Type‐1 and type‐2 astrocytes are distinct targets for prostaglandins D2, E2, and F2α

Accumulating evidence has revealed that astrocytes are potential targets for various neurotransmitters. Here we investigated the effects of prostaglandins (PGs) on signal transduction in purified primary cultures of rat type‐1 and type‐2 astrocytes. PGF2α, PGD2, and 9α, 11β‐PGF2, a metabolite of PGD2 and a stereoisomer of PGF2α, evoked a rapid rise in the intracellular Ca2 concentration ([Ca2+]i) in type‐1, but not in type‐2, astrocytes. STA2, a stable analogue of thromboxane A2, was less effective, and PGE2 showed little effect. The PG‐induced rise in [Ca2+]i was not blocked by an antagonist of either PGD2 receptor or thromboxane A2 receptor. PGF2α and 9α, 11β‐PGF2 stimulated rapid formation of inositol trisphosphate followed by inositol bisphosphate and inositol monophosphate. On the other hand, PGE2 increased the intracellular level of cyclic AMP in type‐2 astrocytes, rather than in type‐1 astrocytes. The potency of PGs for cyclic AMP formation was in the following order: PGE2 > PGE1 ≥ STA2 > iloprost, a stable analogue of PGI2. PGD2 and PGF2α had no effect on cyclic AMP formation. These results demonstrate that type‐1 astrocytes preferentially express PGF2α receptors, the activation of which leads to phosphoinositide metabolism and [Ca2+]i elevation, whereas type‐2 astrocytes possess PGE receptors that are linked to cyclic AMP formation. © 1992 Wiley‐Liss, Inc.