Time-dependent effects of treadmill exercise on aversive memory and cyclooxygenase pathway function

Exercise induces brain function adaptations and improves learning and memory; however the time window of exercise effects has been poorly investigated. Studies demonstrate an important role for cyclooxygenase-2 (COX-2) pathway function in the mechanisms underlying memory formation. The aim of present work was to investigate the effects of treadmill exercise on aversive memory and COX-2, PGE2 and E-prostanoid receptors contents in the rat hippocampus at different time points after exercise has ended. Adult male Wistar rats were assigned to non-exercised (sedentary) and exercised (running daily for 20 min, for 2 weeks) groups. The inhibitory avoidance task was used to assess aversive memory and the COX-2, PGE2 and E-prostanoid receptors (EP1, EP2, EP3 and EP4) levels were determined 1 h, 18 h, 3 days or 7 days after the last training session of treadmill exercise. The step down latency in the inhibitory avoidance, COX-2 and EP4 receptors levels were acutely increased by exercise, with a significant positive correlation between aversive memory performance and COX-2 levels. Increased EP2 content decreased PGE2 levels were observed 7 days after the last running session. The treadmill exercise protocol facilitates inhibitory avoidance memory and induces time-dependent changes on COX-2 pathways function (COX-2, PGE2 and EP receptors).

► The exercise effects have a temporal profile with acute and delayed outcomes.
► Treadmill exercise protocol transiently improves aversive memory performance.
► The exercise acutely increases COX-2 and EP4 receptor contents in hippocampus.
► There is a positive correlation between memory performance and COX-2 levels.