Differential effects of Triton X-100 on ligand binding to GABAB receptors in mouse cerebral cortex, cerebellum and whole brain.
1. Pretreatment of whole brain membranes with Triton X-100 (0.01-0.05 v/v%) increased the specific binding of [3H]baclofen without change of non-specific binding. Although the treatment increased the affinity of all the GABAB agonists tested, that of antagonists either tend to be decreased or unchanged. Furthermore, the treatment potentiated Gpp(NH)p-induced inhibition of [3H]baclofen binding. 2. Affinity for [3H]baclofen in the cerebral cortex was increased following Triton X-100 (0.02 v/v%) treatment, whereas binding characteristics in the cerebellum were not significantly changed. 3. These results suggest that the properties of cerebellar and cerebral cortical GABAB receptors differ from each other, and that pretreatment with Triton X-100 not only affects agonist and antagonist binding to GABAB receptors differentially, but also changes the coupling between GABAB receptors and guanine nucleotide regulatory proteins.
Ishige
K
K
Department of Pharmacology, College of Pharmacy, Nihon University, Japan.
Ito
Y
Y
Fukuda
H
H
D000818:Animals; D001418:Baclofen / Q000378:metabolism / Q000493:pharmacokinetics; D001923:Brain Chemistry / Q000187:drug effects*; D002531:Cerebellum / Q000187:drug effects / Q000378:metabolism; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D058788:GABA-B Receptor Antagonists; D006165:Guanylyl Imidodiphosphate / Q000378:metabolism; D066298:In Vitro Techniques; D008024:Ligands; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D017830:Octoxynol / Q000494:pharmacology*; D018080:Receptors, GABA-B / Q000187:drug effects / Q000378:metabolism*
D058788:GABA-B Receptor Antagonists; D008024:Ligands; D018080:Receptors, GABA-B; D006165:Guanylyl Imidodiphosphate; D017830:Octoxynol; D001418:Baclofen