THE RELEASE OF IMMUNOREACTIVE INTERLEUKIN-1-BETA FROM RAT HYPOTHALAMIC EXPLANTS IS MODULATED BY NEUROTRANSMITTERS AND CORTICOTROPIN-RELEASING HORMONE

Both constitutive and inducible interleukin-l (IL-1) gene expressions have been described in the central nervous system, the former being as sociated with immunoreactive IL-l neurons in human and rat hypothalami . While most studies have focused on the role of IL-l as a mediator of pathological events in the brain, the cytokine of neuronal origin mig ht also be involved in the regulation of physiological processes. In t his study we used a previously validated technique to investigate the effects of classical neurotransmitters and the hypophysiotropic peptid e corticotropin-releasing hormone (CRH) on the release of immunoreacti ve (ir) IL-1 beta from acute rat hypothalamic explants. We found that basal irIL-1 beta secretion is significantly inhibited by acetylcholin e and histamine and increased by dopamine, while dexamethasone, IL-4 a nd IL-10 have no effect. Moreover, cytokine release is dose-dependentl y increased by CRH. Such effects of the neurotransmitters and CRH are observed in short-term incubation experiments, indicating that a pre-f ormed pool of hypothalamic IL-1 beta is involved. These findings also suggest that the interaction between IL-1, neurotransmitters and neuro peptides might play a role in the physiological regulation of such pro cesses as body temperature, food intake and the control of hypothalami c-hypophyseal axes. (C) 1997 The Italian Pharmacological Society.