Putative membrane-bound estrogen receptors possibly stimulate mitogen-activated protein kinase in the rat hippocampus

We investigated whether 17 beta-estradiol affects the activity of extracellular signal-regulated kinase (ERK) in the central nervous system in vivo. 17 beta-Estradiol was administered intracerebroventricularly, and then ERK activity in the rat hippocampus was measured. We found that ERK activity in the rat hippocampus had increased to approximately threefold its basal level at 5 min. This rapid effect was mimicked by thr membrane-impermeable estradiol, bovine serum albumin-conjugated 17 beta-estradiol, and was not inhibited by tamoxifen and 7 alpha,9-(4,4,5,5,5-pentafluoropentylsulphinyl)nonylestra-1,3,5(10)-triene-3,17 beta-diol (ICI 182780), classical nuclear estrogen receptor antagonists. These data suggest that the rapid activation of ERK by estradiol in vivo is mediated through a putative membrane estrogen receptor in the rat hippocampus. (C) 2000 Published by Elsevier Science B.V.