Comparative Analysis of the Effect of Cytokines on the Thymus, Adrenal Glands, and Spleen in Rats with Various Behavioral Characteristics

We compared the effect of a pro-inflammatory cytokine IL-1β and anti-inflammatory cytokine IL-4 on the state of stress-marker organs in rats with various behavioral characteristics in the open-field test. Intraperitoneal injection of the cytokines was followed by a slight decrease in the relative weight of the thymus, adrenal glands, and spleen in behaviorally active and, especially, in passive animals. These changes are probably associated with the effect of the test immunomodulators on apoptosis and migration of cells of the immunocompetent organs. Pretreatment with IL-1β and IL-4 was shown to prevent involution of the thymus and spleen in rats during acute stress on the model of immobilization with simultaneous electrocutaneous stimulation. Hence, these cytokines have the same effects on functional state of stressmarker organs in animals. IL-1β and IL-4 have a greater effect in passive rats than in active specimens, which reflects specific features of immune mechanisms in animals with different emotional reactivity.