Effect of intravenous injection of IL-1 beta on PGE2 levels in several brain areas as determined by microdialysis

Using perfusion microdialysis, the effect of intravenous injection of recombinant human interleukin-1 beta (IL-1 beta) on prostaglandin E2 (PGE2) release into the interstitial fluid of the organum vasculosum laminae terminalis (OVLT), medial preoptic area (MPOA), paraventricular nucleus (PVN), dorsal hippocampus (HPC), and cerebrospinal fluid (CSF) of the lateral ventricle (LV) was examined. Artificial CSF was perfused through the dialysis probe and collected at 20-min intervals before and after IL-1 beta (1 microgram/100 g body wt iv). The results showed that 1) IL-1 beta induced a significant increase in PGE2 levels in the OVLT and the medial part of the MPOA in the first 20 min, which is more rapid and to a greater extent than that in PVN, HPC, and LV; 2) inclusion of indomethacin in the perfusate abolished the IL-1 beta-induced PGE2 response in the OVLT, but a suppressive effect in the PVN was insignificant. These results suggest that OVLT may be a gate for the entry of blood-borne IL-1 beta into the brain and a site where the initial biochemical response to IL-1 beta occurs.