Neuronal Plasticity and Dendritic Spines: Effect of Environmental Enrichment on Intact and Postischemic Rat Brain

Abstract

The authors compared the influence of environmental enrichment on intact and lesioned brain, and tested the hypothesis that postischemic exposure to an enriched environment can alter dendritic spine density in pyramidal neurons contralateral to a cortical infarct. The middle cerebral artery was occluded distal to the striatal branches in spontaneously hypertensive rats postoperatively housed either in a standard or in an enriched environment. Intact rats were housed in the same environment. Three weeks later the brains were perfused in situ. The dendritic and spine morphology was studied with three-dimensional confocal laser scanning microscopy after microinjection of Lucifer yellow in pyramidal neurons in layers II/III and V/VI in the somatosensory cortex. In intact rats, the number of dendritic spines was significantly higher in the enriched group than in the standard group in all layers ( P < 0.05). Contralateral to the infarct, pyramidal neurons in layers II/III, which have extensive intracortical connections that may play a role in cortical plasticity, had significantly more spines in the enriched group than in the standard group ( P < 0.05). No difference was observed in layers V/VI. They conclude that housing rats in an enriched environment significantly increases spine density in superficial cortical layers in intact and lesioned brain, but in deeper layers of intact brain.

VEGF reverts the cognitive impairment induced by a focal traumatic brain injury during the development of rats raised under environmental enrichment

“…Exposure to an enriched environment has been shown to induce morphological changes in the brain, both in normal and pathological conditions [51,52]. These morphological changes include structural reorganization, especially in the visual cortex [53], which is associated with improved learning and memory and enhanced neural plasticity [54].…”

Thinning, movement, and volume loss of residual cortical tissue occurs after stroke in the adult rat as identified by histological and magnetic resonance imaging analysis

“…Novel horizontal axonal cortical connections have also been observed in post-stroke peri-infarct tissue (Carmichael et al, 2001). Dendritic and axonal sprouting in residual cortical tissue can be modulated by tactile stimulation (Gibb et al, 2010), motor skill training (Biernaske and Corbett, 2001;Kleim et al, 2004), environmental enrichment (Johansson and Belichenko, 2002;Kolb and Gibb, 1991a), and pharmacological manipulations (Ramic et al, 2006).…”

Inhibition of CXCL12 Signaling Attenuates the Postischemic Immune Response and Improves Functional Recovery after Stroke

“…Here, the beneficial processes stimulate glia cells to encapsulate the infarct [13][14][15] or enhance neuronal plasticity. 16 Importantly, enriched housing has a profound effect on the inflammatory reponse after brain injury 14 and modulates cell genesis. 17 Means to optimize the inflammatory response in order to balance the removal of debris and to stimulate brain plasticity in the injured hemisphere are indeed warranted.…”