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Kasanga EA, Soto I, Centner A, McManus R, Shifflet MK, Navarrete W, Han Y, Lisk J, Ehrhardt T, Wheeler K, Mhatre-Winters I, Richardson JR, Bishop C, Nejtek VA, Salvatore MF. Moderate intensity aerobic exercise alleviates motor deficits in 6-OHDA lesioned rats and reduces serum levels of biomarkers of Parkinson's disease severity without recovery of striatal dopamine or tyrosine hydroxylase. Exp Neurol 2024; 379:114875. [PMID: 38944332 DOI: 10.1016/j.expneurol.2024.114875] [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: 03/20/2024] [Revised: 06/11/2024] [Accepted: 06/20/2024] [Indexed: 07/01/2024]
Abstract
Alleviation of motor impairment by aerobic exercise (AE) in Parkinson's disease (PD) patients points to activation of neurobiological mechanisms that may be targetable by therapeutic approaches. However, evidence for AE-related recovery of striatal dopamine (DA) signaling or tyrosine hydroxylase (TH) loss has been inconsistent in rodent studies. This ambiguity may be related to the timing of AE intervention in relation to the status of nigrostriatal neuron loss. Here, we replicated human PD at diagnosis by establishing motor impairment with >80% striatal DA and TH loss prior to initiating AE, and assessed its potential to alleviate motor decline and restore DA and TH loss. We also evaluated if serum levels of neurofilament light (NfL) and glial fibrillary acidic protein (GFAP), biomarkers of human PD severity, changed in response to AE. 6-hydroxydopamine (6-OHDA) was infused unilaterally into rat medial forebrain bundle to induce progressive nigrostriatal neuron loss over 28 days. Moderate intensity AE (3× per week, 40 min/session), began 8-10 days post-lesion following establishment of impaired forelimb use. Striatal tissue DA, TH protein and mRNA, and serum levels of NfL/GFAP were determined 3-wks after AE began. Despite severe striatal DA depletion at AE initiation, forelimb use deficits and hypokinesia onset were alleviated by AE, without recovery of striatal DA or TH protein loss, but reduced NfL and GFAP serum levels. This proof-of-concept study shows AE alleviates motor impairment when initiated with >80% striatal DA loss without obligate recovery of striatal DA or TH protein. Moreover, the AE-related reduction of NfL and GFAP serum levels may serve as objective blood-based biomarkers of AE efficacy.
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Affiliation(s)
- Ella A Kasanga
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States of America
| | - Isabel Soto
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States of America
| | - Ashley Centner
- Department of Psychology, Binghamton University, Binghamton, NY, United States of America
| | - Robert McManus
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States of America
| | - Marla K Shifflet
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States of America
| | - Walter Navarrete
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States of America
| | - Yoonhee Han
- Department of Environmental Health Sciences, Robert Stempel School of Public Health & Social Work, Florida International University, Miami, FL, United States of America; Isakson Center for Neurological Disease Research, College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
| | - Jerome Lisk
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States of America
| | - Travis Ehrhardt
- Clearcut Ortho Rehab & Diagnostics, Fort Worth, TX, United States of America
| | - Ken Wheeler
- Clearcut Ortho Rehab & Diagnostics, Fort Worth, TX, United States of America
| | - Isha Mhatre-Winters
- Department of Environmental Health Sciences, Robert Stempel School of Public Health & Social Work, Florida International University, Miami, FL, United States of America; Isakson Center for Neurological Disease Research, College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
| | - Jason R Richardson
- Department of Environmental Health Sciences, Robert Stempel School of Public Health & Social Work, Florida International University, Miami, FL, United States of America; Isakson Center for Neurological Disease Research, College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
| | - Christopher Bishop
- Department of Psychology, Binghamton University, Binghamton, NY, United States of America
| | - Vicki A Nejtek
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States of America
| | - Michael F Salvatore
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States of America.
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Soto I, McManus R, Navarrete W, Kasanga EA, Doshier K, Nejtek VA, Salvatore MF. Aging accelerates locomotor decline in PINK1 knockout rats in association with decreased nigral, but not striatal, dopamine and tyrosine hydroxylase expression. Exp Neurol 2024; 376:114771. [PMID: 38580154 DOI: 10.1016/j.expneurol.2024.114771] [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: 02/01/2024] [Revised: 03/15/2024] [Accepted: 04/02/2024] [Indexed: 04/07/2024]
Abstract
Parkinson's disease (PD) rodent models provide insight into the relationship between nigrostriatal dopamine (DA) signaling and locomotor function. Although toxin-based rat models produce frank nigrostriatal neuron loss and eventual motor decline characteristic of PD, the rapid nature of neuronal loss may not adequately translate premotor traits, such as cognitive decline. Unfortunately, rodent genetic PD models, like the Pink1 knockout (KO) rat, often fail to replicate the differential severity of striatal DA and tyrosine hydroxylase (TH) loss, and a bradykinetic phenotype, reminiscent of human PD. To elucidate this inconsistency, we evaluated aging as a progression factor in the timing of motor and non-motor cognitive impairments. Male PINK1 KO and age-matched wild type (WT) rats were evaluated in a longitudinal study from 3 to 16 months old in one cohort, and in a cross-sectional study of young adult (6-7 months) and aged (18-19 months) in another cohort. Young adult PINK1 KO rats exhibited hyperkinetic behavior associated with elevated DA and TH in the substantia nigra (SN), which decreased therein, but not striatum, in the aged KO rats. Additionally, norepinephrine levels decreased in aged KO rats in the prefrontal cortex (PFC), paired with a higher DA levels in young and aged KO. Although a younger age of onset characterizes familial forms of PD, our results underscore the critical need to consider age-related factors. Moreover, the results indicate that compensatory mechanisms may exist to preserve locomotor function, evidenced by increased DA in the SN early in the lifespan, in response to deficient PINK1 function, which declines with aging and the onset of motor decline.
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Affiliation(s)
- Isabel Soto
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America
| | - Robert McManus
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America
| | - Walter Navarrete
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America
| | - Ella A Kasanga
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America
| | - Kirby Doshier
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America
| | - Vicki A Nejtek
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America
| | - Michael F Salvatore
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America.
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Soto I, Nejtek VA, Siderovski DP, Salvatore MF. PINK1 knockout rats show premotor cognitive deficits measured through a complex maze. Front Neurosci 2024; 18:1390215. [PMID: 38817910 PMCID: PMC11137248 DOI: 10.3389/fnins.2024.1390215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 04/26/2024] [Indexed: 06/01/2024] Open
Abstract
Cognitive decline in Parkinson's disease (PD) is a critical premotor sign that may occur in approximately 40% of PD patients up to 10 years prior to clinical recognition and diagnosis. Delineating the mechanisms and specific behavioral signs of cognitive decline associated with PD prior to motor impairment is a critical unmet need. Rodent PD models that have an impairment in a cognitive phenotype for a time period sufficiently long enough prior to motor decline can be useful to establish viable candidate mechanisms. Arguably, the methods used to evaluate cognitive decline in rodent models should emulate methods used in the assessment of humans to optimize translation. Premotor cognitive decline in human PD can potentially be examined in the genetically altered PINK1-/- rat model, which exhibits a protracted onset of motor decline in most studies. To increase translation to cognitive assessment in human PD, we used a modified non-water multiple T-maze, which assesses attention, cognitive flexibility, and working memory similarly to the Trail Making Test (TMT) in humans. Similar to the deficiencies revealed in TMT test outcomes in human PD, 4-month-old PINK1-/- rats made more errors and took longer to complete the maze, despite a hyperkinetic phenotype, compared to wild-type rats. Thus, we have identified a potential methodological tool with cross-species translation to evaluate executive functioning in an established PD rat model.
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Affiliation(s)
- Isabel Soto
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States
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Soto I, McManus R, Navarrete-Barahona W, Kasanga EA, Doshier K, Nejtek VA, Salvatore MF. Aging hastens locomotor decline in PINK1 knockout rats in association with decreased nigral, but not striatal, dopamine and tyrosine hydroxylase expression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.01.578317. [PMID: 38352365 PMCID: PMC10862808 DOI: 10.1101/2024.02.01.578317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Parkinson's disease (PD) rodent models provide insight into the relationship between nigrostriatal dopamine (DA) signaling and locomotor function. Although toxin-based rat models produce frank nigrostriatal neuron loss and eventual motor decline characteristic of PD, the rapid nature of neuronal loss may not adequately translate premotor traits, such as cognitive decline. Unfortunately, rodent genetic PD models, like the Pink1 knockout (KO) rat, often fail to replicate the differential severity of striatal DA and tyrosine hydroxylase (TH) loss, and a bradykinetic phenotype, reminiscent of human PD. To elucidate this inconsistency, we evaluated aging as a progression factor in the timing of motor and non-motor cognitive impairments. Male PINK1 KO and age-matched wild type (WT) rats were evaluated in a longitudinal study from 3 to 16 months old in one cohort, and in a cross-sectional study of young adult (6-7 months) and aged (18-19 months) in another cohort. Young adult PINK1 KO rats exhibited hyperkinetic behavior associated with elevated DA and TH in the substantia nigra (SN), which decreased therein, but not striatum, in the aged KO rats. Additionally, norepinephrine levels decreased in aged KO rats in the prefrontal cortex (PFC), paired with a higher DA content in young and aged KO. Although a younger age of onset characterizes familial forms of PD, our results underscore the critical need to consider age-related factors. Moreover, the results indicate that compensatory mechanisms may exist to preserve locomotor function, evidenced by increased DA in the SN early in the lifespan, in response to deficient PINK1 function, which declines with aging and the onset of motor impairment.
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Soto I, Nejtek VA, Siderovski DP, Salvatore MF. PINK1 knockout rats show premotor cognitive deficits measured through a complex maze. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.18.576285. [PMID: 38293068 PMCID: PMC10827158 DOI: 10.1101/2024.01.18.576285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Cognitive decline in Parkinson's disease (PD) emerges up to 10 years before clinical recognition. Neurobiological mechanisms underlying premotor cognitive impairment in PD can potentially be examined in the PINK1 -/- rat, which exhibits a protracted motor onset. To enhance translation to human PD cognitive assessments, we tested a modified multiple T-maze, which measures cognitive flexibility similarly to the Trail-Making Test in humans. Like human PD outcomes, PINK1 -/- rats made more errors and took longer to complete the maze than wild types. Thus, we have identified a potential tool for assessing cross-species translation of cognitive functioning in an established PD animal model.
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Kasanga EA, Han Y, Shifflet MK, Navarrete W, McManus R, Parry C, Barahona A, Nejtek VA, Manfredsson FP, Kordower JH, Richardson JR, Salvatore MF. Nigral-specific increase in ser31 phosphorylation compensates for tyrosine hydroxylase protein and nigrostriatal neuron loss: Implications for delaying parkinsonian signs. Exp Neurol 2023; 368:114509. [PMID: 37634696 DOI: 10.1016/j.expneurol.2023.114509] [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: 05/22/2023] [Revised: 08/08/2023] [Accepted: 08/23/2023] [Indexed: 08/29/2023]
Abstract
Compensatory mechanisms that augment dopamine (DA) signaling are thought to mitigate onset of hypokinesia prior to major loss of tyrosine hydroxylase (TH) in striatum that occurs in Parkinson's disease. However, the identity of such mechanisms remains elusive. In the present study, the rat nigrostriatal pathway was unilaterally-lesioned with 6-hydroxydopamine (6-OHDA) to determine whether differences in DA content, TH protein, TH phosphorylation, or D1 receptor expression in striatum or substantia nigra (SN) aligned with hypokinesia onset and severity at two time points. In striatum, DA and TH loss reached its maximum (>90%) 7 days after lesion induction. However, in SN, no DA loss occurred, despite ∼60% TH loss. Hypokinesia was established at 21 days post-lesion and maintained at 28 days. At this time, DA loss was ∼60% in the SN, but still of lesser magnitude than TH loss. At day 7 and 28, ser31 TH phosphorylation increased only in SN, corresponding to less DA versus TH protein loss. In contrast, ser40 TH phosphorylation was unaffected in either region. Despite DA loss in both regions at day 28, D1 receptor expression increased only in lesioned SN. These results support the concept that augmented components of DA signaling in the SN, through increased ser31 TH phosphorylation and D1 receptor expression, contribute as compensatory mechanisms against progressive nigrostriatal neuron and TH protein loss, and may mitigate hypokinesia severity.
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Affiliation(s)
- Ella A Kasanga
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76117, USA
| | - Yoonhee Han
- Robert Stempel School of Public Health and Social Work, Florida International University, Miami, FL 33199, USA
| | - Marla K Shifflet
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76117, USA
| | - Walter Navarrete
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76117, USA
| | - Robert McManus
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76117, USA
| | - Caleb Parry
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76117, USA
| | - Arturo Barahona
- Robert Stempel School of Public Health and Social Work, Florida International University, Miami, FL 33199, USA
| | - Vicki A Nejtek
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76117, USA
| | - Fredric P Manfredsson
- Parkinson's Disease Research Unit, Department of Translational Neuroscience, Barrow Neurological Institute, Phoenix, AZ 85013, USA
| | - Jeffrey H Kordower
- ASU-Banner Neurodegenerative Disease Research Center, Arizona State University, Tempe, AZ 85287, USA
| | - Jason R Richardson
- Robert Stempel School of Public Health and Social Work, Florida International University, Miami, FL 33199, USA
| | - Michael F Salvatore
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76117, USA.
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Kasanga EA, Soto I, Centner A, McManus R, Shifflet MK, Navarrete W, Han Y, Lisk J, Wheeler K, Mhatre-Winters I, Richardson JR, Bishop C, Nejtek VA, Salvatore MF. Moderate intensity aerobic exercise in 6-OHDA-lesioned rats alleviates established motor deficits and reduces neurofilament light and glial fibrillary acidic protein serum levels without increased striatal dopamine or tyrosine hydroxylase protein. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.11.548638. [PMID: 37502851 PMCID: PMC10369940 DOI: 10.1101/2023.07.11.548638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Background Alleviation of motor impairment by aerobic exercise (AE) in Parkinson's disease (PD) points to a CNS response that could be targeted by therapeutic approaches, but recovery of striatal dopamine (DA) or tyrosine hydroxylase (TH) has been inconsistent in rodent studies. Objective To increase translation of AE, 3 components were implemented into AE design to determine if recovery of established motor impairment, concomitant with >80% striatal DA and TH loss, was possible. We also evaluated if serum levels of neurofilament light (NfL) and glial fibrillary acidic protein (GFAP), blood-based biomarkers of disease severity in human PD, were affected. Methods We used a 6-OHDA hemiparkinson rat model featuring progressive nigrostriatal neuron loss over 28 days, with impaired forelimb use 7 days post-lesion, and hypokinesia onset 21 days post-lesion. After establishing forelimb use deficits, moderate intensity AE began 1-3 days later, 3x per week, for 40 min/session. Motor assessments were conducted weekly for 3 wks, followed by determination of striatal DA, TH protein and mRNA, and NfL and GFAP serum levels. Results Seven days after 6-OHDA lesion, recovery of depolarization-stimulated extracellular DA and DA tissue content was <10%, representing severity of DA loss in human PD, concomitant with 50% reduction in forelimb use. Despite severe DA loss, recovery of forelimb use deficits and alleviation of hypokinesia progression began after 2 weeks of AE and was maintained. Increased NfLand GFAP levels from lesion were reduced by AE. Despite these AE-driven changes, striatal DA tissue and TH protein levels were unaffected. Conclusions This proof-of-concept study shows AE, using exercise parameters within the capabilities most PD patients, promotes recovery of established motor deficits in a rodent PD model, concomitant with reduced levels of blood-based biomarkers associated with PD severity, without commensurate increase in striatal DA or TH protein.
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