High levels of estradiol disrupt conditioned place preference learning, stimulus response learning and reference memory but have limited effects on working memory

The present study investigated the effects of high levels of estradiol in female rats on four different radial arm maze tasks: the hippocampus-dependent spatial working-reference memory task; the prefrontal cortex- hippocampus dependent delayed win-shift task; the striatum-dependent cued win-stay task; and the amygdala-dependent conditioned place preference task. Ovariectomized female rats were injected daily with either 10 mug of estradiol benzoate or sesame oil vehicle similar to 4 h prior to testing. In Experiment 1, treatment with estradiol disrupted learning on the spatial working-reference memory task by increasing the number of reference memory errors to reach criterion. In Experiment 2, treatment with estradiol had no significant effect on the delayed win-shift task. In Experiment 3, treatment with estradiol resulted in impaired performance on a striatum-dependent cued win-stay task. In Experiment 4, treatment with estradiol impaired the acquisition of a conditioned place-preference task. Taken together these findings suggest that high levels of estradiol inhibit reference memory, stimulus response learning, and amygdala-dependent appetitive conditioning while having little effect on working memory. (C) 2001 Elsevier Science B.V. All rights reserved.