- Florey Department of Neuroscience and Mental Health - Research Publications
Florey Department of Neuroscience and Mental Health - Research Publications
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ItemThe novel compound PBT434 prevents iron mediated neurodegeneration and alpha-synuclein toxicity in multiple models of Parkinson's disease (vol 5, 53, 2017)Finkelstein, DI ; Billings, JL ; Adlard, PA ; Ayton, S ; Sedjahtera, A ; Masters, CL ; Wilkins, S ; Shackleford, DM ; Charman, SA ; Bal, W ; Zawisza, IA ; Kurowska, E ; Gundlach, AL ; Ma, S ; Bush, AI ; Hare, DJ ; Doble, PA ; Crawford, S ; Gautier, ECL ; Parsons, J ; Huggins, P ; Barnham, KJ ; Cherny, RA (BMC, 2021-09-29)
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ItemThe hypoxia imaging agent CuII(atsm) is neuroprotective and improves motor and cognitive functions in multiple animal models of Parkinson's diseaseHung, LW ; Villemagne, VL ; Cheng, L ; Sherratt, NA ; Ayton, S ; White, AR ; Crouch, PJ ; Lim, S ; Leong, SL ; Wilkins, S ; George, J ; Roberts, BR ; Pham, CLL ; Liu, X ; Chiu, FCK ; Shackleford, DM ; Powell, AK ; Masters, CL ; Bush, AI ; O'Keefe, G ; Culvenor, JG ; Cappai, R ; Cherny, RA ; Donnelly, PS ; Hill, AF ; Finkelstein, DI ; Barnham, KJ (ROCKEFELLER UNIV PRESS, 2012-04-09)Parkinson's disease (PD) is a progressive, chronic disease characterized by dyskinesia, rigidity, instability, and tremors. The disease is defined by the presence of Lewy bodies, which primarily consist of aggregated α-synuclein protein, and is accompanied by the loss of monoaminergic neurons. Current therapeutic strategies only give symptomatic relief of motor impairment and do not address the underlying neurodegeneration. Hence, we have identified Cu(II)(atsm) as a potential therapeutic for PD. Drug administration to four different animal models of PD resulted in improved motor and cognition function, rescued nigral cell loss, and improved dopamine metabolism. In vitro, this compound is able to inhibit the effects of peroxynitrite-driven toxicity, including the formation of nitrated α-synuclein oligomers. Our results show that Cu(II)(atsm) is effective in reversing parkinsonian defects in animal models and has the potential to be a successful treatment of PD.
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ItemThe novel compound PBT434 prevents iron mediated neurodegeneration and alpha-synuclein toxicity in multiple models of Parkinson's diseaseFinkelstein, DI ; Billings, JL ; Adlard, PA ; Ayton, S ; Sedjahtera, A ; Masters, CL ; Wilkins, S ; Shackleford, DM ; Charman, SA ; Bal, W ; Zawisza, IA ; Kurowska, E ; Gundlach, AL ; Ma, S ; Bush, AI ; Hare, DJ ; Doble, PA ; Crawford, S ; Gautier, ECL ; Parsons, J ; Huggins, P ; Barnham, KJ ; Cherny, RA (BMC, 2017-06-28)Elevated iron in the SNpc may play a key role in Parkinson's disease (PD) neurodegeneration since drug candidates with high iron affinity rescue PD animal models, and one candidate, deferirpone, has shown efficacy recently in a phase two clinical trial. However, strong iron chelators may perturb essential iron metabolism, and it is not yet known whether the damage associated with iron is mediated by a tightly bound (eg ferritin) or lower-affinity, labile, iron pool. Here we report the preclinical characterization of PBT434, a novel quinazolinone compound bearing a moderate affinity metal-binding motif, which is in development for Parkinsonian conditions. In vitro, PBT434 was far less potent than deferiprone or deferoxamine at lowering cellular iron levels, yet was found to inhibit iron-mediated redox activity and iron-mediated aggregation of α-synuclein, a protein that aggregates in the neuropathology. In vivo, PBT434 did not deplete tissue iron stores in normal rodents, yet prevented loss of substantia nigra pars compacta neurons (SNpc), lowered nigral α-synuclein accumulation, and rescued motor performance in mice exposed to the Parkinsonian toxins 6-OHDA and MPTP, and in a transgenic animal model (hA53T α-synuclein) of PD. These improvements were associated with reduced markers of oxidative damage, and increased levels of ferroportin (an iron exporter) and DJ-1. We conclude that compounds designed to target a pool of pathological iron that is not held in high-affinity complexes in the tissue can maintain the survival of SNpc neurons and could be disease-modifying in PD.
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ItemLithium suppression of tau induces brain iron accumulation and neurodegenerationLei, P ; Ayton, S ; Appukuttan, AT ; Moon, S ; Duce, JA ; Volitakis, I ; Cherny, R ; Wood, SJ ; Greenough, M ; Berger, G ; Pantelis, C ; McGorry, P ; Yung, A ; Finkelstein, DI ; Bush, AI (NATURE PUBLISHING GROUP, 2017-03)Lithium is a first-line therapy for bipolar affective disorder. However, various adverse effects, including a Parkinson-like hand tremor, often limit its use. The understanding of the neurobiological basis of these side effects is still very limited. Nigral iron elevation is also a feature of Parkinsonian degeneration that may be related to soluble tau reduction. We found that magnetic resonance imaging T2 relaxation time changes in subjects commenced on lithium therapy were consistent with iron elevation. In mice, lithium treatment lowers brain tau levels and increases nigral and cortical iron elevation that is closely associated with neurodegeneration, cognitive loss and parkinsonian features. In neuronal cultures lithium attenuates iron efflux by lowering tau protein that traffics amyloid precursor protein to facilitate iron efflux. Thus, tau- and amyloid protein precursor-knockout mice were protected against lithium-induced iron elevation and neurotoxicity. These findings challenge the appropriateness of lithium as a potential treatment for disorders where brain iron is elevated (for example, Alzheimer's disease), and may explain lithium-associated motor symptoms in susceptible patients.
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ItemParkinson's Disease Iron Deposition Caused by Nitric Oxide-Induced Loss of β-Amyloid Precursor ProteinAyton, S ; Lei, P ; Hare, DJ ; Duce, JA ; George, JL ; Adlard, PA ; McLean, C ; Rogers, JT ; Cherny, RA ; Finkelstein, DI ; Bush, AI (SOC NEUROSCIENCE, 2015-02-25)Elevation of both neuronal iron and nitric oxide (NO) in the substantia nigra are associated with Parkinson's disease (PD) pathogenesis. We reported previously that the Alzheimer-associated β-amyloid precursor protein (APP) facilitates neuronal iron export. Here we report markedly decreased APP expression in dopaminergic neurons of human PD nigra and that APP(-/-) mice develop iron-dependent nigral cell loss. Conversely, APP-overexpressing mice are protected in the MPTP PD model. NO suppresses APP translation in mouse MPTP models, explaining how elevated NO causes iron-dependent neurodegeneration in PD.
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ItemIron accumulation confers neurotoxicity to a vulnerable population of nigral neurons: implications for Parkinson's diseaseAyton, S ; Lei, P ; Adlard, PA ; Volitakis, I ; Cherny, RA ; Bush, AI ; Finkelstein, DI (BMC, 2014-07-10)BACKGROUND: The substantia nigra (SN) midbrain nucleus is constitutively iron rich. Iron levels elevate further with age, and pathologically in Parkinson's disease (PD). Iron accumulation in PD SN involves dysfunction of ceruloplasmin (CP), which normally promotes iron export. We previously showed that ceruloplasmin knockout (CP KO) mice exhibit Parkinsonian neurodegeneration (~30% nigral loss) by 6 months, which is prevented by iron chelation. Here, we explored whether known iron-stressors of the SN (1) aging and (2) MPTP, would exaggerate the lesion severity of CP KO mice. FINDINGS: We show that while 5 month old CP KO mice exhibited nigral iron elevation and loss of SN neurons, surprisingly, aging CP KO mice to 14 months did not exacerbate iron elevation or SN neuronal loss. Unlike young mice, iron chelation therapy in CP KO mice between 9-14 months did not rescue neuronal loss. MPTP exaggerated iron elevation in young CP KO mice but did not increase cell death when compared to WTs. CONCLUSIONS: We conclude that there may exist a proportion of substantia nigra neurons that depend on CP for protection against iron neurotoxicity and could be protected by iron-based therapeutics. Death of the remaining neurons in Parkinson's disease is likely caused by parallel disease mechanisms, which may call for additional therapeutic options.
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ItemThe effect of dopamine on MPTP-induced rotarod disabilityAyton, S ; George, JL ; Adlard, PA ; Bush, AI ; Cherny, RA ; Finkelstein, DI (ELSEVIER IRELAND LTD, 2013-05-24)UNLABELLED: Dopamine depletion in Parkinson's disease (PD) results in bradykinesia and tremor. Therapeutic administration of the dopamine precursor, l-Dopa, alleviates these symptoms but dyskinesia's can manifest with chronic treatment. In the MPTP toxin mouse model of PD, lesion severity is often assessed by the rotarod behavioral assay. Dopamine depletion by MPTP is thought to induce rotarod behavioral decline. Here we surveyed rotarod behavior and striatal dopamine at timed intervals post-MPTP. Paradoxically, rotarod disability coincided with gradual striatal dopamine restoration. l-Dopa supplementation exacerbated rotarod disability, whereas dopamine antagonism restored performance. CONCLUSION: dopamine restoration, not depletion, precipitates rotarod disability after MPTP intoxication, and caution should be applied when using this assay for MPTP.