Edited sentence: As the serotonergic system may be involved in the regulation of sleep, mood and anxiety, the stimulation of this system by high doses of GHB may be involved in certain neuropharmacological events induced by GHB administration.GHB induces the accumulation of either a derivative of or [3H]-tryptophan itself in the extracellular space, possibly by increasing tryptophan transport across the blood-brain barrier.GHB-induced stimulation of tissue serotonin turnover may be due to an increase in tryptophan transport to the brain and in its uptake by serotonergic cells.The blood content of certain neutral amino-acids, including tryptophan, is also increased by peripheral GHB administration