Participation of adenosine system in the ketamine-induced motor activity in mice.

The influence of adenosine receptor ligands on ketamine-induced locomotor activity was studied in mice. Ketamine-induced hyperactivity (10 mg/kg) was significantly and dose-dependently attenuated by CGS 21680 (selective A 2 A receptor agonist), and NECA (A 1 /A 2 adenosine receptor agonist), but not by CPA (cyclopentyladenosine, selective A 1 adenosine receptor agonist). Motor activity produced by subthreshold dose (2.5 mg/kg) of ketamine was significantly increased by DMPX (selective A 2 A receptor antagonist) and caffeine (A 1 /A 2 adenosine receptor antagonist), but not by DPCPX (selective A 1 adenosine receptor antagonist). These results suggest that adenosinergic system is involved in ketamine-induced motor activity and seem to indicate a predominant role of A 2 A adenosine receptor in this effect.