Long-Term Effects of Transient Estradiol Exposure on Hippocampal Function

Tulane University, New Orleans LA

Investigators

Abstract

Gonadal hormones can act to permanently organize the brain and behavior. Traditionally, these actions have been thought to occur during a sensitive period early in development. However, results of recent experiments conducted in Dr. Daniel's lab indicate that administration of a transient period of estradiol, the primary estrogen produced by the ovaries, to middle-age rats at the time of cessation of ovarian function results in lasting enhancements on measures of learning and memory that persist well beyond the period of exposure. Furthermore, these enhancements in performance are associated with permanent increases in levels of a type of receptor for estrogen, estrogen receptor alpha (ERá) in the hippocampus, a brain area important for learning and memory. This project will determine the temporal characteristics of the sensitive period following loss of ovarian function during which transient exposure to estradiol can exert lasting effects on cognition and the hippocampus. The project will also determine if permanent changes in levels of ERá mediate the long-term effects exerted on the hippocampus and associated behaviors as a result of a period of transient exposure to estradiol. Lastly, the project will investigate how estrogen receptors can affect cognition in the absence of ovarian estrogens. These experiments will use behavioral, molecular, and electrophysiological techniques to investigate how and under what conditions a transient period of estradiol exposure in adult mammals can permanently affect the brain and behavior. The activities involved in this project will provide increased research opportunities for undergraduate and graduate students from the state of Louisiana, a geographical region that has traditionally been underrepresented in the sciences.