Quantitative autoradiographic study of L‐glutamate binding sites in normal and atrophic human cerebellum

Hatziefthimiou, Apostolia; Mitsacos, Ada; Mitsaki, E.; Plaitakis, Andreas; Kouvelas, Elias D.

doi:10.1002/jnr.490280308

Cited by 7 publications

(1 citation statement)

References 63 publications

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“…10 Results revealed the L-glutamate binding was significantly decreased (to 30% of control) in all these patients without a change in the affinities and the pharmacologic properties of the binding sites. 42 Additional autoradiographic studies 43 showed significant decreases in quisqualate-sensitive L-glutamate binding in the molecular layer of the cerebellum. In some patients, particularly those associated with GDH abnormalities, L-glutamate binding was decreased in the granule layer as well.…”

Section: L-glutamate Receptors In Opcamentioning

confidence: 98%

Glutamate Dehydrogenase Deficiency in Cerebellar Degenerations: Clinical, Biochemical and Molecular Genetic Aspects

Plaitakis

Flessas

Natsiou

et al. 1993

Can. J. Neurol. Sci.

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Glutamate dehydrogenase (GDH), an enzyme central to glutamate metabolism, is significantly reduced in patients with heterogenous neurological disorders characterized by multiple system atrophy (MSA) and predominant involvement of the cerebellum and its connections. In human brain, GDH exists in multiple isoforms differing in their isoelectric point and molecular mass. These are differentially reduced in quantity and altered in catalytic activity in patients with clinically distinct forms of MSA, thus suggesting that these GDH isoproteins are under different genetic control. Dysregulation of glutamate metabolism occurs in patients with GDH deficiency and is thought to mediate the disease's neurodegeneration via neuroexcitotoxic mechanisms. This possibility is supported by additional data showing that glutamate binding sites are significantly decreased in cerebellar tissue obtained at autopsy from MSA patients. At the molecular biological level, several cDNAs specific for human GDH have been isolated recently and cloned. Northern blot analysis of various human tissues, including brain, has revealed the presence of multiple GDH-specific mRNAs. In addition, multiple GDH-specific genes are present in humans and these data are consistent with the possibility that the various GDH isoproteins are encoded by different genes. These advances have laid the groundwork for characterizing the human GDH genes and their products in health and disease. RESUME: Deficit en glutamate dehydrogenase dans les degenerescences cerebelleuses: aspects cliniques, biochimiques et de genetique moleculaire. La glutamate dehydrogenase (GDH), un enzyme important du metabolisme du glutamate, est diminuee de facon significative chez les patients souffrant de maladies neurologiques heterogenes caracterisees par une atrophie multi-systemique (AMS) et une atteinte principalement localisee au cervelet et a ses voies de communication. Dans le cerveau humain, la GDH existe sous de multiples isoformes, qui different par leur point isoelectrique et leur masse moleculaire, dont la quantite est diminuee differentiellement et dont l'activite catalytique est alteree, chez les patients qui ont des formes d'AMS cliniquement distinctes, suggerant que ces isoproteines sont sous un controle genetique different. Un dereglement du metabolisme du glutamate survient chez les patients qui ont un deficit en GDH et Ton pense qu'il est a l'origine de la neurodegenerescence presente dans cette maladie via des mecanismes neuro-excitotoxiques. Des donnees additionnelles supportent cette possibilite: les sites de liaison du glutamate sont diminues de facon significative dans le tissu cerebelleux provenant d'autopsies de patients atteints d'AMS. Au niveau de la biologie moleculaire, plusieurs ADN complementaires specifiques pour la GDH humaine ont ete isoles et clones recemment. L'analyse par Northern blot de differents tissus humains incluant le cerveau, a revele la presence de multiples ARN messagers specifiques de la GDH. De plus, plusieurs genes specifiques a la ...

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Section: L-glutamate Receptors In Opcamentioning

confidence: 98%

Glutamate Dehydrogenase Deficiency in Cerebellar Degenerations: Clinical, Biochemical and Molecular Genetic Aspects

Plaitakis

Flessas

Natsiou

et al. 1993

Can. J. Neurol. Sci.

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Autoradiographic characterization of the non‐N‐methyl‐D‐aspartate binding sites in human cerebellum using the antagonist [³H]6‐cyano‐7‐nitroquinoxaline‐2,3‐dione

Hatziefthimiou

Mitsacos

Kouvelas

1994

J of Neuroscience Research

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Using quantitative autoradiography, we have characterized the binding properties of the non-N-methyl-D-aspartate (NMDA) glutamate receptor antagonist [3H]6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) in adult human cerebellum. Saturation experiments revealed [3H]CNQX binding to a single class of sites with similar affinity in the molecular and granule cell layer (Kd = 89.0 +/- 6.4 and 83.3 +/- 9.9 nM, respectively). The maximum number of [3H]CNQX binding sites was much higher in the molecular compared to the granule cell layer (Bmax = 16.2 +/- 1.1 and 2.8 +/- 0.5 pmol/mg protein, respectively). Inhibition experiments were performed in order to examine the pharmacological profile of [3H]CNQX binding in the molecular layer. [3H]CNQX labeled sites with high affinity for both non-NMDA agonists, (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and kainate. Dose-response curves for inhibition of [3H]CNQX by AMPA and kainate were biphasic. The potency of AMPA for displacement of [3H]CNQX binding (Ki: 2.8 +/- 0.8 nM and 12.5 +/- 0.8 microM) was 4- to 6-fold greater than the corresponding potency of kainate (Ki: 18.1 +/- 5.7 nM and 48.7 +/- 9.3 microM). In conclusion, the pharmacological analysis of [3H]CNQX binding in the human cerebellar molecular layer reflects the existence of multiple binding sites of the non-NMDA receptor that have different affinities for both AMPA and kainate.

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Glutamate-like immunoreactivity in chick cerebellum and optic tectum

et al. 1992

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Glutamate was coupled via glutaraldehyde to bovine serum albumin. The conjugate was used for raising specific anti-glutamate antibodies. The purified antibody was used for immunostaining of chick cerebellum and optic tectum. Staining was intense in the molecular layer and in cell bodies of the granule cell layer. In the optic tectum a diffuse staining was detected in the superficial layers of stratum griseum fibrosum superficiale and in cell bodies especially in the layers a and e. Large cell bodies located in the stratum griseum centrale were also stained.

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Quantitative autoradiographic study of L‐glutamate binding sites in normal and atrophic human cerebellum

Cited by 7 publications

References 63 publications

Glutamate Dehydrogenase Deficiency in Cerebellar Degenerations: Clinical, Biochemical and Molecular Genetic Aspects

Glutamate Dehydrogenase Deficiency in Cerebellar Degenerations: Clinical, Biochemical and Molecular Genetic Aspects

Autoradiographic characterization of the non‐N‐methyl‐D‐aspartate binding sites in human cerebellum using the antagonist [³H]6‐cyano‐7‐nitroquinoxaline‐2,3‐dione

Glutamate-like immunoreactivity in chick cerebellum and optic tectum

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Quantitative autoradiographic study of L‐glutamate binding sites in normal and atrophic human cerebellum

Cited by 7 publications

References 63 publications

Glutamate Dehydrogenase Deficiency in Cerebellar Degenerations: Clinical, Biochemical and Molecular Genetic Aspects

Glutamate Dehydrogenase Deficiency in Cerebellar Degenerations: Clinical, Biochemical and Molecular Genetic Aspects

Autoradiographic characterization of the non‐N‐methyl‐D‐aspartate binding sites in human cerebellum using the antagonist [3H]6‐cyano‐7‐nitroquinoxaline‐2,3‐dione

Glutamate-like immunoreactivity in chick cerebellum and optic tectum

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Autoradiographic characterization of the non‐N‐methyl‐D‐aspartate binding sites in human cerebellum using the antagonist [³H]6‐cyano‐7‐nitroquinoxaline‐2,3‐dione