Most clinical trials describe a good antipsychotic effect of the currently used antipsychotic drugs. The efficacy and safety of the antipsychotic drugs also depend on the form of schizophrenia, for example, the chronic recurrent form of schizophrenia. Clozapine and olanzapine have the safest therapeutic effect, while the side effect of neutropenia must be controlled by 3 weekly blood controls. If schizophrenia has remitted and if patients show a good compliance, the adverse effects can be controlled. The pharmacological treatment should be combined with social therapies and psychoeducation in order to reach a good therapeutic outcome.
We propose several pathways that could be involved in major depression. According to our proposal, noradrenaline hypoactivity could occur through a strong presynaptic GABAergic inhibition, via GABA(B) receptors, and serotonin hypoactivity through a strong glutaminergic inhibition via subreceptor 5 of the metabotropic glutaminergic receptor. In this sense, it is important to know whether the antagonists of such receptors might be able to improve the symptoms observed in major depression. Some neuropeptides are also altered in such states (corticotropin-releasing hormone, neuropeptide Y, galanin). It is also important to know whether in addition to current antidepressants the administration of neuropeptides and their agonists/antagonists could ameliorate depressive symptoms.
We summarize the alterations of classical neurotransmitters and neuropeptides and the corresponding subreceptors involved in major depression. Neuronal circuits in the brainstem, hippocampus and hypothalamus are developed, since they can be used to derive a multimodal pharmacotherapy. In this sense, serotonin hypoactivity could occur through a strong presynaptic inhibition of glutaminergic neurons via the subtype 5 of metabotropic glutaminergic receptors, and noradrenaline hypoactivity could be due to an enhanced presynaptic inhibition of GABAergic neurons via GABAB receptors. In the hippocampus, dopamine hypoactivity leads to a decreased positive effect. In clinical trials, the antidepressant effect of drugs interfering with the mentioned subreceptors, for example the triple reuptake inhibitor amitifadine, is being investigated. Moreover, the alterations of neuropeptides, such as corticotropin-releasing hormone, neuropeptide Y and galanin are pointed out. The additional antidepressant effect of analogs, agonists and antagonists of the mentioned neuropeptides should be examined.
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