Stimulating dopamine D₁ receptors increases the locomotor activity of developing rats

Abstract

To determine the role of dopamine D₁ receptors in the locomotor activity of developing rats, male offspring were habituated to an animal activity monitor and were then injected with the dopamine D₁ receptor antagonist, SCH 23390 (R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine), or vehicle and returned to the activity monitors. 30 min later, they were injected with the dopamine D₁ receptor agonist, SKF 38393 (R(+)-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol), or vehicle and were again placed in the activity boxes where their locomotor activity was monitored individually for 1 h. The litter was used as the unit for statistical analyses. There was a significant increase in the locomotor activity of 10- and 21-day-old offspring injected with SKF 38393. This effect was antagonized by pretreatment with SCH 23390. These data provide the strongest evidence to date that stimulation of dopamine D₁ receptors increases the locomotor activity of habituated developing rats