Behavioral evaluation of hemiparkinsonian MPTP monkeys following dopamine pharmacological manipulation and adrenal co-graft transplantation

Bradykinesia and rigidity are the symptoms that most directly correlate wit h loss of striatal dopamine in Parkinson's disease. In the hemiparkinsonian (HP) monkey, this is represented by paucity of movement as measured by com puterized movement analysis, diminished manual dexterity on clinical examin ation, and diminished performance on operant behavioral tasks. The present study used an MPTP-induced HP model in rhesus monkeys to evaluate the effec tiveness of adrenal medullary and peripheral nerve co-grafts in diminishing parkinsonian symptoms. Unoperated controls (N = 4), surgical controls with caudate lesioning (N = 4), and caudate co-grafted (N = 4) HP monkeys demon strated diminished movement in the home cage following MPTP. This behavior persisted in unoperated controls: but improved in both surgical control and co-grafted monkeys. Functional hand dexterity evaluations demonstrated sim ilar impairment in all three groups, but only surgical controls and co-graf ted monkeys demonstrated improvement. In general, rotational behavior in re sponse to apomorphine was consistent with recovery of function in surgical controls and cografted monkeys, but marked between-subject variability prec luded group statistical analyses. None of the monkeys could perform the ope rant task using the affected limb following MPTP. However, the performance of two co-grafted animals demonstrated pal tial recovery. L-dopa improved o perant performance, demonstrating a dopaminergic component to the task. The results demonstrate recovery of behavioral function after surgical treatme nt, with adrenal co-grafted monkeys showing the greatest degree of improvem ent.