Differential effects of ketamine and pentobarbitone on acetylcholine release from the rat hippocampus and striatum

Using microdialysis, we examined the effects of ketamine and pentobarbitone on acetylcholine (ACh) release from the rat hippocampus and striatum. Ketamine 25 and 50 mg kg-1 increased ACh release from the hippocampus to 295% and 353% of basal release, respectively, but not from the striatum. SCH 23390 1 mumol litre-1, a D1 antagonist, significantly inhibited the facilitatory effect of ketamine 50 mg kg-1 on hippocampal ACh release (to 241% of basal level). In contrast, pentobarbitone 20 and 40 mumg kg-1 decreased basal ACh release from both the hippocampus by 41% and 69%, respectively, and the striatum by 37% and 58%, respectively. The results suggest that ketamine and pentobarbitone exert opposite effects on ACh release from the rat hippocampus and that the stimulating effect of ketamine may involve dopamine D1 receptors.