Prodynorphin and proenkephalin mRNAs are increased in rat brain after acute and chronic administration of gamma-hydroxybutyrate

Abstract

The effects of gamma-hydroxybutyrate (GHB) on prodynorphin (PD) and proenkephalin (PE) mRNA expression were examined using in situ hybridization histochemistry in discrete rat brain structures rich in GHB receptors. A single dose of GHB (500 mg/kg i.p.) increased striatal PE mRNA levels (+60%) between 15 and 90 min after injection. An increase in PD mRNA expression was observed in the frontal cortex (+90%) 6 h after GHB administration. Chronic exposure to GHB (500 mg/kg i.p. twice a day) for 10 days induced significant increases in both PE and PD mRNA levels in different brain regions examined, suggesting that PD and PE mRNA expressions are modulated by the endogenous GHBergic system.