gamma-Hydroxybutyric acid

GHB is present at much higher concentrations in the brain, where it activates GABA-B receptors to exert its sedative effects. With high affinity, GHB binds to excitatory GHB receptors that are densely expressed throughout the brain, including the cotex and hippocampus. There is some evidence in research that upon activation of GHB receptors in some brain areas, the excitatory neurotransmitter glutamate is released. GHB stimulates dopamin release at low concentrations by acting on the GHB receptor, and the release of dopamine occurs in a biphasic manner. At higher concentrations, GHB inhibits dopamine release by acting on the GABA-B receptors, which is followed by GHB receptor signaling and increased release of dopamine. This explains the paradoxical mix of sedative and stimulatory properties of GHB, as well as the so-called "rebound" effect, experienced by individuals using GHB as a sleeping agent, wherein they awake suddenly after several hours of GHB-induced deep sleep. It is proposed that overtime, the level of GHB in the brain decreases below the threshold for significant GABA-B receptor activation, leading to preferential activation of GHB receptor over GABA-B receptors and enhanced wakefulness.