Wistar-Kyoto rats in the Morris water maze: impaired working memory and hyper-reactivity to stress

Wistar-Kyoto (WKY) rats were tested as a potential animal model for memory dysfunction. These animals were reported to be highly reactive to stress and this was associated with findings of alterations in their hippocampal cholinergic activity. Since hippocampal cholinergic hypofunction is often associated with deficits in memory processes, untreated WKY rats were tested here in a working memory task in the Morris water maze. Animals were tested for five daily sessions, with two identical trials per day, and their performance was compared to that of Sprague-Dawley (SD) rats. Results show that WKY rats failed to improve their performance both from day to day and within the two trials each day. This suggests impaired memory capabilities of WKY rats and may support their use as an animal model of memory dysfunction. However, because of their increased tendency to float, speed of performance was also reduced in WKY compared to SD rats. This difference may be associated with their increased reactivity to stress. The combination of memory dysfunction and stress hyper-reactivity seen in WKY rats may be used to study the association between these two functions, particularly the possible interaction between memory and depression.