[The effect of MPTP on the neuronal uptake of monoamines]

The results of kinetic analysis of synaptosomal uptake of dopamine, noradrenaline, adrenaline and serotonin showed the presence of their own carrier systems with high or low affinity for each monoamine. The low affinity system of the uptake of monoamines by nerve endings differs from extraneuronal one by higher affinity. MPTP noncompetitively inhibits the system of highly effective uptake of the studied monoamines by nerve endings, competitively inhibiting synaptosomal uptake with low affinity of noradrenaline, adrenaline and noncompetitively serotonin and dopamine. The constant values of inhibition showed that MPTP most strongly blocks the system of synaptosomal uptake of low affinity serotonin and approximately 2-times weaker affects its system of high affinity. Carrier systems of high affinity of dopamine, adrenaline and noradrenaline block MPTP 150-500 times weaker than that of serotonin, and as for low affinity--in 2000-4000 times. It may be supposed that synaptosomal uptake of low affinity serotonin is most perceptible to the effect of MPTP and is of a particular importance in the development of Parkinson's disease symptoms.