Naloxone reverses the inhibitory effect of gamma-hydroxybutyrate on central DA release in vivo in awake animals: a microdialysis study.

gamma-Hydroxybutyrate (GHB) is a 4-carbon anesthetic that acts primarily by inhibiting presynaptic dopamine (DA) release in vivo. A number of studies have reported a reversal of many of the central effects of GHB by the allegedly pure opiate antagonist naloxone (NX) but its mechanism of action is unclear. In vivo microdialysis performed in the present preliminary study disclosed a significant inhibitory effect of GHB (500 mg/kg) on striatal DA release which was completely reversed by a low dose of NX (0.8 mg/kg). The results indicate that NX likely inhibits many of the central effects produced by GHB primarily through its reversal of the GHB induced inhibition of central DA release.