Di Cesare A, Del Piccolo P, Zacchetti D, Grohovaz F
San Raffaele Scientific Institute, Milano, Italy.
Cell Mol Life Sci. 2006 Nov;63(21):2546-53. doi: 10.1007/s00018-006-6262-9.
Astrocytes are a heterogeneous population of cells that are endowed with a great variety of receptors for neurotransmitters and neuromodulators. Recently prostaglandin E2 has attracted great interest since it is not only released by astrocytes but also activates receptors coupled to either phospholipase C or adenylyl cyclase. We report that EP2 receptor stimulation triggers cAMP production but also causes release of Ca2+ from intracellular stores. This effect is shared by other receptors similarly coupled to adenylyl cyclase and elicited by direct stimulation of the enzyme or application of cAMP analogues. However, the stimulation of the Ca2+ response by cAMP is not mediated by protein kinase A, since a specific antagonist of this kinase had no effect. Such a cross-talk between cAMP and Ca2+ was not observed in all astrocytes. It might therefore reflect a specific resource of either a subpopulation or astrocytes in a specific functional state.
星形胶质细胞是一类异质性细胞群体，它们具有多种神经递质和神经调质受体。最近，前列腺素E2引起了极大关注，因为它不仅由星形胶质细胞释放，还能激活与磷脂酶C或腺苷酸环化酶偶联的受体。我们报告，EP2受体刺激可触发环磷酸腺苷（cAMP）生成，还能促使细胞内储存的钙离子（Ca2+）释放。这种效应与其他同样与腺苷酸环化酶偶联的受体相同，并且可通过直接刺激该酶或应用cAMP类似物引发。然而，cAMP对Ca2+反应的刺激并非由蛋白激酶A介导，因为该激酶的特异性拮抗剂没有作用。并非在所有星形胶质细胞中都观察到cAMP与Ca2+之间的这种相互作用。因此，它可能反映了特定功能状态下亚群星形胶质细胞或星形胶质细胞的一种特定特性。
