EFFECTS OF INTERLEUKIN-1-BETA AND MILD STRESS ON ALTERATIONS OF NOREPINEPHRINE, DOPAMINE AND SEROTONIN NEUROTRANSMISSION - A REGIONAL MICRODIALYSIS STUDY

The effects of systemically administered interleukin-1 beta (1.0 mu g) on in vivo variations of monoamines was assessed in several brain reg ions. Administration of the cytokine provoked a modest increase of ext racellular 5-HIAA and HVA from the nucleus accumbens, and 5-HIAA from the hippocampus. Following mild neurogenic stressor (application of a series of air puffs), a still greater increase of accumbal 5-HIAA and HVA was evident, a transient increase of hippocampal 5-HT was noted an d the 5-HIAA increases were augmented. Additionally, while the air puf f stress was without effect on DOPAC and HVA in the prefrontal cortex of saline treated rats, a significant rise of these metabolites was ap parent in rats treated with the cytokine. It appears that interleukin- l administration may have effects on forebrain monoamines, and also re sults in greater neuronal reactivity to mild neurogenic stressors. Thi s study reveals that although effects of neurogenic stressors (air puf fs) and cytokine (somatic stressor) may share some similarities (e.g., HPA activation), the pattern of central neurochemical changes elicite d by the cytokine could be distinguished from that induced by a more n eurogenic stressor (air puffs), and that these effects showed selectiv e synergism. These data also lend support to the contention that neuro genic stressors may have a much greater impact on central neurotransmi ssion under conditions of immune activation.