Tremor and involuntary movements in monkeys: effect of L-dopa and of a dopamine receptor stimulating agent.

Either L-dopa, in combination with 1-alpha-methyldopa hydrazine (MK-486), or 1-(2''-pyrimidyl)-4-piperonylpiperazine, an agent that stimulates dopamine receptors, relieves surgically induced tremor in monkeys and concomitantly evokes involuntary movements. These results indicate that tremor and involuntary movements are associated with a common mechanism and that the activity of the dopamine receptors is involved in the regulation of these dysfunctions.

Dopamine- -hydroxylase activity in mouse neuroblastoma tumors and in cell cultures.

Dopamine-beta-hydroxylase activity is present in mouse neuroblastoma C-1300 tumors. The activity is proportional to the weight of the tumor. Serum activity is markedly increased in mice that bear the tumors.

Norepinephrine biosynthesis inhibition: effects on memory in mice.

Diethyldithiocarbamate, a dopamine beta hydroxylase inhibitor, decreases biosynthesis of norepinephrine in the brain. The effects of this inhibitor coincide with alterations in memory as demonstrated in single-trial passive avoidance in C57BL/6J mice.

The effects of centrally acting drugs on tremor in monkeys with mesencephalic lesions.

The effects of centrally acting drugs on tremor were investigated in monkeys with ventromedial tegmental lesions exhibiting hypokinesia or hypokinesia and tremor. In monkeys with resting tremor, the administration of DL-5-HTP (5-hydroxytryptophan) or of DL-DOPA (3,4-dihydroxyphenylalanine) relieves the tremor, but the simultaneous administration of DL-5-HTP or DL-DOPA and atropine results in a much more pronounced relief. These results point to an imbalance between the cholinergic and adrenergic-serotonergic systems in parkinsonism.