Uma sessão de exercício físico como estratégia moduladora da extinção da memória aversiva

Abstract

Introduction. Aversive memory when constantly evoked, is related to a psychopathology known as Post Traumatic Stress Disorder (PTSD), causing damage to the quality of life. Exposure therapy is the most widely used method for the treatment of this disorder. However, its effects may not persist for long. Objectives. Assess whether a single physical exercise session is capable of facilitating extinction and decreased persistence of aversive memory. Method. We used male Wistar rats, which were divided into three groups: control, exercise habituation and physical exercise. Initially, the aversive memory was conditioned in the perforating inhibitory avoidance and, 24 hours later, three extinction sessions were 8 performed. Immediately before the first extinction session, the animals of the physical exercise group were submitted to a physical exercise protocol on a treadmill (30 min under intensity of 60-70% of indirect maximum VO2). Memory was tested 24 hours, 7, 14 and 21 days after extinction sessions. Hippocampal dopamine and norepinephrine levels were quantified by High Efficiency Liquid Chromatography (HPLC). Results. We have demonstrated that a session of physical exercise raises the hippocampal levels of the neurotransmitters dopamine and norepinephrine. However, this strategy was not efficient to modulate the extinction of aversive memory, since the animals continued to show an aversive response from the original memory after the extinction protocol used, regardless of the practice of exercise. Conclusions. A single session of physical exercise is not able to facilitate the extinction of aversive memory;