Estrogen stimulates the mitogen-activated protein kinase pathway in midbrain astroglia.

Estrogen stimulates the development of midbrain dopamine neurons predominantly by acting through membrane receptors coupled to Ca(2+)-signaling. In this report, we describe that estrogen activates extracellular signal-regulated kinases (ERK1/2) in midbrain astrocytes but not neurons. This effect was inhibited by BAPTA which interrupts Ca(2+)-signaling but not by antagonists specific for other signaling pathways. The activation of the MAP kinase pathway suggests a potential role for astrocytes in mediating estrogen effects in the midbrain.