Effect of chronically electric foot shock stress on spatial memory and hippocampal blood brain barrier permeability

Maintaining blood-brain barrier (BBB) contributes critically to preserving normal brain functions. According to the available evidence, intense or chronic exposure to stress would potentially affect different brain structures, such as the hippocampus, negatively. The purpose of this study was to define the relationship between the BBB permeability of the hippocampus and the performance of spatial learning and memory under chronically electric foot shock stress. Sixteen rats were divided into the control and stress groups equally. Animals in the stress group were exposed to foot shock (1 mA, 1 Hz) for 10-s duration every 60 s (1 h/day) for 10 consecutive days. The anxiety-related behavior, spatial learning, and memory were assessed by an Open Field (OF) and the Morris Water Maze (MWM) respectively. The hippocampal BBB permeability was determined by Evans blue penetration assay. Our results demonstrated that the stress model not only increased locomotor activities in the OF test but reduced spatial learning and memory in MWM. Moreover, these effects coincided with a significant increase in hippocampal BBB permeability. In sum, the stress model can be used in future studies focusing on the relationship between stress and BBB permeability of the hippocampus.