Interleukin-1 beta-induced expression of the prostaglandin E sub(2)-receptor subtype EP3 in U373 astrocytoma cells depends on protein kinase C and nuclear factor-kappaB

Both interleukin-1 beta (IL-1 beta ) and prostaglandins (PGs) are important mediators of physiological and pathophysiological processes in the brain. PGE sub(2) exerts its effects by binding to four different types of PGE sub(2) receptors named EP1-EP4. EP3 has found to be expressed in neurons, whereas expression of EP3 in glial cells has not been reported in the brain yet. Here we describe IL-1 beta -induced EP3 receptor expression in human astrocytoma cells, primary astrocytes of rat and human origin and in rat brain. Using western blot, we found a marked up-regulation of EP3 receptor synthesis in human and rat primary glial cells. Intracerebroventricular administration of IL-1 beta stimulated EP3 receptor synthesis in rat hippocampus. The analysis of involved signal transduction pathways by pathway-specific inhibitors revealed an essential role of protein kinase C and nuclear factor- Kappa B in astrocytic IL-1 beta -induced EP3 synthesis. Our data suggest that PGE sub(2) signaling in the brain may be altered after IL-1 beta release due to up-regulation of EP3 receptors. This might play an important role in acute and chronic conditions such as cerebral ischemia, traumatic brain injury, HIV-encephalitis, Alzheimer's disease and prion diseases in which a marked up-regulation of IL-1 beta is followed by a prolonged increase of PGE sub(2) levels in the brain.