Effects of 17β-estradiol on learning and memory and strategy use during a hole board spatial navigation task in aged male rats
Treatment with 17β- estradiol has been shown to ameliorate age related deficits in spatial learning and memory as well as to promote the use of an allocentric strategy during spatial navigation. While the majority of research using 17β- estradiol has been done using females rodents, there have been studies showing an improvement in spatial learning and memory and promoted use of allocentric strategies in spatial navigation in males as well. In males testosterone (T) is metabolized into estradiol by aromatase. As circulating levels of T decline with aging there is less available T to be metabolized into estradiol. The current study sought to determine whether treatment of aged male rats with17β- estradiol improves spatial learning and memory in a hole-board task and promotes the use of an allocentric strategy (use of extramaze cues). Control and 17β- estradiol treated groups showed decreased latencies to find all baited holes and a significant decrease in visits and revisits to unbaited holes over days. Inconsistent with prior research there was no group difference in performance, and probe tests with extramaze cues removed indicated that an allocentric strategy was not used by either group. It is possible that the lack of group differences was due to estradiol levels that were too low or too high. These results also suggest that rats tested in a hole-board task may prefer other search strategies over an allocentric strategy. Any study using the hole-board task to investigate allocentric search performance must include probe tests to confirm that the rats are actually using the provided extramaze cues to guide their search behavior.
estradiol, spatial navigation, learning, memory, aging, male rats, Animal Studies, Biological Psychology, Cognitive Neuroscience, Experimental Analysis of Behavior
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