Article date: 1987/9/23
PubMed ID: 2822450
Journal name: European journal of pharmacology (ISSN: 0014-2999)
(-)Baclofen, a GABAB receptor agonist, and GABA attenuated by 60% the high K+-evoked 45Ca2+ uptake into cultured cerebellar granule cells with an EC50 of 110 +/- 18 nM and 2.4 +/- 0.2 microM, respectively. The attenuation by baclofen of 45Ca2+ uptake was stereospecific and the effect of GABA was unaffected by bicuculline. Moreover, muscimol, a GABAA receptor agonist did not affect the K+-evoked 45Ca2+ uptake. (-)Baclofen and GABA also decreased the K+-evoked and calcium-dependent release of preloaded [3H]D-aspartate from granule cells; however, their potency and efficacy appeared to be less than those for inhibiting the 45Ca2+ uptake. (+)Baclofen and muscimol failed to change this K+-evoked release. The release of [3H]D-aspartate induced by the calcium ionophore A23187 was unaffected by (-)-baclofen. The K+-evoked release of [3H]D-aspartate was effectively inhibited by nimodipine, a voltage sensitive calcium channel blocker. The results suggest that GABAB receptor in cultured cerebellar granule cells plays a crucial role in modulating the uptake of calcium and release of the excitatory transmitter. Moreover, these two effects mediated by GABAB receptor activation may be casually related.
Author List: Zhu X Z, Chuang D M
Publication Types: Journal Article
Substances mentioned in the article: Calcium Radioisotopes; Receptors, GABA-A; Muscimol; Aspartic Acid; Calcimycin; gamma-Aminobutyric Acid; Nimodipine; Baclofen; Calcium;
Mesh terms: Animals; Aspartic Acid/metabolism; Baclofen/pharmacology; Calcimycin/pharmacology; Calcium/metabolism; Calcium Radioisotopes; Cells, Cultured; Cerebellum/metabolism; Muscimol/pharmacology; Nimodipine/pharmacology; Rats; Receptors, GABA-A/metabolism; gamma-Aminobutyric Acid/pharmacology;