title: Interaction of age and chronic estradiol replacement on memory and markers of brain aging.
abstract: The current study examined effects of chronic estradiol replacement on cognition and biomarkers of aging. Young, middle-aged, and aged rats were ovariectomized and implanted with blank capsules, or capsules containing high or low doses of estradiol benzoate (EB). Three weeks later, animals were tested on inhibitory avoidance and cue and spatial discrimination on the Morris water maze. High plasma estradiol levels were associated with slower swim speed and impaired retention of inhibitory avoidance. No effect of EB treatment was observed for acquisition of the spatial discrimination task, however, a dose by age interaction was observed for retention of spatial discrimination such that higher retention scores were observed for young, middle-aged and aged animals under blank, low and high dose conditions, respectively. EB treatment reversed several hippocampal markers of age-related memory impairment, blocking induction of long-term depression and decreasing cytosolic calcineurin activity. Results indicate that the level of chronic hormone replacement interacts with age to influence hippocampal function.
authors.affiliation: Department of Molecular and Biomedical Pharmacology, College of Medicine, University of Kentucky, Lexington, KY 40536, USA. tfoster@uky.edu
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Foster
authors.forename: Keith M
authors.initials: KM
authors.lastname: Sharrow
authors.forename: Ashok
authors.initials: A
authors.lastname: Kumar
authors.forename: James
authors.initials: J
authors.lastname: Masse
mesh_terms: D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D015415:Biomarkers; D019703:Calcineurin / Q000378:metabolism; D004193:Discrimination Learning / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004958:Estradiol / Q000008:administration & dosage / Q000378:metabolism*; D015914:Estrogen Replacement Therapy; D005260:Female; D006624:Hippocampus / Q000378:metabolism*; D008568:Memory / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology; D051381:Rats; D011916:Rats, Inbred F344; D013028:Space Perception / Q000502:physiology
chemical_list: D015415:Biomarkers; D004958:Estradiol; D019703:Calcineurin