EXPRESSION OF TYPE-I INTERLEUKIN-1 RECEPTOR MESSENGER-RNA AND ITS REGULATION IN CULTURED ASTROCYTES

The expression of type I interleukin-1 receptor (IL-1RI) mRNA in enriched astrocytes and microglia was investigated by Northern blot analysis. IL-1RI mRNA was expressed in untreated astrocytes, but not in microglia. This expression was markedly suppressed by a treatment with isoproterenol, a beta-adrenoceptor agonist (1 x 10(-8) to 1 x 10(-6) M). This suppression was clearly reversed by propranolol, a beta-adrenoceptor antagonist. Dibutyryl cAMP (dbcAMP) also suppressed the expression of IL-1RI mRNA. The suppression by isoproterenol or dbcAMP was blocked by H8 or H89, inhibitors of cAMP-dependent protein kinase. The present results suggest that IL-1RI mRNA expression in cultured astrocytes may be regulated by intracellular cAMP, elevated upon the activation of beta-adrenoceptors as an example, and cAMP-dependent protein kinase.