Objectives. Our knowledge of the role of cytokines in the pathogenesis of mental disorders is still insufficient. The aim of this study was to evaluate the effect of antidepressants such as venlafaxine or paroxetine, as well as that of an atypical antipsychotic, i.e. aripiprazole, on the level of TNFα in the peripheral blood of rats.
Material and methods. The study was carried out in three separate experiments on male Wistar rats, each time dividing them into two groups. The first group was subjected for 6 weeks to chronic mild stress (CMS) and the second was a control group (of unstressed animals). Following the development of induced anhedonia, some of the stressed and control rats were treated with venlafaxine (20 mg/kg, p.o. daily), paroxetine (12.5 mg/kg, p.o. daily) or aripiprazole (2,5 mg/kg, p.o. daily) for 3 weeks. On the last day of the experiment a lipopolysaccharide (LPS, 100 µg/kg b.m., i.p.) was injected into 25% of the rats and levels of TNF-α were assayed with ELISA.
Results. The results indicated an increase of TNF-α level in the stressed animals administered LPS. The paroxetine treatment resulted in a significant decrease in TNF-α level in the stressed animals that were also administered LPS. Venlafaxine did not have a significant effect on TNF-α level, whereas aripiprazole significantly increased the level of TNF-α in animals which were administered LPS.
Conclusions. The paroxetine-induced normalisation of the TNF-α level, increased by CMS and LPS, confirms the hypothesis of the influence of some antidepressants on the immunological system. Some atypical antipsychotics, on the other hand, such as aripiprazole can have a stimulatory effect on the immunological factors in the case of acute stress.