Effects of estradiol on radial arm maze performance of young and aged rats

Abstract

Gonadectomized male and female Sprague-Dawley rats, given estradiol (E₂) via sc Silastic capsules that generated proestrus levels of hormones, were tested for spatial memory performance on an 8-arm radial maze. Performance of males, with or without E₂, exceeded that of females, with or without E₂, for choice accuracy parameters over 20 trials. In addition, males reached criterion earlier than females (6 vs 11 trials). There were no significant effects of E₂ on performance of either sex. When a 1-h delay was instituted between the 4th and 5th choices, the performance of males remained better than that of the females, and E₂ administration was associated with a small, but significant, improvement in performance of the males but not the females. E₂ administration to 25-month-old males also did not affect performance in regular trials, but performance was enhanced in trials with delays of 1–3 h after the 4th choice. These results show that estradiol can influence spatial memory performance and suggest that E₂ may be beneficial for age and/or disease-related memory impairments.