The effects of the prodrug Vyvanse on spatial working memory and adiposity in rats

The present study investigated the influence of Vyvanse (lisdexamfetamine), a psychomotor stimulant, on spatial working memory, body weight, and adiposity in rats. Control and experimental rats were placed in individual cages equipped with a running wheel, and food and water were provided ad-libitum. The study was divided into three periods: 1) habituation, 2) experimental, and 3) withdrawal. Control rats received a placebo in periods 1, 2 and 3, while experimental rats received a placebo in periods 1 and 3. Experimental rats received a treatment of Vyvanse in place of the placebo during period 2. Spatial working memory was examined by utilizing the methodology of the Morris Water Maze. Rats were evaluated by performance in the maze each day during the experimental and withdrawal periods. Each assessment consisted of two trials. The first was a sample trial in which an escape platform was discovered by trial and error. The second was a test trial in which the platform location was recalled using working memory. Platform placement and start location of the rats were changed every session. It was hypothesized that Vyvanse would effectively enhance spatial working memory, and significantly decrease body weight and adiposity without side effects on activity level and anxiety in rats. Results supported the hypothesis. Compared to control rats, Vyvanse treated rats had significant improvement in working memory and significantly lowered body weight, as well as significantly decreased mesenteric, renal, and epididymal adiposity. No significant effects on activity level and task specific anxiety were noted in experimental animals. When compared to placebo treatment, Vyvanse treatment produced no significant influence on food and water intake. It was concluded that Vyvanse treatment in rats can enhance spatial working memory, and decrease adiposity without suppressing normal appetite.