RESUMO
The neutrotransmitter dopamine mediates its central nervous system actions via 2 types of receptors: D1 and D2, each of which exist in a low or a high affinity state. In schizophrenic patients, it appears that part of the symptomatology may be secondary to dopaminergic hyperactivity (the so called positive symptoms), whereas negative symptoms would be secondary to structural damage. Antipsychotic drugs that are used in clinics are antidopaminergic. It is interesting to note that those drugs are ineffective in part of the schizophrenic population, the chronic one. This inefficiency might be due to primary resistance or to adaptation of the central nervous system to the drugs. Some authors tried dopamine agonists to treat schizophrenic patients. Apomorphine, N-n-propylnorapomorphine, l-DOPA and bromocriptine were tried. The purpose of these substances was to desensitize dopaminergic system, or to inhibit it via presynaptic autoreceptor stimulation, depending of the study. Some authors hypothesized a drop in frontal cortical dopaminergic system to explain part of the schizophrenic symptomatology. Dopamine agonists might act at this level to enhance frontal dopaminergic activity. After those experimentations with dopamine agonist drugs, it appears that 2 of them might have efficiency and clinical use: l-DOPA and bromocriptine.
