Reinnervation after destruction of the dopaminergic system in the rat nucleus accumbens: a quantitative immunohistochemical analysis.

The recurrence of dopamine-immunoreactive (DAi) fibers and the effect of the adrenocorticotrophic hormone (ACTH)-(4-9) analog ORG 2766 on this process were investigated 1, 4, 12 and 24 weeks after a unilateral 6-hydroxydopamine (6-OHDA) lesion in the nucleus accumbens (NAc). DAi fibers were almost completely absent 1 week after the lesion. A gradual increase in DAi fibers throughout the NAc was observed, with subnormal values at 24 weeks. Treatment with ORG 2766 during the first week after the lesion resulted in more DAi fibers 4 weeks after the lesion as compared to placebo treatment, but not 12 and 24 weeks after the lesion. After 6-OHDA lesioning reinnervation of the NAc takes place and this process is transiently facilitated by ORG 2766.