APOMORPHINE EFFECT ON SINGLE AND PAIRED RAT OPEN-FIELD BEHAVIOR

The present study aims to investigate the effect of apomorphine, dopamine agonist, on single and paired rat open-field behavior by using a video analysis system. Experimental rats were injected with saline or apomorphine (0.01, 0.05, 0.1, 0.5, 1.0, 5.0 mg/kg, SC) and put into an open field for 30 min singly or paired with another rat. The rats' movement were plotted on XY coordinates by a video analysis system every 0.5 s and analyzed by distance and time factors. Although when paired, the experimental rat moved more than when single, the total distance moved decreased according to dose of apomorphine. While two rats in the open field often stand in contact with each other, apomorphine in doses of over 0.5 mg/kg tends to keep the two rats separate. These phenomena show that apomorphine induces indifference toward others.