enhances the ATP-evoked release of acid from mouse astrocytes.

During neuropathological states associated with inflammation, the levels of cytokines such as interleukin-1 (cid:98) (IL-1 (cid:98) ) are increased. Several studies have suggested that the neuronal damage observed in pathogenesis implicating IL-1 (cid:98) are caused by an alteration in the neurochemical interactions between neurons and astrocytes. We report here that treating striatal astrocytes in primary culture with IL-1 (cid:98) for 22–24 hr enhances the ATP-evoked release of arachidonic acid (AA) with no effect on the ATP-induced accumulation of inositol phosphates. The molecular mechanism responsible for this effect involves the expression of P 2Y2 receptors (a subtype of purinoceptor activated by ATP) and cytosolic phospholipase A2 (cPLA 2 , an enzyme that mediates AA release). Indeed, P 2Y2 antisense oligonucleotides reduce the ATP-evoked release of AA only from IL-1 (cid:98) -treated astrocytes. Further, both the amount of cPLA2 (as assessed by Western blotting) and the release of AA resulting from direct activation of cPLA 2 increased fourfold in cells treated with IL-1 (cid:98) . We also report evidence indicating that the coupling of newly expressed P 2Y2 receptors to cPLA 2 is dependent on PKC activity. These results suggest that during inflammatory conditions, IL-1 (cid:98) reveals a functional P 2Y2 signaling pathway in astrocytes that results in a dramatic increase in the levels of free AA. This pathway may thus contribute to the neuronal loss associated with cerebral ischemia or traumatic brain injury. onto for SDS-PAGE. transferred electrophoretically to lose Immunoblot analysis was performed with rabbit anti-cPLA 2 antibodies in 150 m M NaCl, 5% (wt/vol) free-fat dry milk and 50 m M 7.4. Immunoreactivity was detected with ECL using HRP-coupled donkey anti-rabbit secondary antibodies (Amersham). Immunoreactive bands were quantified using a computer-assisted densitometer (IM- Statistical analysis. Results are expressed in (percent of the control ATP response), where data (cid:53) response in the presence of all the agents tested (cid:50) corresponding basal AA response (i.e., in the absence of ATP)/response evoked by 200 (cid:109) M ATP from untreated cells (cid:50) basal AA release from untreated cells. Data are expressed as mean (cid:54) SEM of n independent determinations and were statistically analyzed using InStat (GraphPad Software, San Diego, CA).