Environmental enrichment enhances post-ischemic cerebral blood flow and functional hyperemia in the ipsilesional somatosensory cortex

Abstract

Environmental enrichment has been reported to promote functional recovery in an ischemic stroke. However, the underlying mechanism remains unclear. This study aimed to investigate the effect of environmental enrichment treatment on post-ischemic cerebral blood flow and functional hyperemia in the ipsilesional primary somatosensory cortex of rats. With laser speckle imaging, we were able to monitor the resting cerebral blood flow alteration in the middle cerebral artery occlusion model. Both 3- and 28-day post-ischemic infarct volumes were then examined with triphenyltetrazolium chloride and cresyl violet staining, respectively. We found that an exposure to environmental enrichment was associated with higher post-ischemic cerebral blood flow and less brain tissue loss in the ipsilesional primary somatosensory cortex compared with the standard cage environment. Furthermore, environmental enrichment also enhanced the cerebral blood flow response to whisker stimulation in the ipsilesional barrel cortex when measured 28 days after the middle cerebral artery occlusion. Together, the data suggested that an exposure to environmental enrichment promoted the restoration of cerebral blood flow in the ipsilesional cortex and contributed to a better coupling between functional activation and cerebral blood flow change, which might be the possible mechanisms underlying the neuroprotective effects of EE after ischemia.

Keywords: Cerebral blood flow; Environmental enrichment; Hyperemia; Laser speckle imaging; MCAO; Stroke.