| 1. |
- Fridjonsdottir, Elva, et al.
(författare)
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Mass spectrometry imaging reveals brain-region specific changes in metabolism and acetylcholine levels in experimental Parkinson’s disease and L-DOPA-induced dyskinesia
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- There is evidence that cholinergic alterations are linked to various motor and non-motor symptoms of Parkinson’s disease. We therefore used mass spectrometry imaging to investigate regional changes in acetylcholine abundance in the brain of a non-human primate model of Parkinson’s disease (PD) and L-DOPA-induced dyskinesia (LID). We also present an experimental design for performing untargeted analysis using MALDI-MSI with multiple experiments incorporating quality control samples to monitor experimental variability. We observed that MPTP treatment (i) led to reductions in putaminal acetylcholine levels that persisted after L-DOPA treatment and (ii) appeared to induce a shift of choline metabolism from α-glycerophosphocholine towards betaine. LID animals exhibited reduced levels of various metabolites important for brain homeostasis including S-adenosylmethionine, glutathione, adenosine monophosphate, and acylcarnitines. The vasculature marker heme B was upregulated in the putamen of LID animals, suggesting increased blood-flow in the dyskinetic putamen. These results provide new insights into pathological choline-related metabolic changes in PD and LID.
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| 2. |
- Fridjonsdottir, Elva, et al.
(författare)
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Region-Specific and Age-Dependent Multitarget Effects of Acetylcholinesterase Inhibitor Tacrine on Comprehensive Neurotransmitter Systems
- 2022
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Ingår i: ACS Chemical Biology. - : American Chemical Society (ACS). - 1554-8929 .- 1554-8937. ; 17:1, s. 147-158
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Tidskriftsartikel (refereegranskat)abstract
- Regional brain distribution and metabolism of neurotransmitters and their response to drug treatment are fundamentally important for understanding the central effects of neuroactive substances. We used matrix-assisted laser desorption/ionization mass spectrometry imaging in combination with multivariate analysis to visualize in anatomical detail metabolic effects of aging and tacrine-mediated acetylcholinesterase inhibition on comprehensive neurotransmitter systems in multiple mouse brain regions of 12-week-old and 14-month-old mice. We detected age-related increases in 3,4-dihydroxyphenylacetaldehyde and histamine, indicating oxidative stress and aging deficits in astrocytes. Tacrine had a significant impact on the metabolism of neurotransmitters in both age groups; predominantly, there was an increased norepinephrine turnover throughout the brain and decreased 3-methoxy tyramine, a marker for dopamine release, in the striatum. The striatal levels of histamine were only elevated after tacrine administration in the older animals. Our results demonstrated that tacrine is a multitarget and region-specific neuroactive agent, inducing age-specific responses. Although well-studied, the complete mechanisms of the action of tacrine are not fully understood, and the current findings reveal features that may help explain its treatment-related effectiveness and central side effects.
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| 3. |
- Mantas, Ioannis, et al.
(författare)
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TAAR1-Dependent and-Independent Actions of Tyramine in Interaction With Glutamate Underlie Central Effects of Monoamine Oxidase Inhibition
- 2021
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Ingår i: Biological Psychiatry. - : Elsevier. - 0006-3223 .- 1873-2402. ; 90:1, s. 16-27
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Monoamine oxidase inhibitors (MAOIs) exert therapeutic actions by elevating extracellular levels of monoamines in the brain. Irreversible MAOIs cause serious hypertensive crises owing to peripheral accumulation of tyramine, but the role of tyramine in the central effects of MAOIs remains elusive, an issue addressed herein. To achieve robust inhibition of MAOA/B, the clinically used antidepressant tranylcypromine (TCP) was employed. METHODS: Behavioral, histological, mass spectrometry imaging, and biosensor-mediated measures of glutamate were conducted with MAOIs in wild-type and TAAR1-knockout (KO) mice. RESULTS: Both antidepressant and locomotion responses to TCP were enhanced in TAAR1-KO mice. A recently developed fluoromethylpyridinium-based mass spectrometry imaging method revealed robust accumulation of striatal tyramine on TCP administration. Furthermore, tyramine accumulation was higher in TAAR1-KO versus wild type mice, suggesting a negative feedback mechanism for TAAR1 in sensing tyramine levels. Combined histoenzymological and immunohistological studies revealed hitherto unknown TAAR1 localization in brain areas projecting to the substantia nigra/ventral tegmental area. Using an enzyme-based biosensor technology, we found that both TCP and tyramine reduced glutamate release in the substantia nigra in wild-type but not in TAAR1-KO mice. Moreover, glutamate measures in freely moving animals treated with TCP demonstrated that TAAR1 prevents glutamate accumulation in the substantia nigra during hyperlocomotive states. CONCLUSIONS: These observations suggest that tyramine, in interaction with glutamate, is involved in centrally mediated behavioral, transcriptional, and neurochemical effects of MAOIs.
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| 4. |
- Shariatgorji, Mohammadreza, et al.
(författare)
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Comprehensive mapping of neurotransmitter networks by MALDI-MS imaging
- 2019
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Ingår i: Nature Methods. - : NATURE PUBLISHING GROUP. - 1548-7091 .- 1548-7105. ; 16:10, s. 1021-1028
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Tidskriftsartikel (refereegranskat)abstract
- We present a mass spectrometry imaging (MSI) approach for the comprehensive mapping of neurotransmitter networks in specific brain regions. Our fluoromethylpyridinium-based reactive matrices facilitate the covalent charge-tagging of molecules containing phenolic hydroxyl and/or primary or secondary amine groups, including dopaminergic and serotonergic neurotransmitters and their associated metabolites. These matrices improved the matrix-assisted laser desorption/ionization (MALDI)-MSI detection limit toward low-abundance neurotransmitters and facilitated the simultaneous imaging of neurotransmitters in fine structures of the brain at a lateral resolution of 10 mu m. We demonstrate strategies for the identification of unknown molecular species using the innate chemoselectivity of the reactive matrices and the unique isotopic pattern of a brominated reactive matrix. We illustrate the capabilities of the developed method on Parkinsonian brain samples from human post-mortem tissue and animal models. The direct imaging of neurotransmitter systems provides a method for exploring how various neurological diseases affect specific brain regions through neurotransmitter modulation.
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| 5. |
- Zhang, Xiaoqun, et al.
(författare)
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Deficits in Motor Performance, Neurotransmitters and Synaptic Plasticity in Elderly and Experimental Parkinsonian Mice Lacking GPR37
- 2020
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Ingår i: Frontiers in Aging Neuroscience. - : FRONTIERS MEDIA SA. - 1663-4365. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Parkinson's disease (PD) etiology is attributed to aging and the progressive neurodegeneration of dopamine (DA) neurons of substantia nigra pars compacta (SNc). GPR37 is an orphan G-protein Coupled Receptor (GPCR) that is linked to the juvenile form of PD. In addition, misfolded GPR37 has been found in Lewy bodies. However, properly folded GPR37 found at the cell membrane appears to exert neuroprotection. In the present study we investigated the role of GPR37 in motor deficits due to aging or toxin-induced experimental parkinsonism. Elderly GPR37 knock out (KO) mice displayed hypolocomotion and worse fine movement performance compared to their WT counterparts. Striatal slice electrophysiology reveiled that GPR37 KO mice show profound decrease in long term potentiation (LTP) formation which is accompanied by an alteration in glutamate receptor subunit content. GPR37 KO animals exposed to intrastriatal 6-hydroxydopamine (6-OHDA) show poorer score in the behavioral cylinder test and more loss of the DA transporter (DAT) in striatum. The GPR37 KO striata exhibit a significant increase in GABA which is aggravated after DA depletion. Our data indicate that GPR37 KO mice have DA neuron deficit, enhanced striatal GABA levels and deficient corticostriatal LTP. They also respond stronger to 6-OHDA-induced neurotoxicity. Taken together, the data indicate that properly functional GPR37 may counteract aging processes and parkinsonism.
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| 6. |
- Zhang, Xiaoqun, et al.
(författare)
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Striatal Tyrosine Hydroxylase Is Stimulated via TAAR1 by 3-Iodothyronamine, But Not by Tyramine or beta-Phenylethylamine
- 2018
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Ingår i: Frontiers in Pharmacology. - : FRONTIERS MEDIA SA. - 1663-9812. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The trace amine-associated receptor 1 (TAAR1) is expressed by dopaminergic neurons, but the precise influence of trace amines upon their functional activity remains to be fully characterized. Here, we examined the regulation of tyrosine hydroxylase (TH) by tyramine and beta-phenylethylamine (beta-PEA) compared to 3-iodothyronamine (T(1)AM). Immunoblotting and amperometry were performed in dorsal striatal slices from wildtype (WT) and TAAR1 knockout (KO) mice. T(1)AM increased TH phosphorylation at both Ser(19) and Ser(40), actions that should promote functional activity of TH. Indeed, HPLC data revealed higher rates of L-dihydroxyphenylalanine (DOPA) accumulation in WT animals treated with T(1)AM after the administration of a DOPA decarboxylase inhibitor. These effects were abolished both in TAAR1 KO mice and by the TAAR1 antagonist, EPPTB. Further, they were specific inasmuch as Ser(845) phosphorylation of the post-synaptic GluA1 AMPAR subunit was unaffected. The effects of T1AM on TH phosphorylation at both Ser(19) (CamKII-targeted), and Ser40 (PKA-phosphorylated) were inhibited by KN-92 and H-89, inhibitors of CamKII and PKA respectively. Conversely, there was no effect of an EPAC analog, 8-CPT-2Me-cAMP, on TH phosphorylation. In line with these data, T(1)AM increased evoked striatal dopamine release in TAAR1 WT mice, an action blunted in TAAR1 KO mice and by EPPTB. Mass spectrometry imaging revealed no endogenous T(1)AM in the brain, but detected T(1)AM in several brain areas upon systemic administration in both WT and TAAR1 KO mice. In contrast to T1AM, tyramine decreased the phosphorylation of Ser40-TH, while increasing Ser(845)-GluA1 phosphorylation, actions that were not blocked in TAAR1 KO mice. Likewise, beta-PEA reduced Ser(40)-TH and tended to promote Ser845-GluA1 phosphorylation. The D-1 receptor antagonist SCH23390 blocked tyramine-induced Ser(845)-GluA1 phosphorylation, but had no effect on tyramine-or beta-PEA-induced Ser(40)-TH phosphorylation. In conclusion, by intracellular cascades involving CaMKII and PKA, T(1)AM, but not tyramine and beta-PEA, acts via TAAR1 to promote the phosphorylation and functional activity of TH in the dorsal striatum, supporting a modulatory influence on dopamine transmission.
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