The Role of Membrane-Bound Receptors in the Rapid Estrogenic Enhancements of Learning and Memory Within the Hippocampus

Abstract

Estrogens play a role in learning and memory on a rapid time scale. Systemic treatment with 17β-estradiol rapidly improves object recognition, social recognition and object place learning in ovariectomized female mice within a timescale of only 40 minutes following administration. Studies have identified the dorsal hippocampus as one site of these estrogenic enhancing effects. Whether these rapid estrogenic effects are mediated solely by membrane-bound estrogen receptors is currently unknown. This study sought to determine the role of membrane estrogen receptors in the rapid effects of 17-β estradiol within the hippocampus. By conjugating 17-β estradiol to a large bovine serum albumin molecule (BSA-E2), the estradiol is prevented from passing through the cellular membrane and thus, from binding to intracellular receptors. We were able to demonstrate that the rapid effects of estrogens on learning and memory are mediated by membrane-bound estrogen receptors, independent of intracellular mechanisms.