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Journal of Parkinson's Disease 2024Increased activity across corticostriatal glutamatergic synapses may contribute to L-DOPA-induced dyskinesia in Parkinson's disease. Given the weak efficacy and...
BACKGROUND
Increased activity across corticostriatal glutamatergic synapses may contribute to L-DOPA-induced dyskinesia in Parkinson's disease. Given the weak efficacy and side-effect profile of amantadine, alternative strategies to reduce glutamate transmission are being investigated. Metabotropic glutamate receptor 4 (mGlu4) is a promising target since its activation would reduce glutamate release.
OBJECTIVE
We hypothesized that two mGlu4 positive allosteric modulators, Lu AF21934 ((1 S,2 R)-N1-(3,4-dichlorophenyl)cyclohexane-1,2-dicarboxamide) and ADX88178 (5-Methyl-N-(4-methylpyrimidin-2-yl)-4-(1H-pyrazol-4-yl)thiazol-2-amine), would provide relief in rat and primate models of L-DOPA-induced dyskinesia.
METHODS
The ability of Lu AF21934 or ADX88178 to reverse pre-established dyskinesia was examined in L-DOPA-primed 6-hydroxydopamine-lesioned rats expressing abnormal involuntary movements (AIMs) or in 1-methyl-4-phenyl,1,2,3,6-tetrahydropyridine (MPTP)-treated common marmosets expressing L-DOPA-induced dyskinesia. Additionally, the ability of Lu AF21934 to prevent the development of de novo L-DOPA-induced AIMs was explored in the 6-hydroxydopamine-lesioned rats.
RESULTS
Neither Lu AF21934 (10 or 30 mg/kg p.o.) nor ADX88178 (10 or 30 mg/kg p.o.) reduced pre-established AIMs in 6-hydroxydopamine-lesioned rats. Similarly, in L-DOPA-primed common marmosets, no reduction in established dyskinesia was observed with Lu AF21934 (3 or 10 mg/kg p.o.). Conversely, amantadine significantly reduced (>40%) the expression of dyskinesia in both models. Lu AF21934 also failed to suppress the development of AIMs in 6-hydroxydopamine-lesioned rats.
CONCLUSIONS
This study found no benefit of mGlu4 positive allosteric modulators in tackling L-DOPA-induced dyskinesia. These findings are concordant with the recent failure of foliglurax in phase II clinical trials supporting the predictive validity of these pre-clinical dyskinesia models, while raising further doubt on the anti-dyskinetic potential of mGlu4 positive allosteric modulators.
Topics: Rats; Animals; Levodopa; Callithrix; Parkinson Disease; Oxidopamine; Dyskinesia, Drug-Induced; Antiparkinson Agents; Amantadine; Glutamates; Disease Models, Animal; Pyrimidines; Cyclohexanecarboxylic Acids; Anilides; Receptors, Metabotropic Glutamate; Thiazoles
PubMed: 38427500
DOI: 10.3233/JPD-230296 -
Journal of Neurology Aug 2023
Topics: Humans; Multiple Sclerosis; Memantine; Nystagmus, Pathologic; Eye Movements
PubMed: 37106258
DOI: 10.1007/s00415-023-11730-1 -
Tremor and Other Hyperkinetic Movements... 2024Opsoclonus is a rare disorder characterized by conjugate multidirectional, horizontal, vertical, and torsional saccadic oscillations, without intersaccadic interval,...
BACKGROUND
Opsoclonus is a rare disorder characterized by conjugate multidirectional, horizontal, vertical, and torsional saccadic oscillations, without intersaccadic interval, resulting from dysfunction within complex neuronal pathways in the brainstem and cerebellum. While most cases of opsoclonus are associated with autoimmune or paraneoplastic disorders, infectious agents, trauma, or remain idiopathic, opsoclonus can also be caused by medications affecting neurotransmission. This review was prompted by a case of opsoclonus occurring in a patient with Multiple System Atrophy, where amantadine, an NMDA-receptor antagonist, appeared to induce opsoclonus.
METHODS
Case report of a single patient and systematized review of toxic/drug-induced opsoclonus, selecting articles based on predefined criteria and assessing the quality of included studies.
RESULTS
The review included 30 articles encompassing 158 cases of toxic/drug-induced opsoclonus. 74% of cases were attributed to bark scorpion poisoning, followed by 9% of cases associated with chlordecone intoxication. The remaining cases were due to various toxics/drugs, highlighting the involvement of various neurotransmitters, including acetylcholine, glutamate, GABA, dopamine, glycine, and sodium channels, in the development of opsoclonus.
CONCLUSION
Toxic/drug-induced opsoclonus is very rare. The diversity of toxics/drugs impacting different neurotransmitter systems makes it challenging to define a unifying mechanism, given the intricate neuronal pathways underlying eye movement physiology and opsoclonus pathophysiology.
Topics: Humans; Male; Amantadine; Multiple System Atrophy; Ocular Motility Disorders; Aged
PubMed: 38737300
DOI: 10.5334/tohm.832 -
Nutrients Apr 2024The excessive activation of glutamate in the brain is a factor in the development of vascular dementia. γ-Oryzanol is a natural compound that has been shown to enhance...
The excessive activation of glutamate in the brain is a factor in the development of vascular dementia. γ-Oryzanol is a natural compound that has been shown to enhance brain function, but more research is needed to determine its potential as a treatment for vascular dementia. This study investigated if γ-oryzanol can delay or improve glutamate neurotoxicity in an in vitro model of differentiated HT-22 cells and explored its neuroprotective mechanisms. The differentiated HT-22 cells were treated with 0.1 mmol/L glutamate for 24 h then given γ-oryzanol at appropriate concentrations or memantine (10 µmol/L) for another 24 h. Glutamate produced reactive oxygen species and depleted glutathione in the cells, which reduced their viability. Mitochondrial dysfunction was also observed, including the inhibition of mitochondrial respiratory chain complex I activity, the collapse of mitochondrial transmembrane potential, and the reduction of intracellular ATP levels in the HT-22 cells. Calcium influx triggered by glutamate subsequently activated type II calcium/calmodulin-dependent protein kinase (CaMKII) in the HT-22 cells. The activation of CaMKII-ASK1-JNK MAP kinase cascade, decreased Bcl-2/Bax ratio, and increased Apaf-1-dependent caspase-9 activation were also observed due to glutamate induction, which were associated with increased DNA fragmentation. These events were attenuated when the cells were treated with γ-oryzanol (0.4 mmol/L) or the N-methyl-D-aspartate receptor antagonist memantine. The results suggest that γ-oryzanol has potent neuroprotective properties against glutamate excitotoxicity in differentiated HT-22 cells. Therefore, γ-oryzanol could be a promising candidate for the development of therapies for glutamate excitotoxicity-associated neurodegenerative diseases, including vascular dementia.
Topics: Glutamic Acid; Phenylpropionates; Animals; Neuroprotective Agents; Mice; Cell Line; Reactive Oxygen Species; Mitochondria; Oryza; Membrane Potential, Mitochondrial; Cell Differentiation; Cell Survival; Memantine; Apoptosis; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Neurons
PubMed: 38674927
DOI: 10.3390/nu16081237 -
Maturitas Feb 2024History of cancer has been associated with decreased risk of dementia, but it is unclear if this is due to the use of antineoplastic medications. Participants were...
History of cancer has been associated with decreased risk of dementia, but it is unclear if this is due to the use of antineoplastic medications. Participants were 442,795 adults aged ≥60 years, of whom 235,841 (53.26 %) were women. Those dispensed antineoplastic medications during 2012-2013 had lower odds of being dispensed an anti-dementia drug between 2015 and 2021 (age/sex-adjusted OR = 0.60, 95%CI = 0.55-0.66). The dispensing of antineoplastic medications was associated with an adjusted hazard ratio of 0.72 (95%CI = 0.65-0.80) of subsequent dispensing of an anti-dementia drug. Understanding the mechanisms that support this association may contribute to the introduction of novel approaches to dementia prevention.
Topics: Humans; Female; Male; Cohort Studies; Memantine; Cholinesterase Inhibitors; Dementia; Antineoplastic Agents; Alzheimer Disease
PubMed: 38006816
DOI: 10.1016/j.maturitas.2023.107888 -
BMC Neurology Apr 2024Guillain Barre syndrome (GBS) following Varicella zoster is a rare presentation and has only been reported in a few cases around the world. Of the reported cases, the...
Guillain Barre syndrome (GBS) following Varicella zoster is a rare presentation and has only been reported in a few cases around the world. Of the reported cases, the type of GBS is not specified in the majority, and where specified is of the acute inflammatory demyelinating polyradiculoneuropathy (AIDP) type. We report a case of acute motor axonal neuropathy (AMAN) type GBS following herpes zoster in a 27-year-old male who presented with bilateral lower limb weakness and left sided lower motor neuron type facial nerve palsy a week after herpes zoster infection.
Topics: Male; Humans; Adult; Guillain-Barre Syndrome; Herpes Zoster; Varicella Zoster Virus Infection; Neural Conduction; Amantadine
PubMed: 38570806
DOI: 10.1186/s12883-024-03607-1