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Salvatore MF. Dopamine Signaling in Substantia Nigra and Its Impact on Locomotor Function-Not a New Concept, but Neglected Reality. Int J Mol Sci 2024; 25:1131. [PMID: 38256204 PMCID: PMC10815979 DOI: 10.3390/ijms25021131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 01/11/2024] [Accepted: 01/13/2024] [Indexed: 01/24/2024] Open
Abstract
The mechanistic influences of dopamine (DA) signaling and impact on motor function are nearly always interpreted from changes in nigrostriatal neuron terminals in striatum. This is a standard practice in studies of human Parkinson's disease (PD) and aging and related animal models of PD and aging-related parkinsonism. However, despite dozens of studies indicating an ambiguous relationship between changes in striatal DA signaling and motor phenotype, this perseverating focus on striatum continues. Although DA release in substantia nigra (SN) was first reported almost 50 years ago, assessment of nigral DA signaling changes in relation to motor function is rarely considered. Whereas DA signaling has been well-characterized in striatum at all five steps of neurotransmission (biosynthesis and turnover, storage, release, reuptake, and post-synaptic binding) in the nigrostriatal pathway, the depth of such interrogations in the SN, outside of cell counts, is sparse. However, there is sufficient evidence that these steps in DA neurotransmission in the SN are operational and regulated autonomously from striatum and are present in human PD and aging and related animal models. To complete our understanding of how nigrostriatal DA signaling affects motor function, it is past time to include interrogation of nigral DA signaling. This brief review highlights evidence that changes in nigral DA signaling at each step in DA neurotransmission are autonomous from those in striatum and changes in the SN alone can influence locomotor function. Accordingly, for full characterization of how nigrostriatal DA signaling affects locomotor activity, interrogation of DA signaling in SN is essential.
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Affiliation(s)
- Michael F Salvatore
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
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2
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Sandberg SG, Sanford CA, Phillips PEM. Substantial decline of phasic dopamine signaling in senescent male rats does not impact dopamine-dependent Pavlovian conditioning. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.21.572806. [PMID: 38187581 PMCID: PMC10769384 DOI: 10.1101/2023.12.21.572806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Normal aging is associated with cognitive decline which impacts financial decision making. One of the underlying features of decision making is probability estimation, in which nucleus accumbens dopamine signaling has been implicated. Here we used fast-scan cyclic voltammetry to probe for age differences in dopamine signaling, and pharmacological manipulation to test for age differences in the dopamine dependence of Pavlovian conditioning. We found differences in phasic dopamine signaling to reward delivery, and unconditioned and conditioned stimuli, but no difference in conditioned approach between adult and senescent groups. In addition, we found that dopamine receptor antagonism with flupenthixol (225 μg/kg, i.p.) partially inhibited conditioned approach in the adult group, whereas it completely blocked conditioned approach in the senescent group. Further increase in concentration to 300 μg/kg, i.p. resulted in complete inhibition of conditioned approach behavior in both age groups. Therefore, while phasic dopamine signaling in the nucleus accumbens of senescent animals is greatly diminished in concentration, these animals maintain dopamine dependent Pavlovian conditioning.
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Affiliation(s)
- Stefan G. Sandberg
- Center for Neurobiology of Addiction, Pain & Emotion, University of Washington, Seattle, WA 98195, USA
- Department of Psychiatry & Behavioral Sciences, University of Washington, Seattle, WA 98195, USA
| | - Christina A. Sanford
- Department of Psychiatry & Behavioral Sciences, University of Washington, Seattle, WA 98195, USA
| | - Paul E. M. Phillips
- Center for Neurobiology of Addiction, Pain & Emotion, University of Washington, Seattle, WA 98195, USA
- Department of Psychiatry & Behavioral Sciences, University of Washington, Seattle, WA 98195, USA
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
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3
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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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4
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Inoue R, Nishimune H. Neuronal Plasticity and Age-Related Functional Decline in the Motor Cortex. Cells 2023; 12:2142. [PMID: 37681874 PMCID: PMC10487126 DOI: 10.3390/cells12172142] [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: 07/16/2023] [Revised: 08/16/2023] [Accepted: 08/23/2023] [Indexed: 09/09/2023] Open
Abstract
Physiological aging causes a decline of motor function due to impairment of motor cortex function, losses of motor neurons and neuromuscular junctions, sarcopenia, and frailty. There is increasing evidence suggesting that the changes in motor function start earlier in the middle-aged stage. The mechanism underlining the middle-aged decline in motor function seems to relate to the central nervous system rather than the peripheral neuromuscular system. The motor cortex is one of the responsible central nervous systems for coordinating and learning motor functions. The neuronal circuits in the motor cortex show plasticity in response to motor learning, including LTP. This motor cortex plasticity seems important for the intervention method mechanisms that revert the age-related decline of motor function. This review will focus on recent findings on the role of plasticity in the motor cortex for motor function and age-related changes. The review will also introduce our recent identification of an age-related decline of neuronal activity in the primary motor cortex of middle-aged mice using electrophysiological recordings of brain slices.
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Affiliation(s)
- Ritsuko Inoue
- Laboratory of Neurobiology of Aging, Tokyo Metropolitan Institute for Geriatrics and Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo 173-0015, Japan;
| | - Hiroshi Nishimune
- Laboratory of Neurobiology of Aging, Tokyo Metropolitan Institute for Geriatrics and Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo 173-0015, Japan;
- Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-8-1 Harumicho, Fuchu-shi, Tokyo 183-8538, Japan
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Modulation of nigral dopamine signaling mitigates parkinsonian signs of aging: evidence from intervention with calorie restriction or inhibition of dopamine uptake. GeroScience 2023; 45:45-63. [PMID: 35635679 PMCID: PMC9886753 DOI: 10.1007/s11357-022-00583-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 04/29/2022] [Indexed: 02/03/2023] Open
Abstract
Identifying neurobiological mechanisms of aging-related parkinsonism, and lifestyle interventions that mitigate them, remain critical knowledge gaps. No aging study, from rodent to human, has reported loss of any dopamine (DA) signaling marker near the magnitude associated with onset of parkinsonian signs in Parkinson's disease (PD). However, in substantia nigra (SN), similar loss of DA signaling markers in PD or aging coincide with parkinsonian signs. Alleviation of these parkinsonian signs may be possible by interventions such as calorie restriction (CR), which augment DA signaling markers like tyrosine hydroxylase (TH) expression in the SN, but not striatum. Here, we interrogated respective contributions of nigral and striatal DA mechanisms to aging-related parkinsonian signs in aging (18 months old) rats in two studies: by the imposition of CR for 6 months, and inhibition of DA uptake within the SN or striatum by cannula-directed infusion of nomifensine. Parkinsonian signs were mitigated within 12 weeks after CR and maintained until 24 months old, commensurate with increased D1 receptor expression in the SN alone, and increased GDNF family receptor, GFR-α1, in the striatum, suggesting increased GDNF signaling. Nomifensine infusion into the SN or striatum selectively increased extracellular DA. However, only nigral infusion increased locomotor activity. These results indicate mechanisms that increase components of DA signaling in the SN alone mitigate parkinsonian signs in aging, and are modifiable by interventions, like CR, to offset parkinsonian signs, even at advanced age. Moreover, these results give evidence that changes in nigral DA signaling may modulate some parameters of locomotor activity autonomously from striatal DA signaling.
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Parecoxib alleviates the motor behavioral decline of aged rats by ameliorating mitochondrial dysfunction in the substantia nigra via COX-2/PGE2 pathway inhibition. Neuropharmacology 2021; 194:108627. [PMID: 34089729 DOI: 10.1016/j.neuropharm.2021.108627] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 05/15/2021] [Accepted: 05/19/2021] [Indexed: 12/17/2022]
Abstract
Mitochondrial dysfunction manifests as an early event in the substantia nigra (SN) in aging and Parkinson disease. Cyclooxygenase 2 (COX-2), the rate-limiting enzyme in the prostaglandin E2 (PGE2) synthesis pathway, is implicated in aging and age-related neurodegenerative diseases; moreover, inhibition of COX-2 expression has been shown to be neuroprotective for nigrostriatal dopaminergic neurons. However, it is not known whether the neuroprotective effect of COX-2 inhibition is related to improved mitochondrial function during the aging process. To this end, we explored the effects of the selective COX-2 inhibitor parecoxib on mitochondrial function in the SN of aged rats. We found that parecoxib administration to aged rats for 10 weeks decreased COX-2/PGE2 expression, increased tyrosine hydroxylase and dopamine transporter expression in nigrostriatal dopaminergic neurons, and alleviated motor behavioral decline. Decreased malondialdehyde levels and an increased GSH/GSSG ratio as well as enhanced enzymatic activities of catalase and manganese superoxide dismutase in parecoxib-treated aged rats indicate that parecoxib administration elevated antioxidative ability in the SN during the aging process. Parecoxib treatment to aged rats promoted mitochondrial biogenesis by upregulating PGC-1α/NRF-1/TFAM, enhancing mitochondrial fusion by decreasing Drp1 levels and increasing Mfn1 and OPA1 levels, and activated mitophagy by increasing PINK1/Parkin levels while reducing p62/SQSTM1 levels, thereby coordinating mitochondrial homeostasis via inhibiting the COX-2/PGE2 pathway. Thus, our results strongly support the conclusion that parecoxib treatment is conducive to improving mitochondrial dysfunction in the SN upon aging in rats.
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Rojic-Becker D, Portero-Tresserra M, Martí-Nicolovius M, Vale-Martínez A, Guillazo-Blanch G. Effects of caloric restriction on monoaminergic neurotransmission, peripheral hormones, and olfactory memory in aged rats. Behav Brain Res 2021; 409:113328. [PMID: 33930470 DOI: 10.1016/j.bbr.2021.113328] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 03/30/2021] [Accepted: 04/25/2021] [Indexed: 01/02/2023]
Abstract
Aging is associated with a reduced ability to identify and discriminate scents, and olfactory dysfunction has been linked to preclinical stages of neurodegenerative diseases in humans. Moreover, emerging evidence suggests that smell-driven behaviors are regulated by hormones like insulin or leptin, and by metabolic parameters like glucose, which in turn may influence monoaminergic neurotransmission in brain areas related to cognition. Several studies have suggested that dietary interventions like caloric restriction (CR) can mitigate the age-induced decline in memory by modifying metabolic parameters and brain monoaminergic levels. The present study explored the effects of CR on age-dependent olfactory memory deficits, as well as their relationship with peripheral leptin, insulin and glucose levels, and brain monoamines. To this end, aged rats (24-months-old) fed on a CR diet or with ad libitum access to food, and adult rats (3-4 months), were trained in an odor discrimination task (ODT). The peripheral plasma levels of insulin, leptin, and glucose, and of monoamines and metabolites/precursors in brain areas related to olfactory learning and memory processes, such as the striatum and frontal cortex (FC), were determined. The data obtained indicated that CR attenuated the age-dependent decline in olfactory sensitivity in old animals fed ad libitum, which was correlated with the performance in ODT retention trial, as well as with leptin plasma levels. CR enhanced dopamine levels in the striatum, while it attenuated the age-related decline in serotonin levels in the striatum and FC. Such findings support a positive effect of CR on age-dependent olfactory sensitivity decline and dysfunctions in brain monoamine levels.
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Affiliation(s)
- Divka Rojic-Becker
- Departament de Psicobiologia i Metodologia de les Ciències de la Salut, Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Marta Portero-Tresserra
- Departament de Psicobiologia i Metodologia de les Ciències de la Salut, Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Margarita Martí-Nicolovius
- Departament de Psicobiologia i Metodologia de les Ciències de la Salut, Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Anna Vale-Martínez
- Departament de Psicobiologia i Metodologia de les Ciències de la Salut, Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Gemma Guillazo-Blanch
- Departament de Psicobiologia i Metodologia de les Ciències de la Salut, Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain.
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8
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Kasanga EA, Little J, McInnis TR, Bugnariu N, Cunningham JT, Salvatore MF. Cardiovascular Metrics Associated With Prevention of Aging-Related Parkinsonian Signs Following Exercise Intervention in Sedentary Older Rats. Front Aging Neurosci 2021; 13:775355. [PMID: 34975456 PMCID: PMC8714671 DOI: 10.3389/fnagi.2021.775355] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 11/18/2021] [Indexed: 11/29/2022] Open
Abstract
Preservation of motor capabilities is vital to maintaining independent daily living throughout a person's lifespan and may mitigate aging-related parkinsonism, a progressive and prevalent motor impairment. Physically active lifestyles can mitigate aging-related motor impairment. However, the metrics of physical activity necessary for mitigating parkinsonian signs are not established. Consistent moderate intensity (~10 m/min) treadmill exercise can reverse aging-related parkinsonian signs by 20 weeks in a 2-week on, 2-week off, regimen in previously sedentary advanced middle-aged rats. In this study, we initiated treadmill exercise in sedentary 18-month-old male rats to address two questions: (1) if a rest period not longer than 1-week off exercise, with 15 exercise sessions per month, could attenuate parkinsonian signs within 2 months after exercise initiation, and the associated impact on heart rate (HR) and mean arterial pressure (MAP) and (2) if continuation of this regimen, up to 20 weeks, will be associated with continual prevention of parkinsonian signs. The intensity and frequency of treadmill exercise attenuated aging-related parkinsonian signs by 8 weeks and were maintained till 23 months old. The exercise regimen increased HR by 25% above baseline and gradually reduced pre-intervention MAP. Together, these studies indicate that a practicable frequency and intensity of exercise reduces parkinsonian sign severity commensurate with a modest increase in HR after exercise. These cardiovascular changes provide a baseline of metrics, easily measured in humans, for predictive validity that practicable exercise intensity and schedule can be initiated in previously sedentary older adults to delay the onset of aging-related parkinsonian signs.
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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
| | - Joel Little
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - Tamara R McInnis
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - Nicoleta Bugnariu
- School of Health Sciences, University of the Pacific, Sacramento, CA, United States
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - Michael F Salvatore
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States
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Portero-Tresserra M, Rojic-Becker D, Vega-Carbajal C, Guillazo-Blanch G, Vale-Martínez A, Martí-Nicolovius M. Caloric restriction modulates the monoaminergic system and metabolic hormones in aged rats. Sci Rep 2020; 10:19299. [PMID: 33168891 PMCID: PMC7653031 DOI: 10.1038/s41598-020-76219-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 09/30/2020] [Indexed: 12/11/2022] Open
Abstract
Caloric restriction (CR) can attenuate the general loss of health observed during aging, being one of the mechanisms involved the reduction of hormonal alteration, such as insulin and leptin. This change could also prevent age-specific fluctuations in brain monoamines, although few studies have addressed the effects of CR on peripheral hormones and central neurotransmitters exhaustively. Therefore, the variations in brain monoamine levels and some peripheral hormones were assessed here in adult 4-month old and 24-month old male Wistar rats fed ad libitum (AL) or maintained on a 30% CR diet from four months of age. Noradrenaline (NA), dopamine (DA), serotonin (5-HT) and its metabolites were measured by high-performance liquid chromatography with electrochemical detection (HPLC-ED) in nine brain regions: cerebellum, pons, midbrain, hypothalamus, thalamus, hippocampus, striatum, frontal cortex, and occipital cortex. In addition, the blood plasma levels of hormones like corticosterone, insulin and leptin were also evaluated, as were insulin-like growth factor 1 and other basal metabolic parameters using enzyme-linked immunosorbent assays (ELISAs): cholesterol, glucose, triglycerides, albumin, low-density lipoprotein, calcium and high-density lipoprotein (HDLc). CR was seen to increase the NA levels that are altered by aging in specific brain regions like the striatum, thalamus, cerebellum and hypothalamus, and the DA levels in the striatum, as well as modifying the 5-HT levels in the striatum, hypothalamus, pons and hippocampus. Moreover, the insulin, leptin, calcium and HDLc levels in the blood were restored in old animals maintained on a CR diet. These results suggest that a dietary intervention like CR may have beneficial health effects, recovering some negative effects on peripheral hormones, metabolic parameters and brain monoamine concentrations.
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Affiliation(s)
- Marta Portero-Tresserra
- Departament de Psicobiologia i Metodologia de les Ciències de la Salut, Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain.
| | - D Rojic-Becker
- Departament de Psicobiologia i Metodologia de les Ciències de la Salut, Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - C Vega-Carbajal
- Departament de Psicobiologia i Metodologia de les Ciències de la Salut, Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - G Guillazo-Blanch
- Departament de Psicobiologia i Metodologia de les Ciències de la Salut, Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - A Vale-Martínez
- Departament de Psicobiologia i Metodologia de les Ciències de la Salut, Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - M Martí-Nicolovius
- Departament de Psicobiologia i Metodologia de les Ciències de la Salut, Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
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Morgan LD, Mohammed A, Patel BA, Arundell M, Jennert-Burtson K, Hernádi L, Overall A, Bowler LD, O'Hare D, Yeoman MS. Decreased 14-3-3 expression correlates with age-related regional reductions in CNS dopamine and motor function in the pond snail, Lymnaea. Eur J Neurosci 2020; 53:1394-1411. [PMID: 33131114 DOI: 10.1111/ejn.15033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 10/23/2020] [Accepted: 10/24/2020] [Indexed: 11/28/2022]
Abstract
Ageing is associated in many organisms with a reduction in motor movements. We have previously shown that the rate of feeding movements of the pond snail, Lymnaea, decreased with age but the underlying cause is not fully understood. Here, we show that dopamine in the cerebro-buccal complex is an important signalling molecule regulating feeding frequency in Lymnaea and that ageing is associated with a decrease in CNS dopamine. A proteomic screen of young and old CNSs highlighted a group of proteins that regulate stress responses. One of the proteins identified was 14-3-3, which can enhance the synthesis of dopamine. We show that the Lymnaea 14-3-3 family exists as three distinct isoforms. The expression of the 29 kDa isoform (14-3-3Lym3) in the cerebro-buccal complex decreased with age and correlated with feeding rate. Using a 14-3-3 antagonist (R18) we were able to reduce the synthesis of L-DOPA and dopamine in ex vivo cerebro-buccal complexes. Together these data suggest that an age-related reduction in 14-3-3 can decrease CNS dopamine leading to a consequential reduction in feeding rate.
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Affiliation(s)
- Lindsay D Morgan
- Centre for Stress and Age-Related Disease, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK
| | - Aiyaz Mohammed
- Centre for Stress and Age-Related Disease, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK
| | - Bhavik Anil Patel
- Centre for Stress and Age-Related Disease, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK
| | - Martin Arundell
- Department of Bioengineering, College of Science Technology & Medicine, Imperial College, University of London, London, UK
| | - Katrin Jennert-Burtson
- Centre for Stress and Age-Related Disease, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK
| | - László Hernádi
- Balaton Limnological Institute, Centre for Ecological Research, Tihany, Hungary
| | - Andrew Overall
- Centre for Stress and Age-Related Disease, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK
| | - Lucas D Bowler
- Centre for Stress and Age-Related Disease, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK
| | - Danny O'Hare
- Department of Bioengineering, College of Science Technology & Medicine, Imperial College, University of London, London, UK
| | - Mark S Yeoman
- Centre for Stress and Age-Related Disease, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK
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11
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Zhang Y, Meng X, Jiao Z, Liu Y, Zhang X, Qu S. Generation of a Novel Mouse Model of Parkinson's Disease via Targeted Knockdown of Glutamate Transporter GLT-1 in the Substantia Nigra. ACS Chem Neurosci 2020; 11:406-417. [PMID: 31909584 DOI: 10.1021/acschemneuro.9b00609] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Parkinson's disease (PD) is a common neurodegenerative disease that is characterized by pathological dopaminergic (DA) neuronal death and α-synuclein aggregation. Glutamate excitotoxicity is a well-established pathogenesis of PD that involves dysfunctional expression of glutamate transporters. Glutamate transporter-1 (GLT-1) is mainly responsible for clearance of glutamate at synapses, including DA synapses. However, the role of GLT-1 in the aberrant synaptic transmission in PD remains elusive. In the present study, we generated small-interfering RNAs (siRNAs) to knockdown GLT-1 expression in primary astrocytes, and we report that siRNA knockdown of astrocytic GLT-1 decreased postsynaptic density-95 (PSD-95) expression in neuron-astrocyte cocultures in vitro. Using adeno-associated viruses (AAVs) targeting GLT-1 short-hairpin RNA (shRNA) sequences with a glial fibrillary acidic protein (GFAP) promoter, we abolished astrocytic GLT-1 expression in the substantia nigra pars compacta (SNpc) of mice. We found that GLT-1 deficiency in the SNpc induced parkinsonian phenotypes in terms of progressive motor deficits and nigral DA neuronal death in mice. We also found that there were reactive astrocytes and microglia in the SNpc upon GLT-1 knockdown. Furthermore, we used RNA sequencing to determine altered gene expression patterns upon GLT-1 knockdown in the SNpc, which revealed that disrupted calcium signaling pathways may be responsible for GLT-1 deficiency-mediated DA neuronal death in the SNpc. Taken together, our findings provide evidence for a novel role of GLT-1 in parkinsonian phenotypes in mice, which may contribute to further elucidation of the mechanisms of PD pathogenesis.
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Affiliation(s)
- Yunlong Zhang
- Institute of Neuroscience
and the Second Affiliated Hospital of Guangzhou Medical University, Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou 510260, China
- Shenzhen Research Institute of Xiamen University, Shenzhen 518000, China
| | - Xingjun Meng
- Central Laboratory and Department of Neurology, Shunde Hospital, Southern Medical University (The First People’s Hospital of Shunde Foshan), Foshan 528300, China
| | - Zhigang Jiao
- Central Laboratory and Department of Neurology, Shunde Hospital, Southern Medical University (The First People’s Hospital of Shunde Foshan), Foshan 528300, China
| | - Yan Liu
- Department of Traditional Chinese Medicine, Medical College, Xiamen University, Xiamen 361102, China
| | - Xiuping Zhang
- Teaching Center of Experimental Medicine, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Shaogang Qu
- Central Laboratory and Department of Neurology, Shunde Hospital, Southern Medical University (The First People’s Hospital of Shunde Foshan), Foshan 528300, China
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12
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Demir EA, Karagoz M. Platelet-Rich Plasma (PRP) is a Potential Self-Sourced Cognition Booster in Elderly Mice. Exp Aging Res 2020; 46:139-153. [PMID: 31939709 DOI: 10.1080/0361073x.2020.1716154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Background: A complex set of neurotrophic growth factors participates in neuroplasticity in the aging brain. Platelets are a copious source of growth factors, most of which display also the neurotropic activity. On this basis, we investigated behavioral and cognitive consequences of the administration of intravenous allogeneic platelet-rich plasma (PRP) in senescent mice.Methods: The animals (16-18 months old) were injected with either physiological saline or PRP which was acquired from age-matched counterparts and subjected to a battery of tests comprised of open-field, elevated-plus maze, tail suspension, and Morris water maze test.Results: We found that PRP treatment increases locomotion and improves learning and memory in elderly mice. Importantly, the PRP-treated animals did not exhibit any anxiety- or depression-like behaviors.Conclusion: The present study is the first to demonstrate that allogeneic PRP possesses beneficial effects against cognitive aging and it signifies that PRP may be used as a novel self-sourced treatment in age-related cognitive decline.
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Affiliation(s)
- Enver Ahmet Demir
- Department of Physiology, Faculty of Medicine, Hatay Mustafa Kemal University, Hatay, Turkey
| | - Mehtap Karagoz
- Faculty of Medicine, Hatay Mustafa Kemal University, Hatay, Turkey
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13
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Rojic-Becker D, Portero-Tresserra M, Martí-Nicolovius M, Vale-Martínez A, Guillazo-Blanch G. Caloric restriction modulates the monoaminergic and glutamatergic systems in the hippocampus, and attenuates age-dependent spatial memory decline. Neurobiol Learn Mem 2019; 166:107107. [DOI: 10.1016/j.nlm.2019.107107] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 10/29/2019] [Accepted: 11/04/2019] [Indexed: 12/27/2022]
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14
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Salvatore MF, McInnis TR, Cantu MA, Apple DM, Pruett BS. Tyrosine Hydroxylase Inhibition in Substantia Nigra Decreases Movement Frequency. Mol Neurobiol 2018; 56:2728-2740. [PMID: 30056575 DOI: 10.1007/s12035-018-1256-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 07/17/2018] [Indexed: 10/28/2022]
Abstract
Reduced movement frequency or physical activity (bradykinesia) occurs with high prevalence in the elderly. However, loss of striatal tyrosine hydroxylase (TH) in aging humans, non-human primates, or rodents does not reach the ~ 80% loss threshold associated with bradykinesia onset in Parkinson's disease. Moderate striatal dopamine (DA) loss, either following TH inhibition or decreased TH expression, may not affect movement frequency. In contrast, moderate DA or TH loss in the substantia nigra (SN), as occurs in aging, is of similar magnitude (~ 40%) to nigral TH loss at bradykinesia onset in Parkinson's disease. In aged rats, increased TH expression and DA in SN alone increases movement frequency, suggesting aging-related TH and DA loss in the SN contributes to aging-related bradykinesia or decreased physical activity. To test this hypothesis, the SN was targeted with bilateral guide cannula in young (6 months old) rats, in a within-subjects design, to evaluate the impact of nigral TH inhibition on movement frequency and speed. The TH inhibitor, α-methyl-p-tyrosine (AMPT) reduced nigral DA (~ 40%) 45-150 min following infusion, without affecting DA in striatum, nucleus accumbens, or adjacent ventral tegmental area. Locomotor activity in the open-field was recorded up to 3 h following nigral saline or AMPT infusion in each test subject. During the period of nigra-specific DA reduction, movement frequency, but not movement speed, was significantly decreased. These results indicate that DA or TH loss in the SN, as observed in aging, contributes as a central mechanism of reduced movement frequency.
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Affiliation(s)
- Michael F Salvatore
- Institute for Healthy Aging and Center for Neuroscience Discovery, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX, 76107, USA.
| | - Tamara R McInnis
- Institute for Healthy Aging and Center for Neuroscience Discovery, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX, 76107, USA
| | - Mark A Cantu
- Institute for Healthy Aging and Center for Neuroscience Discovery, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX, 76107, USA
| | - Deana M Apple
- Department of Cell Systems and Anatomy, Barshop Institute for Aging and Longevity Studies, UT Health San Antonio, San Antonio, TX, 78229, USA
| | - Brandon S Pruett
- Department of Psychiatry and Human Behavior, Warren Alpert Medical School of Brown University, Providence, RI, 02912, USA.,Department of Pharmacology, Toxicology, & Neuroscience, Louisiana State University Health Sciences Center, Shreveport, LA, 71130, USA
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15
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Garrido-Gil P, Dominguez-Meijide A, Moratalla R, Guerra MJ, Labandeira-Garcia JL. Aging-related dysregulation in enteric dopamine and angiotensin system interactions: implications for gastrointestinal dysfunction in the elderly. Oncotarget 2018. [PMID: 29541380 PMCID: PMC5834264 DOI: 10.18632/oncotarget.24330] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Gastrointestinal dysfunction is a common problem in the elderly. Aging-related changes in interactions between local dopaminergic and renin-angiotensin systems (RAS) have been observed in the brain, renal and vascular tissues. However, it is not known if these interactions also occur in the gut, and are dysregulated with aging. We showed a mutual regulation between the colonic dopaminergic system and RAS using young and aged mice deficient for major angiotensin and dopamine receptors. Aged rats showed a marked decrease in colonic dopamine D2 receptor expression, together with an increase in angiotensin type 1 (AT1) receptor expression, a decrease in angiotensin type 2 (AT2) receptor expression (i.e. an increase in the RAS pro-inflammatory arm activity), and increased levels of inflammatory and oxidative markers. Aged rats also showed increased levels of colonic dopamine and noradrenalin, and a marked decrease in acetylcholine and serotonin levels. The present observations contribute to explain an aging-related pro-inflammatory state and dysregulation in gastrointestinal function, which may be counteracted by treatment of aged animals with the AT1 receptor blocker candesartan.
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Affiliation(s)
- Pablo Garrido-Gil
- Laboratory of Neuroanatomy and Experimental Neurology, Department of Morphological Sciences, Research Center for Molecular Medicine and Chronic Diseases, University of Santiago de Compostela, Santiago de Compostela, Spain.,Networking Research Centre on Neurodegenerative Diseases, Madrid, Spain
| | - Antonio Dominguez-Meijide
- Laboratory of Neuroanatomy and Experimental Neurology, Department of Morphological Sciences, Research Center for Molecular Medicine and Chronic Diseases, University of Santiago de Compostela, Santiago de Compostela, Spain.,Networking Research Centre on Neurodegenerative Diseases, Madrid, Spain
| | - Rosario Moratalla
- Networking Research Centre on Neurodegenerative Diseases, Madrid, Spain.,Instituto Cajal, Madrid, Spain
| | - Maria J Guerra
- Laboratory of Neuroanatomy and Experimental Neurology, Department of Morphological Sciences, Research Center for Molecular Medicine and Chronic Diseases, University of Santiago de Compostela, Santiago de Compostela, Spain.,Networking Research Centre on Neurodegenerative Diseases, Madrid, Spain
| | - Jose L Labandeira-Garcia
- Laboratory of Neuroanatomy and Experimental Neurology, Department of Morphological Sciences, Research Center for Molecular Medicine and Chronic Diseases, University of Santiago de Compostela, Santiago de Compostela, Spain.,Networking Research Centre on Neurodegenerative Diseases, Madrid, Spain
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16
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Salvatore MF, Terrebonne J, Cantu MA, McInnis TR, Venable K, Kelley P, Kasanga EA, Latimer B, Owens CL, Pruett BS, Yu Y, Luedtke R, Forster MJ, Sumien N, Ingram DK. Dissociation of Striatal Dopamine and Tyrosine Hydroxylase Expression from Aging-Related Motor Decline: Evidence from Calorie Restriction Intervention. J Gerontol A Biol Sci Med Sci 2017. [PMID: 28637176 DOI: 10.1093/gerona/glx119] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The escalating increase in retirees living beyond their eighth decade brings increased prevalence of aging-related impairments, including locomotor impairment (Parkinsonism) that may affect ~50% of those reaching age 80, but has no confirmed neurobiological mechanism. Lifestyle strategies that attenuate motor decline, and its allied mechanisms, must be identified. Aging studies report little to moderate loss of striatal dopamine (DA) or tyrosine hydroxylase (TH) in nigrostriatal terminals, in contrast to ~70%-80% loss associated with bradykinesia onset in Parkinson's disease. These studies evaluated the effect of ~6 months 30% calorie restriction (CR) on nigrostriatal DA regulation and aging-related locomotor decline initiated at 12 months of age in Brown-Norway Fischer F1 hybrid rats. The aging-related decline in locomotor activity was prevented by CR. However, striatal DA or TH expression was decreased in the CR group, but increased in substantia nigra versus the ad libitum group or 12-month-old cohort. In a 4- to 6-month-old cohort, pharmacological TH inhibition reduced striatal DA ~30%, comparable with decreases reported in aged rats and the CR group, without affecting locomotor activity. The dissociation of moderate striatal DA reduction from locomotor activity seen in both studies suggests that aging-related decreases in striatal DA are dissociated from locomotor decline.
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Affiliation(s)
- Michael F Salvatore
- Institute for Healthy Aging and Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth
| | | | - Mark A Cantu
- Institute for Healthy Aging and Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth
| | - Tamara R McInnis
- Institute for Healthy Aging and Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth
| | - Katy Venable
- Pennington Biomedical Research Center, Baton Rouge, Louisiana
| | - Parker Kelley
- Pennington Biomedical Research Center, Baton Rouge, Louisiana
| | - Ella A Kasanga
- Institute for Healthy Aging and Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth
| | - Brian Latimer
- Louisiana State University Health Sciences Center-Shreveport
| | | | | | - Yongmei Yu
- Pennington Biomedical Research Center, Baton Rouge, Louisiana
| | - Robert Luedtke
- Institute for Healthy Aging and Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth
| | - Michael J Forster
- Institute for Healthy Aging and Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth
| | - Nathalie Sumien
- Institute for Healthy Aging and Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth
| | - Donald K Ingram
- Pennington Biomedical Research Center, Baton Rouge, Louisiana
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17
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Arnold JC, Cantu MA, Kasanga EA, Nejtek VA, Papa EV, Bugnariu N, Salvatore MF. Aging-related limit of exercise efficacy on motor decline. PLoS One 2017; 12:e0188538. [PMID: 29176896 PMCID: PMC5703560 DOI: 10.1371/journal.pone.0188538] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Accepted: 11/08/2017] [Indexed: 01/05/2023] Open
Abstract
Identifying lifestyle strategies and allied neurobiological mechanisms that reduce aging-related motor impairment is imperative, given the accelerating number of retirees and increased life expectancy. A physically active lifestyle prior to old age can reduce risk of debilitating motor decline. However, if exercise is initiated after motor decline has begun in the lifespan, it is unknown if aging itself may impose a limit on exercise efficacy to decelerate further aging-related motor decline. In Brown-Norway/Fischer 344 F1 hybrid (BNF) rats, locomotor activity begins to decrease in middle age (12-18 months). One mechanism of aging-related motor decline may be decreased expression of GDNF family receptor, GFRα-1, which is decreased in substantia nigra (SN) between 12 and 30 months old. Moderate exercise, beginning at 18 months old, increases nigral GFRα-1 and tyrosine hydroxylase (TH) expression within 2 months. In aged rats, replenishing aging-related loss of GFRα-1 in SN increases TH in SN alone and locomotor activity. A moderate exercise regimen was initiated in sedentary male BNF rats in a longitudinal study to evaluate if exercise could attenuate aging-related motor decline when initiated at two different ages in the latter half of the lifespan (18 or 24 months old). Motor decline was reversed in the 18-, but not 24-month-old, cohort. However, exercise efficacy in the 18-month-old group was reduced as the rats reached 27 months old. GFRα-1 expression was not increased in either cohort. These studies suggest exercise can decelerate motor decline when begun in the latter half of the lifespan, but its efficacy may be limited by age of initiation. Decreased plasticity of GFRα-1 expression following exercise may limit its efficacy to reverse motor decline.
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Affiliation(s)
- Jennifer C. Arnold
- Department of Pharmacology, Toxicology, and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
- Department of Neurosurgery, New York University School of Medicine, New York, New York, United States of America
| | - Mark A. Cantu
- Institute for Healthy Aging and Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth, Texas, United States of America
| | - Ella A. Kasanga
- Institute for Healthy Aging and Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth, Texas, United States of America
| | - Vicki A. Nejtek
- Institute for Healthy Aging and Center for Alzheimer’s and Neurodegenerative Disease Research, University of North Texas Health Science Center, Fort Worth, Texas, United States of America
| | - Evan V. Papa
- Department of Physical & Occupational Therapy, Idaho State University–Meridian Health Science Center, Meridian, ID, United States of America
| | - Nicoleta Bugnariu
- School of Health Professions, University of North Texas Health Science Center, Fort Worth, Texas, United States of America
| | - Michael F. Salvatore
- Department of Pharmacology, Toxicology, and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
- Institute for Healthy Aging and Center for Neuroscience Discovery, University of North Texas Health Science Center, Fort Worth, Texas, United States of America
- * E-mail:
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18
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Moinard C, Tliba L, Diaz J, Le Plénier S, Nay L, Neveux N, Cynober L, Raynaud-Simon A. Citrulline stimulates locomotor activity in aged rats: Implication of the dopaminergic pathway. Nutrition 2017; 38:9-12. [DOI: 10.1016/j.nut.2017.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 12/21/2016] [Accepted: 01/01/2017] [Indexed: 12/20/2022]
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19
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Deficits in coordinated motor behavior and in nigrostriatal dopaminergic system ameliorated and VMAT2 expression up-regulated in aged male rats by administration of testosterone propionate. Exp Gerontol 2016; 78:1-11. [PMID: 26956479 DOI: 10.1016/j.exger.2016.03.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 02/23/2016] [Accepted: 03/02/2016] [Indexed: 12/16/2022]
Abstract
The effects of testosterone propionate (TP) supplements on the coordinated motor behavior and nigrostriatal dopaminergic (NSDA) system were analyzed in aged male rats. The present study showed the coordinated motor behavioral deficits, the reduced activity of NSDA system and the decreased expression of vesicular monoamine transporter 2 (VMAT2) in 24 month-old male rats. Long term TP treatment improved the motor coordination dysfunction with aging. Increased tyrosine hydroxylase and dopamine transporter, as well as dopamine and its metabolites were found in the NSDA system of TP-treated 24 month-old male rats, indicative of the amelioratory effects of TP supplements on NSDA system of aged male rats. The enhancement of dopaminergic (DAergic) activity of NSDA system by TP supplements might underlie the amelioration of the coordinated motor dysfunction in aged male rats. TP supplements up-regulated VMAT2 expression in NSDA system of aged male rats. Up-regulation of VMAT2 expression in aged male rats following chronic TP treatment might be involved in the maintenance of DAergic function of NSDA system in aged male rats.
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20
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Arnold JC, Salvatore MF. Exercise-Mediated Increase in Nigral Tyrosine Hydroxylase Is Accompanied by Increased Nigral GFR-α1 and EAAC1 Expression in Aging Rats. ACS Chem Neurosci 2016; 7:227-39. [PMID: 26599339 PMCID: PMC4926611 DOI: 10.1021/acschemneuro.5b00282] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Exercise may alleviate locomotor impairment in Parkinson's disease (PD) or aging. Identifying molecular responses immediately engaged by exercise in the nigrostriatal pathway and allied tissue may reveal critical targets associated with its long-term benefits. In aging, there is loss of tyrosine hydroxylase (TH) and the glial cell line-derived neurotrophic factor (GDNF) receptor, GFR-α1, in the substantia nigra (SN). Exercise can increase GDNF expression, but its effect on GFR-α1 expression is unknown. Infusion of GDNF into striatum or GFR-α1 in SN, respectively, can increase locomotor activity and TH function in SN but not striatum in aged rats. GDNF may also increase glutamate transporter expression, which attenuates TH loss in PD models. We utilized a footshock-free treadmill exercise regimen to determine the immediate impact of short-term exercise on GFR-α1 expression, dopamine regulation, glutamate transporter expression, and glutamate uptake in 18 month old male Brown-Norway/Fischer 344 F1 hybrid rats. GFR-α1 and TH expression significantly increased in SN but not striatum. This exercise regimen did not affect glutamate uptake or glutamate transporter expression in striatum. However, EAAC1 expression increased in SN. These results indicate that nigral GFR-α1 and EAAC1 expression increased in conjunction with increased nigral TH expression following short-term exercise.
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Affiliation(s)
- Jennifer C. Arnold
- Department of Pharmacology, Toxicology & Neuroscience, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130, United States
| | - Michael F. Salvatore
- Department of Pharmacology, Toxicology & Neuroscience, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130, United States
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas 76107, United States
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21
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Salvatore MF, Terrebonne J, Fields V, Nodurft D, Runfalo C, Latimer B, Ingram DK. Initiation of calorie restriction in middle-aged male rats attenuates aging-related motoric decline and bradykinesia without increased striatal dopamine. Neurobiol Aging 2016; 37:192-207. [PMID: 26610387 PMCID: PMC4688216 DOI: 10.1016/j.neurobiolaging.2015.10.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Revised: 10/07/2015] [Accepted: 10/08/2015] [Indexed: 01/07/2023]
Abstract
Aging-related bradykinesia affects ∼ 15% of those reaching age 65 and 50% of those reaching their 80s. Given this high risk and lack of pharmacologic therapeutics, noninvasive lifestyle strategies should be identified to diminish its risk and identify the neurobiological targets to reduce aging-related bradykinesia. Early-life, long-term calorie restriction (CR) attenuates aging-related bradykinesia in rodents. Here, we addressed whether CR initiation at middle age could attenuate aging-related bradykinesia and motoric decline measured as rotarod performance. A 30% CR regimen was implemented for 6 months duration in 12-month-old male Brown-Norway Fischer 344 F1 hybrid rats after establishing individual baseline locomotor activities. Locomotor capacity was assessed every 6 weeks thereafter. The ad libitum group exhibited predictably decreased locomotor activity, except movement speed, out to 18 months of age. In contrast, in the CR group, movement number and horizontal activity did not decrease during the 6-month trial, and aging-related decline in rotarod performance was attenuated. The response to CR was influenced by baseline locomotor activity. The lower the locomotor activity level at baseline, the greater the response to CR. Rats in the lower 50th percentile surpassed their baseline level of activity, whereas rats in the top 50th percentile decreased at 6 weeks and then returned to baseline by 12 weeks of CR. We hypothesized that nigrostriatal dopamine tissue content would be greater in the CR group and observed a modest increase only in substantia nigra with no group differences in striatum, nucleus accumbens, or ventral tegmental area. These results indicate that initiation of CR at middle age may reduce aging-related bradykinesia, and, furthermore, subjects with below average locomotor activity may increase baseline activity. Sustaining nigral dopamine neurotransmission may be one component of preserving locomotor capabilities during aging.
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Affiliation(s)
- Michael F Salvatore
- Department of Pharmacology, Toxicology, & Neuroscience, Louisiana State University Health Sciences Center, Shreveport, LA, USA; Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, USA.
| | - Jennifer Terrebonne
- Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA, USA
| | - Victoria Fields
- Department of Pharmacology, Toxicology, & Neuroscience, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Danielle Nodurft
- Department of Pharmacology, Toxicology, & Neuroscience, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Cori Runfalo
- Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA, USA
| | - Brian Latimer
- Department of Pharmacology, Toxicology, & Neuroscience, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | - Donald K Ingram
- Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA, USA
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Parkinson GM, Dayas CV, Smith DW. Age-related gene expression changes in substantia nigra dopamine neurons of the rat. Mech Ageing Dev 2015; 149:41-9. [PMID: 26065381 DOI: 10.1016/j.mad.2015.06.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 06/01/2015] [Accepted: 06/02/2015] [Indexed: 02/01/2023]
Abstract
Ageing affects most, if not all, functional systems in the body. For example, the somatic motor nervous system, responsible for initiating and regulating motor output to skeletal musculature, is vulnerable to ageing. The nigrostriatal dopamine pathway is one component of this system, with deficits in dopamine signalling contributing to major motor dysfunction, as exemplified in Parkinson's disease (PD). However, while the dopamine deficit in PD is due to degeneration of substantia nigra (SN) dopamine (DA) neurons, it is unclear whether there is sufficient loss of SN DA neurons with ageing to explain observed motor impairments. Instead, evidence suggests that age-related loss of DA neuron function may be more important than frank cell loss. To further elucidate the mechanisms of functional decline, we have investigated age-related changes in gene expression specifically in laser microdissected SN DA neurons. There were significant age-related changes in the expression of genes associated with neurotrophic factor signalling and the regulation of tyrosine hydroxylase activity. Furthermore, reduced expression of the DA neuron-associated transcription factor, Nurr1, may contribute to these changes. Together, these results suggest that altered neurotrophic signalling and tyrosine hydroxylase activity may contribute to altered DA neuron signalling and motor nervous system regulation in ageing.
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Affiliation(s)
- Gemma M Parkinson
- Preclinical Neurobiology Research Program, School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW 2308, Australia; Centre for Translational Neuroscience and Mental Health Research, University of Newcastle, Callaghan, NSW 2308, Australia; Hunter Medical Research Institute, 1/Kookaburra Circuit, New Lambton Heights, NSW 2305, Australia.
| | - Christopher V Dayas
- Preclinical Neurobiology Research Program, School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW 2308, Australia; Centre for Translational Neuroscience and Mental Health Research, University of Newcastle, Callaghan, NSW 2308, Australia; Hunter Medical Research Institute, 1/Kookaburra Circuit, New Lambton Heights, NSW 2305, Australia.
| | - Doug W Smith
- Preclinical Neurobiology Research Program, School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW 2308, Australia; Centre for Translational Neuroscience and Mental Health Research, University of Newcastle, Callaghan, NSW 2308, Australia; Hunter Medical Research Institute, 1/Kookaburra Circuit, New Lambton Heights, NSW 2305, Australia.
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Differential effects of amphetamine and GBR-12909 on orolingual motor function in young vs aged F344/BN rats. Psychopharmacology (Berl) 2014; 231:4695-701. [PMID: 24923981 PMCID: PMC4301607 DOI: 10.1007/s00213-014-3620-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 05/13/2014] [Indexed: 10/25/2022]
Abstract
RATIONALE Orolingual motor deficits, such as dysarthria and dysphagia, contribute to increased morbidity and mortality in the elderly. In preclinical studies, we and others have reported age-related decreases in tongue motility in both F344 and F344/BN rats. The fact that these deficits are associated with nigrostriatal dopamine (DA), tissue measures suggest that increasing dopamine function might normalize tongue motility. OBJECTIVE The purpose of the current study was to determine whether two indirect dopamine agonists with locomotor-enhancing effects, d-amphetamine (amphetamine; 1 and 2 mg/kg) and GBR-12909 (5, 10, and 20 mg/kg), can improve tongue motility in aged F344/BN rats. METHODS Young (6 months) and aged (30 months) F344/BN rats licked water from an isometric force disc so that tongue motility (licks/second) and tongue force could be measured as a function of age and drug dose. RESULTS Consistent with our previous studies, tongue force was greater and tongue motility was lower in the aged group. Tongue motility was increased by amphetamine but not by GBR-12909. Amphetamine decreased peak tongue force, primarily in the young group. GBR-12909 did not affect tongue force. GBR-12909 increased the number of licks/session in the young group but not in the aged group, while amphetamine increased this measure in both groups. CONCLUSION These results demonstrate differential effects of these drugs on orolingual motor function and suggest that blocking DA uptake is insufficient to increase tongue motility in aging.
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Arnold JC, Salvatore MF. Getting to compliance in forced exercise in rodents: a critical standard to evaluate exercise impact in aging-related disorders and disease. J Vis Exp 2014. [PMID: 25178094 DOI: 10.3791/51827] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
There is a major increase in the awareness of the positive impact of exercise on improving several disease states with neurobiological basis; these include improving cognitive function and physical performance. As a result, there is an increase in the number of animal studies employing exercise. It is argued that one intrinsic value of forced exercise is that the investigator has control over the factors that can influence the impact of exercise on behavioral outcomes, notably exercise frequency, duration, and intensity of the exercise regimen. However, compliance in forced exercise regimens may be an issue, particularly if potential confounds of employing foot-shock are to be avoided. It is also important to consider that since most cognitive and locomotor impairments strike in the aged individual, determining impact of exercise on these impairments should consider using aged rodents with a highest possible level of compliance to ensure minimal need for test subjects. Here, the pertinent steps and considerations necessary to achieve nearly 100% compliance to treadmill exercise in an aged rodent model will be presented and discussed. Notwithstanding the particular exercise regimen being employed by the investigator, our protocol should be of use to investigators that are particularly interested in the potential impact of forced exercise on aging-related impairments, including aging-related Parkinsonism and Parkinson's disease.
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Affiliation(s)
- Jennifer C Arnold
- Department of Pharmacology, Toxicology, & Neuroscience, Louisiana State University Health Sciences Center
| | - Michael F Salvatore
- Department of Pharmacology, Toxicology, & Neuroscience, Louisiana State University Health Sciences Center;
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25
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Aging-related dysregulation of dopamine and angiotensin receptor interaction. Neurobiol Aging 2014; 35:1726-38. [PMID: 24529758 DOI: 10.1016/j.neurobiolaging.2014.01.017] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 01/10/2014] [Accepted: 01/13/2014] [Indexed: 12/22/2022]
Abstract
It is not known whether the aging-related decrease in dopaminergic function leads to the aging-related higher vulnerability of dopaminergic neurons and risk for Parkinson's disease. The renin-angiotensin system (RAS) plays a major role in the inflammatory response, neuronal oxidative stress, and dopaminergic vulnerability via type 1 (AT1) receptors. In the present study, we observed a counterregulatory interaction between dopamine and angiotensin receptors. We observed overexpression of AT1 receptors in the striatum and substantia nigra of young adult dopamine D1 and D2 receptor-deficient mice and young dopamine-depleted rats, together with compensatory overexpression of AT2 receptors or compensatory downregulation of angiotensinogen and/or angiotensin. In aged rats, we observed downregulation of dopamine and dopamine receptors and overexpression of AT1 receptors in aged rats, without compensatory changes observed in young animals. L-Dopa therapy inhibited RAS overactivity in young dopamine-depleted rats, but was ineffective in aged rats. The results suggest that dopamine may play an important role in modulating oxidative stress and inflammation in the substantia nigra and striatum via the RAS, which is impaired by aging.
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Parmar MS, Jaumotte JD, Wyrostek SL, Zigmond MJ, Cavanaugh JE. Role of ERK1, 2, and 5 in dopamine neuron survival during aging. Neurobiol Aging 2013; 35:669-79. [PMID: 24411019 DOI: 10.1016/j.neurobiolaging.2013.09.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 07/15/2013] [Accepted: 09/19/2013] [Indexed: 11/27/2022]
Abstract
Extracellular signal-regulated kinases (ERKs) 1, 2, and 5 have been shown to play distinct roles in proliferation, differentiation, and neuronal viability. In this study, we examined ERK1, 2, and 5 expression and activation in the substantia nigra (SN), striatum (STR), and ventral tegmental area (VTA) during aging. An age-related decrease in phosphorylated ERK5 was observed in the SN and STR, whereas an increase in total ERK1 was observed in all 3 regions. In primary cultures of the SN and VTA, inhibition of ERK5 but not ERK1 and 2 decreased dopamine neuronal viability significantly. These data suggest that ERK5 is essential for the basal survival of SN and VTA dopaminergic neurons. This is the first study to examine ERK1, 2, and 5 expression and activation in the SN, STR, and VTA during aging, and the relative roles of ERK1, 2, and 5 in basal survival of SN and VTA dopaminergic neurons. These data raise the possibility that a decline in ERK5 signaling may play a role in age-related impairments in dopaminergic function.
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Affiliation(s)
- Mayur S Parmar
- Division of Pharmaceutical Sciences, Mylan School of Pharmacy, Duquesne University, Pittsburgh, PA, USA
| | - Juliann D Jaumotte
- Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USA
| | - Stephanie L Wyrostek
- Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USA
| | - Michael J Zigmond
- Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jane E Cavanaugh
- Division of Pharmaceutical Sciences, Mylan School of Pharmacy, Duquesne University, Pittsburgh, PA, USA.
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Hall FS, Itokawa K, Schmitt A, Moessner R, Sora I, Lesch KP, Uhl GR. Decreased vesicular monoamine transporter 2 (VMAT2) and dopamine transporter (DAT) function in knockout mice affects aging of dopaminergic systems. Neuropharmacology 2013; 76 Pt A:146-55. [PMID: 23978383 DOI: 10.1016/j.neuropharm.2013.07.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 07/22/2013] [Accepted: 07/30/2013] [Indexed: 01/15/2023]
Abstract
Dopamine (DA) is accumulated and compartmentalized by the dopamine transporter (DAT; SLC3A6) and the vesicular monoamine transporter 2 (VMAT2; SLC18A2). These transporters work at the plasma and vesicular membranes of dopaminergic neurons, respectively, and thus regulate levels of DA in neuronal compartments that include the extravesicular cytoplasmic compartment. DA in this compartment has been hypothesized to contribute to oxidative damage that can reduce the function of dopaminergic neurons in aging brains and may contribute to reductions in dopaminergic neurochemical markers, locomotor behavior and responses to dopaminergic drugs that are found in aged animals. The studies reported here examined aged mice with heterozygous deletions of VMAT2 or of DAT, which each reduce transporter expression to about 50% of levels found in wild-type (WT) mice. Aged mice displayed reduced locomotor responses under a variety of circumstances, including in response to locomotor stimulants, as well as changes in monoamine levels and metabolites in a regionally dependent manner. Several effects of aging were more pronounced in heterozygous VMAT2 knockout (KO) mice, including aging induced reductions in locomotion and reduced locomotor responses to cocaine. By contrast, some effects of aging were reduced or not observed in heterozygous DAT KO mice. These findings support the idea that altered DAT and VMAT2 expression affect age-related changes in dopaminergic function. These effects are most likely mediated by alterations in DA compartmentalization, and might be hypothesized to be exacerbated by other factors that affect the metabolism of cytosolic DA. This article is part of the Special Issue entitled 'The Synaptic Basis of Neurodegenerative Disorders'.
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Affiliation(s)
- F S Hall
- Molecular Neurobiology Branch, Intramural Research Program, NIDA, NIH/DHHS, Baltimore, MD 21224, USA.
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Janać B, Selaković V, Rauš S, Radenović L, Zrnić M, Prolić Z. Temporal patterns of extremely low frequency magnetic field-induced motor behavior changes in Mongolian gerbils of different age. Int J Radiat Biol 2012; 88:359-66. [DOI: 10.3109/09553002.2012.652725] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Salvatore MF, Pruett BS. Dichotomy of tyrosine hydroxylase and dopamine regulation between somatodendritic and terminal field areas of nigrostriatal and mesoaccumbens pathways. PLoS One 2012; 7:e29867. [PMID: 22242182 PMCID: PMC3252325 DOI: 10.1371/journal.pone.0029867] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 12/06/2011] [Indexed: 01/25/2023] Open
Abstract
Measures of dopamine-regulating proteins in somatodendritic regions are often used only as static indicators of neuron viability, overlooking the possible impact of somatodendritic dopamine (DA) signaling on behavior and the potential autonomy of DA regulation between somatodendritic and terminal field compartments. DA reuptake capacity is less in somatodendritic regions, possibly placing a greater burden on de novo DA biosynthesis within this compartment to maintain DA signaling. Therefore, regulation of tyrosine hydroxylase (TH) activity may be particularly critical for somatodendritic DA signaling. Phosphorylation of TH at ser31 or ser40 can increase activity, but their impact on L-DOPA biosynthesis in vivo is unknown. Thus, determining their relationship with L-DOPA tissue content could reveal a mechanism by which DA signaling is normally maintained. In Brown-Norway Fischer 344 F1 hybrid rats, we quantified TH phosphorylation versus L-DOPA accumulation. After inhibition of aromatic acid decarboxylase, L-DOPA tissue content per recovered TH protein was greatest in NAc, matched by differences in ser31, but not ser40, phosphorylation. The L-DOPA per catecholamine and DA turnover ratios were significantly greater in SN and VTA, suggesting greater reliance on de novo DA biosynthesis therein. These compartmental differences reflected an overall autonomy of DA regulation, as seen by decreased DA content in SN and VTA, but not in striatum or NAc, following short-term DA biosynthesis inhibition from local infusion of the TH inhibitor α-methyl-p-tyrosine, as well as in the long-term process of aging. Such data suggest ser31 phosphorylation plays a significant role in regulating TH activity in vivo, particularly in somatodendritic regions, which may have a greater reliance on de novo DA biosynthesis. Thus, to the extent that somatodendritic DA release affects behavior, TH regulation in the midbrain may be critical for DA bioavailability to influence behavior.
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Affiliation(s)
- Michael F Salvatore
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America.
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30
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The aging striatal dopamine function. Parkinsonism Relat Disord 2011; 18:426-32. [PMID: 22176812 DOI: 10.1016/j.parkreldis.2011.11.025] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2011] [Revised: 11/23/2011] [Accepted: 11/27/2011] [Indexed: 11/21/2022]
Abstract
Movement disorders are prevalent in the elderly and may have both central and peripheral origins. Age-related parkinsonism often results in movement disorders identical to some of the cardinal symptoms of typical Parkinson's disease (TPD). Nevertheless, there may be limited similarity in the underlying dysfunction of the sensory-motor circuitry since these two conditions exhibit different changes in the nigro-striatal pathway. In this short review, we highlight some of the key distinctions between aging and TPD regarding striatal dopaminergic activity and discuss them in the context of therapeutic strategies to alleviate motor decline in the elderly.
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Littrell OM, Pomerleau F, Huettl P, Surgener S, McGinty JF, Middaugh LD, Granholm AC, Gerhardt GA, Boger HA. Enhanced dopamine transporter activity in middle-aged Gdnf heterozygous mice. Neurobiol Aging 2010; 33:427.e1-14. [PMID: 21144620 DOI: 10.1016/j.neurobiolaging.2010.10.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Revised: 08/24/2010] [Accepted: 10/16/2010] [Indexed: 01/14/2023]
Abstract
Glial cell line-derived neurotrophic factor (GDNF) supports the viability of midbrain dopamine (DA) neurons that degenerate in Parkinson's disease. Middle-aged, 12 month old, Gdnf heterozygous (Gdnf(+/-)) mice have diminished spontaneous locomotor activity and enhanced synaptosomal DA uptake compared with wild type mice. In this study, dopamine transporter (DAT) function in middle-aged, 12 month old Gdnf(+/-) mice was more thoroughly investigated using in vivo electrochemistry. Gdnf(+/-) mice injected with the DAT inhibitor, nomifensine, exhibited significantly more locomotor activity than wild type mice. In vivo electrochemistry with carbon fiber microelectrodes demonstrated enhanced clearance of DA in the striatum of Gdnf(+/-) mice, suggesting greater surface expression of DAT than in wild type littermates. Additionally, 12 month old Gdnf(+/-) mice expressed greater D(2) receptor mRNA and protein in the striatum than wild type mice. Neurochemical analyses of striatal tissue samples indicated significant reductions in DA and a faster DA metabolic rate in Gdnf(+/-) mice than in wild type mice. Altogether, these data support an important role for GDNF in the regulation of uptake, synthesis, and metabolism of DA during aging.
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Affiliation(s)
- Ofelia M Littrell
- Department of Anatomy and Neurobiology, Morris K. Udall Parkinson's Disease Research, Center of Excellence, University of Kentucky Medical Center, 306 Davis Mills Bldg, 800 Rose St., Lexington, KY 40536, USA
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Frutos MGS, Pistell PJ, Ingram DK, Berthoud HR. Feed efficiency, food choice, and food reward behaviors in young and old Fischer rats. Neurobiol Aging 2010; 33:206.e41-53. [PMID: 20970890 DOI: 10.1016/j.neurobiolaging.2010.09.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 08/25/2010] [Accepted: 09/09/2010] [Indexed: 11/25/2022]
Abstract
Increased susceptibility to energy imbalance and anorexia in old age are risk factors for malnutrition during aging, but the underlying mechanisms are not well understood. Here, we explored changes in taste-guided hedonic value ("liking") and motivation to obtain ("wanting") palatable foods as potential mediators of age-associated anorexia and weight loss in old Fischer-344 rats. "Liking" as measured by the number of positive hedonic orofacial responses to sucrose and corn oil was not different in old compared with young rats. Taste-guided, low effort "wanting" as measured by the number of licks per 10 seconds was also not different, although old rats exhibited a slight oromotor impairment as revealed by significantly increased interlick intervals. Medium effort "wanting" as measured by performance in the incentive runway was significantly decreased in old versus young rats. Although decreased net running speed was partially accountable, significantly increased duration of distractions suggested additional deficits in motivation and/or reinforcement learning. Together with early satiation on corn oil but not sucrose in aged rats, these changes are likely to have resulted in the significantly greater sucrose preference of old rats in 12-hour tests, and may ultimately lead to reduced energy intake and weight loss.
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Affiliation(s)
- Miriam García-San Frutos
- Neurobiology of Nutrition Laboratory, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA, USA.
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Pruett BS, Salvatore MF. GFR α-1 receptor expression in the aging nigrostriatal and mesoaccumbens pathways. J Neurochem 2010; 115:707-15. [DOI: 10.1111/j.1471-4159.2010.06963.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Within-session analysis of amphetamine-elicited rotation behavior reveals differences between young adult and middle-aged F344/BN rats with partial unilateral striatal dopamine depletion. Pharmacol Biochem Behav 2010; 96:423-8. [PMID: 20600242 DOI: 10.1016/j.pbb.2010.06.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 05/19/2010] [Accepted: 06/25/2010] [Indexed: 11/21/2022]
Abstract
Preclinical modeling of Parkinson's disease using 6-hydroxydopamine (6-OHDA) has been valuable in developing and testing therapeutic strategies. Recent efforts have focused on modeling early stages of disease by infusing 6-OHDA into the striatum. The partial DA depletion that follows intrastriatal 6-OHDA is more variable than the near-complete depletion following medial forebrain bundle infusion, and behavioral screening assays are not as well characterized in the partial lesion model. We compared relationships between amphetamine-elicited rotation behavior and DA depletion following intrastriatal 6-OHDA (12.5 microg) in 6 month vs. 18 month F344/BN rats, at 2-weeks and 6-weeks post-lesion. We compared the total number of rotations with within-session (bin-by-bin) parameters of rotation behavior as indicators of DA depletion. Striatal DA depletion was greater in the young adult than in the middle-aged rats at 2 weeks but not at 6 weeks post-lesion. The total number of rotations for the whole session and striatal DA depletion did not differ between the two age groups. Regression analysis revealed a greater relationship between within-session parameters of rotation behavior and DA depletion in the middle-aged group than in the young adult group. These results have implications for estimating DA depletion in preclinical studies using rats of different ages.
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Salvatore MF, Pruett BS, Spann SL, Dempsey C. Aging reveals a role for nigral tyrosine hydroxylase ser31 phosphorylation in locomotor activity generation. PLoS One 2009; 4:e8466. [PMID: 20037632 PMCID: PMC2791868 DOI: 10.1371/journal.pone.0008466] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Accepted: 11/29/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Tyrosine hydroxylase (TH) regulates dopamine (DA) bioavailability. Its product, L-DOPA, is an established treatment for Parkinson's disease (PD), suggesting that TH regulation influences locomotion. Site-specific phosphorylation of TH at ser31 and ser40 regulates activity. No direct evidence shows that ser40 phosphorylation is the dominating mechanism of regulating TH activity in vivo, and physiologically-relevant stimuli increase L-DOPA biosynthesis independent of ser40 phosphorylation. Significant loss of locomotor activity occurs in aging as in PD, despite less loss of striatal DA or TH in aging compared to the loss associated with symptomatic PD. However, in the substantia nigra (SN), there is equivalent loss of DA or TH in aging and at the onset of PD symptoms. Growth factors increase locomotor activity in both PD and aging models and increase DA bioavailability and ser31 TH phosphorylation in SN, suggesting that ser31 TH phosphorylation status in the SN, not striatum, regulates DA bioavailability necessary for locomotor activity. METHODOLOGY AND PRINCIPAL FINDINGS We longitudinally characterized locomotor activity in young and older Brown-Norway Fischer 344 F(1) hybrid rats (18 months apart in age) at two time periods, eight months apart. The aged group served as an intact and pharmacologically-naïve source of deficient locomotor activity. Following locomotor testing, we analyzed DA tissue content, TH protein, and TH phosphorylation in striatum, SN, nucleus accumbens, and VTA. Levels of TH protein combined with ser31 phosphorylation alone reflected inherent differences in DA levels among the four regions. Measures strictly pertaining to locomotor activity initiation significantly correlated to DA content only in the SN. Nigral TH protein and ser31 phosphorylation together significantly correlated to test subject's maximum movement number, horizontal activity, and duration. CONCLUSIONS/SIGNIFICANCE Together, these results show ser31 TH phosphorylation regulates DA bioavailability in intact neuropil, its status in the SN may regulate locomotor activity generation, and it may represent an accurate target for treating locomotor deficiency. They also show that neurotransmitter regulation in cell body regions can mediate behavioral outcomes and that ser31 TH phosphorylation plays a role in behaviors dependent upon catecholamines, such as dopamine.
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Affiliation(s)
- Michael F Salvatore
- Department of Pharmacology, Toxicology, and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, Louisiana, USA.
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Experimental manipulations blunt time-induced changes in brain monoamine levels and completely reverse stress, but not Pb+/-stress-related modifications to these trajectories. Behav Brain Res 2009; 205:76-87. [PMID: 19631235 DOI: 10.1016/j.bbr.2009.06.040] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 05/30/2009] [Accepted: 06/04/2009] [Indexed: 12/13/2022]
Abstract
This study sought to further understand how environmental conditions influence the outcomes of early developmental insults. It compared changes in monoamine levels in frontal cortex, nucleus accumbens and striatum of male and female Long-Evans rat offspring subjected to maternal Pb exposure (0, 50 or 150ppm in drinking water from 2 months pre-breeding until pup weaning)+/-prenatal (PS) (restraint on GD16-17) or PS+offspring stress (OS; three variable stress challenges to young adults) determined at 2 months of age and at 6 months of age in littermates subsequently exposed either to experimental manipulations (EM: daily handling and performance on an operant fixed interval (FI) schedule of food reward), or to no experience (NEM; time alone). Time alone (NEM conditions), even in normal (control) animals, modified the trajectory of neurochemical changes between 2 and 6 months across brain regions and monoamines. EM significantly modified the NEM trajectories, and except NE and striatal DA, which increased, blunted the changes in monoamine levels that occurred over time alone. Pb+/-stress modified the trajectory of monoamine changes in both EM and NEM conditions, but these predominated under NEM conditions. Stress-associated modifications, occurring mainly with NEM OS groups, were fully reversed by EM procedures, while reversals of Pb+/-stress-associated modifications occurred primarily in nucleus accumbens, a region critical to mediation of FI response rates. These results extend the known environmental conditions that modify developmental Pb+/-stress insults, which is critical to ultimately understanding whether early insults lead to adaptive or maladaptive behavior and to devising behavioral therapeutic strategies. That time alone and a set of EM conditions typically used as outcome measures in intervention studies can themselves invoke neurochemical changes, moreover, has significant implications for experimental design of such studies.
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Dickerson JW, Hemmerle AM, Numan S, Lundgren KH, Seroogy KB. Decreased expression of ErbB4 and tyrosine hydroxylase mRNA and protein in the ventral midbrain of aged rats. Neuroscience 2009; 163:482-9. [PMID: 19505538 DOI: 10.1016/j.neuroscience.2009.06.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 06/03/2009] [Accepted: 06/04/2009] [Indexed: 10/20/2022]
Abstract
Decreased availability or efficacy of neurotrophic factors may underlie an increased susceptibility of mesencephalic dopaminergic cells to age-related degeneration. Neuregulins (NRGs) are pleotrophic growth factors for many cell types, including mesencephalic dopamine cells in culture and in vivo. The functional NRG receptor ErbB4 is expressed by virtually all midbrain dopamine neurons. To determine if levels of the NRG receptor are maintained during aging in the dopaminergic ventral mesencephalon, expression of ErbB4 mRNA and protein was examined in young (3 months), middle-aged (18 months), and old (24-25 months) Brown Norway/Fischer 344 F1 rats. ErbB4 mRNA levels in the substantia nigra pars compacta (SNpc), but not the adjacent ventral tegmental area (VTA) or subtantia nigra pars lateralis (SNl), were significantly reduced in the middle-aged and old animals when compared to young rats. Protein expression of ErbB4 in the ventral midbrain was significantly decreased in the old rats when compared to the young rats. Expression of tyrosine hydroxylase (TH) mRNA levels was significantly reduced in the old rats when compared to young animals in the SNpc, but not in the VTA or SNI. TH protein levels in the ventral midbrain were also decreased in the old animals when compared to the young animals. These data demonstrate a progressive decline of ErbB4 expression, coinciding with a loss of the dopamine-synthesizing enzyme TH, in the ventral midbrain of aged rats, particularly in the SNpc. These findings may implicate a role for diminished NRG/ErbB4 trophic support in dopamine-related neurodegenerative disorders of aging such as Parkinson's disease.
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Affiliation(s)
- J W Dickerson
- Department of Neurology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
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The modulation of striatal dopamine release correlates with water-maze performance in aged rats. Neurobiol Aging 2009; 30:957-72. [DOI: 10.1016/j.neurobiolaging.2007.09.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Revised: 09/27/2007] [Accepted: 09/28/2007] [Indexed: 11/20/2022]
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Abstract
Clinical subtyping of delirium according to motor-activity profile has considerable potential to account for the heterogeneity of this complex and multifactorial syndrome. Previous work has identified a range of clinically important differences between motor subtypes in relation to detection, causation, treatment experience and prognosis, but studies have been hampered by inconsistent methodology, especially in relation to definition of subtypes. This article considers research to date, including a number of recent studies that have attempted to address these issues and identify a means of achieving greater consistency in approaches to subtyping. Possibilities for future work are discussed and a research plan for the field is outlined.
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Affiliation(s)
- David Meagher
- Department of Adult Psychiatry, Midwestern Regional Hospital, Limerick, Health Systems Research Centre, University of Limerick, Limerick, Ireland.
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Zaman V, Boger HA, Granholm AC, Rohrer B, Moore A, Buhusi M, Gerhardt GA, Hoffer BJ, Middaugh LD. The nigrostriatal dopamine system of aging GFRalpha-1 heterozygous mice: neurochemistry, morphology and behavior. Eur J Neurosci 2009; 28:1557-68. [PMID: 18973577 DOI: 10.1111/j.1460-9568.2008.06456.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Given the established importance of glial cell line-derived neurotrophic factor (GDNF) in maintaining dopaminergic neurotransmitter systems, the nigrostriatal system and associated behaviors of mice with genetic reduction of its high-affinity receptor, GDNF receptor (GFR)alpha-1 (GFRalpha-1(+/-)), were compared with wild-type controls. Motor activity and the stimulatory effects of a dopamine (DA) D1 receptor agonist (SKF 82958) were assessed longitudinally at 8 and 18 months of age. Monoamine concentrations and dopaminergic nerve terminals in the striatum and the number of dopaminergic neurons in the substantia nigra (SN) were assessed. The results support the importance of GFRalpha-1 in maintaining normal function of the nigrostriatal dopaminergic system, with deficits being observed for GFRalpha-1(+/-) mice at both ages. Motor activity was lower and the stimulatory effects of the DA agonist were enhanced for the older GFRalpha-1(+/-) mice. DA in the striatum was reduced in the GFRalpha-1(+/-) mice at both ages, and tyrosine hydroxylase-positive cell numbers in the SN were reduced most substantially in the older GFRalpha-1(+/-) mice. The combined behavioral, pharmacological probe, neurochemical and morphological measures provide evidence of abnormalities in GFRalpha-1(+/-) mice that are indicative of an exacerbated aging-related decline in dopaminergic system function. The noted deficiencies, in turn, suggest that GFRalpha-1 is necessary for GDNF to maintain normal function of the nigrostriatal dopaminergic system. Although the precise mechanism(s) for the aging-related changes in the dopaminergic system remain to be established, the present study clearly establishes that genetic reductions in GFRalpha-1 can contribute to the degenerative changes observed in this system during the aging process.
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Affiliation(s)
- Vandana Zaman
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, USA.
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Baumann MH, Clark RD, Rothman RB. Locomotor stimulation produced by 3,4-methylenedioxymethamphetamine (MDMA) is correlated with dialysate levels of serotonin and dopamine in rat brain. Pharmacol Biochem Behav 2008; 90:208-17. [PMID: 18403002 PMCID: PMC2491560 DOI: 10.1016/j.pbb.2008.02.018] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Revised: 12/27/2007] [Accepted: 02/19/2008] [Indexed: 10/22/2022]
Abstract
(+/-)-3,4-Methylenedioxymethamphetamine (MDMA, or Ecstasy) is an illicit drug that evokes transporter-mediated release of monoamines, including serotonin (5-HT) and dopamine (DA). Here we monitored the effects of MDMA on neurochemistry and motor activity in rats, as a means to evaluate relationships between 5-HT, DA, and behavior. Male rats undergoing in vivo microdialysis were housed in chambers equipped with photobeams for measurement of ambulation (i.e., forward locomotion) and stereotypy (i.e., head weaving and forepaw treading). Microdialysis probes were placed into the n. accumbens, striatum or prefrontal cortex in separate groups of rats. Dialysate samples were assayed for 5-HT and DA by microbore HPLC-ECD. Rats received two i.v. injections of MDMA, 1 mg/kg followed by 3 mg/kg 60 min later; neurochemical and locomotor parameters were measured concurrently. MDMA produced dose-related elevations in extracellular 5-HT and DA in all regions, with the magnitude of 5-HT release always exceeding that of DA release. MDMA-induced ambulation was positively correlated with dialysate DA levels in all regions (P<0.05-0.0001) and with dialysate 5-HT in striatum and cortex (P<0.001-0.0001). Stereotypy was strongly correlated with dialysate 5-HT in all areas (P<0.001-0.0001) and with dialysate DA in accumbens and striatum (P<0.001-0.0001). These data support previous work and suggest the complex spectrum of behaviors produced by MDMA involves 5-HT and DA in a region- and modality-specific manner.
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Affiliation(s)
- Michael H Baumann
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, United States.
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Zhang H, Bethel CS, Smittkamp SE, Stanford JA. Age-related changes in orolingual motor function in F344 vs F344/BN rats. Physiol Behav 2007; 93:461-6. [PMID: 17980393 DOI: 10.1016/j.physbeh.2007.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 08/30/2007] [Accepted: 10/05/2007] [Indexed: 10/22/2022]
Abstract
Normal aging is associated with both locomotor and orolingual motor deficits. Preclinical studies of motor function in normal aging, however, have focused primarily on locomotor activity. The purpose of this study was to measure age-related changes in orolingual motor function and compare these changes between two rat strains commonly used in aging studies: Fischer 344 (F344) and Fischer 344/Brown Norway hybrid (F344/BN) rats. Rats (6-, 12-, 18- and 24-months of age) were trained to lick water from an isometric force-sensing operandum so that the number of licks per session, licking rhythm (licks/second) and lick force could be measured. In both strains, the number of licks per session was greatest in the oldest group, while this measure was greater for F344/BN rats at all ages. Peak tongue force increased with age in F344/BN rats, did not change with age in the F344 rats, and was greater for the F344/BN rats at all ages. Both strains exhibited an age-related slowing of licking rhythm beginning with the 18-month-old group. These findings suggest that despite lifespan differences between these two rat strains, diminished tongue motility emerges at the same age.
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Affiliation(s)
- Hongyu Zhang
- Department of Molecular & Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160, USA
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Cassel JC, Lazaris A, Birthelmer A, Jackisch R. Spatial reference- (not working- or procedural-) memory performance of aged rats in the water maze predicts the magnitude of sulpiride-induced facilitation of acetylcholine release by striatal slices. Neurobiol Aging 2007; 28:1270-85. [PMID: 16843572 DOI: 10.1016/j.neurobiolaging.2006.05.032] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Revised: 05/18/2006] [Accepted: 05/30/2006] [Indexed: 11/17/2022]
Abstract
Cluster analysis of water-maze reference-memory performance distinguished subpopulations of young adult (3-5 months), aged (25-27 months) unimpaired (AU) and aged impaired (AI) rats. Working-memory performances of AU and AI rats were close to normal (though young and aged rats differed in exploration strategies). All aged rats showed impaired procedural-memory. Electrically evoked release of tritium was assessed in striatal slices (preloaded with [(3)H]choline) in the presence of oxotremorine, physostigmine, atropine+physostigmine, quinpirole, nomifensine or sulpiride. Aged rats exhibited reduced accumulation of [(3)H]choline (-30%) and weaker transmitter release. Drug effects (highest concentration) were reductions of release by 44% (oxotremorine), 72% (physostigmine), 84% (quinpirole) and 65% (nomifensine) regardless of age. Sulpiride and atropine+physostigmine facilitated the release more efficiently in young rats versus aged rats. The sulpiride-induced facilitation was weaker in AI rats versus AU rats; it significantly correlated with reference-memory performance. The results confirm age-related alterations of cholinergic and dopaminergic striatal functions, and point to the possibility that alterations in the D(2)-mediated dopaminergic regulation of these functions contribute to age-related reference-memory deficits.
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Affiliation(s)
- Jean-Christophe Cassel
- Laboratoire de Neurosciences Comportementales et Cognitives, FRE 2855, CNRS-Université Louis Pasteur, IFR 37 Neurosciences, GDR CNRS 2905, Strasbourg, France.
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Curtis JT, Wang Z. Amphetamine effects in microtine rodents: a comparative study using monogamous and promiscuous vole species. Neuroscience 2007; 148:857-66. [PMID: 17706877 PMCID: PMC2211418 DOI: 10.1016/j.neuroscience.2007.07.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Revised: 06/14/2007] [Accepted: 07/12/2007] [Indexed: 10/23/2022]
Abstract
We compared amphetamine-induced dopamine release in the nucleus accumbens of vole species that exhibit differing mating systems to examine potential interactions between social organization and substance abuse. We found no species or regional differences in basal extracellular dopamine, however, monogamous voles had greater and longer-lasting increases in extracellular dopamine after amphetamine treatment than did promiscuous voles. We then examined whether amphetamine-induced increase in extracellular dopamine could induce pair bonds in monogamous voles. We found that, despite increasing dopamine in the nucleus accumbens, amphetamine administration did not induce pair-bonds in male prairie voles unless the animals were pretreated to preclude D1 receptor activation, which is known to inhibit pair-bond formation. These results support suggestions that social attachment and substance abuse share a common neural substrate.
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Affiliation(s)
- J T Curtis
- Program for Neuroscience, Department of Psychology, Florida State University, Tallahassee, FL 32306, USA.
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Ling Z, Zhu Y, Tong CW, Snyder JA, Lipton JW, Carvey PM. Progressive dopamine neuron loss following supra-nigral lipopolysaccharide (LPS) infusion into rats exposed to LPS prenatally. Exp Neurol 2006; 199:499-512. [PMID: 16504177 DOI: 10.1016/j.expneurol.2006.01.010] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Revised: 12/08/2005] [Accepted: 01/12/2006] [Indexed: 11/30/2022]
Abstract
Toxin-induced animal models of Parkinson's disease (PD) exhibit many of the same neuroinflammatory changes seen in patients suggesting a role for inflammation in DA neuron loss. Yet, despite this inflammation, the progressive loss of DA neurons that characterizes PD is rarely seen in animals. We infused lipopolysaccharide (LPS) or saline into 7-month-old rats that had been exposed to LPS or saline prenatally and assessed them for DA neuron loss and inflammatory measures (interleukin 1 beta, tumor necrosis factor-alpha, glutathione, and activated microglia) over a period of 84 days to examine the role of pre-existing inflammation in progressive DA neuron loss. LPS infusion into both prenatal treatment groups produced neuroinflammation during the 14 days of LPS infusion that subsequently reverted toward normal over the next 70 days. In animals with pre-existing inflammation (i.e., prenatal LPS), however, the acute changes seen were attenuated, but took much longer to return to normal suggesting a prolonged inflammatory response. These inflammatory changes were consistent with the greater acute DA neuron loss seen in the prenatal saline controls and the progressive DA neuron loss seen only in the animals exposed to LPS prenatally. Interestingly, both prenatal treatment groups exhibited increases in microglia over the entire 84-day course of the study. These data suggest that pre-existing neuroinflammation prolongs the inflammatory response that occurs with a second toxic exposure, which may be responsible for progressive DA neuron loss. This provides further support for the "multiple hit" hypothesis of PD.
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Affiliation(s)
- Zaodung Ling
- Department of Pharmacology, Rush University Medical Center, Chicago, IL 60612, USA
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46
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Akopian G, Walsh JP. Pre- and postsynaptic contributions to age-related alterations in corticostriatal synaptic plasticity. Synapse 2006; 60:223-38. [PMID: 16739119 DOI: 10.1002/syn.20289] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Aging creates deficits in motor performance related to changes in striatal processing of cortical information. This study describes age-related changes in corticostriatal snaptic plasticity and associated mechanisms, which may contribute to declines in motor behavior. Intracellular recordings revealed an age-related decrease in the expression of paired-pulse, posttetanic, and long-term potentiation (LTP). The age-related difference in LTP was associated with reduced sensitivity to block of N-methyl-D-aspartate (NMDA) receptors in the aged population. These age-related changes could not be explained by increased L-type Ca(2+)channel activity, since block of L-type Ca(2+) channels with nifedipine increased rather than decreased the age-related difference in long-term plasticity. Age-related increases in reactive oxygen species (ROS) modulation were also ruled out, since application of H(2)O(2) produced changes in synaptic function that were opposite to trends seen in aging, and addition of the antioxidant Trolox-C had a larger effect on long-term plasticity in young rats than in older rats. A robust age-related difference in long-term synaptic plasticity was found by studying synaptic plasticity following the blocking of D2 receptors with l-sulpiride, which may involve age-difference in NMDA receptor function. l-sulpiride consistently enabled a slow development of LTP at young (but not aged) corticostriatal synapses. However, No age differences were found in the sensitivity to the addition of the D2 receptor agonist quinpirole. These findings provide evidence for age-induced changes in the release properties of cortical terminals and in the functioning of postsynaptic striatal NMDA receptors, which may contribute to age-related deficits in striatum control of movement.
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Affiliation(s)
- G Akopian
- Andrus Gerontology Center, USC Program in Neuroscience, University of Southern California, Los Angeles, California 90089-0191, USA
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Wang L, Pooler AM, Albrecht MA, Wurtman RJ. Dietary uridine-5'-monophosphate supplementation increases potassium-evoked dopamine release and promotes neurite outgrowth in aged rats. J Mol Neurosci 2005; 27:137-45. [PMID: 16055952 DOI: 10.1385/jmn:27:1:137] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Membrane phospholipids like phosphatidylcholine (PC) are required for cellular growth and repair, and specifically for synaptic function. PC synthesis is controlled by cellular levels of its precursor, cytidine-5'-diphosphate choline (CDP-choline), which is produced from cytidine triphosphate (CTP) and phosphocholine. In rat PC12 cells exogenous uridine was shown to elevate intracellular CDP-choline levels, by promoting the synthesis of uridine triphosphate (UTP), which was partly converted to CTP. In such cells uridine also enhanced the neurite outgrowth produced by nerve growth factor (NGF). The present study assessed the effect of dietary supplementation with uridine-5'-monophosphate disodium (UMP-2Na+, an additive in infant milk formulas) on striatal dopamine (DA) release in aged rats. Male Fischer 344 rats consumed either a control diet or one fortified with 2.5% UMP for 6 wk, ad libitum. In vivo microdialysis was then used to measure spontaneous and potassium (K+)-evoked DA release in the right striatum. Potassium (K+)-evoked DA release was significantly greater among UMP-treated rats, i.e., 341+/-21% of basal levels vs. 283+/-9% of basal levels in control rats (p<0.05); basal DA release was unchanged. In general, each animal's K+-evoked DA release correlated with its striatal DA content, measured postmortem. The levels of neurofilament-70 and neurofilament-M proteins, biomarkers of neurite outgrowth, increased to 182+/-25% (p<0.05) and 221+/-34% (p<0.01) of control values, respectively, with UMP consumption. Hence, UMP treatment not only enhances membrane phosphatide production but also can modulate two membrane-dependent processes, neurotransmitter release and neurite outgrowth, in vivo.
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Affiliation(s)
- Lei Wang
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
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Kim I, Wilson RE, Wellman CL. Aging and cholinergic deafferentation alter GluR1 expression in rat frontal cortex. Neurobiol Aging 2005; 26:1073-81. [PMID: 15748787 DOI: 10.1016/j.neurobiolaging.2004.09.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Revised: 08/13/2004] [Accepted: 09/13/2004] [Indexed: 10/26/2022]
Abstract
Previously, we demonstrated that plasticity of frontal cortex is altered in aging rats: lesions of the nucleus basalis magnocellularis (NBM) produce larger declines in dendritic morphology in frontal cortex of aged rats compared to young adults. Cholinergic afferents from the NBM modulate glutamatergic transmission in neocortex, and glutamate is known to be involved in dendritic plasticity. To begin to identify possible mechanisms underlying age-related differences in plasticity after NBM lesion, we assessed the effect of cholinergic deafferentation on expression of the AMPA receptor subunit GluR1 in frontal cortex of young adult and aging rats. Young adult, middle-aged, and aged rats received sham or 192 IgG-saporin lesions of the NBM, and an unbiased stereological technique was used to estimate the total number of intensely GluR1-immunopositive neurons in layer II-III of frontal cortex. While the number of GluR1-positive neurons was increased in both middle-aged and aged rats, lesions markedly increased the number of intensely GluR1-immunopositive neurons in frontal cortex of young adult rats only. This age-related difference in lesion-induced expression of AMPA receptor subunit protein could underlie the age-related differences in dendritic plasticity after NBM lesions.
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Affiliation(s)
- Irene Kim
- Department of Psychology, Indiana University, Bloomington, IN 47405, USA
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Orset C, Parrot S, Sauvinet V, Cottet-Emard JM, Bérod A, Pequignot JM, Denoroy L. Dopamine transporters are involved in the onset of hypoxia-induced dopamine efflux in striatum as revealed by in vivo microdialysis. Neurochem Int 2005; 46:623-33. [PMID: 15863240 DOI: 10.1016/j.neuint.2005.02.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2004] [Revised: 02/08/2005] [Accepted: 02/18/2005] [Indexed: 11/26/2022]
Abstract
Although many studies have revealed alterations in neurotransmission during ischaemia, few works have been devoted to the neurochemical effects of mild hypoxia, a situation encountered during life in altitude or in several pathologies. In that context, the present work was undertaken to determine the in vivo mechanisms underlying the striatal dopamine efflux induced by mild hypoxaemic hypoxia. For that purpose, the extracellular concentrations of dopamine and its metabolite 3,4-dihydroxyphenyl acetic acid were simultaneously measured using brain microdialysis during acute hypoxic exposure (10% O(2), 1h) in awake rats. Hypoxia induced a +80% increase in dopamine. Application of the dopamine transporters inhibitor, nomifensine (10 microM), just before the hypoxia prevented the rise in dopamine during the early part of hypoxia; in contrast the application of nomifensine after the beginning of hypoxia, failed to alter the increase in dopamine. Application of the voltage-dependent Na(+) channel blocker tetrodotoxin abolished the increase in dopamine, whether administered just before or after the beginning of hypoxia. These data show that the neurochemical mechanisms of the dopamine efflux may change over the course of the hypoxic exposure, dopamine transporters being involved only at the beginning of hypoxia.
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Affiliation(s)
- Cyrille Orset
- Laboratoire de Neuropharmacologie et Neurochimie, IFR 19, Faculté de Pharmacie, Université Claude Bernard, 8 Avenue Rockefeller, 69373 Lyon Cedex 08, France
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Abstract
Aging is associated with a progressive decline in physical and cognitive functions. The impact of age-dependent endocrine changes regulated by the central nervous system on the dynamics of neuronal behavior, neurodegeneration, cognition, biological rhythms, sexual behavior, and metabolism are reviewed. We also briefly review how functional deficits associated with increases in glucocorticoids and cytokines and declining production of sex steroids, GH, and IGF are likely exacerbated by age-dependent molecular misreading and alterations in components of signal transduction pathways and transcription factors.
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Affiliation(s)
- Roy G Smith
- Huffington Center on Aging, Baylor College of Medicine, One Baylor Plaza, M320, Houston, TX 77030, USA.
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