[Neurobiological and pharmacologic aspects of atypical antipsychotic drugs].

Atypical (second generation) antipsychotic drugs have radically changed and revolutionized the pharmacological treatment of schizophrenia and related disorders. The currently approved atypical antipsychotic drugs, which are available, are characterized by relatively weak affinities for D2-type dopamine receptors and relatively high affinities for 5-HT2A serotonin receptors, when compared with typical (conventional) antipsychotic drugs. The strong interaction with 5-HT2A receptors, with a relative sparing of D2-type dopamine receptors, is likely responsible for the optimal effects of atypical antipsychotic drugs on affective and cognitive symptoms in comparison with conventional antipsychotic drugs. In addition to these actions, several atypical antipsychotic drugs are characterized by a "fast dissociation" rate from D2-dopamine receptors. Mediating special signal transduction pathways, their activity on neuronal survival and plasticity might also contribute to their clinical advantage over typical neuroleptic drugs. By modulating chemical neurotransmission and the intracellular signal transduction systems, antipsychotic drugs may influence a variety of functions regulating neuronal resilience and viability and may have their potential for neuroprotection.