Changes in hypothalamic-pituitary-adrenal axis activity related to the acquisition of a spatial task in the Barnes maze

Abstract

It is well known that animals can learn escape responses when exposed to aversive stimuli. Additionally, it has been described that as effective behaviors to reduce contact with aversive stimuli are developed, the level of arousal decreases. However, the avoidance tasks, typically described, are based on the learning of simple motor patterns that do not allow a detailed description of the process of acquisition and refinement of the escape task. The present study aimed to describe the changes in the performance of animals that received one or two training sessions in the Barnes circular maze and the activity of the hypothalamic-pituitary-adrenal (HPA) axis as an indicator of the arousal associated with the learning of escape responses. Our findings showed that extended training results in lower HPA axis activity than standard training as reflected by corticosterone release and paraventricular hypothalamic nucleus activity. This result suggests that the HPA axis functioning may be associated with the predictability and control that animals acquire through the learning of a navigation route that allows them to escape from an aversive situation in spatial tasks.