ABSTRACT
Products of activated immune cells (cytokines), which ordinarily serve as signaling molecules, may contribute to communication between the immune, endocrine, autonomic, and central nervous systems in this respect (Anisman, Zalcman, & Zacharko, 1993; Dunn, 1995; Rothwell & Hopkins, 1995). Interestingly, cytokine activation gives rise to several central and peripheral neurochemical changes reminiscent of those ordinarily elicited by stressors. Moreover, like stressors, cytokines may proactively influence the response to subsequent cytokine and stressor challenges (sensitization). Thus, it was suggested that immune activation may be interpreted by the central nervous system (CNS) as a stressor (Anisman et al., 1993; Dunn, 1995). Indeed, cytokines may be part of a regulatory loop that, by virtue of their effects on CNS functioning, might contribute to the symptoms of behavioral pathologies, including mood and anxiety-related disorders (Anisman, Ravindran, Griffiths & Merali, 1999; Maes, 1995).
