ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract: We have examined the development of γ-aminobutyric acidB (GABAB) receptors in rat cerebrum using a binding assay that has achieved specific binding levels of ∼50% with the GABAB ligand (–)-[3H]baclofen. As early as postnatal day 1, GABAB receptors are present and are linked to both calcium- and guanosine triphosphate-binding protein (G protein)-regulatory sites, as indicated by the stimulation of binding by calcium and the inhibition of binding by the guanine nucleotide guanosine 5′-O-(3-thiotriphosphate) (GTPγS). However, whereas the EC50 for the calcium effect was at a mature value in the neonate, the IC50 for the inhibition of binding by GTPγS was not, and declined more than two orders of magnitude by adulthood. Moreover, while many previous studies had shown that manipulation of G proteins by guanine nucleotides affects receptor affinity rather than density, our saturation analysis of binding suggests that calcium affected GABAB receptor density rather than affinity. The results therefore suggest that calcium and the manipulation of G proteins by GTPγS may affect the GABAB receptor by different mechanisms.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1989.tb10933.x
