Intermediatory relationships between the cholinergic and dopaminergic neurotransmission systems were analyzed using published data and the original experimental results obtained on Daphnia magna Straus, a new test object. Based on these results, the antihaloperidol activity of a series of M- cholinoblocking agents with different receptor selectivities were studied in comparison to the new cholinoblocker pentifin exceeding in the activity the classical antiparkinsonian drugs such as cyclodol, amedin, and norakin.