Functional coupling of GABAA receptors and benzodiazepine recognition site subtypes in the spinal cord of the rat
| Autor: | Giovanni Biggio, Ennio Ongini, Osvaldo Giorgi, Biancamaria Longoni, G Pesce, R Cruciani, Mg Corda |
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| Rok vydání: | 1989 |
| Předmět: |
Male
medicine.medical_specialty Cerebellum medicine.drug_class Central nervous system In Vitro Techniques Binding Competitive Benzodiazepines Internal medicine medicine Animals Binding site gamma-Aminobutyric Acid Pharmacology Benzodiazepine Membranes GABAA receptor Chemistry Rats Inbred Strains Receptors GABA-A Spinal cord Rats Kinetics medicine.anatomical_structure Endocrinology Spinal Cord Flunitrazepam ZK-93423 medicine.drug |
| Zdroj: | European Journal of Pharmacology. 169:205-213 |
| ISSN: | 0014-2999 |
| DOI: | 10.1016/0014-2999(89)90017-4 |
| Popis: | The interaction between GABAA receptors and benzodiazepine (BZD) recognition site subtypes in the spinal cord of the rat was investigated. Computer analysis of displacement curves for [3H]flunitrazepam [( 3H]FNT) binding by 2-oxo-quazepam (2OXOQ) indicated the presence of two subtypes of BZD recognition sites in this region. Type I sites accounted for approximately 25% of the total number of BZD recognition sites, the remainder being Type II sites. A similar proportion of Type I and Type II sites was obtained by Scatchard analysis of the saturation curves for [3H]FNT, [3H]2OXOQ and [3H]ethyl-beta-carboline-3-carboxylate [( 3H]beta CCE) binding. The in vitro addition of GABA (10(-8)-10(-4) M) to spinal cord membrane preparations produced an increase in the binding of [3H]FNT and [3H]2OXOQ. The maximal enhancement produced by GABA was 50 and 82% above control values for [3H]FNT and [3H]2OXOQ, respectively. In contrast, GABA stimulated both [3H]FNT and [3H]2OXOQ binding in the cerebellum to a similar extent. We also evaluated the effects of different ligands for BZD recognition sites on the binding of [3H]GABA to spinal cord membranes, as compared with brain areas containing a higher proportion ( greater than 30%) of Type I sites. Diazepam, quazepam and the beta-carboline, ZK 93423, enhanced the specific binding of [3H]GABA in a concentration-dependent manner (10(-7)-10(-5) M) in the cerebral cortex and hippocampus but not in the spinal cord and cerebellum. These results indicate that there is a regional variation in the interaction between GABA and BZD recognition sites in the central nervous system. |
| Databáze: | OpenAIRE |
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