Tiapride-induced catalepsy is potentiated by gamma-hydroxybutyric acid administration.

1. The effect of administration of gammahydroxybutyrate (GHB) and tiapride, either alone or in combination, on catalepsy behavior was examined in male mice. 2. Catalepsy was measured by bar and grid tests. Two successive evaluations were carried out 30 and 60 min after injections. 3. Tiapride (175 and 200 mg/kg) and gammahydroxybutyrate (200 mg/kg) provoked an increase of catalepsy scores, exhibiting different time courses. GHB produced a marked but short lasting catalepsy with a peak of action at 30 min, while tiapride produced a catalepsy state with a peak of action at 60 min. 4. Tiapride-induced catalepsy was potentiated by gammahydroxybutyrate administration at 30 min (bar test) and 60 min (bar and grid tests). 5. These results underlie the view that GHB interacts with central dopamine D2 transmission.