Circling behavior after narcotic drugs and during XXXX -precipitated abstinence in @entity35 with unilateral nigral lesions.

@entity1766 @entity717 @entity12586 @entity2254 @entity3034 @entity75 @entity14887 @entity935 @entity24458 @entity1510 @entity3826 @entity1286 @entity284 @entity35 @entity4944 @entity3982 @entity2955 @entity1767
@entity75 (SNC) in @entity35 were produced by electrolytic coagulation or by an injection of @entity2955 . Two to 5 weeks later, after being preselected for @entity4944 -induced @entity717 behavior, the animals were administered narcotic agonists or antagonists and their circling behavior was observed. @entity1286 , @entity284 , @entity14887 , @entity24458 or @entity12586 induced @entity717 movements; both @entity1510 and @entity3982 were without effect. Ipsilateral circling was also observed in @entity35 with unilateral electrolytic lesions after administration of agents that are thought to enhance central dopaminergic activities: @entity2254 , @entity3034 and @entity3826 . In @entity35 with unilateral electrolytic or @entity2955 SNC lesions that were rendered highly @entity1286 -dependent by multiple- @entity1286 pellet implantation, contralateral (C) circling behavior was observed within 1 to 2 minutes after a @entity1510 challenge; the onset and duration of C circling behavior coincided with the initial appearance and duration of precipitated- @entity1286 withdrawal signs. C circling was also observed after administration of putative @entity935 receptor blockers, @entity1767 and @entity1766 in @entity35 with either unilateral electrolytic or @entity2955 SNC lesions. @entity1286 pretreatment diminished both the C circling intensity and the appearance of withdrawal signs observed after a @entity1510 challenge in @entity1286 -dependent, SNC-lesioned @entity35 . The @entity1510 -precipitated withdrawal in unilaterally lesioned @entity1286 -dependent @entity35 was accompanied by a 20% elevation of neostriatal @entity935 in the intact side. In contrast to the effects of a chronic @entity75 in decreasing neostriatal @entity935 , a 77% increase was observed in the lesioned side 30 minutes after electrolytic coagulation. Thus, narcotic agonists and partial agonists may enhance central dopaminergic activities and @entity1510 -precipitated withdrawal may involve a diminution in central dopaminergic activities of the nigroneostriatal pathway.
