抄録
The effects of i.p. injections of the non-selective dopamine (DA) agonist apomorphine on open-field behavior were examined in high- (H) and low-activity (L) strains of mice selected for open-field activity. ICR mice used as a foundation population for selection were also included. In all strains, apomorphine (0.01, 0.1, and 1mg/kg) dose-dependently reduced ambulatory activity, defecation, locomotion, and leaning. Significant decreases were found at 0.1-1mg/kg compared to the vehicle control. The occurrence of grooming reached a peak in the second minute at 1mg/kg, whereas it gradually increased during testing at other doses and in the vehicle control. The strains showed different dose responses for stretching and rearing: significant reductions were detected only in L at 1mg/kg for stretching and only in ICR at 0.1-1mg/kg for rearing. These strain differences suggest that the DA systems were genetically modified during selection in both strains.
