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Figueroa KP, Anderson CJ, Paul S, Dansithong W, Gandelman M, Scoles DR, Pulst SM. Slc9a6 mutation causes Purkinje cell loss and ataxia in the shaker rat. Hum Mol Genet 2023; 32:1647-1659. [PMID: 36621975 PMCID: PMC10162436 DOI: 10.1093/hmg/ddad004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 12/29/2022] [Accepted: 01/05/2023] [Indexed: 01/10/2023] Open
Abstract
The shaker rat carries a naturally occurring mutation leading to progressive ataxia characterized by Purkinje cell (PC) loss. We previously reported on fine-mapping the shaker locus to the long arm of the rat X chromosome. In this work, we sought to identify the mutated gene underlying the shaker phenotype and confirm its identity by functional complementation. We fine-mapped the candidate region and analyzed cerebellar transcriptomes, identifying a XM_217630.9 (Slc9a6):c.[191_195delinsA] variant in the Slc9a6 gene that segregated with disease. We generated an adeno-associated virus (AAV) targeting Slc9a6 expression to PCs using the mouse L7-6 (L7) promoter. We administered the AAV prior to the onset of PC degeneration through intracerebroventricular injection and found that it reduced the shaker motor, molecular and cellular phenotypes. Therefore, Slc9a6 is mutated in shaker and AAV-based gene therapy may be a viable therapeutic strategy for Christianson syndrome, also caused by Slc9a6 mutation.
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Affiliation(s)
- Karla P Figueroa
- Department of Neurology, University of Utah, Salt Lake City, UT 84132, USA
| | - Collin J Anderson
- Department of Neurology, University of Utah, Salt Lake City, UT 84132, USA
- School of Medical Sciences, University of Sydney, Camperdown NSW 2006, Australia
- School of Biomedical Engineering University of Sydney, Darlington NSW 2008, Australia
| | - Sharan Paul
- Department of Neurology, University of Utah, Salt Lake City, UT 84132, USA
| | - Warunee Dansithong
- Department of Neurology, University of Utah, Salt Lake City, UT 84132, USA
| | - Mandi Gandelman
- Department of Neurology, University of Utah, Salt Lake City, UT 84132, USA
| | - Daniel R Scoles
- Department of Neurology, University of Utah, Salt Lake City, UT 84132, USA
| | - Stefan M Pulst
- Department of Neurology, University of Utah, Salt Lake City, UT 84132, USA
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Buceta I, Elezgarai I, Rico‐Barrio I, Gerrikagoitia I, Puente N, Grandes P. Deletion of the cannabinoid CB
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receptor impacts on the ultrastructure of the cerebellar parallel fiber‐Purkinje cell synapses. J Comp Neurol 2019; 528:1041-1052. [DOI: 10.1002/cne.24808] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 10/09/2019] [Accepted: 10/31/2019] [Indexed: 12/15/2022]
Affiliation(s)
- Ianire Buceta
- Department of Neurosciences, Faculty of Medicine and Nursing University of the Basque Country UPV/EHU Leioa Spain
- Achucarro Basque Center for Neuroscience Science Park of the University of the Basque Country UPV/EHU Leioa Spain
| | - Izaskun Elezgarai
- Department of Neurosciences, Faculty of Medicine and Nursing University of the Basque Country UPV/EHU Leioa Spain
- Achucarro Basque Center for Neuroscience Science Park of the University of the Basque Country UPV/EHU Leioa Spain
| | - Irantzu Rico‐Barrio
- Department of Neurosciences, Faculty of Medicine and Nursing University of the Basque Country UPV/EHU Leioa Spain
- Achucarro Basque Center for Neuroscience Science Park of the University of the Basque Country UPV/EHU Leioa Spain
| | - Inmaculada Gerrikagoitia
- Department of Neurosciences, Faculty of Medicine and Nursing University of the Basque Country UPV/EHU Leioa Spain
- Achucarro Basque Center for Neuroscience Science Park of the University of the Basque Country UPV/EHU Leioa Spain
| | - Nagore Puente
- Department of Neurosciences, Faculty of Medicine and Nursing University of the Basque Country UPV/EHU Leioa Spain
- Achucarro Basque Center for Neuroscience Science Park of the University of the Basque Country UPV/EHU Leioa Spain
| | - Pedro Grandes
- Department of Neurosciences, Faculty of Medicine and Nursing University of the Basque Country UPV/EHU Leioa Spain
- Achucarro Basque Center for Neuroscience Science Park of the University of the Basque Country UPV/EHU Leioa Spain
- Division of Medical Sciences University of Victoria Victoria British Columbia Canada
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Erekat NS. Active caspase-3 upregulation is augmented in at-risk cerebellar Purkinje cells following inferior olive chemoablation in the shaker mutant rat: an immunofluorescence study. Neurol Res 2018; 41:234-241. [DOI: 10.1080/01616412.2018.1548792] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Nour S. Erekat
- Department of Anatomy, Faculty of Medicine, Jordan University of Science and Technology (JUST), Irbid, Jordan
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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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Erekat NS. Autophagy precedes apoptosis among at risk cerebellar Purkinje cells in the shaker mutant rat: an ultrastructural study. Ultrastruct Pathol 2018; 42:162-169. [PMID: 29419349 DOI: 10.1080/01913123.2018.1424744] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Cerebellar Purkinje cell (PC) death has been shown to occur in essential tremor, ataxia, and many other neurodegenerative diseases in humans. Shaker mutant rats have an X-linked recessive mutation that causes hereditary degeneration of "at risk" cerebellar PCs. This defect can occur in the restricted anterior (ADC) and posterior (PDC) vermal degeneration compartments postnatally within 7 to 14 weeks of age as a natural phenotype in the shaker mutant rat. "Secure" PCs persist in a flocculonodular survival compartment (FNSC). Because we have previously shown that "at risk" PCs die due to apoptosis in the shaker mutant rat, we hypothesized that the PC death observed in the hereditary shaker mutant rat may be due to the activation of more than one type of death pathway. This ultrastructural investigation suggests that "at risk" PCs die due to apoptosis as a result of autophagic activation. Moreover, our data suggest that both apoptosis and autophagy must be simultaneously inhibited to rescue "at risk" PCs from death.
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Affiliation(s)
- Nour S Erekat
- a Department of Anatomy, Faculty of Medicine , Jordan University of Science and Technology (JUST) , Irbid , Jordan
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Erekat NS. Cerebellar Purkinje cells die by apoptosis in the shaker mutant rat. Brain Res 2017; 1657:323-332. [DOI: 10.1016/j.brainres.2016.12.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 10/29/2016] [Accepted: 12/27/2016] [Indexed: 12/15/2022]
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Figueroa KP, Paul S, Calì T, Lopreiato R, Karan S, Frizzarin M, Ames D, Zanni G, Brini M, Dansithong W, Milash B, Scoles DR, Carafoli E, Pulst SM. Spontaneous shaker rat mutant - a new model for X-linked tremor/ataxia. Dis Model Mech 2016; 9:553-62. [PMID: 27013529 PMCID: PMC4892658 DOI: 10.1242/dmm.022848] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 02/29/2016] [Indexed: 12/18/2022] Open
Abstract
The shaker rat is an X-linked recessive spontaneous model of progressive Purkinje cell (PC) degeneration exhibiting a shaking ataxia and wide stance. Generation of Wistar Furth (WF)/Brown Norwegian (BN) F1 hybrids and genetic mapping of F2 sib-sib offspring using polymorphic markers narrowed the candidate gene region to 26 Mbp denoted by the last recombinant genetic marker DXRat21 at 133 Mbp to qter (the end of the long arm). In the WF background, the shaker mutation has complete penetrance, results in a stereotypic phenotype and there is a narrow window for age of disease onset; by contrast, the F2 hybrid phenotype was more varied, with a later age of onset and likely non-penetrance of the mutation. By deep RNA-sequencing, five variants were found in the candidate region; four were novel without known annotation. One of the variants caused an arginine (R) to cysteine (C) change at codon 35 of the ATPase, Ca2+ transporting, plasma membrane 3 (Atp2b3) gene encoding PMCA3 that has high expression in the cerebellum. The variant was well supported by hundreds of overlapping reads, and was found in 100% of all affected replicas and 0% of the wild-type (WT) replicas. The mutation segregated with disease in all affected animals and the amino acid change was found in an evolutionarily conserved region of PMCA3. Despite strong genetic evidence for pathogenicity, in vitro analyses of PMCA3R35C function did not show any differences to WT PMCA3. Because Atp2b3 mutation leads to congenital ataxia in humans, the identified Atp2b3 missense change in the shaker rat presents a good candidate for the shaker rat phenotype based on genetic criteria, but cannot yet be considered a definite pathogenic variant owing to lack of functional changes. Summary: The shaker rat mutant: a new model for essential tremors and ataxia characterized by Purkinje cell degeneration.
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Affiliation(s)
- Karla P Figueroa
- Department of Neurology, University of Utah, Salt Lake City, UT 84112, USA
| | - Sharan Paul
- Department of Neurology, University of Utah, Salt Lake City, UT 84112, USA
| | - Tito Calì
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | | | - Sukanya Karan
- Department of Neurology, University of Utah, Salt Lake City, UT 84112, USA
| | - Martina Frizzarin
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Darren Ames
- Bioinformatics Shared Resource, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA
| | - Ginevra Zanni
- Unit of Molecular Medicine for Neuromuscular and Neurodegenerative Disorders, Department of Neurosciences, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Marisa Brini
- Department of Biology, University of Padova, Padova, Italy
| | - Warunee Dansithong
- Department of Neurology, University of Utah, Salt Lake City, UT 84112, USA
| | - Brett Milash
- Bioinformatics Shared Resource, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA
| | - Daniel R Scoles
- Department of Neurology, University of Utah, Salt Lake City, UT 84112, USA
| | | | - Stefan M Pulst
- Department of Neurology, University of Utah, Salt Lake City, UT 84112, USA
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Handforth A. Linking Essential Tremor to the Cerebellum—Animal Model Evidence. THE CEREBELLUM 2015; 15:285-98. [DOI: 10.1007/s12311-015-0750-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Lalonde R, Strazielle C. Behavioral effects of neonatal lesions on the cerebellar system. Int J Dev Neurosci 2015; 43:58-65. [PMID: 25907855 DOI: 10.1016/j.ijdevneu.2015.04.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 04/04/2015] [Accepted: 04/13/2015] [Indexed: 12/18/2022] Open
Abstract
Several rodent models with spontaneous mutations causing cerebellar pathology are impaired in motor functions during the neonatal period, including Grid2(Lc), Rora(sg), Dab1(scm), Girk2(Wv), Lmx1a(dr-sst), Myo5a(dn), Inpp4a(wbl), and Cacna1a(rol) mice as well as shaker and dystonic rats. Deficits are also evident in murine null mutants such as Zic1, Fgfr1/FgFr2, and Xpa/Ercc8. Behavioral deficits are time-dependent following X-irradiated- or aspiration-induced lesions of the cerebellum in rats. In addition, motor functions are deficient after lesions in cerebellar-related pathways. As in animal subjects, sensorimotor disturbances have been described in children with cerebellar lesions. These results underline the importance of the cerebellum and its connections in the development of motor functions.
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Affiliation(s)
- Robert Lalonde
- Université de Rouen, Département Psychologie, Laboratoire ICONES EA 4699, 76821 Mont-Saint-Aignan Cedex, France.
| | - Catherine Strazielle
- Université de Lorraine, Laboratoire "Stress, Immunité, Pathogènes" EA 7300, and Service de Microscopie Electronique, Faculté de Médecine, 9 avenue de la Forêt de Haye, and CHU de Nancy, 54500 Vandoeuvre-les-Nancy, France
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Modeling Disorders of Movement. Mov Disord 2015. [DOI: 10.1016/b978-0-12-405195-9.00002-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Beckett J, Jin W, Schultz M, Chen A, Tolbert D, Moed BR, Zhang Z. Excessive running induces cartilage degeneration in knee joints and alters gait of rats. J Orthop Res 2012; 30:1604-10. [PMID: 22508407 DOI: 10.1002/jor.22124] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 03/23/2012] [Indexed: 02/04/2023]
Abstract
The goal of this study was to develop an aggressive running regimen for modeling osteoarthritis (OA) in rats. Twelve Wistar rats were randomly placed into either a running group or a non-running group to serve as the control. The running rats used a motorized treadmill to run either 30 km in 3 weeks or 55 km in 6 weeks. Each week, the prints of hind paws were obtained when rats were made to walk through a tunnel. The resulting prints were digitalized for analyses of stride length and step angle. The histology of the knees was examined at 3 and 6 weeks and the OA pathology in the knees was quantified by Mankin's score. Osteoarthritic pathology developed in the knees of the running rats, including decreased proteoglycan content, uneven type II collagen distribution in the cartilage matrix, increased MMP-13 expression, expanded calcified cartilage zone, and clefts and defects in articular cartilage. The pathology worsened from running for 3 to 6 weeks. Gait analysis revealed an inverse correlation between paw angle and the grades of OA pathology. In conclusion, excessive running induces joint degeneration and a unique gait pattern in rats.
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Affiliation(s)
- Jeffrey Beckett
- Center for Anatomical Science and Education, Saint Louis University, St. Louis, MO, USA
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Zanni G, Bertini E, Bellcross C, Nedelec B, Froyen G, Neuhäuser G, Opitz JM, Chelly J. X-linked congenital ataxia: a new locus maps to Xq25-q27.1. Am J Med Genet A 2008; 146A:593-600. [PMID: 18241076 DOI: 10.1002/ajmg.a.32186] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We report clinical and molecular studies on a large American family of Norwegian descent with X-linked nonprogressive congenital ataxia (XCA) in six affected males over three generations. Neuroimaging showed global cerebellar hypoplasia without evidence of supratentorial anomalies. Linkage analysis resulted in a maximum LOD score Z = 3.44 for marker DXS1192 at Theta = 0.0 with flanking markers DXS1047 and DXS1227 defining a region of 12 cM in Xq25-q27.1. The clinical and neuroradiological findings in the present family are very similar to those described in two reported X-linked families [Illarioshkin et al., 1996; Bertini et al., 2000]; however, the newly identified locus does not overlap with the one defined previously, indicating that there are at least two genes responsible for this rare form of X-linked congenital cerebellar ataxia with normal intelligence.
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Affiliation(s)
- Ginevra Zanni
- Institut Cochin, Université Paris Descartes, CNRS (UMR 8104) Paris, France.
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Abstract
The object of this review is to assemble much of the literature concerning Purkinje cell death in cerebellar pathology and to relate this to what is now known about the complex topography of the cerebellar cortex. A brief introduction to Purkinje cells, and their regionalization is provided, and then the data on Purkinje cell death in mouse models and, where appropriate, their human counterparts, have been arranged according to several broad categories--naturally-occurring and targeted mutations leading to Purkinje cell death, Purkinje cell death due to toxins, Purkinje cell death in ischemia, Purkinje cell death in infection and in inherited disorders, etc. The data reveal that cerebellar Purkinje cell death is much more topographically complex than is usually appreciated.
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Affiliation(s)
- Justyna R Sarna
- Genes Development Research Group, Department of Cell Biology & Anatomy, Faculty of Medicine, The University of Calgary, 3330 Hospital Drive NW, Calgary, Alta., Canada T2N 4N1
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Tolbert DL, Clark BR. GDNF and IGF-I trophic factors delay hereditary Purkinje cell degeneration and the progression of gait ataxia. Exp Neurol 2003; 183:205-19. [PMID: 12957504 DOI: 10.1016/s0014-4886(03)00172-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Neurotrophic factors GDNF and/or IGF-I were chronically infused into shaker mutant rats to rescue cerebellar Purkinje neurons from adult-onset heredodegeneration. The natural expression of the shaker mutation is characterized by spatially restricted degeneration of Purkinje cells that occurs earlier and faster in an anterior vermal compartment and slightly later and more slowly in a posterior vermal compartment. Gait ataxia and whole body tremor develop concomitant with the degeneration of Purkinje neurons. The number and spatial distribution of surviving Purkinje neurons, identified by cell-specific calbindin immunoreactivity, were quantitatively analyzed in mid-sagittal sections and correlated with quantitative movement analysis of hindlimb gait patterns. Compared to the number of surviving Purkinje cells in age-matched, non-infused, or saline-infused control mutants, 4 weeks of infusion of GDNF or IGF-I rescued many anterior compartment Purkinje cells from early degeneration. However, 2 and 4 weeks after cessation of GDNF or IGF-I infusion, respectively, the number and spatial distribution of surviving Purkinje cells was comparable to that observed in age-matched controls. Eight weeks of infusion of trophic factors did not support the continued survival of most anterior compartment Purkinje cells and was partially, and probably only transiently, neuroprotective for some posterior compartment Purkinje cells. When GDNF and IGF-I were infused together for 4 weeks the number of surviving Purkinje cells was additively greater than with either factor alone. Behaviorally, 4 weeks of infusion of trophic factors delayed the development of gait ataxia. Infused GDNF appeared to preserve hip stability, whereas IGF-I stabilized step length. Tremor was attenuated with 8 weeks of infusion of GDNF or IGF-I. GDNF-infused animals showed low power tremor frequencies, whereas IGF-I infusion resulted in a single large power peak with decreased numbers of low-amplitude frequencies. Collectively these findings indicate that exogenous trophic factors can delay the onset of hereditary Purkinje cell degeneration and gait ataxia. Quite surprisingly, GDNF and IGF-I appeared to act on disparate populations of mutant Purkinje cells, whose differential survival affected different aspects of locomotion.
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Affiliation(s)
- Daniel L Tolbert
- Department of Anatomy and Neurobiology, Saint Louis University School of Medicine, St Louis, MO 63104, USA.
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Tolbert DL, Bradley MW, Tolod EG, Torres-Aleman I, Clark BR. Chronic intraventricular infusion of glial cell line-derived neurotrophic factor (GDNF) rescues some cerebellar Purkinje cells from heredodegeneration. Exp Neurol 2001; 170:375-9. [PMID: 11476604 DOI: 10.1006/exnr.2001.7718] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cerebellar Purkinje cells degenerate in shaker mutant rats. Glia cell line-derived neurotrophic factor (GDNF) was chronically infused intraventricularly in an attempt to rescue mutant Purkinje cells from dying. Four weeks of chronic GDNF infusion delayed the degeneration of many but not all Purkinje cells. Surviving Purkinje cells formed spatially related groups interrupted by other groups of degenerated Purkinje cells. There was a positive correlation in GDNF-supported Purkinje cell survival and persistence of normal motor behaviors.
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Affiliation(s)
- D L Tolbert
- Francis and Doris Murphy Neuroanatomy Research Laboratory, Department of Anatomy and Neurobiology, Saint Louis University School of Medicine, St. Louis, Missouri 63104, USA
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Abstract
Brainstem inferior olivary neurons, through their olivocerebellar efferent projections, dynamically regulate the structure and function of Purkinje neurons. To test the hypothesis that the inferior olive can epigenetically modify adult-onset hereditary Purkinje cell death, olivocerebellar projections were destroyed by 3-acetylpyridine chemoablation of the inferior olive in Shaker mutant rats. Starting around seven weeks of age, mutant Purkinje cells degenerate in a highly predictable spatial and temporal pattern. Chemoablation of the inferior olive at the onset of hereditary Purkinje cell degeneration accelerated the temporal pattern of Purkinje cell death from a natural phenotypic course of six to eight weeks to one and two weeks. When chemoablation of the inferior olive was performed three and a half weeks earlier, the onset of Purkinje cell death was accelerated by seven to 10days, but the spatial pattern and natural rate of temporal degeneration was maintained. Chemoablation of the inferior olive in normal rats did not result in any apparent death of Purkinje cells. These findings indicate that the olivocerebellar system can markedly modify hereditary Purkinje cell death. The accelerated death of Purkinje cells following chemoablation of the inferior olive can result from either the interruption of a trophic signal by climbing fiber deafferentation or parallel fiber excitotoxicity due to cortical disinhibition, but not due to olivocerebellar excitotoxicity.
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Affiliation(s)
- D L Tolbert
- Francis and Doris Murphy Neuroanatomy Research Laboratory, Department of Anatomy and Neurobiology, and Department of Surgery (Neurosurgery), Saint Louis University School of Medicine, St Louis, MO 63104, USA.
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