Changes in dopamine synthesis rate in the supersensitivity phase after treatment with a single dose of neuroleptics

The changes in ¹⁴C-dopamine accumulation formed from ¹⁴C-tyrosine in mice after treatment with three neuroleptics, cis (Z)-flupenthixol, fluphenazine, and haloperidol, were followed for 6 days. The neuroleptics all changed DA synthesis rate in the same way, initially causing an increase which was followed by a decrease after approximately 3 days. The results are compared with pharmacological results (Christensen et al., 1976) and there seems to be a very close correlation between receptor blockade and increase in DA synthesis on the one hand and on the other hand receptor supersensitivity and decrease in DA synthesis, as was also shown previously for teflutixol (Hyttel, 1975). It is concluded that the changes in receptor activity are always followed by compensatory changes in DA synthesis rate.