Sex Differences in Rat Behavioral Responses to Acute Wheel Running During Stress and Ambiguity.

Acute aerobic exercise activates physiological stress systems yet is widely viewed as a strategy for improving cognitive and emotional functioning. While studies in humans suggest that a single bout of exercise can alter responses to stress, relatively little is known about the behavioral effects of acute exercise in rodents, particularly in females. We investigated the effects of a brief bout of voluntary wheel running on spatial working memory, anxiety-like behavior, cognitive bias, and corticosterone concentrations in adult Long-Evans rats. Male and female rats were tested separately using within-subjects designs under baseline conditions and following acute loud music stress. In male rats, acute stress elevated corticosterone concentrations and slowed performance on a radial arm maze without increasing memory errors. Acute wheel running prevented this stress-induced slowing, increased open-arm exploration on the elevated plus-maze, and promoted more optimistic responding during cognitive bias testing. In contrast, female rats displayed a different pattern of effects. Acute wheel running increased corticosterone concentrations, impaired radial arm maze performance, and promoted more pessimistic responses to ambiguous cues. Although running increased open-arm exploration in females, it generally failed to buffer the behavioral effects of stress and often produced responses resembling those observed following stress exposure. Individual running distance was unrelated to behavioral performance in either sex. Together, these findings suggest that acute exercise rapidly alters behavioral responses to stress and ambiguity, but that these effects differ substantially between males and females. Acute wheel running may function as a stress-buffering experience in males while producing stress-like effects in females.