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Zhan X, Do LV, Zou L, Zhan RS, Jones M, Nawaz S, Manaye K. Harmaline toxicity on dorsal striatal neurons and its role in tremor. Neurotoxicology 2023; 99:152-161. [PMID: 37838252 DOI: 10.1016/j.neuro.2023.10.005] [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: 12/30/2022] [Revised: 08/28/2023] [Accepted: 10/08/2023] [Indexed: 10/16/2023]
Abstract
Harmaline is one of the β-carboline derivative compounds that is widely distributed in the food chain and human tissues. Harmine, a dehydrogenated form of harmaline, appeared to have a higher concentration in the brain, and appeared to be elevated in essential tremor (ET) and Parkinson's disease. Exogenous harmaline exposure in high concentration has myriad consequences, including inducing tremor, and causing neurodegeneration of Purkinje cells in the cerebellum. Harmaline-induced tremor is an established animal model for human ET, but its underlying mechanism is still controversial. One hypothesis posits that the inferior olive-cerebellum pathway is involved, and CaV3.1 T-type Ca2+ channel is a critical target of action. However, accumulating evidence indicates that tremor can be generated without disturbing T-type channels. This implies that additional neural circuits or molecular targets are involved. Using in vitro slice Ca2+-imaging and patch clamping, we demonstrated that harmaline reduced intracellular Ca2+ and suppressed depolarization-induced spiking activity of medium spiny striatal neurons (MSN), and this effect of harmaline can be partially attenuated by sulpiride (5 µM). In addition, the frequencies of spontaneous excitatory post-synaptic currents (sEPSCs) on MSNs were also significantly attenuated. Furthermore, the induced tremor in C57BL/6 J mice by harmaline injections (i.p. 12.5-18 mg/kg) was also shown to be attenuated by sulpiride (20 mg/kg). This series of experiments suggests that the dorsal striatum is a site of harmaline toxic action and might contribute to tremor generation. The findings also provide evidence that D2 signaling might be a part of the mechanism underlying essential tremor.
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Affiliation(s)
- Xiping Zhan
- Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, DC 20059, USA; Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Ly V Do
- Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, DC 20059, USA
| | - Li Zou
- Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, DC 20059, USA
| | - Ryan Shu Zhan
- Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, DC 20059, USA
| | - Michael Jones
- Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, DC 20059, USA
| | - Saba Nawaz
- Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, DC 20059, USA
| | - Kebreten Manaye
- Department of Physiology and Biophysics, College of Medicine, Howard University, Washington, DC 20059, USA
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Gonçalves FB, Garcia-Gomes MSA, Silva-Sampaio AC, Kirsten TB, Bondan EF, Sandini TM, Flório JC, Lebrun I, Coque ADC, Alexandre-Ribeiro SR, Massironi SMG, Mori CMC, Bernardi MM. Progressive tremor and motor impairment in seizure-prone mutant tremor mice are associated with neurotransmitter dysfunction. Behav Brain Res 2023; 443:114329. [PMID: 36746310 DOI: 10.1016/j.bbr.2023.114329] [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: 07/21/2022] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 02/05/2023]
Abstract
BACKGROUND The tremor mutant mice present motor impairments comprised of whole-body tremors, ataxia, decreased exploratory behavior, and audiogenic seizures. OBJECTIVES This study aims to investigate the development of motor dysfunction in this mutant mouse and the relationships with cortical, striatal, and cerebellar levels of GABA, glutamate, glycine, dopamine (DA), serotonin (5-HT), noradrenaline (NOR), and its metabolites. The serum cytokines levels, myelin content, and the astrocytic expression of the glial fibrillary acidic protein (GFAP) investigated the possible influence of inflammation in motor dysfunction. RESULTS Relative to wild-type (WT) mice, the tremor mice presented: increased tremors and bradykinesia associated with postural instability, decreased range of motion, and difficulty in initiating voluntary movements directly proportional to age; reduced step length for right and left hindlimbs; reduced cortical GABA, glutamate and, aspartate levels, the DOPAC/DA and ratio and increased the NOR levels; in the striatum, the levels of glycine and aspartate were reduced while the HVA levels, the HVA/DA and 5HIAA/5-HT ratios increased; in the cerebellum the glycine, NOR and 5-HIAA levels increased. CONCLUSIONS We suggest that the motor disturbances resulted mainly from the activation of the indirect striatal inhibitory pathway to the frontal cortex mediated by GABA, glutamate, and aspartate, reducing the dopaminergic activity at the prefrontal cortex, which was associated with the progressive tremor. The reduced striatal and increased cerebellar glycine levels could be partially responsible for the mutant tremor motor disturbances.
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Affiliation(s)
- Flávio B Gonçalves
- Psychoneuroimmunology Laboratory, Program in Environmental and Experimental Pathology, Paulista University, Rua Dr. Bacelar, 1212, São Paulo, SP 04026-002, Brazil
| | - Mariana S A Garcia-Gomes
- Department of Psychiatric, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Ana Claudia Silva-Sampaio
- Psychoneuroimmunology Laboratory, Program in Environmental and Experimental Pathology, Paulista University, Rua Dr. Bacelar, 1212, São Paulo, SP 04026-002, Brazil
| | - Thiago B Kirsten
- Psychoneuroimmunology Laboratory, Program in Environmental and Experimental Pathology, Paulista University, Rua Dr. Bacelar, 1212, São Paulo, SP 04026-002, Brazil
| | - Eduardo F Bondan
- Psychoneuroimmunology Laboratory, Program in Environmental and Experimental Pathology, Paulista University, Rua Dr. Bacelar, 1212, São Paulo, SP 04026-002, Brazil
| | - Thaísa M Sandini
- Department of Psychiatric, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Jorge C Flório
- Program in Experimental and Comparative Pathology, Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, Av. Prof. Dr. Orlando Marques de Paiva, 87, São Paulo, SP 05508-270, Brazil
| | - Ivo Lebrun
- Laboratory of Biochemistry and Biophysics, Program in Toxinology, Butantan Institute, Brazil
| | - Alex de C Coque
- Psychoneuroimmunology Laboratory, Program in Environmental and Experimental Pathology, Paulista University, Rua Dr. Bacelar, 1212, São Paulo, SP 04026-002, Brazil
| | | | - Silvia M G Massironi
- Program in Experimental and Comparative Pathology, Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, Av. Prof. Dr. Orlando Marques de Paiva, 87, São Paulo, SP 05508-270, Brazil
| | - Claudia M C Mori
- Program in Experimental and Comparative Pathology, Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, Av. Prof. Dr. Orlando Marques de Paiva, 87, São Paulo, SP 05508-270, Brazil
| | - Maria M Bernardi
- Psychoneuroimmunology Laboratory, Program in Environmental and Experimental Pathology, Paulista University, Rua Dr. Bacelar, 1212, São Paulo, SP 04026-002, Brazil.
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Expression of Concern: Hcn1 Is a Tremorgenic Genetic Component in a Rat Model of Essential Tremor. PLoS One 2023; 18:e0279459. [PMID: 36630358 PMCID: PMC9833531 DOI: 10.1371/journal.pone.0279459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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Kuramoto T. Positional cloning of rat mutant genes reveals new functions of these genes. Exp Anim 2023; 72:1-8. [PMID: 36058846 PMCID: PMC9978133 DOI: 10.1538/expanim.22-0089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The laboratory rat (Rattus norvegicus) is a key model organism for biomedical research. Rats can be subjected to strict genetic and environmental controls. The rat's large body size is suitable for both surgical operations and repeated measurements of physiological parameters. These advantages have led to the development of numerous rat models for genetic diseases. Forward genetics is a proven approach for identifying the causative genes of these disease models but requires genome resources including genetic markers and genome sequences. Over the last few decades, rat genome resources have been developed and deposited in bioresource centers, which have enabled us to perform positional cloning in rats. To date, more than 100 disease-related genes have been identified by positional cloning. Since some disease models are more accessible in rats than mice, the identification of causative genes in these models has sometimes led to the discovery of novel functions of genes. As before, various mutant rats are also expected to be discovered and developed as disease models in the future. Thus, the forward genetics continues to be an important approach to find genes involved in disease phenotypes in rats. In this review, I provide an overview the development of rat genome resources and describe examples of positional cloning in rats in which novel gene functions have been identified.
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Affiliation(s)
- Takashi Kuramoto
- Laboratory of Animal Nutrition, Department of Animal Science, Faculty of Agriculture, Tokyo University of Agriculture, 1737 Funako, Atsugi, Kanagawa 243-0034, Japan
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Kato M, Kunisawa N, Shimizu S, Iha HA, Ohno Y. Mechanisms Underlying Dopaminergic Regulation of Nicotine-Induced Kinetic Tremor. Front Pharmacol 2022; 13:938175. [PMID: 35784764 PMCID: PMC9243423 DOI: 10.3389/fphar.2022.938175] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Accepted: 05/30/2022] [Indexed: 11/13/2022] Open
Abstract
Nicotine induces kinetic tremor, which resembles pharmacological features of essential tremors, via activating the inferior olive (IO) neurons. Since nicotine is known to enhance dopamine release by stimulating α4β2 and/or α6 nACh receptors, we examined the effects of various dopamine receptor ligands on nicotine-induced tremor to clarify the role of the dopaminergic system in modulating nicotine tremor. A tremorgenic dose of nicotine increased the dopamine level in the pons and medulla oblongata (P/MO), and the levels of dopamine metabolites in the hippocampus, P/MO, and striatum. Treatment of animals with the D1/5 agonist SKF-38393 inhibited the induction of nicotine tremor, whereas the D3 agonist PD-128,907 facilitated nicotine-induced tremor. The D2 agonist sumanirole showed no effect. In addition, nicotine tremor was significantly enhanced by the D1/5 antagonist SCH-23390 and inhibited by the D3 antagonist U-99194. Neither the D2 (L-741,626) nor D4 (L-745,870) antagonist affected the generation of nicotine tremor. Furthermore, microinjection of U-99194 into the cerebellum significantly inhibited nicotine-induced tremor, whereas its injection into IO or the striatum did not affect tremor generation. Although intrastriatal injection of SCH-23390 showed no effects, its injection into IO tended to enhance nicotine-induced tremor. The present study suggests that dopamine D3 and D1/5 receptors regulate the induction of nicotine tremor in an opposite way, D3 receptors facilitately and D1/5 receptors inhibitorily. In addition, the cerebellar D3 receptors may play an important role in modulating the induction of nicotine tremor mediated by the olivo-cerebellar system.
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Wagle Shukla A. Reduction of neuronal hyperexcitability with modulation of T-type calcium channel or SK channel in essential tremor. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2022; 163:335-355. [PMID: 35750369 DOI: 10.1016/bs.irn.2022.02.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Essential tremor is one of the most prevalent movement disorders. Propranolol and primidone are the first-line pharmacological therapies. They provide symptomatic control in less than 50% of patients. Topiramate, alprazolam, clonazepam, gabapentin, and botulinum toxin injections are the next line of treatments. These medications lead to modest improvements and are therefore commonly used as add-on agents. Surgical therapies, including deep brain stimulation (DBS) surgery and focused ultrasound beam targeted to the thalamus, are considered for treating tremor refractory to medications and lead to greater than 75% improvements in tremor symptoms. However, DBS is a costly and an invasive procedure; some patients report tolerance to benefits. Focused ultrasound therapy leading to brain lesions is associated with a possibility for permanent clinical deficits. Therefore, research efforts to develop the next generation of oral medications with greater benefits and lesser adverse effects are warranted. There is considerable evidence that the increased functions of calcium channels (P/Q-type and T-type channels) and reduced functions of calcium-activated potassium channels (SK channels) located in the neuronal membranes lead to tremor oscillations. Consequently, many new pharmacological studies have targeted these channels to leverage better clinical outcomes. The current review will discuss the pathophysiology, the specific importance of these channels, and the early clinical experience of using compounds targeting these channels to treat essential tremor.
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Affiliation(s)
- Aparna Wagle Shukla
- Department of Neurology, Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, United States.
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Jiménez-Jiménez FJ, Alonso-Navarro H, García-Martín E, Álvarez I, Pastor P, Agúndez JAG. Genomic Markers for Essential Tremor. Pharmaceuticals (Basel) 2021; 14:ph14060516. [PMID: 34072005 PMCID: PMC8226734 DOI: 10.3390/ph14060516] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/23/2021] [Accepted: 05/24/2021] [Indexed: 12/13/2022] Open
Abstract
There are many reports suggesting an important role of genetic factors in the etiopathogenesis of essential tremor (ET), encouraging continuing the research for possible genetic markers. Linkage studies in families with ET have identified 4 genes/loci for familial ET, although the responsible gene(s) have not been identified. Genome-wide association studies (GWAS) described several variants in LINGO1, SLC1A2, STK32B, PPARGC1A, and CTNNA3, related with ET, but none of them have been confirmed in replication studies. In addition, the case-control association studies performed for candidate variants have not convincingly linked any gene with the risk for ET. Exome studies described the association of several genes with familial ET (FUS, HTRA2, TENM4, SORT1, SCN11A, NOTCH2NLC, NOS3, KCNS2, HAPLN4, USP46, CACNA1G, SLIT3, CCDC183, MMP10, and GPR151), but they were found only in singular families and, again, not found in other families or other populations, suggesting that some can be private polymorphisms. The search for responsible genes for ET is still ongoing.
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Affiliation(s)
- Félix Javier Jiménez-Jiménez
- Section of Neurology, Hospital Universitario del Sureste, E28500 Arganda del Rey, Spain;
- Correspondence: ; Tel.: +34-636-96-83-95; Fax: +34-913-28-07-04
| | | | - Elena García-Martín
- ARADyAL Instituto de Salud Carlos III, University Institute of Molecular Pathology Biomarkers, University of Extremadura, E10071 Caceres, Spain; (E.G.-M.); (J.A.G.A.)
| | - Ignacio Álvarez
- Movement Disorders Unit, Department of Neurology, University Hospital Mútua de Terrassa, Fundació Docencia i Recerça Mútua de Terrassa, E08221 Terrassa, Spain; (I.Á.); (P.P.)
| | - Pau Pastor
- Movement Disorders Unit, Department of Neurology, University Hospital Mútua de Terrassa, Fundació Docencia i Recerça Mútua de Terrassa, E08221 Terrassa, Spain; (I.Á.); (P.P.)
| | - José A. G. Agúndez
- ARADyAL Instituto de Salud Carlos III, University Institute of Molecular Pathology Biomarkers, University of Extremadura, E10071 Caceres, Spain; (E.G.-M.); (J.A.G.A.)
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8
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Szpirer C. Rat models of human diseases and related phenotypes: a systematic inventory of the causative genes. J Biomed Sci 2020; 27:84. [PMID: 32741357 PMCID: PMC7395987 DOI: 10.1186/s12929-020-00673-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 07/09/2020] [Indexed: 12/13/2022] Open
Abstract
The laboratory rat has been used for a long time as the model of choice in several biomedical disciplines. Numerous inbred strains have been isolated, displaying a wide range of phenotypes and providing many models of human traits and diseases. Rat genome mapping and genomics was considerably developed in the last decades. The availability of these resources has stimulated numerous studies aimed at discovering causal disease genes by positional identification. Numerous rat genes have now been identified that underlie monogenic or complex diseases and remarkably, these results have been translated to the human in a significant proportion of cases, leading to the identification of novel human disease susceptibility genes, helping in studying the mechanisms underlying the pathological abnormalities and also suggesting new therapeutic approaches. In addition, reverse genetic tools have been developed. Several genome-editing methods were introduced to generate targeted mutations in genes the function of which could be clarified in this manner [generally these are knockout mutations]. Furthermore, even when the human gene causing a disease had been identified without resorting to a rat model, mutated rat strains (in particular KO strains) were created to analyze the gene function and the disease pathogenesis. Today, over 350 rat genes have been identified as underlying diseases or playing a key role in critical biological processes that are altered in diseases, thereby providing a rich resource of disease models. This article is an update of the progress made in this research and provides the reader with an inventory of these disease genes, a significant number of which have similar effects in rat and humans.
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Affiliation(s)
- Claude Szpirer
- Université Libre de Bruxelles, B-6041, Gosselies, Belgium.
- , Waterloo, Belgium.
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9
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Nishitani A, Nagayoshi H, Takenaka S, Asano M, Shimizu S, Ohno Y, Kuramoto T. Involvement of NMDA receptors in tremor expression in Aspa/Hcn1 double-knockout rats. Exp Anim 2020; 69:388-394. [PMID: 32507787 PMCID: PMC7677080 DOI: 10.1538/expanim.20-0025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
We recently demonstrated that aspartoacylase (Aspa) and
hyperpolarization-activated cyclic nucleotide-gated potassium channel 1
(Hcn1) genes were causative of essential tremor (ET) in rats. This
finding was obtained using
Aspaem34Kyo/Hcn1A354V
double-mutant rats, but they were bred on a heterogeneous genetic background of two
strains, F344 and WTC. Here, we developed an
Aspaem34Kyo/Hcn1em1Kyo
double-knockout rat strain with a homogenous F344 genetic background and studied the
ability of glutamate receptor antagonists to suppress ET. The
F344-Aspa/Hcn1 double-knockout rats exhibited
spontaneous, intense body tremor equivalent to that in the double-mutant rats.
N-acetyl-aspartate (NAA), a substrate of ASPA, showed accumulation in
all brain regions and in the spinal cord. However,
N-acetyl-aspartyl-glutamate (NAAG), which is derived from NAA and
interacts with glutamatergic receptors, was decreased in the medulla oblongata of the
double-knockout rats. The tremor was suppressed by
3-[(R)-2-carboxypiperazin-4-yl]-prop-2-enyl-1-phosphonic acid, an
N-methyl-D-aspartate (NMDA) receptor antagonist, in
F344-Aspa/Hcn1 double-knockout rats. The non-NMDA
glutamate receptor antagonist NBQX weakly inhibited the tremor, while the metabotropic
glutamate receptor antagonist LY341495 showed no effect. In addition, both NR2B
subunit-specific (Ro 25-6981) and NR2C/NR2D subunit-specific (cis-piperidine dicarboxylic
acid) NMDA receptor antagonists suppressed the tremor. These data indicated that the
pathogenesis of tremor in Aspa/Hcn1 double-knockout rats
involved ionotropic glutamate receptors, particularly NMDA receptors.
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Affiliation(s)
- Ai Nishitani
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Haruna Nagayoshi
- Osaka Institute of Public Health, 1-3-69 Nakamichi, Higashinari-ku, Osaka 537-0025, Japan
| | - Shigeo Takenaka
- Department of Clinical Nutrition, Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, 3-7-30 Habikino, Osaka 583-8555, Japan
| | - Masahide Asano
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Saki Shimizu
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Yukihiro Ohno
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Takashi Kuramoto
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Department of Animal Science, Faculty of Agriculture, Tokyo University of Agriculture, 1737 Funako, Atsugi, Kanagawa 243-0034, Japan
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Abstract
Essential tremor (ET) is a neurological movement disorder characterised by bilateral limb kinetic/postural tremor, with or without tremor in other body parts including head, voice and lower limbs. Since no causative genes for ET have been identified, it is likely that the disorder occurs as a result of complex genetic factors interacting with various cellular and environmental factors that can result in abnormal function of circuitry involving the cerebello-thalamo-cortical pathway. Genetic analyses have uncovered at least 14 loci and 11 genes that are related to ET, as well as various risk or protective genetic factors. Limitations in ET genetic analyses include inconsistent disease definition, small sample size, varied ethnic backgrounds and many other factors that may contribute to paucity of relevant genetic data in ET. Genetic analyses, coupled with functional and animal studies, have led to better insights into possible pathogenic mechanisms underlying ET. These genetic studies may guide the future development of genetic testing and counselling, and specific, pathogenesis-targeted, therapeutic strategies.
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Kuo SH, Louis ED, Faust PL, Handforth A, Chang SY, Avlar B, Lang EJ, Pan MK, Miterko LN, Brown AM, Sillitoe RV, Anderson CJ, Pulst SM, Gallagher MJ, Lyman KA, Chetkovich DM, Clark LN, Tio M, Tan EK, Elble RJ. Current Opinions and Consensus for Studying Tremor in Animal Models. CEREBELLUM (LONDON, ENGLAND) 2019; 18:1036-1063. [PMID: 31124049 PMCID: PMC6872927 DOI: 10.1007/s12311-019-01037-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Tremor is the most common movement disorder; however, we are just beginning to understand the brain circuitry that generates tremor. Various neuroimaging, neuropathological, and physiological studies in human tremor disorders have been performed to further our knowledge of tremor. But, the causal relationship between these observations and tremor is usually difficult to establish and detailed mechanisms are not sufficiently studied. To overcome these obstacles, animal models can provide an important means to look into human tremor disorders. In this manuscript, we will discuss the use of different species of animals (mice, rats, fruit flies, pigs, and monkeys) to model human tremor disorders. Several ways to manipulate the brain circuitry and physiology in these animal models (pharmacology, genetics, and lesioning) will also be discussed. Finally, we will discuss how these animal models can help us to gain knowledge of the pathophysiology of human tremor disorders, which could serve as a platform towards developing novel therapies for tremor.
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Affiliation(s)
- Sheng-Han Kuo
- Department of Neurology, Columbia University, 650 West 168th Street, Room 305, New York, NY, 10032, USA.
| | - Elan D Louis
- Department of Neurology, Yale School of Medicine, Yale University, 800 Howard Avenue, Ste Lower Level, New Haven, CT, 06519, USA.
- Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale University, New Haven, CT, USA.
- Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine, Yale University, New Haven, CT, USA.
| | - Phyllis L Faust
- Department of Pathology and Cell Biology, Columbia University Medical Center and the New York Presbyterian Hospital, New York, NY, USA
| | - Adrian Handforth
- Neurology Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Su-Youne Chang
- Department of Neurologic Surgery and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | - Billur Avlar
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Eric J Lang
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Ming-Kai Pan
- Department of Medical Research and Neurology, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Lauren N Miterko
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
| | - Amanda M Brown
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Roy V Sillitoe
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Collin J Anderson
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | - Stefan M Pulst
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | | | - Kyle A Lyman
- Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | | | - Lorraine N Clark
- Department of Pathology and Cell Biology, Columbia University Medical Center and the New York Presbyterian Hospital, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Murni Tio
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
- Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Eng-King Tan
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
- Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Rodger J Elble
- Department of Neurology, Southern Illinois University School of Medicine, Springfield, IL, USA
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He D, Yuan L, Song Z, Deng X, Chen Y, Lu H, Deng H. Lack of association between methylenetetrahydrofolate reductase gene variants & essential tremor in Han Chinese. Indian J Med Res 2019; 149:67-70. [PMID: 31115378 PMCID: PMC6507536 DOI: 10.4103/ijmr.ijmr_432_17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- Dan He
- Center for Experimental Medicine; Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, PR China
| | - Lamei Yuan
- Center for Experimental Medicine, The Third Xiangya Hospital, Central South University, Changsha, PR China
| | - Zhi Song
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, PR China
| | - Xiong Deng
- Center for Experimental Medicine, The Third Xiangya Hospital, Central South University, Changsha, PR China
| | - Yizhi Chen
- Center for Experimental Medicine, The Third Xiangya Hospital, Central South University, Changsha, PR China
| | - Hongwei Lu
- Center for Experimental Medicine, The Third Xiangya Hospital, Central South University, Changsha, PR China
| | - Hao Deng
- Center for Experimental Medicine; Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha, PR China
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Iha HA, Kunisawa N, Shimizu S, Onishi M, Nomura Y, Matsubara N, Iwai C, Ogawa M, Hashimura M, Sato K, Kato M, Ohno Y. Mechanism Underlying Organophosphate Paraoxon-Induced Kinetic Tremor. Neurotox Res 2019; 35:575-583. [DOI: 10.1007/s12640-019-0007-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 01/22/2019] [Accepted: 01/28/2019] [Indexed: 12/18/2022]
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14
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Pan MK, Ni CL, Wu YC, Li YS, Kuo SH. Animal Models of Tremor: Relevance to Human Tremor Disorders. Tremor Other Hyperkinet Mov (N Y) 2018; 8:587. [PMID: 30402338 PMCID: PMC6214818 DOI: 10.7916/d89s37mv] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 08/10/2018] [Indexed: 12/17/2022] Open
Abstract
Background Tremor is the most common movement disorder; however, the pathophysiology of tremor remains elusive. While several neuropathological alterations in tremor disorders have been observed in post-mortem studies of human brains, a full understanding of the relationship between brain circuitry alterations and tremor requires testing in animal models. Additionally, tremor animal models are critical for our understanding of tremor pathophysiology, and/or to serve as a platform for therapy development. Methods A PubMed search was conducted in May 2018 to identify published papers for review. Results The methodology used in most studies on animal models of tremor lacks standardized measurement of tremor frequency and amplitude; instead, these studies are based on the visual inspection of phenotypes, which may fail to delineate tremor from other movement disorders such as ataxia. Of the animal models with extensive tremor characterization, harmaline-induced rodent tremor models provide an important framework showing that rhythmic and synchronous neuronal activities within the olivocerebellar circuit can drive action tremor. In addition, dopamine-depleted monkey and mouse models may develop rest tremor, highlighting the role of dopamine in rest tremor generation. Finally, other animal models of tremor have involvement of the cerebellar circuitry, leading to altered Purkinje cell physiology. Discussion Both the cerebellum and the basal ganglia are likely to play a role in tremor generation. While the cerebellar circuitry can generate rhythmic movements, the nigrostriatal system is likely to modulate the tremor circuit. Tremor disorders are heterogeneous in nature. Therefore, each animal model may represent a subset of tremor disorders, which collectively can advance our understanding of tremor.
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Affiliation(s)
- Ming-Kai Pan
- Department of Medical Research, National Taiwan University, Taipei, TW
| | - Chun-Lun Ni
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Yeuh-Chi Wu
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Yong-Shi Li
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Sheng-Han Kuo
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
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Kunisawa N, Shimizu S, Kato M, Iha HA, Iwai C, Hashimura M, Ogawa M, Kawaji S, Kawakita K, Abe K, Ohno Y. Pharmacological characterization of nicotine-induced tremor: Responses to anti-tremor and anti-epileptic agents. J Pharmacol Sci 2018; 137:162-169. [PMID: 29945769 DOI: 10.1016/j.jphs.2018.05.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/18/2018] [Accepted: 05/23/2018] [Indexed: 12/19/2022] Open
Abstract
We previously showed that nicotine evoked kinetic tremor by activating the inferior olive, which is implicated in the pathogenesis of essential tremor, via α7 nicotinic acetylcholine receptors. Here, we evaluated the effects of various anti-tremor and anti-epileptic agents on nicotine-induced tremor in mice to clarify the pharmacological characteristics of nicotine tremor. Drugs effective for essential tremor, propranolol, diazepam and phenobarbital, all significantly inhibited kinetic tremor induced by an intraperitoneal (i.p.) injection of nicotine (1 mg/kg). In contrast, none of the medications for Parkinson's disease, l-DOPA, bromocriptine or trihexyphenidyl, affected the nicotine tremor. Among the anti-epileptic agents examined, valproate, carbamazepine and ethosuximide, significantly inhibited nicotine-induced tremor. In addition, a selective T-type Ca2+ channel blocker, TTA-A2, also suppressed the nicotine tremor. However, neither gabapentin, topiramate, zonisamide nor levetiracetam significantly affected nicotine-induced tremor. The present results show that nicotine-induced tremor resembles essential tremor not only on the neural basis, but also in terms of the pharmacological responses to anti-tremor agents, implying that nicotine-induced tremor can serve as a model for essential tremor. In addition, it is suggested that anti-epileptic agents, which have stimulant actions on the GABAergic system or blocking actions on voltage-gated Na+ channels and T-type Ca2+ channels, can alleviate essential tremor.
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Affiliation(s)
- Naofumi Kunisawa
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Saki Shimizu
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Masaki Kato
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Higor A Iha
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Chihiro Iwai
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Mai Hashimura
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Mizuki Ogawa
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Shohei Kawaji
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Kazuma Kawakita
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Keisuke Abe
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Yukihiro Ohno
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan.
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Tremor dominant Kyoto (Trdk) rats carry a missense mutation in the gene encoding the SK2 subunit of small-conductance Ca 2+-activated K + channel. Brain Res 2017; 1676:38-45. [PMID: 28917524 DOI: 10.1016/j.brainres.2017.09.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 09/07/2017] [Accepted: 09/08/2017] [Indexed: 11/22/2022]
Abstract
Tremor dominant Kyoto (Trdk) is an autosomal dominant mutation that appeared in F344/NSlc rats mutagenized with N-ethyl-N-nitrosourea (ENU). In this study, we characterized and genetically analyzed F344-Trdk/+ heterozygous rats. The rats exhibited a tremor that was especially evident around weaning but persisted throughout life. The tremors of F344-Trdk/+ rats were attenuated by drugs effective against essential tremor (ET) but not drugs used to treat Parkinson's disease-related tremor, indicating that the pharmacological phenotype of F344-Trdk/+ rats was similar to human ET. Using positional candidate approach, we identified the Trdk mutation as a missense substitution (c. 866T>A, p. I289N) in Kcnn2, which encodes the SK2 subunit of the small-conductance Ca2+-activated K+ channel. In vitro electrophysiological studies revealed that the I289N mutation diminished SK2 channel activity. These findings demonstrate that F344-Trdk/+ rats represent a novel model of ET, and strongly suggest that Kcnn2 is the causative gene for the tremor phenotype in F344-Trdk/+ rats.
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Abstract
We describe two cases of typical essential tremor with aspartic acidemia and mildly increased concentrations of plasma glutamic acid. Although this is a preliminary report, we emphasize the possibility of using amino acids, including aspartic acid, as biomarkers for the detection of essential tremor.
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Affiliation(s)
- Shiroh Miura
- Division of Respirology, Neurology and Rheumatology, Department of Medicine, Kurume University School of Medicine
| | - Ryuta Fujioka
- Department of Food and Nutrition, Beppu University Junior College
| | - Takayuki Taniwaki
- Division of Respirology, Neurology and Rheumatology, Department of Medicine, Kurume University School of Medicine
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18
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Iha HA, Kunisawa N, Shimizu S, Tokudome K, Mukai T, Kinboshi M, Ikeda A, Ito H, Serikawa T, Ohno Y. Nicotine Elicits Convulsive Seizures by Activating Amygdalar Neurons. Front Pharmacol 2017; 8:57. [PMID: 28232801 PMCID: PMC5298991 DOI: 10.3389/fphar.2017.00057] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 01/26/2017] [Indexed: 12/14/2022] Open
Abstract
Nicotinic acetylcholine (nACh) receptors are implicated in the pathogenesis of epileptic disorders; however, the mechanisms of nACh receptors in seizure generation remain unknown. Here, we performed behavioral and immunohistochemical studies in mice and rats to clarify the mechanisms underlying nicotine-induced seizures. Treatment of animals with nicotine (1–4 mg/kg, i.p.) produced motor excitement in a dose-dependent manner and elicited convulsive seizures at 3 and 4 mg/kg. The nicotine-induced seizures were abolished by a subtype non-selective nACh antagonist, mecamylamine (MEC). An α7 nACh antagonist, methyllycaconitine, also significantly inhibited nicotine-induced seizures whereas an α4β2 nACh antagonist, dihydro-β-erythroidine, affected only weakly. Topographical analysis of Fos protein expression, a biological marker of neural excitation, revealed that a convulsive dose (4 mg/kg) of nicotine region-specifically activated neurons in the piriform cortex, amygdala, medial habenula, paratenial thalamus, anterior hypothalamus and solitary nucleus among 48 brain regions examined, and this was also suppressed by MEC. In addition, electric lesioning of the amygdala, but not the piriform cortex, medial habenula and thalamus, specifically inhibited nicotine-induced seizures. Furthermore, microinjection of nicotine (100 and 300 μg/side) into the amygdala elicited convulsive seizures in a dose-related manner. The present results suggest that nicotine elicits convulsive seizures by activating amygdalar neurons mainly via α7 nACh receptors.
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Affiliation(s)
- Higor A Iha
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Naofumi Kunisawa
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Saki Shimizu
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Kentaro Tokudome
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Takahiro Mukai
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Masato Kinboshi
- Laboratory of Pharmacology, Osaka University of Pharmaceutical SciencesOsaka, Japan; Department of Epilepsy, Movement Disorders and Physiology, Graduate School of Medicine, Kyoto UniversityKyoto, Japan; Department of Neurology, Graduate School of Medicine, Wakayama Medical UniversityWakayama, Japan
| | - Akio Ikeda
- Department of Epilepsy, Movement Disorders and Physiology, Graduate School of Medicine, Kyoto University Kyoto, Japan
| | - Hidefumi Ito
- Department of Neurology, Graduate School of Medicine, Wakayama Medical University Wakayama, Japan
| | - Tadao Serikawa
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Yukihiro Ohno
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
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19
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Kunisawa N, Iha HA, Shimizu S, Tokudome K, Mukai T, Kinboshi M, Serikawa T, Ohno Y. Nicotine evokes kinetic tremor by activating the inferior olive via α7 nicotinic acetylcholine receptors. Behav Brain Res 2016; 314:173-80. [DOI: 10.1016/j.bbr.2016.08.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/02/2016] [Accepted: 08/06/2016] [Indexed: 10/21/2022]
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20
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Tokudome K, Okumura T, Terada R, Shimizu S, Kunisawa N, Mashimo T, Serikawa T, Sasa M, Ohno Y. A Missense Mutation of the Gene Encoding Synaptic Vesicle Glycoprotein 2A (SV2A) Confers Seizure Susceptibility by Disrupting Amygdalar Synaptic GABA Release. Front Pharmacol 2016; 7:210. [PMID: 27471467 PMCID: PMC4943941 DOI: 10.3389/fphar.2016.00210] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Accepted: 06/30/2016] [Indexed: 12/14/2022] Open
Abstract
Synaptic vesicle glycoprotein 2A (SV2A) is specifically expressed in the membranes of synaptic vesicles and modulates action potential-dependent neurotransmitter release. To explore the role of SV2A in the pathogenesis of epileptic disorders, we recently generated a novel rat model (Sv2aL174Q rat) carrying a missense mutation of the Sv2a gene and showed that the Sv2aL174Q rats were hypersensitive to kindling development (Tokudome et al., 2016). Here, we further conducted behavioral and neurochemical studies to clarify the pathophysiological mechanisms underlying the seizure vulnerability in Sv2aL174Q rats. Sv2aL174Q rats were highly susceptible to pentylenetetrazole (PTZ)-induced seizures, yielding a significantly higher seizure scores and seizure incidence than the control animals. Brain mapping analysis of Fos expression, a biological marker of neural excitation, revealed that the seizure threshold level of PTZ region-specifically elevated Fos expression in the amygdala in Sv2aL174Q rats. In vivo microdialysis study showed that the Sv2aL174Q mutation preferentially reduced high K+ (depolarization)-evoked GABA release, but not glutamate release, in the amygdala. In addition, specific control of GABA release by SV2A was supported by its predominant expression in GABAergic neurons, which were co-stained with antibodies against SV2A and glutamate decarboxylase 1. The present results suggest that dysfunction of SV2A by the missense mutation elevates seizure susceptibility in rats by preferentially disrupting synaptic GABA release in the amygdala, illustrating the crucial role of amygdalar SV2A-GABAergic system in epileptogenesis.
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Affiliation(s)
- Kentaro Tokudome
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Takahiro Okumura
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Ryo Terada
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Saki Shimizu
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Naofumi Kunisawa
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
| | - Tomoji Mashimo
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto UniversityKyoto, Japan; Institute of Experimental Animal Sciences, Graduate School of Medicine, Osaka UniversityOsaka, Japan
| | - Tadao Serikawa
- Laboratory of Pharmacology, Osaka University of Pharmaceutical SciencesOsaka, Japan; Institute of Laboratory Animals, Graduate School of Medicine, Kyoto UniversityKyoto, Japan
| | | | - Yukihiro Ohno
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences Osaka, Japan
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21
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Nishitani A, Tanaka M, Shimizu S, Kunisawa N, Yokoe M, Yoshida Y, Suzuki T, Sakuma T, Yamamoto T, Kuwamura M, Takenaka S, Ohno Y, Kuramoto T. Involvement of aspartoacylase in tremor expression in rats. Exp Anim 2016; 65:293-301. [PMID: 27026062 PMCID: PMC4976243 DOI: 10.1538/expanim.16-0007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Essential tremor (ET) is a common movement disorder with a poorly understood etiology.
The TRM/Kyo mutant rat, showing spontaneous tremor, is an animal model of ET. Recently, we
demonstrated that tremors in these rats emerge when two mutant loci, a missense mutation
in the hyperpolarization-activated cyclic nucleotide-gated potassium channel 1
(Hcn1) and the tremor (tm) deletion, are present
simultaneously. However, we did not identify which gene within the tm
deletion causes tremor expression in TRM/Kyo rats. A strong candidate among the 13 genes
within the tm deletion is aspartoacylase (Aspa), because
some Aspa-knockout mouse strains show tremor. Here, we generated
Aspa-knockout rats using transcription activator-like effector nuclease
technology and produced Aspa/Hcn1 double-mutant rats by
crossing Aspa-knockout rats with Hcn1-mutant rats. The
Aspa-knockout rats carried nonsense mutations in exon 4; and ASPA
proteins were not detectable in their brain extracts. They showed elevated levels of
N-acetyl-L-aspartate (NAA) in urine and spongy vacuolation
and abnormal myelination in the central nervous system, but no tremor. By contrast,
Aspa/Hcn1 double-mutant rats spontaneously showed
tremors resembling those in TRM/Kyo rats, and the tremor was suppressed by drugs
therapeutic for ET but not for parkinsonian tremor. These findings indicated that the lack
of the Aspa gene caused tremor expression in TRM/Kyo rats. Our animal
model suggested that the interaction of NAA accumulation due to ASPA deficiency with an
unstable neuronal membrane potential caused by HCN1 deficiency was involved in tremor
development.
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Affiliation(s)
- Ai Nishitani
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Yoshida-konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
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