Blood cytokines in rats with various behavioral characteristics during emotional stress and treatment with interleukin-1beta.

We studied the effect of acute emotional stress and exogenous IL-1beta (5 microg/kg intraperitoneally) on the cytokine profile of blood serum in Wistar rats with various behavioral characteristics in the open-field test. Blood level of proinflammatory cytokine IL-1beta decreased in behaviorally passive rats, but increased in active animals after simultaneous immobilization and electrocutaneous stimulation. These changes reflect the opposite immune responses to a similar stress exposure in rats with different emotional reactivity. Poststress variations in the concentration of circulating IL-1beta differed in rats receiving exogenous IL-1beta. Blood cytokine concentration decreased in behaviorally active rats, but remained unchanged in passive animals that were exposed to immobilization and electrocutaneous stimulation after pretreatment with IL-1beta. Emotional stress and injection of IL-1beta had no effect on blood level of an anti-inflammatory cytokine IL-4 in rats. Our results indicate that rats with various behavioral parameters are characterized by significant differences in the cytokine profile of blood serum under conditions of emotional stress and treatment with IL-1beta. These data illustrate the specific functional features of immune mechanisms, which provide an individual resistance of rats to the same stress exposure.