Interleukin-1 stimulates catecholamine release from the hypothalamus

During a 60-min period, the in vitro release of norepinephrine (NE) from the hypothalami of male rats decreased by 28%. The presence of 50 or 100 ng of interleukin 1-beta (IL-1 beta) in the incubation medium prevented this decrease and raised the release by 17% or 45% respectively (P less than 0.05). The average release of dopamine (DA) decreased by 55% in the control group but 50 ng of IL-1 beta cut this decrease to 25%, and 100 ng of IL-1 beta not only completely prevented the decrease but raised the release by 44% (P less than 0.05). In a following 60-min period, when the hypothalami from the treatment groups were incubated without IL-1 beta, it resulted in sharp declines in the release of NE and DA, confirming that IL-1 beta was the stimulus for the increases in catecholamine release in the previous incubation period. It is concluded that IL-1 beta stimulates the release of catecholamines (and probably other neurotransmitters) in the brain which, in turn, mediate its central and neuroendocrine actions.