INFLUENCE OF INTERLEUKIN-1-BETA ON EXPLORATORY BEHAVIORS, PLASMA ACTH, CORTICOSTERONE, AND CENTRAL BIOGENIC-AMINES IN MICE

Systemic administration of interleukin-1 beta (IL-1 beta) promoted beh avioral changes in an open-field exploratory test. In particular, whil e the cytokine suppressed locomotor activities, these behaviors were n ot particularly sensitive to dosage differences. In contrast, dose-dep endent biphasic variations that varied over time were evident with res pect to the exploration of a novel container. Within this paradigm, th e behavioral changes did not appear to be related to neophobia. In add ition, despite the marked effects of IL-1 beta on exploratory and loco motor behaviors, habituation/exploration in a free-running spontaneous alternation task was unaffected by the cytokine. In addition to the b ehavioral variations, IL-1 beta dose-dependently increased plasma ACTH and corticosterone concentrations, and also induced several central m onoamine alterations. In particular, IL-1 beta increased the utilizati on of norepinephrine (NE) within the paraventricular nucleus, arcuate nucleus/median eminence, locus coeruleus, and prefrontal cortex, while the turnover of dopamine (DA) was evident in the arcuate nucleus/medi an eminence. It is suggested that although systemic IL-1 beta treatmen t induces some stress-like effects, the profile of central neurochemic al changes induced by the cytokine can be distinguished from psycholog ical or processive types of stressors.