Stress after hippocampal stroke enhances spatial performance in rats

The nature of stress-related cognitive changes is still a matter of debate. Stress is often considered to be deleterious to cognitive function, despite many instances in which beneficial effects are evident in neural structure and cognition. Moreover, in some neuropathological conditions such as focal ischemia, stress exaggerates loss of cognitive function. The present experiments set out to investigate the effects of repeated restraint stress on spatial cognition in rats, and on recovery from a focal stroke induced by injection of endothelin-1 (ET-1) into the hippocampus (HPC). We did not observe a deleterious effect of stress on performance in the Morris water task (MWT). The HPC focal stroke induced by ET-1 produced lasting spatial learning impairments. Importantly, rats in the HPC stroke + stress group exhibited superior performance in the MWT compared with the HPC stroke-only group. No between-group structural difference was observed related to stress. These findings confirm that corticosterone-related experiences may be key factors influencing cognitive performance after HPC focal ischemic stroke.

Research Highlights
► Spatial performance in Morris water task (MWT) is not affected by chronic stress.
► ET-1-induced hippocampal focal stroke produces a spatial deficit in the MWT.
► Post-stroke chronic stress enhances spatial function in MWT.