[The relevance of the TNF-alpha system in psychiatric disorders].

Changes regarding the immune system and specifically the cytokine system, of which tumor necrosis factor-alpha (TNF-alpha) is a part, have been shown to be involved in the development of neurological and psychiatric disorders such as multiple sclerosis, Parkinson's and Alzheimer's disease, depression, schizophrenia or narcolepsy. Besides, there is evidence that the risk of stroke correlates with the serum concentrations of different cytokines. Additionally, body weight, age and neuroendocrinological mechanism have a strong influence upon plasma levels of TNF-alpha and its soluble receptors (sTNF-Rs). TNF-alpha might contribute to the pathogenesis of these diseases by an activation of the hypothalamo-pituitary-adrenocortical (HPA) axis, an activation of neuronal serotonin transporters, the stimulation of the indoleamine 2,3-dioxygenase which leads to tryptophan depletion, by immunologically mediated destruction of neurons, or neurotoxic release of glutamate. Psychotropic drugs influence the TNF-alpha system, too. During psychopharmacological treatment of schizophrenia, some antipsychotics might act on neurotransmitter metabolism via inducing the proinflammatory cytokine system. Hopefully, these hypotheses may lead to new therapeutical strategies for psychiatric patients in the near future.