摘要：

γ-Hydroxybutyric Acid (GHB) is thought to be a weak partial agonist at the γ-aminobutyric acidB Receptor (GABABR), but the precise relationship of the GHB receptor (GHBR) to the GABABR remains unclear. In order to test the hypothesis that the GHBR is not identical to the GABABR, we conducted two groups of experiments. First, GABABR subtype 1 (R1) and/or subtype 2 (R2) were over expressed in HEK 293 cells and membrane binding studies on the transfected cells done using [3H]GHB and [3H] (2E)-(5-hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7]annulen-6-ylidene) ethanoic acid ([3H]NCS-382). The latter is a specific antagonist at the GHB binding site. Second, [3H]GHB and [3H]NCS-382 autoradiographic binding studies were done on the brains of mice in which the gene for GABABR1a was deleted. Such mice do not have a functioning GABABR. There was no detectable specific [3H]GHB or [3H]NCS-382 binding in HEK 293 cells transfected with GABABR1, R2, or R1/R2. Binding to [3H]CGP54626A, a high affinity GABABR antagonist, was absent in GABABR1a/ mice. There was no difference in [3H]NCS-382 binding observed in the brains of GABABR1a/, GABABR1a+/ or GABABR1a+/+ mice. Specific [3H]GHB binding was observed in the brain of GABABR1a/ mice but was significantly lower than in wild type mice. These data support the hypothesis that the GHB binding site is separate and distinct from the GABABR.

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