Gamma-hydroxybutyrate and cocaine administration increases mRNA expression of dopamine D1 and D2 receptors in rat brain

The effects of acute and repeated gamma-hydroxybutyrate (GHB) and cocaine administration on D-1 and D-2 dopamine receptor mRNA expression were examined using in situ hybridization histochemistry in different rat brain structures rich in GHB receptors. Six hours after a single GHB administration (500 mg/kg IP), an increase in D-1 and D-2 mRNA expression teas observed in almost all regions examined; whereas, acute cocaine injection (20 mg/kg IP) had no effect. Repeated exposure to GHB (500 mg/kg IP twice daily) for 10 days, followed by a 14-h withdrawal period, induced increasing effects on D-1 and D-2 dopamine receptor mRNA expression, similar to those caused by chronic treatment with cocaine (20 mg/kg IP once a day). These effects of GHB and cocaine on dopamine receptor mRNA expression could be a consequence, for both compounds, of the modulation of dopaminergic activity thus, supporting the benefit of GHB in cocaine substitution therapy. [Neuropsychopharmacology 21: 662-669, 1999] (C) 1999 American College of Neuropsychopharmacology. Published by Elsevier Science Inc.