Neurochemical and electrophysiological evidence for the existence of a functional γ-hydroxybutyrate system in NCB-20 neurons
| Autor: | O. Taleb, J.C Siffert, Michel Maitre, Christian Andriamampandry, J. Mark, A Perard, Véronique Kemmel |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Patch-Clamp Techniques
Stereochemistry medicine.drug_class Population Biology GABAB receptor Cell Line Membrane Potentials Succinic semialdehyde Hydroxybutyrate Dehydrogenase Mice Neuroblastoma chemistry.chemical_compound Cricetulus Cricetinae medicine Animals Binding site Receptor education Neurons HEPES education.field_of_study Binding Sites Hybridomas Valproic Acid General Neuroscience Brain Biological Transport Receptor antagonist Immunohistochemistry Molecular biology Rats Kinetics chemistry Cell culture Calcium Calcium Channels Sodium Oxybate |
| Zdroj: | Neuroscience. 86:989-1000 |
| ISSN: | 0306-4522 |
| DOI: | 10.1016/s0306-4522(98)00085-2 |
| Popis: | Clonal neurohybridoma NCB-20 cells express a valproate-insensitive succinic semialdehyde reductase activity that transforms succinic semialdehyde into γ -hydroxybutyrate. This activity (1.14±0.16 nmol/min/mg protein) was similar to the lowest activity existing in adult rat brain. [ 3 H] γ -Hydroxybutyrate labels a homogeneous population of sites on NCB-20 cell membranes ( K d =250±44.4 nM, B max =180±16.2 fmol/mg protein) that apparently represents specific γ -hydroxybutyrate binding sites characterized previously on brain cell membranes. Finally, an Na + -dependent uptake of [ 3 H] γ -hydroxybutyrate was expressed in NCB-20 cells with a K m of 35+21.1 μ M and a V max of 80±14.2 pmol/min/mg protein. A three-day treatment with 1 mM dibutyryl-cyclic-AMP induced a three-fold increase in the cellular succinic semialdehyde reductase activity. In parallel, a K + -evoked release of [ 3 H] γ -hydroxybutyrate occurred. This release was Ca 2+ dependent and was not present in undifferentiated cells. Cyclic-AMP treatment induced a decrease of [ 3 H] γ -hydroxybutyrate binding sites, which could be due to spontaneous γ -hydroxybutyrate release. Patch-clamp experiments carried out on differentiated NCB-20 cells revealed the presence of Ca 2+ conductances which were partially inhibited by 50 μ M γ -hydroxybutyrate. This γ -hydroxybutyrate-induced effect was blocked by the γ -hydroxybutyrate receptor antagonist NCS-382, but not by the GABA B antagonist CGP-55 845. These results demonstrate the presence of an active γ -hydroxybutyratergic system in NCB-20 cells which possesses the ability to release γ -hydroxybutyrate. These cells express specific γ -hydroxybutyrate receptors which modulate Ca 2+ currents independently of GABA B receptors. |
| Databáze: | OpenAIRE |
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