in M259V. Moreover, increases by RIM3 in depolarization-induced Ca(2+) influx and acetylcholine release are significantly attenuated by E176A in rat pheochromocytoma PC12 cells. Thus, our data raise the interesting possibility that autism phenotypes are elicited by synaptic dysfunction via altered regulation of presynaptic VDCC function and neurotransmitter release.
Collapse
Affiliation(s)
- Yoshinori Takada
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Mitsuru Hirano
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Shigeki Kiyonaka
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan; Laboratory of Environmental Systems Biology, Department of Technology and Ecology, Hall of Global Environmental Studies, Kyoto University, Kyoto 615-8510, Japan
| | - Yoshifumi Ueda
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Kazuma Yamaguchi
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Keiko Nakahara
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Masayuki X Mori
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Yasuo Mori
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan; Laboratory of Environmental Systems Biology, Department of Technology and Ecology, Hall of Global Environmental Studies, Kyoto University, Kyoto 615-8510, Japan.
| |
Collapse
|
30
|
Lenkey N, Kirizs T, Holderith N, Máté Z, Szabó G, Vizi ES, Hájos N, Nusser Z. Tonic endocannabinoid-mediated modulation of GABA release is independent of the CB1 content of axon terminals. Nat Commun 2015; 6:6557. [PMID: 25891347 PMCID: PMC4413030 DOI: 10.1038/ncomms7557] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 02/06/2015] [Indexed: 12/28/2022] Open
Abstract
The release of GABA from cholecystokinin-containing interneurons is modulated by type-1 cannabinoid receptors (CB1). Here we tested the hypothesis that the strength of CB1-mediated modulation of GABA release is related to the CB1 content of axon terminals. Basket cell boutons have on average 78% higher CB1 content than those of dendritic-layer-innervating (DLI) cells, a consequence of larger bouton surface and higher CB1 density. The CB1 antagonist AM251 caused a 54% increase in action potential-evoked [Ca(2+)] in boutons of basket cells, but not in DLI cells. However, the effect of AM251 did not correlate with CB1 immunoreactivity of individual boutons. Moreover, a CB1 agonist decreased [Ca(2+)] in a cell type- and CB1-content-independent manner. Replica immunogold labelling demonstrated the colocalization of CB1 with the Cav2.2 Ca(2+) channel subunit. Our data suggest that only a subpopulation of CB1s, within nanometre distances from their target Cav2.2 channels, are responsible for endocannabinoid-mediated modulation of GABA release.
Collapse
Affiliation(s)
- Nora Lenkey
- Lendület Laboratory of Cellular Neurophysiology,
Institute of Experimental Medicine, Hungarian Academy of Sciences,
Budapest
H1083, Hungary
| | - Tekla Kirizs
- Lendület Laboratory of Cellular Neurophysiology,
Institute of Experimental Medicine, Hungarian Academy of Sciences,
Budapest
H1083, Hungary
- János Szentágothai School of
Neurosciences, Semmelweis University, Budapest H1085,
Hungary
| | - Noemi Holderith
- Lendület Laboratory of Cellular Neurophysiology,
Institute of Experimental Medicine, Hungarian Academy of Sciences,
Budapest
H1083, Hungary
| | - Zoltán Máté
- Division of Medical Gene Technology, Institute of
Experimental Medicine, Hungarian Academy of Sciences, Budapest
H1083, Hungary
| | - Gábor Szabó
- Division of Medical Gene Technology, Institute of
Experimental Medicine, Hungarian Academy of Sciences, Budapest
H1083, Hungary
| | - E. Sylvester Vizi
- Laboratory of Drug Research, Institute of Experimental
Medicine, Hungarian Academy of Sciences, Budapest H1083,
Hungary
| | - Norbert Hájos
- Lendület Laboratory of Network Neurophysiology,
Institute of Experimental Medicine, Hungarian Academy of Sciences,
Szigony street 43, Budapest
H1083, Hungary
| | - Zoltan Nusser
- Lendület Laboratory of Cellular Neurophysiology,
Institute of Experimental Medicine, Hungarian Academy of Sciences,
Budapest
H1083, Hungary
| |
Collapse
|
31
|
ZC88, a novel N-type calcium channel blocker from 4-amino-piperidine derivatives state-dependent inhibits Cav2.2 calcium channels. Brain Res 2015; 1605:12-21. [DOI: 10.1016/j.brainres.2015.01.054] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 01/22/2015] [Accepted: 01/23/2015] [Indexed: 11/23/2022]
|
32
|
Völgyi K, Gulyássy P, Háden K, Kis V, Badics K, Kékesi KA, Simor A, Györffy B, Tóth EA, Lubec G, Juhász G, Dobolyi A. Synaptic mitochondria: a brain mitochondria cluster with a specific proteome. J Proteomics 2015; 120:142-57. [PMID: 25782751 DOI: 10.1016/j.jprot.2015.03.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 02/16/2015] [Accepted: 03/04/2015] [Indexed: 01/15/2023]
Abstract
UNLABELLED The synapse is a particularly important compartment of neurons. To reveal its molecular characteristics we isolated whole brain synaptic (sMito) and non-synaptic mitochondria (nsMito) from the mouse brain with purity validated by electron microscopy and fluorescence activated cell analysis and sorting. Two-dimensional differential gel electrophoresis and mass spectrometry based proteomics revealed 22 proteins with significantly higher and 34 proteins with significantly lower levels in sMito compared to nsMito. Expression differences in some oxidative stress related proteins, such as superoxide dismutase [Mn] (Sod2) and complement component 1Q subcomponent-binding protein (C1qbp), as well as some tricarboxylic acid cycle proteins, including isocitrate dehydrogenase subunit alpha (Idh3a) and ATP-forming β subunit of succinyl-CoA ligase (SuclA2), were verified by Western blot, the latter two also by immunohistochemistry. The data suggest altered tricarboxylic acid metabolism in energy supply of synapse while the marked differences in Sod2 and C1qbp support high sensitivity of synapses to oxidative stress. Further functional clustering demonstrated that proteins with higher synaptic levels are involved in synaptic transmission, lactate and glutathione metabolism. In contrast, mitochondrial proteins associated with glucose, lipid, ketone metabolism, signal transduction, morphogenesis, protein synthesis and transcription were enriched in nsMito. Altogether, the results suggest a specifically tuned composition of synaptic mitochondria. BIOLOGICAL SIGNIFICANCE Neurons communicate with each other through synapse, a compartment metabolically isolated from the cell body. Mitochondria are concentrated in presynaptic terminals by active transport to provide energy supply for information transfer. Mitochondrial composition in the synapse may be different than in the cell body as some examples have demonstrated altered mitochondrial composition with cell type and cellular function in the muscle, heart and liver. Therefore, we posed the question whether protein composition of synaptic mitochondria reflects its specific functions. The determined protein difference pattern was in accordance with known functional specialties of high demand synaptic mitochondria. The data also suggest specifically tuned metabolic fluxes for energy production by means of interaction with glial cells surrounding the synapse. These findings provide possible mechanisms for dynamically adapting synaptic mitochondrial output to actual demand. In turn, an increased vulnerability of synaptic mitochondria to oxidative stress is implied by the data. This is important from theoretical but potentially also from therapeutic aspects. Mitochondria are known to be affected in some neurodegenerative and psychiatric disorders, and proteins with elevated level in synaptic mitochondria, e.g. C1qbp represent targets for future drug development, by which synaptic and non-synaptic mitochondria can be differentially affected.
Collapse
Affiliation(s)
- Katalin Völgyi
- MTA-ELTE NAP Laboratory of Molecular and Systems Neurobiology, Institute of Biology, Hungarian Academy of Sciences and Eötvös Loránd University, Budapest H-1117, Hungary; Laboratory of Proteomics, Institute of Biology, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Péter Gulyássy
- Laboratory of Proteomics, Institute of Biology, Eötvös Loránd University, Budapest H-1117, Hungary; MTA-TTK NAP MS Neuroproteomics Research Group, Hungarian Academy of Sciences, Budapest H-1117, Hungary
| | - Krisztina Háden
- Laboratory of Proteomics, Institute of Biology, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Viktor Kis
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, H-1117 Budapest, Hungary
| | - Kata Badics
- Laboratory of Proteomics, Institute of Biology, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Katalin Adrienna Kékesi
- Laboratory of Proteomics, Institute of Biology, Eötvös Loránd University, Budapest H-1117, Hungary; Department of Physiology and Neurobiology, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Attila Simor
- Laboratory of Proteomics, Institute of Biology, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Balázs Györffy
- Laboratory of Proteomics, Institute of Biology, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Eszter Angéla Tóth
- Department of Immunology, Eötvös Loránd University, Budapest H-1117, Hungary; Faculty of Science Research and Instrument Core Facility (ELTE FS-RICF), Eötvös Loránd University, Budapest H-1117, Hungary
| | - Gert Lubec
- Department of Pediatrics, Medical University of Vienna, Vienna A-1090, Austria
| | - Gábor Juhász
- Laboratory of Proteomics, Institute of Biology, Eötvös Loránd University, Budapest H-1117, Hungary; MTA-TTK NAP MS Neuroproteomics Research Group, Hungarian Academy of Sciences, Budapest H-1117, Hungary
| | - Arpád Dobolyi
- MTA-ELTE NAP Laboratory of Molecular and Systems Neurobiology, Institute of Biology, Hungarian Academy of Sciences and Eötvös Loránd University, Budapest H-1117, Hungary.
| |
Collapse
|
33
|
Calcium ions facilitate body heat emission response to warming. Bull Exp Biol Med 2015; 158:291-4. [PMID: 25573352 DOI: 10.1007/s10517-015-2743-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Indexed: 10/24/2022]
Abstract
Involvement of various areas of the body surface in heat emission response to warming is characterized by a certain succession. The first response preceding the deep body temperature rise is dilation of ear skin vessels. Then, an increase in deep body temperature is counterbalanced by vascular reaction in the tail region, which plays the leading role in up-regulation of heat emission. Calcium ions accelerate the vascular response to warming in both regions, although they produce no effect on the maximum level of heat emission. Our findings confirm the involvement of Ca(2+)-dependent mechanisms in activation of the processes aimed at stabilization of body temperature in warm-blooded animals. The role of heat-sensitive TRPV1 ion channels determining modality of the temperature signal and direction of effector reactions is discussed.
Collapse
|
34
|
Pekala D, Baginskas A, Szkudlarek HJ, Raastad M. Components of action potential repolarization in cerebellar parallel fibres. J Physiol 2014; 592:4911-29. [PMID: 25239461 DOI: 10.1113/jphysiol.2014.280719] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Repolarization of the presynaptic action potential is essential for transmitter release, excitability and energy expenditure. Little is known about repolarization in thin, unmyelinated axons forming en passant synapses, which represent the most common type of axons in the mammalian brain's grey matter.We used rat cerebellar parallel fibres, an example of typical grey matter axons, to investigate the effects of K(+) channel blockers on repolarization. We show that repolarization is composed of a fast tetraethylammonium (TEA)-sensitive component, determining the width and amplitude of the spike, and a slow margatoxin (MgTX)-sensitive depolarized after-potential (DAP). These two components could be recorded at the granule cell soma as antidromic action potentials and from the axons with a newly developed miniaturized grease-gap method. A considerable proportion of fast repolarization remained in the presence of TEA, MgTX, or both. This residual was abolished by the addition of quinine. The importance of proper control of fast repolarization was demonstrated by somatic recordings of antidromic action potentials. In these experiments, the relatively broad K(+) channel blocker 4-aminopyridine reduced the fast repolarization, resulting in bursts of action potentials forming on top of the DAP. We conclude that repolarization of the action potential in parallel fibres is supported by at least three groups of K(+) channels. Differences in their temporal profiles allow relatively independent control of the spike and the DAP, whereas overlap of their temporal profiles provides robust control of axonal bursting properties.
Collapse
Affiliation(s)
- Dobromila Pekala
- Department of Physiology, Emory University School of Medicine, Atlanta GA, USA
| | - Armantas Baginskas
- Department of Physics, Mathematics and Biophysics, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Hanna J Szkudlarek
- Department of Neurophysiology and Chronobiology, Institute of Zoology, Jagiellonian University, Krakow, Poland
| | - Morten Raastad
- Department of Physiology, Emory University School of Medicine, Atlanta GA, USA
| |
Collapse
|
35
|
Aviner B, Gradwohl G, Mor Aviner M, Levy S, Grossman Y. Selective modulation of cellular voltage-dependent calcium channels by hyperbaric pressure-a suggested HPNS partial mechanism. Front Cell Neurosci 2014; 8:136. [PMID: 24904281 PMCID: PMC4034351 DOI: 10.3389/fncel.2014.00136] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 04/30/2014] [Indexed: 11/30/2022] Open
Abstract
Professional deep sea divers experience motor and cognitive impairment, known as High Pressure Neurological Syndrome (HPNS), when exposed to pressures of 100 msw (1.1 MPa) and above, considered to be the result of synaptic transmission alteration. Previous studies have indicated modulation of presynaptic Ca2+ currents at high pressure. We directly measured for the first time pressure effects on the currents of voltage dependent Ca2+ channels (VDCCs) expressed in Xenopus oocytes. Pressure selectivity augmented the current in CaV1.2 and depressed it in CaV3.2 channels. Pressure application also affected the channels' kinetics, such as ƮRise, ƮDecay. Pressure modulation of VDCCs seems to play an important role in generation of HPNS signs and symptoms.
Collapse
Affiliation(s)
- Ben Aviner
- Department of Physiology and Neurobiology, Ben Gurion University of the Negev Beer Sheva, Israel
| | - Gideon Gradwohl
- Department of Physics, Jerusalem College of Technology Jerusalem, Israel
| | - Merav Mor Aviner
- Department of Physiology and Neurobiology, Ben Gurion University of the Negev Beer Sheva, Israel
| | - Shiri Levy
- Department of Physiology and Neurobiology, Ben Gurion University of the Negev Beer Sheva, Israel
| | - Yoram Grossman
- Department of Physiology and Neurobiology, Ben Gurion University of the Negev Beer Sheva, Israel
| |
Collapse
|
36
|
Rowe DL, Hermens DF. Attention-deficit/hyperactivity disorder: neurophysiology, information processing, arousal and drug development. Expert Rev Neurother 2014; 6:1721-34. [PMID: 17144785 DOI: 10.1586/14737175.6.11.1721] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this review, we draw on literature from both animal and human neurophysiological studies to consider the neurochemical mechanisms underlying attention-deficit/ hyperactivity disorder (ADHD). Psychophysiological and neuropsychological research is used to propose possible etiological endophenotypes of ADHD. These are conceptualized as patients with distinct cortical-arousal, information-processing or maturational abnormalities, or a combination thereof, and how the endophenotypes can be used to help drug development and optimize treatment and management. To illustrate, the paper focuses on neuro- and psychophysiological evidence that suggests cholinergic mechanisms may underlie specific information-processing abnormalities that occur in ADHD. The clinical implications for a cholinergic hypothesis of ADHD are considered, along with its possible implications for treatment and pharmacological development.
Collapse
Affiliation(s)
- Donald L Rowe
- The Brain Dynamics Centre and Department of Psychological Medicine, Westmead Hospital and University of Sydney, NSW, Australia.
| | | |
Collapse
|
37
|
L-type Ca2+ channel activity determines modulation of GABA release by dopamine in the substantia nigra reticulata and the globus pallidus of the rat. Neuroscience 2014; 256:292-301. [DOI: 10.1016/j.neuroscience.2013.10.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
38
|
Aviner B, Gradwohl G, Moore HJ, Grossman Y. Modulation of presynaptic Ca(2+) currents in frog motor nerve terminals by high pressure. Eur J Neurosci 2013; 38:2716-29. [PMID: 23738821 DOI: 10.1111/ejn.12267] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 04/17/2013] [Accepted: 04/29/2013] [Indexed: 11/27/2022]
Abstract
Presynaptic Ca(2+) -dependent mechanisms have already been implicated in depression of evoked synaptic transmission by high pressure (HP). Therefore, pressure effects on terminal Ca(2+) currents were studied in Rana pipiens peripheral motor nerves. The terminal currents, evoked by nerve or direct stimulation, were recorded under the nerve perineurial sheath with a loose macropatch clamp technique. The combined use of Na(+) and K(+) channel blockers, [Ca(2+) ]o changes, voltage-dependent Ca(2+) channel (VDCC) blocker treatments and HP perturbations revealed two components of presynaptic Ca(2+) currents: an early fast Ca(2+) current (ICaF ), possibly carried by N-type (CaV 2.2) Ca(2+) channels, and a late slow Ca(2+) current (ICaS ), possibly mediated by L-type (CaV 1) Ca(2+) channels. HP reduced the amplitude and decreased the maximum (saturation level) of the Ca(2+) currents, ICaF being more sensitive to pressure, and may have slightly shifted the voltage dependence. HP also moderately diminished the Na(+) action current, which contributed to the depression of VDCC currents. Computer-based modeling was used to verify the interpretation of the currents and investigate the influence of HP on the presynaptic currents. The direct HP reduction of the VDCC currents and the indirect effect of the action potential decrease are probably the major cause of pressure depression of synaptic release.
Collapse
Affiliation(s)
- Ben Aviner
- Department of Physiology and Neurobiology, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
| | | | | | | |
Collapse
|
39
|
Nurullin LF, Tsentsevitsky AN, Malomouzh AI, Nikolsky EE. Revealing of T-type low-voltage activated calcium channels (CaV3) in frog neuromuscular junctions. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2013; 449:73-5. [PMID: 23652430 DOI: 10.1134/s0012496613020038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Indexed: 11/23/2022]
Affiliation(s)
- L F Nurullin
- Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, Kazan, 420111 Tatarstan, Russia
| | | | | | | |
Collapse
|
40
|
Baker KD, Edwards TM, Rickard NS. The role of intracellular calcium stores in synaptic plasticity and memory consolidation. Neurosci Biobehav Rev 2013; 37:1211-39. [PMID: 23639769 DOI: 10.1016/j.neubiorev.2013.04.011] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 04/18/2013] [Accepted: 04/22/2013] [Indexed: 12/20/2022]
Abstract
Memory processing requires tightly controlled signalling cascades, many of which are dependent upon intracellular calcium (Ca(2+)). Despite this, most work investigating calcium signalling in memory formation has focused on plasma membrane channels and extracellular sources of Ca(2+). The intracellular Ca(2+) release channels, ryanodine receptors (RyRs) and inositol (1,4,5)-trisphosphate receptors (IP3Rs) have a significant capacity to regulate intracellular Ca(2+) signalling. Evidence at both cellular and behavioural levels implicates both RyRs and IP3Rs in synaptic plasticity and memory formation. Pharmacobehavioural experiments using young chicks trained on a single-trial discrimination avoidance task have been particularly useful by demonstrating that RyRs and IP3Rs have distinct roles in memory formation. RyR-dependent Ca(2+) release appears to aid the consolidation of labile memory into a persistent long-term memory trace. In contrast, IP3Rs are required during long-term memory. This review discusses various functions for RyRs and IP3Rs in memory processing, including neuro- and glio-transmitter release, dendritic spine remodelling, facilitating vasodilation, and the regulation of gene transcription and dendritic excitability. Altered Ca(2+) release from intracellular stores also has significant implications for neurodegenerative conditions.
Collapse
Affiliation(s)
- Kathryn D Baker
- School of Psychology and Psychiatry, Monash University, Clayton 3800, Victoria, Australia.
| | | | | |
Collapse
|
41
|
Volkov ME, Volkov EM, Nurullin LF. Immunocytochemical identification of synaptotagmin 1, syntaxin 1, Ca2+ channel of the N-type, and nicotinic cholinoreceptor in motor neuromuscular junctions of somatic muscle of the earthworm Lumbricus terrestris. ACTA ACUST UNITED AC 2013. [DOI: 10.1134/s1990519x13010148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
42
|
Adams DJ, Berecki G. Mechanisms of conotoxin inhibition of N-type (Ca(v)2.2) calcium channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1619-28. [PMID: 23380425 DOI: 10.1016/j.bbamem.2013.01.019] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 01/16/2013] [Accepted: 01/19/2013] [Indexed: 12/27/2022]
Abstract
N-type (Ca(v)2.2) voltage-gated calcium channels (VGCC) transduce electrical activity into other cellular functions, regulate calcium homeostasis and play a major role in processing pain information. Although the distribution and function of these channels vary widely among different classes of neurons, they are predominantly expressed in nerve terminals, where they control neurotransmitter release. To date, genetic and pharmacological studies have identified that high-threshold, N-type VGCCs are important for pain sensation in disease models. This suggests that N-type VGCC inhibitors or modulators could be developed into useful drugs to treat neuropathic pain. This review discusses the role of N-type (Ca(v)2.2) VGCCs in nociception and pain transmission through primary sensory dorsal root ganglion (DRG) neurons (nociceptors). It also outlines the potent and selective inhibition of N-type VGCCs by conotoxins, small disulfide-rich peptides isolated from the venom of marine cone snails. Of these conotoxins, ω-conotoxins are selective N-type VGCC antagonists that preferentially block nociception in inflammatory pain models, and allodynia and/or hyperalgesia in neuropathic pain models. Another conotoxin family, α-conotoxins, were initially proposed as competitive antagonists of muscle and neuronal nicotinic acetylcholine receptors (nAChR). Surprisingly, however, α-conotoxins Vc1.1 and RgIA, also potently inhibit N-type VGCC currents in the sensory DRG neurons of rodents and α9 nAChR knockout mice, via intracellular signaling mediated by G protein-coupled GABAB receptors. Understanding how conotoxins inhibit VGCCs is critical for developing these peptides into analgesics and may result in better pain management. This article is part of a Special Issue entitled: Calcium channels.
Collapse
Affiliation(s)
- David J Adams
- Health Innovations Research Institute, RMIT University, Melbourne, Victoria, Australia.
| | | |
Collapse
|
43
|
Multi-walled carbon nanotube increases the excitability of hippocampal CA1 neurons through inhibition of potassium channels in rat's brain slices. Toxicol Lett 2013; 217:121-8. [DOI: 10.1016/j.toxlet.2012.12.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Revised: 12/16/2012] [Accepted: 12/17/2012] [Indexed: 10/27/2022]
|
44
|
Westphalen RI, Desai KM, Hemmings HC. Presynaptic inhibition of the release of multiple major central nervous system neurotransmitter types by the inhaled anaesthetic isoflurane. Br J Anaesth 2012; 110:592-9. [PMID: 23213036 DOI: 10.1093/bja/aes448] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Presynaptic effects of general anaesthetics are not well characterized. We tested the hypothesis that isoflurane exhibits transmitter-specific effects on neurotransmitter release from neurochemically and functionally distinct isolated mammalian nerve terminals. METHODS Nerve terminals from adult male rat brain were prelabelled with [(3)H]glutamate and [(14)C]GABA (cerebral cortex), [(3)H]norepinephrine (hippocampus), [(14)C]dopamine (striatum), or [(3)H]choline (precursor of [(3)H]acetylcholine; striatum). Release evoked by depolarizing pulses of 4-aminopyridine (4AP) or elevated KCl was quantified using a closed superfusion system. RESULTS Isoflurane at clinical concentrations (<0.7 mM; ~2 times median anaesthetic concentration) inhibited Na(+) channel-dependent 4AP-evoked release of the five neurotransmitters tested in a concentration-dependent manner. Isoflurane was a more potent inhibitor [expressed as IC(50) (SEM)] of glutamate release [0.37 (0.03) mM; P<0.05] compared with the release of GABA [0.52 (0.03) mM], norepinephrine [0.48 (0.03) mM], dopamine [0.48 (0.03) mM], or acetylcholine [0.49 (0.02) mM]. Inhibition of Na(+) channel-independent release evoked by elevated K(+) was not significant at clinical concentrations of isoflurane, with the exception of dopamine release [IC(50)=0.59 (0.03) mM]. CONCLUSIONS Isoflurane inhibited the release of the major central nervous system neurotransmitters with selectivity for glutamate release, consistent with both widespread inhibition and nerve terminal-specific presynaptic effects. Glutamate release was most sensitive to inhibition compared with GABA, acetylcholine, dopamine, and norepinephrine release due to presynaptic specializations in ion channel expression, regulation, and/or coupling to exocytosis. Reductions in neurotransmitter release by volatile anaesthetics could contribute to altered synaptic transmission, leading to therapeutic and toxic effects involving all major neurotransmitter systems.
Collapse
Affiliation(s)
- R I Westphalen
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY 10065, USA
| | | | | |
Collapse
|
45
|
Yau KH, Mak JCW, Leung SWS, Yang D, Vanhoutte PM. A synthetic chloride channel relaxes airway smooth muscle of the rat. PLoS One 2012; 7:e45340. [PMID: 23049786 PMCID: PMC3458840 DOI: 10.1371/journal.pone.0045340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 08/16/2012] [Indexed: 02/03/2023] Open
Abstract
Synthetic ion channels may have potential therapeutic applications, provided they possess appropriate biological activities. The present study was designed to examine the ability of small molecule-based synthetic Cl– channels to modulate airway smooth muscle responsiveness. Changes in isometric tension were measured in rat tracheal rings. Relaxations to the synthetic chloride channel SCC-1 were obtained during sustained contractions to KCl. The anion dependency of the effect of SCC-1 was evaluated by ion substitution experiments. The sensitivity to conventional Cl– transport inhibitors was also tested. SCC-1 caused concentration-dependent relaxations during sustained contractions to potassium chloride. This relaxing effect was dependent on the presence of extracellular Cl– and HCO3−. It was insensitive to conventional Cl– channels/transport inhibitors that blocked the cystic fibrosis transmembrane conductance regulator and calcium-activated Cl– channels. SCC-1 did not inhibit contractions induced by carbachol, endothelin-1, 5-hydroxytryptamine or the calcium ionophore A23187. SCC-1 relaxes airway smooth muscle during contractions evoked by depolarizing solutions. The Cl– conductance conferred by this synthetic compound is distinct from the endogenous transport systems for chloride anions.
Collapse
Affiliation(s)
- Kwok-hei Yau
- Morningside Laboratory for Chemical Biology, Department of Chemistry, Faculty of Science, The University of Hong Kong, Hong Kong SAR, China
| | - Judith Choi-wo Mak
- Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Susan Wai-sum Leung
- Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Dan Yang
- Morningside Laboratory for Chemical Biology, Department of Chemistry, Faculty of Science, The University of Hong Kong, Hong Kong SAR, China
| | - Paul M. Vanhoutte
- Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- * E-mail:
| |
Collapse
|
46
|
Raveh A, Valitsky M, Shani L, Coorssen JR, Blank PS, Zimmerberg J, Rahamimoff R. Observations of calcium dynamics in cortical secretory vesicles. Cell Calcium 2012; 52:217-25. [PMID: 22831912 PMCID: PMC3433649 DOI: 10.1016/j.ceca.2012.06.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 06/06/2012] [Accepted: 06/18/2012] [Indexed: 11/15/2022]
Abstract
Calcium (Ca(2+)) dynamics were evaluated in fluorescently labeled sea urchin secretory vesicles using confocal microscopy. 71% of the vesicles examined exhibited one or more transient increases in the fluorescence signal that was damped in time. The detection of transient increases in signal was dependent upon the affinity of the fluorescence indicator; the free Ca(2+) concentration in the secretory vesicles was estimated to be in the range of ∼10 to 100 μM. Non-linear stochastic analysis revealed the presence of extra variance in the Ca(2+) dependent fluorescence signal. This noise process increased linearly with the amplitude of the Ca(2+) signal. Both the magnitude and spatial properties of this noise process were dependent upon the activity of vesicle p-type (Ca(v)2.1) Ca(2+) channels. Blocking the p-type Ca(2+) channels with ω-agatoxin decreased signal variance, and altered the spatial noise pattern within the vesicle. These fluorescence signal properties are consistent with vesicle Ca(2+) dynamics and not simply due to obvious physical properties such as gross movement artifacts or pH driven changes in Ca(2+) indicator fluorescence. The results suggest that the free Ca(2+) content of cortical secretory vesicles is dynamic; this property may modulate the exocytotic fusion process.
Collapse
Affiliation(s)
- Adi Raveh
- Department of Physiology and the Bernard Katz Minerva Centre for Cell Biophysics, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Michael Valitsky
- Department of Physiology and the Bernard Katz Minerva Centre for Cell Biophysics, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Liora Shani
- Department of Physiology and the Bernard Katz Minerva Centre for Cell Biophysics, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Jens R. Coorssen
- Department of Molecular Physiology, School of Medicine, College of Health and Science, and Molecular Medicine Research Group, University of Western Sydney, Campbelltown, Australia
| | - Paul S. Blank
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Joshua Zimmerberg
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Rami Rahamimoff
- Department of Physiology and the Bernard Katz Minerva Centre for Cell Biophysics, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| |
Collapse
|
47
|
Cho S, von Gersdorff H. Ca(2+) influx and neurotransmitter release at ribbon synapses. Cell Calcium 2012; 52:208-16. [PMID: 22776680 DOI: 10.1016/j.ceca.2012.06.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 06/10/2012] [Accepted: 06/13/2012] [Indexed: 12/11/2022]
Abstract
Ca(2+) influx through voltage-gated Ca(2+) channels triggers the release of neurotransmitters at presynaptic terminals. Some sensory receptor cells in the peripheral auditory and visual systems have specialized synapses that express an electron-dense organelle called a synaptic ribbon. Like conventional synapses, ribbon synapses exhibit SNARE-mediated exocytosis, clathrin-mediated endocytosis, and short-term plasticity. However, unlike non-ribbon synapses, voltage-gated L-type Ca(2+) channel opening at ribbon synapses triggers a form of multiquantal release that can be highly synchronous. Furthermore, ribbon synapses appear to be specialized for fast and high throughput exocytosis controlled by graded membrane potential changes. Here we will discuss some of the basic aspects of synaptic transmission at different types of ribbon synapses, and we will emphasize recent evidence that auditory and retinal ribbon synapses have marked differences. This will lead us to suggest that ribbon synapses are specialized for particular operating ranges and frequencies of stimulation. We propose that different types of ribbon synapses transfer diverse rates of sensory information by expressing a particular repertoire of critical components, and by placing them at precise and strategic locations, so that a continuous supply of primed vesicles and Ca(2+) influx leads to fast, accurate, and ongoing exocytosis.
Collapse
Affiliation(s)
- Soyoun Cho
- The Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | | |
Collapse
|
48
|
Kirby ED, Friedman AR, Covarrubias D, Ying C, Sun WG, Goosens KA, Sapolsky RM, Kaufer D. Basolateral amygdala regulation of adult hippocampal neurogenesis and fear-related activation of newborn neurons. Mol Psychiatry 2012; 17:527-36. [PMID: 21670733 PMCID: PMC4310700 DOI: 10.1038/mp.2011.71] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Impaired regulation of emotional memory is a feature of several affective disorders, including depression, anxiety and post-traumatic stress disorder. Such regulation occurs, in part, by interactions between the hippocampus and the basolateral amygdala (BLA). Recent studies have indicated that within the adult hippocampus, newborn neurons may contribute to support emotional memory, and that regulation of hippocampal neurogenesis is implicated in depressive disorders. How emotional information affects newborn neurons in adults is not clear. Given the role of the BLA in hippocampus-dependent emotional memory, we investigated whether hippocampal neurogenesis was sensitive to emotional stimuli from the BLA. We show that BLA lesions suppress adult neurogenesis, while lesions of the central nucleus of the amygdala do not. Similarly, we show that reducing BLA activity through viral vector-mediated overexpression of an outwardly rectifying potassium channel suppresses neurogenesis. We also show that BLA lesions prevent selective activation of immature newborn neurons in response to a fear-conditioning task. These results demonstrate that BLA activity regulates adult hippocampal neurogenesis and the fear context-specific activation of newborn neurons. Together, these findings denote functional implications for proliferation and recruitment of new neurons into emotional memory circuits.
Collapse
Affiliation(s)
| | | | | | | | | | - Ki A. Goosens
- McGovern Institute for Brain Research, Massachusetts Institute of Technology
| | - Robert M. Sapolsky
- Department of Biological Sciences, Stanford University, Stanford, CA and Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA
| | - Daniela Kaufer
- Helen Wills Neuroscience Institute, UC Berkeley,Integrative Biology, UC Berkeley,Corresponding author: Daniela Kaufer, 3060 Valley Life Sciences Bldg. #3140, Berkeley, CA 94720, Phone: (510) 642-9346, Fax: (510) 643-6264,
| |
Collapse
|
49
|
He S, Shao LR, Rittase WB, Bausch SB. Increased Kv1 channel expression may contribute to decreased sIPSC frequency following chronic inhibition of NR2B-containing NMDAR. Neuropsychopharmacology 2012; 37:1338-56. [PMID: 22218089 PMCID: PMC3327840 DOI: 10.1038/npp.2011.320] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 10/21/2011] [Accepted: 11/29/2011] [Indexed: 12/20/2022]
Abstract
Numerous studies have documented the effects of chronic N-methyl-D-aspartate receptor (NMDAR) blockade on excitatory circuits, but the effects on inhibitory circuitry are not well studied. NR2A- and NR2B-containing NMDARs play differential roles in physiological processes, but the consequences of chronic NR2A- or NR2B-containing NMDAR inhibition on glutamatergic and GABAergic neurotransmission are unknown. We investigated altered GABAergic neurotransmission in dentate granule cells and interneurons following chronic treatment with the NR2B-selective antagonist, Ro25,6981, the NR2A-prefering antagonist, NVP-AAM077, or the non-subunit-selective NMDAR antagonist, D-APV, in organotypic hippocampal slice cultures. Electrophysiological recordings revealed large reductions in spontaneous inhibitory postsynaptic current (sIPSC) frequency in both granule cells and interneurons following chronic Ro25,6981 treatment, which was associated with minimally altered sIPSC amplitude, miniature inhibitory postsynaptic current (mIPSC) frequency, and mIPSC amplitude, suggesting diminished action potential-dependent GABA release. Chronic NVP-AAM077 or D-APV treatment had little effect on these measures. Reduced sIPSC frequency did not arise from downregulated GABA(A)R, altered excitatory or inhibitory drive to interneurons, altered interneuron membrane properties, increased failure rate, decreased action potential-dependent release probability, or mGluR/GABA(B) receptor modulation of GABA release. However, chronic Ro25,6981-mediated reductions in sIPSC frequency were occluded by the K+ channel blockers, dendrotoxin, margatoxin, and agitoxin, but not dendrotoxin-K or XE991. Immunohistochemistry also showed increased Kv1.2, Kv1.3, and Kv1.6 in the dentate molecular layer following chronic Ro25,6981 treatment. Our findings suggest that increased Kv1 channel expression/function contributed to diminished action potential-dependent GABA release following chronic NR2B-containing NMDAR inhibition and that these Kv1 channels may be heteromeric complexes containing Kv1.2, Kv1.3, and Kv1.6.
Collapse
Affiliation(s)
- Shuijin He
- Department of Pharmacology, Uniformed Services University School of Medicine, Bethesda, MD, USA
- Graduate Program in Neuroscience, Uniformed Services University School of Medicine, Bethesda, MD, USA
| | - Li-Rong Shao
- Department of Pharmacology, Uniformed Services University School of Medicine, Bethesda, MD, USA
| | - W Bradley Rittase
- Department of Pharmacology, Uniformed Services University School of Medicine, Bethesda, MD, USA
| | - Suzanne B Bausch
- Department of Pharmacology, Uniformed Services University School of Medicine, Bethesda, MD, USA
- Graduate Program in Neuroscience, Uniformed Services University School of Medicine, Bethesda, MD, USA
| |
Collapse
|
50
|
Tuckwell HC. Quantitative aspects of L-type Ca2+ currents. Prog Neurobiol 2012; 96:1-31. [DOI: 10.1016/j.pneurobio.2011.09.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 09/16/2011] [Accepted: 09/23/2011] [Indexed: 12/24/2022]
|