Interleukin-1 beta increases prostaglandin E2 in rat astrocyte cultures: modulatory effect of neuropeptides

Recombinant human interleukin-1 beta (IL-1 beta) significantly increased prostaglandin E2 (PGE2) in a dose-dependent manner in rat astrocyte culture. The minimum effective dose of IL-1 beta was 10(-10)M. IL-1 alpha also increased PGE2, but at a higher concentration. The minimum effective dose of IL-1 alpha was 10(-8)M, indicating it to be 100-fold less effective than IL-1 beta. On the other hand neither IL-1 beta nor IL-1 alpha increased PGE2 production by neuron cultures at any concentration tested. PGE2 response to IL-1 beta was suppressed by simultaneous addition of CRH, somatostatin-14 and LHRH, while these neuropeptides alone did not alter the basal PGE2 levels. Substance P, vasoactive intestinal polypeptide and alpha-MSH altered neither basal nor IL-1 beta-induced increase in PGE2 levels. Angiotensin II (AII) alone also increased PGE2 in cultured astrocytes. Combined addition of AII and IL-1 beta induced a synergistic effect in increasing PGE2 levels. The direct action of IL-1 beta on astrocyte culture suggests that astrocytes may be the target cells for IL-1 beta in the central nervous system. In view of the essential role of central PGE2 in IL-1 beta-induced CRH/ACTH release, these findings suggest the presence of a sophisticated regulatory network in the immune-neuroendocrine interaction.