1
|
Davis MJ, Castorena-Gonzalez JA, Zawieja SD. Electric field stimulation unmasks a subtle role for T-type calcium channels in regulating lymphatic contraction. Sci Rep 2023; 13:15862. [PMID: 37739992 PMCID: PMC10516884 DOI: 10.1038/s41598-023-42877-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 09/15/2023] [Indexed: 09/24/2023] Open
Abstract
We previously identified two isoforms of T-type, voltage-gated calcium (Cav3) channels (Cav3.1, Cav3.2) that are functionally expressed in murine lymphatic muscle cells; however, contractile tests of lymphatic vessels from single and double Cav3 knock-out (DKO) mice, exhibited nearly identical parameters of spontaneous twitch contractions as wild-type (WT) vessels, suggesting that Cav3 channels play no significant role. Here, we considered the possibility that the contribution of Cav3 channels might be too subtle to detect in standard contraction analyses. We compared the sensitivity of lymphatic vessels from WT and Cav3 DKO mice to the L-type calcium channel (Cav1.2) inhibitor nifedipine and found that the latter vessels were significantly more sensitive to inhibition, suggesting that the contribution of Cav3 channels might normally be masked by Cav1.2 channel activity. We hypothesized that shifting the resting membrane potential (Vm) of lymphatic muscle to a more negative voltage might enhance the contribution of Cav3 channels. Because even slight hyperpolarization is known to completely silence spontaneous contractions, we devised a method to evoke nerve-independent, twitch contractions from mouse lymphatic vessels using single, short pulses of electric field stimulation (EFS). TTX was present throughout to block the potential contributions of voltage-gated Na+ channels in perivascular nerves and lymphatic muscle. In WT vessels, EFS evoked single contractions that were comparable in amplitude and degree of entrainment to those occurring spontaneously. When Cav1.2 channels were blocked or deleted, only small residual EFS-evoked contractions (~ 5% of normal amplitude) were present. These residual, EFS-evoked contractions were enhanced (to 10-15%) by the KATP channel activator pinacidil (PIN) but were absent in Cav3 DKO vessels. Our results point to a subtle contribution of Cav3 channels to lymphatic contractions that can be unmasked in the absence of Cav1.2 channel activity and when the resting Vm is more hyperpolarized than normal.
Collapse
Affiliation(s)
- Michael J Davis
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, One Hospital Drive, MA415 Medical Sciences Building, Columbia, MO, 65212, USA.
| | | | - Scott D Zawieja
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, One Hospital Drive, MA415 Medical Sciences Building, Columbia, MO, 65212, USA
| |
Collapse
|
2
|
Davis MJ, Castorena-Gonzalez JA, Zawieja SD. Electric field stimulation unmasks a subtle role for T-type calcium channels in regulating lymphatic contraction. RESEARCH SQUARE 2023:rs.3.rs-2938440. [PMID: 37333279 PMCID: PMC10275045 DOI: 10.21203/rs.3.rs-2938440/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
We previously identified two isoforms of T-type, voltage-gated calcium (Ca v 3) channels (Ca v 3.1, Ca v 3.2) that are functionally expressed in murine lymphatic muscle cells; however, contractile tests of lymphatic vessels from single and double Ca v 3 knock-out (DKO) mice, exhibited nearly identical parameters of spontaneous twitch contractions as wild-type (WT) vessels, suggesting that Ca v 3 channels play no significant role. Here, we considered the possibility that the contribution of Ca v 3 channels might be too subtle to detect in standard contraction analyses. We compared the sensitivity of lymphatic vessels from WT and Ca v 3 DKO mice to the L-type calcium channel (Ca v 1.2) inhibitor nifedipine and found that the latter vessels were significantly more sensitive to inhibition, suggesting that the contribution of Ca v 3 channels might normally be masked by Ca v 1.2 channel activity. We hypothesized that shifting the resting membrane potential (Vm) of lymphatic muscle to a more negative voltage might enhance the contribution of Ca v 3 channels. Because even slight hyperpolarization is known to completely silence spontaneous contractions, we devised a method to evoke nerve-independent, twitch contractions from mouse lymphatic vessels using single, short pulses of electric field stimulation (EFS). TTX was present throughout to block the potential contributions of voltage-gated Na + channels in perivascular nerves and lymphatic muscle. In WT vessels, EFS evoked single contractions that were comparable in amplitude and degree of entrainment to those occurring spontaneously. When Ca v 1.2 channels were blocked or deleted, only small residual EFS-evoked contractions (~ 5% of normal amplitude) were present. These residual, EFS-evoked contractions were enhanced (to 10-15%) by the K ATP channel activator pinacidil (PIN) but were absent in Ca v 3 DKO vessels. Our results point to a subtle contribution of Ca v 3 channels to lymphatic contractions that can be unmasked in the absence of Ca v 1.2 channel activity and when the resting Vm is more hyperpolarized than normal.
Collapse
|
3
|
Filippini L, Ortner NJ, Kaserer T, Striessnig J. Ca v 1.3-selective inhibitors of voltage-gated L-type Ca 2+ channels: Fact or (still) fiction? Br J Pharmacol 2023; 180:1289-1303. [PMID: 36788128 PMCID: PMC10953394 DOI: 10.1111/bph.16060] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/17/2022] [Accepted: 01/29/2023] [Indexed: 02/16/2023] Open
Abstract
Voltage-gated L-type Ca2+ -channels (LTCCs) are the target of Ca2+ -channel blockers (CCBs), which are in clinical use for the evidence-based treatment of hypertension and angina. Their cardiovascular effects are largely mediated by the Cav 1.2-subtype. However, based on our current understanding of their physiological and pathophysiological roles, Cav 1.3 LTCCs also appear as attractive drug targets for the therapy of various diseases, including treatment-resistant hypertension, spasticity after spinal cord injury and neuroprotection in Parkinson's disease. Since CCBs inhibit both Cav 1.2 and Cav 1.3, Cav 1.3-selective inhibitors would be valuable tools to validate the therapeutic potential of Cav 1.3 channel inhibition in preclinical models. Despite a number of publications reporting the discovery of Cav 1.3-selective blockers, their selectivity remains controversial. We conclude that at present no pharmacological tools exist that are suitable to confirm or refute a role of Cav 1.3 channels in cellular responses. We also suggest essential criteria for a small molecule to be considered Cav 1.3-selective.
Collapse
Affiliation(s)
- Ludovica Filippini
- Department of Pharmacology and Toxicology and Center of Molecular BiosciencesUniversity of InnsbruckInnsbruckAustria
- Department of Pharmaceutical Chemistry, Institute of PharmacyUniversity of InnsbruckInnsbruckAustria
| | - Nadine J. Ortner
- Department of Pharmacology and Toxicology and Center of Molecular BiosciencesUniversity of InnsbruckInnsbruckAustria
| | - Teresa Kaserer
- Department of Pharmaceutical Chemistry, Institute of PharmacyUniversity of InnsbruckInnsbruckAustria
| | - Jörg Striessnig
- Department of Pharmacology and Toxicology and Center of Molecular BiosciencesUniversity of InnsbruckInnsbruckAustria
| |
Collapse
|
4
|
Moore SJ, Cazares VA, Temme SJ, Murphy GG. Age-related deficits in neuronal physiology and cognitive function are recapitulated in young mice overexpressing the L-type calcium channel, Ca V 1.3. Aging Cell 2023; 22:e13781. [PMID: 36703244 PMCID: PMC10014069 DOI: 10.1111/acel.13781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 12/21/2022] [Accepted: 12/30/2022] [Indexed: 01/28/2023] Open
Abstract
The calcium dysregulation hypothesis of brain aging posits that an age-related increase in neuronal calcium concentration is responsible for alterations in a variety of cellular processes that ultimately result in learning and memory deficits in aged individuals. We previously generated a novel transgenic mouse line, in which expression of the L-type voltage-gated calcium, CaV 1.3, is increased by ~50% over wild-type littermates. Here, we show that, in young mice, this increase is sufficient to drive changes in neuronal physiology and cognitive function similar to those observed in aged animals. Specifically, there is an increase in the magnitude of the postburst afterhyperpolarization, a deficit in spatial learning and memory (assessed by the Morris water maze), a deficit in recognition memory (assessed in novel object recognition), and an overgeneralization of fear to novel contexts (assessed by contextual fear conditioning). While overexpression of CaV 1.3 recapitulated these key aspects of brain aging, it did not produce alterations in action potential firing rates, basal synaptic communication, or spine number/density. Taken together, these results suggest that increased expression of CaV 1.3 in the aged brain is a crucial factor that acts in concert with age-related changes in other processes to produce the full complement of structural, functional, and behavioral outcomes that are characteristic of aged animals.
Collapse
Affiliation(s)
- Shannon J. Moore
- Michigan Neuroscience InstituteAnn ArborMichiganUSA
- Molecular & Integrative PhysiologyUniversity of MichiganAnn ArborMichiganUSA
| | - Victor A. Cazares
- Molecular & Integrative PhysiologyUniversity of MichiganAnn ArborMichiganUSA
- Department of PsychologyWilliams CollegeWilliamstownMassachusettsUSA
| | | | - Geoffrey G. Murphy
- Michigan Neuroscience InstituteAnn ArborMichiganUSA
- Molecular & Integrative PhysiologyUniversity of MichiganAnn ArborMichiganUSA
| |
Collapse
|
5
|
Actinomycetes-derived imine reductases with a preference towards bulky amine substrates. Commun Chem 2022; 5:123. [PMID: 36697820 PMCID: PMC9814587 DOI: 10.1038/s42004-022-00743-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 09/26/2022] [Indexed: 01/28/2023] Open
Abstract
Since imine reductases (IREDs) were reported to catalyze the reductive amination reactions, they became particularly attractive for producing chiral amines. Though diverse ketones and aldehydes have been proved to be excellent substrates of IREDs, bulky amines have been rarely transformed. Here we report the usage of an Increasing-Molecule-Volume-Screening to identify a group of IREDs (IR-G02, 21, and 35) competent for accepting bulky amine substrates. IR-G02 shows an excellent substrate scope, which is applied to synthesize over 135 amine molecules as well as a range of APIs' substructures. The crystal structure of IR-G02 reveals the determinants for altering the substrate preference. Finally, we demonstrate a gram-scale synthesis of an analogue of the API sensipar via a kinetic resolution approach, which displays ee >99%, total turnover numbers of up to 2087, and space time yield up to 18.10 g L-1 d-1.
Collapse
|
6
|
Structural basis for pore blockade of human voltage-gated calcium channel Ca v1.3 by motion sickness drug cinnarizine. Cell Res 2022; 32:946-948. [PMID: 35477996 PMCID: PMC9525318 DOI: 10.1038/s41422-022-00663-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 04/03/2022] [Indexed: 12/29/2022] Open
|
7
|
Yun J, Jeong D, Xie Z, Lee S, Kim J, Surmeier DJ, Silverman RB, Kang S. Palladium-Catalyzed α-Arylation of Cyclic β-Dicarbonyl Compounds for the Synthesis of Ca V1.3 Inhibitors. ACS OMEGA 2022; 7:14252-14263. [PMID: 35559207 PMCID: PMC9089348 DOI: 10.1021/acsomega.2c00889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 03/31/2022] [Indexed: 06/15/2023]
Abstract
Cyclic α-aryl β-dicarbonyl derivatives are important scaffolds in medicinal chemistry. Palladium-catalyzed coupling reactions of haloarenes were conducted with diverse five- to seven-membered cyclic β-dicarbonyl derivatives including barbiturate, pyrazolidine-3,5-dione, and 1,4-diazepane-5,7-dione. The coupling reactions of various para- or meta-substituted aryl halides occurred efficiently when Pd(t-Bu3P)2, Xphos, and Cs2CO3 were used under 1,4-dioxane reflux conditions. Although the couplings of ortho-substituted aryl halides with pyrazolidine-3,5-dione and 1,4-diazepane-5,7-dione were moderate, the coupling with barbiturate was limited. Using the optimized reaction conditions, we synthesized several 5-aryl barbiturates as new scaffolds of CaV1.3 Ca2+ channel inhibitors. Among the synthesized molecules, 14e was the most potent CaV1.3 inhibitor with an IC50 of 1.42 μM.
Collapse
Affiliation(s)
- Jisu Yun
- College
of Pharmacy and Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Republic
of Korea
| | - Dayeon Jeong
- College
of Pharmacy and Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Republic
of Korea
| | - Zhong Xie
- Department
of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, United States
| | - Sol Lee
- College
of Pharmacy and Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Republic
of Korea
| | - Jiho Kim
- College
of Pharmacy and Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Republic
of Korea
| | - D. James Surmeier
- Department
of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, United States
| | - Richard B. Silverman
- Department
of Chemistry, Chemistry of Life Processes Institute, Center for Developmental
Therapeutics, Northwestern University, Evanston, Illinois 60208, United States
| | - Soosung Kang
- College
of Pharmacy and Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Republic
of Korea
| |
Collapse
|
8
|
Lanzetti S, Di Biase V. Small Molecules as Modulators of Voltage-Gated Calcium Channels in Neurological Disorders: State of the Art and Perspectives. Molecules 2022; 27:1312. [PMID: 35209100 PMCID: PMC8879281 DOI: 10.3390/molecules27041312] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 02/11/2022] [Accepted: 02/11/2022] [Indexed: 01/03/2023] Open
Abstract
Voltage-gated calcium channels (VGCCs) are widely expressed in the brain, heart and vessels, smooth and skeletal muscle, as well as in endocrine cells. VGCCs mediate gene transcription, synaptic and neuronal structural plasticity, muscle contraction, the release of hormones and neurotransmitters, and membrane excitability. Therefore, it is not surprising that VGCC dysfunction results in severe pathologies, such as cardiovascular conditions, neurological and psychiatric disorders, altered glycemic levels, and abnormal smooth muscle tone. The latest research findings and clinical evidence increasingly show the critical role played by VGCCs in autism spectrum disorders, Parkinson's disease, drug addiction, pain, and epilepsy. These findings outline the importance of developing selective calcium channel inhibitors and modulators to treat such prevailing conditions of the central nervous system. Several small molecules inhibiting calcium channels are currently used in clinical practice to successfully treat pain and cardiovascular conditions. However, the limited palette of molecules available and the emerging extent of VGCC pathophysiology require the development of additional drugs targeting these channels. Here, we provide an overview of the role of calcium channels in neurological disorders and discuss possible strategies to generate novel therapeutics.
Collapse
Affiliation(s)
| | - Valentina Di Biase
- Institute of Pharmacology, Department of Medical Statistics, Informatics and Health Economics, Medical University of Innsbruck, Peter-Mayr Strasse 1, A-6020 Innsbruck, Austria;
| |
Collapse
|
9
|
Calcium channels and iron metabolism: A redox catastrophe in Parkinson's disease and an innovative path to novel therapies? Redox Biol 2021; 47:102136. [PMID: 34653841 PMCID: PMC8517601 DOI: 10.1016/j.redox.2021.102136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/30/2021] [Accepted: 09/14/2021] [Indexed: 01/09/2023] Open
Abstract
Autonomously spiking dopaminergic neurons of the substantia nigra pars compacta (SNpc) are exquisitely specialized and suffer toxic iron-loading in Parkinson's disease (PD). However, the molecular mechanism involved remains unclear and critical to decipher for designing new PD therapeutics. The long-lasting (L-type) CaV1.3 voltage-gated calcium channel is expressed at high levels amongst nigral neurons of the SNpc, and due to its role in calcium and iron influx, could play a role in the pathogenesis of PD. Neuronal iron uptake via this route could be unregulated under the pathological setting of PD and potentiate cellular stress due to its redox activity. This Commentary will focus on the role of the CaV1.3 channels in calcium and iron uptake in the context of pharmacological targeting. Prospectively, the audacious use of artificial intelligence to design innovative CaV1.3 channel inhibitors could lead to breakthrough pharmaceuticals that attenuate calcium and iron entry to ameliorate PD pathology.
Collapse
|
10
|
Meyer C, Kettner A, Hochenegg U, Rubi L, Hilber K, Koenig X, Boehm S, Hotka M, Kubista H. On the Origin of Paroxysmal Depolarization Shifts: The Contribution of Ca v1.x Channels as the Common Denominator of a Polymorphous Neuronal Discharge Pattern. Neuroscience 2021; 468:265-281. [PMID: 34015369 DOI: 10.1016/j.neuroscience.2021.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 04/29/2021] [Accepted: 05/08/2021] [Indexed: 11/15/2022]
Abstract
Since their discovery in the 1960s, the term paroxysmal depolarization shift (PDS) has been applied to a wide variety of reinforced neuronal discharge patterns. Occurrence of PDS as cellular correlates of electrographic spikes during latent phases of insult-induced rodent epilepsy models and their resemblance to giant depolarizing potentials (GDPs) nourished the idea that PDS may be involved in epileptogenesis. Both GDPs and - in analogy - PDS may lead to progressive changes of neuronal properties by generation of pulsatile intracellular Ca2+ elevations. Herein, a key element is the gating of L-type voltage gated Ca2+ channels (LTCCs, Cav1.x family), which may convey Ca2+ signals to the nucleus. Accordingly, the present study investigates various insult-associated neuronal challenges for their propensities to trigger PDS in a LTCC-dependent manner. Our data demonstrate that diverse disturbances of neuronal function are variably suited to induce PDS-like events, and the contribution of LTCCs is essential to evoke PDS in rat hippocampal neurons that closely resemble GDPs. These PDS appear to be initiated in the dendritic sub-compartment. Their morphology critically depends on the position of recording electrodes and on their rate of occurrence. These results provide novel insight into induction mechanisms, origin, variability, and co-existence of PDS with other discharge patterns and thereby pave the way for future investigations regarding the role of PDS in epileptogenesis.
Collapse
Affiliation(s)
- Christiane Meyer
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
| | - Annika Kettner
- University of Applied Sciences (FH Campus Wien), Favoritenstrasse 226, 1100 Vienna, Austria.
| | - Ulla Hochenegg
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Lena Rubi
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
| | - Karlheinz Hilber
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
| | - Xaver Koenig
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
| | - Stefan Boehm
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
| | - Matej Hotka
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
| | - Helmut Kubista
- Center of Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria.
| |
Collapse
|
11
|
Jiang MC, Birch DV, Heckman CJ, Tysseling VM. The Involvement of Ca V1.3 Channels in Prolonged Root Reflexes and Its Potential as a Therapeutic Target in Spinal Cord Injury. Front Neural Circuits 2021; 15:642111. [PMID: 33867945 PMCID: PMC8044857 DOI: 10.3389/fncir.2021.642111] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/03/2021] [Indexed: 11/13/2022] Open
Abstract
Spinal cord injury (SCI) results in not only the loss of voluntary muscle control, but also in the presence of involuntary movement or spasms. These spasms post-SCI involve hyperexcitability in the spinal motor system. Hyperactive motor commands post SCI result from enhanced excitatory postsynaptic potentials (EPSPs) and persistent inward currents in voltage-gated L-type calcium channels (LTCCs), which are reflected in evoked root reflexes with different timings. To further understand the contributions of these cellular mechanisms and to explore the involvement of LTCC subtypes in SCI-induced hyperexcitability, we measured root reflexes with ventral root recordings and motoneuron activities with intracellular recordings in an in vitro preparation using a mouse model of chronic SCI (cSCI). Specifically, we explored the effects of 1-(3-chlorophenethyl)-3-cyclopentylpyrimidine-2,4,6-(1H,3H,5H)-trione (CPT), a selective negative allosteric modulator of CaV1.3 LTCCs. Our results suggest a hyperexcitability in the spinal motor system in these SCI mice. Bath application of CPT displayed slow onset but dose-dependent inhibition of the root reflexes with the strongest effect on LLRs. However, the inhibitory effect of CPT is less potent in cSCI mice than in acute SCI (aSCI) mice, suggesting changes either in composition of CaV1.3 or other cellular mechanisms in cSCI mice. For intracellular recordings, the intrinsic plateau potentials, was observed in more motoneurons in cSCI mice than in aSCI mice. CPT inhibited the plateau potentials and reduced motoneuron firings evoked by intracellular current injection. These results suggest that the LLR is an important target and that CPT has potential in the therapy of SCI-induced muscle spasms.
Collapse
Affiliation(s)
- Mingchen C Jiang
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Derin V Birch
- Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Charles J Heckman
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.,Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.,Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Vicki M Tysseling
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.,Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| |
Collapse
|
12
|
Ortner NJ. Voltage-Gated Ca 2+ Channels in Dopaminergic Substantia Nigra Neurons: Therapeutic Targets for Neuroprotection in Parkinson's Disease? Front Synaptic Neurosci 2021; 13:636103. [PMID: 33716705 PMCID: PMC7952618 DOI: 10.3389/fnsyn.2021.636103] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/25/2021] [Indexed: 12/21/2022] Open
Abstract
The loss of dopamine (DA)-producing neurons in the substantia nigra pars compacta (SN) underlies the core motor symptoms of the progressive movement disorder Parkinson's disease (PD). To date, no treatment to prevent or slow SN DA neurodegeneration exists; thus, the identification of the underlying factors contributing to the high vulnerability of these neurons represents the basis for the development of novel therapies. Disrupted Ca2+ homeostasis and mitochondrial dysfunction seem to be key players in the pathophysiology of PD. The autonomous pacemaker activity of SN DA neurons, in combination with low cytosolic Ca2+ buffering, leads to large somatodendritic fluctuations of intracellular Ca2+ levels that are linked to elevated mitochondrial oxidant stress. L-type voltage-gated Ca2+ channels (LTCCs) contribute to these Ca2+ oscillations in dendrites, and LTCC inhibition was beneficial in cellular and in vivo animal models of PD. However, in a recently completed phase 3 clinical trial, the dihydropyridine (DHP) LTCC inhibitor isradipine failed to slow disease progression in early PD patients, questioning the feasibility of DHPs for PD therapy. Novel evidence also suggests that R- and T-type Ca2+ channels (RTCCs and TTCCs, respectively) represent potential PD drug targets. This short review aims to (re)evaluate the therapeutic potential of LTCC, RTCC, and TTCC inhibition in light of novel preclinical and clinical data and the feasibility of available Ca2+ channel blockers to modify PD disease progression. I also summarize their cell-specific roles for SN DA neuron function and describe how their gating properties allow activity (and thus their contribution to stressful Ca2+ oscillations) during pacemaking.
Collapse
Affiliation(s)
- Nadine J. Ortner
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria
| |
Collapse
|