The effect of fatigue on passive avoidance learning and its interaction with simvastatin drug in male Wistar rats

The aim of this study was to evaluate the sequence effects of simvastatin and fatigue, specifically the interaction between fatigue effects and passive avoidance learning in simvastatin treated rats. In this experimental study, 40 male Wistar rats weightening 300-350 g were divided into 4 groups: control group: treated with enough tap (n=10), Sham group: rats which were gavaged with distilled water and food (n=10), first experimental (Exp1) and Second experimental (Exp2) group: rats which were gavaged with distilled water and food (n=10) and simvastatin with dose of 1 mg/kg for 35 days (n=10). Then, both experimental groups were forced to swim in aquariums for 35 days at 9-10 AM to 13-14 PM. At the end of treatment days, passive avoidance learning (PAL) system was considered and monitored. The learning and memory of all groups were studied. After performing behavioral tests, testosterone and cortisol were measured. fatigue decreased learning activity in Exp group one (P<0.001), while simvastatin causes increase in learning actitives in Exp group two. Also, fatigue induced by forced swimming caused significant decrease of testosterone hormone level (P<0.001), increase of cortisole hormone level (P<0.001) in experimental groups in comparison with sham and control groups. Our study showed that fatigue due to long term swimming causes decrease in learning, while simvastatin drug is effective for prevention of decrease of learning and memory in fatigued rats.