Selective facilitation of putative corticotropin-releasing factor-secreting neurones by interleukin-1

The activity of single hypothalamic paraventricular nucleus (PVN) neurones was recorded in order to examine the mechanism by which the endogenous pyrogen interleukin-1 (IL-1) increases activity of the hypothalamo-hypophyseal-adrenocortical axis. IL-1 injected intravenously caused a rapid increase in the electrical activity of putative corticotropin-releasing factor (CRF)-secreting neurones located within the PVN. The activity of neighboring, electrophysiologically identified, vasopressin-secreting neurones was not altered by the stimulus, indicating a lack of involvement of this secretagogue of adrenocorticotropic hormone (ACTH) in this response to IL-1. These results support the concept of a rapid and specific activating effect of IL-1 upon hypothalamic CRF secretion as a part of a bidirectional communicating link between immune and central nervous systems.