Enhancement of rat hippocampal long-term potentiation by 17β-estradiol involves mitogen-activated protein kinase-dependent and -independent components

To investigate if estrogen modulates long-term potentiation (LTP) via mitogen-activated protein kinase (MAPK) activation, in vitro hippocampal slices were used to induce LTP through extracellular field recordings. Slices per-fused with 17beta-estradiol exhibited a significant enhancement of LTP (224 +/- 19%) compared with LTP in control slices (157 +/- 9%). In the presence of PD098059, 17beta-estradiol still produced a significant magnitude of LTP (131 +/- 7%), revealing the existence of p-MAPK-independent LTP mediated by 17beta-estradiol. Immunocytochemistry showed that 17beta-estradiol promoted a transient increase in nuclear translocation of p-MAPK. 17beta-estradiol induced the extracellular proteolysis of neural cell adhesion molecule in a p-MAPK-independent manner, indicating that 17beta-estradiol may act on synaptic remodeling, These results indicate that 17beta-estradiol might affect hippocampal synaptic plasticity in a way involving two separate pathways, which are MAPK-dependent and MAPK-independent. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.