Expression of stereotyped behaviour requires stimulation of nigral D1 dopamine receptors.

Abstract Dopamine receptors in the pars reticulata of the substantia nigra were inactivated following bilateral injections of N -ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ). Loss of D 1 , but not D 2 , receptors was associated with a significant decrease in the incidence of stereotyped head-down sniffing elicited by the mixed D 1 /D 2 receptor agonist, apomorphine. The results support the hypothesis that D 1 receptors in the substantia nigra are necessary for the expression of dopamine mediated stereotyped behaviour.