Differential Effect of Acute Stress on Visuospatial Working Memory and Sexual Motivation in Male Rats

Working memory is an executive function that is highly dependent on the functioning of the prefrontal cortex. Several studies using food or drink as rewards have demonstrated that rats are capable of performing tasks that involve working memory. Sexual behavior is another highlyrewarding, motivated behavior that has proven to be an efficient incentive in classical operant tasks. Considering that both sexual behavior and working memory are sensitive to the effects of stress, the aim of this study was to determine the effect of acute stress on visuospatial working memory during a sexually-motivated task (a nonmatching-to-sample task in a T-maze) in male rats. Thirty-two male Wistar rats were trained in the T-maze using sexual interaction (intromission and ejaculation) as a reinforcer during a 4-day training period (training sessions held every 4th day). On the basis of their performance, the rats were classified as good-learners (n = 12) and bad-learners (n = 20), and on the fifth day, 6 good-learners and 10 bad-learners were subjected to stress using the cold water immersion model (CWI, 15 ̊C) for 15 minutes before they were evaluated in the T-maze. The remaining rats made up the control group (i.e., they performed the task without previous stress). Results showed that acute stress by CWI improved working memory in the bad-learners but did not affect the performance of the good-learners, although in both groups (goodand bad-learners) stress decreased the sexual motivation to perform the task. It is probable that the increased levels of corticosterone in the stress situation could activate glutamatergic transmission in the prefrontal cortex, thus facilitating working memory and, simultaneously, decreasing testosterone levels, which exerts a negative effect on sexual motivation in these male rats. Corresponding author. M. Hernández-González et al.