Search result for : author:péter klivényi

Total 7 result(s) found

The detection of age-, gender-, and region-specific changes in mouse brain tocopherol levels via the application of different validated HPLC methods.

The aging process clearly increases the demand for antioxidant protection, especially in the brain, involving that provided by α-tocopherol (αT). However, little is known about the age-related changes in brain αT levels and the influencing effect of gender on it, in human or murine samples as well. Accordingly, the aim of the current study was to detect age-, gender- and region-specific changes in αT concentrations in mouse brain tissue and to assess the influencing effect of plasma αT levels on it. Female and male C57BL/6 mice at the ages of 6, 16 and 66 weeks (n = 9 in each group) were applied. αT levels were determined with high performance liquid chromatography (HPLC) from the striatum, cortex, hippocampus, cerebellum, brainstem and from plasma samples. A detailed validation process was carried out for the applied HPLC method as well. The results demonstrated that brain αT levels significantly increased in the striatum, cortex, and hippocampus with aging in both genders, but in a more pronounced way in females with an increasing magnitude of this difference. In case of the cerebellum, a moderate elevation could be detected only in females, whereas in case of the brainstem there was no significant change in αT level. With regard to plasma samples, no clear trend could be identified. The current study is the first to present age-dependent gender-specific changes in αT level in certain brain regions of the C57Bl/6 mouse strain, and may provide meaningful information for future therapeutic studies targeting aging-related processes.

Nikolett Nánási, Gábor Veres, Edina K Cseh, Márton Szentirmai, Diána Martos, Evelin Sümegi, Levente Hadady, Péter Klivényi, László Vécsei, Dénes Zádori
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Effects of mitochondrial toxins on the brain amino acid concentrations.

In the pathogenesis of Parkinson's disease and Huntington's disease excitotoxicity may play an important role. The common toxin model for Parkinson's disease is MPTP, while for Huntington's disease it is 3-NP. These toxins inhibit the mitochondrial respiratory chain, resulting in an energy deficit. In the central nervous system, the amino acids act as neurotransmitters and neuromodulators. The energy deficit caused by these neurotoxins may alter the concentrations of amino acids. Thus, it can be claimed that the aminoacidergic neurotransmission can be changed by neurotoxins. To test this hypothesis we studied the amino acid concentrations in different brain regions following MPTP or 3-NP administration. The two toxins were found to produce similar changes. We detected marked decreases in most of the amino acid concentrations in the striatum and in the cortex, while the levels in the cerebellum increased significantly. The decreased amino acid levels can be explained by the reduced levels of ATP produced by these neurotoxins. In the cerebellum, where there is no detectable ATP loss, the elevated amino acid levels may reflect a compensation of the altered neurotransmission.

Peter Klivenyi, Katalin A Kekesi, Zsuzsanna Hartai, Gabor Juhasz, Laszlo Vecsei
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Central nervous system-specific alterations in the tryptophan metabolism in the 3-nitropropionic acid model of Huntington's disease.

Experiments on human samples and on genetic animal models of Huntington's disease (HD) suggest that a number of neuroactive metabolites in the kynurenine (KYN) pathway (KP) of the tryptophan (TRP) catabolism may play a role in the development of HD. Our goal in this study was to assess the concentrations of TRP, KYN, kynurenic acid and 3-hydroxykynurenine (3-OHK) in the serum and brain of 5-month-old C57Bl/6 mice in the widely used 3-nitropropionic acid (3-NP) toxin model of HD. We additionally investigated the behavioral changes through open-field, rotarod and Y-maze tests. Our findings revealed an increased TRP catabolism via the KP as reflected by elevated KYN/TRP ratios in the striatum, hippocampus, cerebellum and brainstem. As regards the other examined metabolites of KP, we found only a significant decrease in the 3-OHK level in the cerebellum of the 3-NP-treated mice. The open-field and rotarod tests demonstrated that treatment with 3-NP resulted in a reduced motor ability, though this had almost totally disappeared a week after the last injection, similarly as observed previously in most murine 3-NP studies. The relevance of the alterations observed in our biochemical and behavioral analyses is discussed. We propose that the identified biochemical alterations could serve as applicable therapeutic endpoints in studies of drug effects on delayed-type neurodegeneration in a relatively fast and cost-effective toxin model of HD.

Gábor Veres, Máté Molnár, Dénes Zádori, Márton Szentirmai, Levente Szalárdy, Rita Török, Emese Fazekas, István Ilisz, László Vécsei, Péter Klivényi
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Drug-induced movement disorders.

Drug-induced movement disorders (DIMDs) can be elicited by several kinds of pharmaceutical agents. The major groups of offending drugs include antidepressants, antipsychotics, antiepileptics, antimicrobials, antiarrhythmics, mood stabilisers and gastrointestinal drugs among others. This paper reviews literature covering each movement disorder induced by commercially available pharmaceuticals. Considering the magnitude of the topic, only the most prominent examples of offending agents were reported in each paragraph paying a special attention to the brief description of the pathomechanism and therapeutic options if available. As the treatment of some DIMDs is quite challenging, a preventive approach is preferable. Accordingly, the use of the offending agents should be strictly limited to appropriate indications and they should be applied in as low doses and as short duration as the patient's condition allows. As most of DIMDs are related to an unspecific adverse action of medications in the basal ganglia and the cerebellum, future research should focus on better characterisation of the neurochemical profile of the affected functional systems, in addition to the development of drugs with higher selectivity and better side-effect profile.

Dénes Zádori, Gábor Veres, Levente Szalárdy, Péter Klivényi, László Vécsei
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mRNA expression levels of PGC-1α in a transgenic and a toxin model of Huntington's disease.

Peroxisome proliferator-activated receptor-gamma (PPARγ) coactivator-1 alpha (PGC-1α) is involved in the regulation of mitochondrial biogenesis, respiration, and adaptive thermogenesis. The full-length PGC-1α (FL-PGC-1α) comprises multiple functional domains interacting with several transcriptional regulatory factors such as nuclear respiratory factors, estrogen-related receptors, and PPARs; however, a number of PGC-1α splice variants have also been reported recently. In this study, we examined the expression levels of FL-PGC-1α and N-truncated PGC-1α (NT-PGC-1α), a shorter but functionally active splice variant of PGC-1α protein, in N171-82Q transgenic and 3-nitropropionic acid-induced murine model of Huntington's disease (HD). The expression levels were determined by RT-PCR in three brain areas (striatum, cortex, and cerebellum) in three age groups (8, 12, and 16 weeks). Besides recapitulating prior findings that NT-PGC-1α is preferentially increased in 16 weeks of age in transgenic HD animals, we detected age-dependent alterations in both models, including a cerebellum-predominant upregulation of both PGC-1α variants in transgenic mice, and a striatum-predominant upregulation of both PGC-1α variants after acute 3-nitropropionic acid intoxication. The possible relevance of this expression pattern is discussed. Based on our results, we assume that increased expression of PGC-1α may serve as a compensatory mechanism in response to mitochondrial damage in transgenic and toxin models of HD, which may be of therapeutic relevance.

Rita Török, Júlia Anna Kónya, Dénes Zádori, Gábor Veres, Levente Szalárdy, László Vécsei, Péter Klivényi
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Neurocognitive Characterization of an SCA28 Family Caused by a Novel AFG3L2 Gene Mutation.

Laszlo Szpisjak, Viola L Nemeth, Noemi Szepfalusi, Denes Zadori, Zoltan Maroti, Tibor Kalmar, Laszlo Vecsei, Peter Klivenyi
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Effect of MPTP on mRNA expression of PGC-1α in mouse brain.

The peroxisome proliferator-activated receptor-γ (PPARγ) coactivator 1α (PGC-1α) is a key regulator of mitochondrial biogenesis, respiration and adaptive thermogenesis. Besides the full-length protein (FL-PGC-1α), several other functionally active PGC-1α isoforms were identified as a result of alternative splicing (e.g., N-truncated PGC-1α; NT-PGC-1α) or alternative promoter usage (e.g., central nervous system-specific PGC-1α isoforms; CNS-PGC-1α). Achieving neuroprotection via CNS-targeted pharmacological stimulation is limited due to poor penetration of the blood brain barrier (BBB) by the proposed pharmaceutical agents, so preconditioning emerged as another option. The current study aimed to examine of how the expression levels of FL-, NT-, CNS- and reference PGC-1α isoforms change in different brain regions following various 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment regimens, including chronic low-dose treatment for preconditioning. Ninety minutes following the acute treatment regimen, the expression levels of FL-, NT- and CNS-PGC-1α isoforms increased significantly in the striatum, cortex and cerebellum. However, this elevation diminished 7days following the last MPTP injection in the acute treatment regimen. The chronic low-dose administration of MPTP, which did not cause significant toxic effects in light of the relatively unaltered dopamine levels, did not result in any significant change of PGC-1α expression. The elevation of PGC-1α levels following acute treatment may demonstrate a short-term compensatory mechanism against mitochondrial damage induced by the complex I inhibitor MPTP. However, drug-induced preconditioning by chronic low-dose MPTP seems not to induce protective responses via the PGC-1α system.

Rita Torok, Andras Salamon, Evelin Sumegi, Denes Zadori, Gabor Veres, Mate Fort Molnar, Laszlo Vecsei, Peter Klivenyi
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