One physical exercise session promotes recognition learning in rats with cognitive deficits related to amyloid beta neurotoxicity

Abstract

Alzheimer’s disease is a progressive neurodegenerative pathological process that causes memory loss and cognitive impairment. One of the pathological characteristics of Alzheimer’s disease is the amyloid-β protein aggregation on the brain. The regular practice of physical exercise is a consolidated strategy on the prevention of cognitive deficits; however, little is known about the effects of acute exercise on memory. We hypothesize that one physical exercise session could act as a modulator of learning. Here we investigated the effects of one single session of running (aerobic) or strength (anaerobic) exercise on memory deficits related to neurotoxicity induced by amyloid-β. Male Wistar rats were submitted to stereotaxic surgery to intrahippocampal infusion of amyloid-β protein or saline (control). Ten days after the surgery the rats were submitted to the object recognition (OR) memory task. Immediately after the OR learning session, some rats were submitted to one treadmill running or strength exercise session. Then, the animals were submitted to memory tests 24 h, 7, and 14 days after the OR learning. We demonstrated that one physical exercise session, both aerobic as anaerobic, performed after learning improves learning and memory, promoting memory persistence in control rats and memory consolidation in rats submitted to amyloid-β neurotoxicity model. Notably, the effects of the aerobic exercise session seem to be more prominent, since they also reflect in an improvement of object discrimination index for 7 days in control animals. We verified that the mechanisms involved in the effects of aerobic exercise include the dopaminergic system activation. The mechanisms involved in the anaerobic exercise effects seem to be others since no alterations on hippocampal dopamine or noradrenaline levels were detected.