Article date: 1989/5/22
PubMed ID: 2543481
Journal name: Brain research (ISSN: 0006-8993)
gamma-Aminobutyric acid (GABA) synaptic pharmacology was studied in cultured mouse spinal cord using various biochemical techniques. The intact cultures were used to study GABA uptake, benzodiazepine (BZ) binding and GABA-stimulated 36Cl-influx, all under similar physiological conditions. The cultures appear to contain a population of GABAergic neurons, since there was evidence of neuronal active transport of [3H]GABA by these cells. There also was a significant population of neuronal BZ receptors based on the finding of clonazepam-displaceable [3H]flunitrazepam (FLU) binding. In addition, the presence of GABA receptors coupled to the BZ receptors was shown by the enhancement of FLU binding by GABA (10-100 microM). GABAA and glycine-coupled Cl- channels were also demonstrated using 36Cl-influx. GABA-induced 36Cl-influx was specific for GABAA agonists, since GABAB receptor agonist, baclofen and other excitatory neurotransmitters did not alter the 36Cl-influx. Both GABA (Km = 9.1 microM) and muscimol (Km = 2.0 microM) produced concentration-dependent increases in 36Cl-influx in the cultures. The GABA-stimulated Cl-influx was blocked by the GABAA receptor antagonist (+)bicuculline (IC50 = 4.5 microM) and by the Cl- channel antagonist picrotoxinin (IC50 = 25 microM). These results indicate that spinal cord cultures are a useful model for comparing the binding characteristics of the GABA receptor complex to the activation of the coupled Cl- channels using the 36Cl-influx assay.
Author List: Lehoullier P F, Ticku M K
Publication Types: Journal Article; Research Support, U.S. Gov't, P.H.S.
Substances mentioned in the article: Chloride Channels; Chlorides; Membrane Proteins; Receptors, GABA-A; gamma-Aminobutyric Acid; Flunitrazepam;
Mesh terms: Animals; Cells, Cultured; Chloride Channels; Chlorides/metabolism; Flunitrazepam/metabolism; Membrane Proteins/metabolism; Mice; Mice, Inbred C57BL; Receptors, GABA-A/drug effects; Spinal Cord/cytology; gamma-Aminobutyric Acid/pharmacokinetics;