Resumo

Intense acute stress can cause long-term behavioral alterations, which may be related to psychiatry disorders such as posttraumatic stress disorder and depression. In this study we used an animal model of traumatic stress (Wistar rats), which consisted of inescapable intense foot shock, to investigate long-term emotional alterations that may represent psychiatry-disorder like symptoms. Avoindance learning and escape were evaluated in the elevated T maze. Freezing upon exposure to a novel environment and upon presentation of a 90 dB pulse tone was evaluated in the open field. Open arms escape latency (in seconds) increased over time only in rats previously exposed to foot shock (control: escape 1 = 9,0±1,6; escape 2 = 10,5±1,3; escape 3 = 10,1±2,1 – shock group: escape 1 = 8,5±1,7; escape 2 = 18,3±3,7; escape 3 = 29,0±9,3). Fear of potentially threatening stimuli presented as an unknown potential aversive acoustic stimulus was potentiated by traumatic stress (31,8±7,8% of time in freezing in control group and 57,8±6,8% in shocked group) with no effect in exploratory behavior in the open field (48,9±4,6 quadrants walked by control rats and 49,4±3,6 quadrants walked by shocked rats). Our results suggest that a single intense traumatic event is able to cause emotional alteration expressed as escape inhibition and fear potentiation in rats. These behavioral data may be useful to the development of studies aimed at investigating neurobiological underpinnings and vulnerability factors involved in stress related disorders.