Gamma-Hydroxybutyrate and Cocaine Administration Increases mRNA Expression of Dopamine D1 and D2 Receptors in Rat Brain

Abstract

The effects of acute and repeated gamma-hydroxybutyrate (GHB) and cocaine administration on D1 and D2 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 D1 and D2 mRNA expression was 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 D1 and D2 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.