[On the proposed mechanism of action of antidepressants (author's transl)].

Classical antidepressants (MAOI, uptake inhibitors) increase monoamine levels in the synaptic cleft. However other presynaptic mechanisms of action have been proposed: increase in release (amineptin), blockade of presynaptic alpha-adrenoceptors (mianserin). A postsynaptic approach is also possible: stimulation of beta-receptor (salbutamol), blockade of muscarinic receptor (quinupramine). Moreover the side effects have been correlated to a blockade of postsynaptic receptors: alpha 1 for aorthostatic hypotension, H1 for sedation and muscarinic for anticholinergic effects. However these effects do not explain the delay for the clinical efficiency of antidepressants. A desensitization of presynaptic receptors or a decrease in beta-postsynaptic receptors have been advanced. In fact a possible pharmacokinetic explanation for the delay of clinical efficiency, i.e. the necessary delay to reach brain steady state level, is possible. Finally the presence of imipramine binding sites might be a new approach of the mechanism of action of antidepressants.