Chronic antidepressant desipramine treatment increases open field-induced brain expression and spleen production of interleukin 10 in rats

• An OF-induced decrease in spleen NKCC was more pronounced in the ChS-DES group.
• Desipramine pretreated LRs and subordinates had the lowest OF-induced NKCC level.
• Chronic desipramine pretreatment induced an increase in the brain IL-10 response.
• Desipramine pretreatment increased IL-10 and decreased IFN-γ splenocyte response.
• Desipramine pretreatment decreased OF-induced plasma corticosterone concentration.

In the present study, we established a role of individual differences in locomotor response to novelty or social position in modulatory effect of chronic (14 consecutive days) antidepressant drug desipramine pretreatment (10 mg/kg i.p.) on acute (30 min), white and illuminated open field (OF)-induced changes in spleen anti-tumor activity of natural killer (NK) cells (chromium release assay) in parallel to the brain anti-inflammatory interleukin 10 (IL-10) and Fos expression (immunohistochemistry), splenocytic pro-inflammatory interferon γ (IFN-γ) and IL-10 production (ELISA), and plasma corticosterone concentration (RIA) in rats. The involvement of individual differences (high (HR) and low (LR) responders to novelty or dominants (D) and subordinates (S)) in the anti-depressive responsiveness, was investigated in the desipramine treated by itself (DES) or following 7 consecutive days of OF exposure (ChS-DES) group.In the desipramine pretreated groups, OF stress decreased spleen NKCC, behavioral activity, the Con A-stimulated splenocyte IFN-γ response and plasma corticosterone concentration whereas it increased the brain and splenocyte IL-10 response. The percentage of OF-induced IL-10/Fos+ cells was increased in the CA1 and dentate gyrus of the hippocampus and amygdaloid nucleus, particularly in the LR-D (DES) and LR-S (ChS-DES) rats. Moreover, a decreased splenocytic ability to produce IFN-γ and IL-10, particularly in the HR-S (DES) and LR-S (ChS-DES) rats, was noted. There were no significant differences in the OF-induced NKCC suppression between the behavioral groups. These studies emphasize that chronic desipramine pretreatment had anti-inflammatory but not immunoprotective properties against OF stress-induced neuroimmunological effects which depend on the animal's behavioral characteristics and treatment.