The effects of proinflammatory cytokines on the formation of behavior in early postnatal ontogenesis.

Studies were performed to investigate impairments to the formation of behavior arising as a result of increases in the proinflammatory cytokine interleukin-1beta in early postnatal ontogenesis. The cytokine was given at pyrogenic or subpyrogenic doses for one week (the first, second, or third week of life). Behavior was assessed at prepubertal age and in the adult state in the open field and elevated cross maze tests. The greatest changes were seen in adolescent rats given interleukin-1beta during the first or third weeks of life. Impairments were seen after administration of pyrogenic and subpyrogenic doses of cytokine and were identical in females and males. Changes consisted of partial substitution of acts, increases in motor activity and decreases in investigative activity. After sexual maturation, these behavioral impairments were no longer seen.