Effect of anticholinergic drugs on striatal acetylcholine release and motor activity in freely moving rats studied by brain microdialysis

We have studied effects of intraperitoneal administration of anticholinergic drugs on striatal acetylcholine release in association with motor activity in freely moving rats using brain microdialysis. A low dose of atropine (2.5 mg/kg) increased striatal acetylcholine release. A high dose of atropine (5 mg/kg) or scopolamine (2.5, 5 and 10 mg/kg) increased both striatal acetylcholine release and motor activity, while its quaternary ammonium compounds, atropine methylbromide (5 and 10 mg/kg) and methscopolamine bromide (5 and 10 mg/kg), increased striatal acetylcholine release without motor excitation. Scopolamine (2.5 mg/kg) produced no significant change in striatal acetylcholine content 4 hr after the injection followed by perfusion. These results suggest that anticholinergic drugs cause an increase in striatal acetylcholine release which does not always result in the increase of motor activity.