[Functions and metabolic rates of transmitters in the basal ganglia]

The caudate nucleus and putamen showed different neuronal circuits with the cerebral cortex and different functions in motor control. The dopamine content was same in the caudate nucleus and putamen, however, the turnover ratio was higher in the putamen than in the caudate nucleus, when it was studied in the control or MPTP-treated marmosets. The dopaminergic neurons projecting to the putamen seemed to show higher activity than those projecting to the caudate nucleus. The caudate nucleus is long in the shape and the dopamine turnover ratio was higher in the former part than in the latter part in normal marmosets. Administration of fluvoxamine increased akinesia in MPTP-treated common marmosets, and systemic administration of 8-OHDPAT, a 5-HT1A receptor or autoreceptor agonist reversed parkinsonism in MPTP-treated common marmosets. These results indicated that serotonergic neurons potentiated hypoactivity in parkinsonism and suppression of serotonergic function may contribute to the remission of parkinsonism.