Social instability blocks functional restitution following motor cortex stroke in rats.
Social interactions have previously been shown to influence stroke outcome. In the current experiment we investigated the effects of a changing social environment on anatomical and behavioral recovery following motor cortex stroke in rats. Adult rats were trained on the Whishaw single pellet reaching task prior to receiving a devascularizing stroke lesion of the motor cortex. During the post-stroke testing period half of the rats were exposed to a form of social experience that has previously been shown to stimulate synaptic plasticity in frontal cortex circuitry, whereas the remaining rats were housed in pairs, in standard cages. At the end of the experiment the brains were processed for Golgi-Cox staining and dendritic length was measured in layer V of the intact forelimb motor area, layer III of Zilles' area Cg3 and layer II/III of Zilles' area AID. Social experience was found to completely block the normal spontaneous behavioural restitution in the lesion animals. Anatomically, whereas social experience selectively increased dendritic length in AID in rats that had not undergone behavioral training or the stroke procedure, this was not seen in the lesion animals, as the lesion alone produced an increase in dendritic length in both AID and Cg3. The findings are discussed in terms of the role of social experiences, including stress, on spontaneous plasticity that occurs following unilateral motor cortex stroke, and the effectiveness of inducing synaptic plasticity to promote behavioural recovery.
Silasi
Gergely
G
Department of Neuroscience, Canadian Centre for Behavioural Neuroscience, University of Lethbridge,Lethbridge, Alberta, Canada. silasi@ualberta.ca <silasi@ualberta.ca>
Hamilton
Derek A
DA
Kolb
Bryan
B
D000222:Adaptation, Physiological; D000223:Adaptation, Psychological; D000704:Analysis of Variance; D000818:Animals; D003345:Corticosterone / Q000097:blood; D003712:Dendrites / Q000502:physiology; D005106:Exploratory Behavior / Q000502:physiology; D005625:Frontal Lobe / Q000502:physiology*; D008297:Male; D016555:Matched-Pair Analysis; D009044:Motor Cortex / Q000473:pathology / Q000503:physiopathology; D009473:Neuronal Plasticity / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D020127:Recovery of Function / Q000502:physiology*; D012919:Social Behavior; D012931:Social Environment; D013315:Stress, Psychological; D020521:Stroke / Q000503:physiopathology* / Q000523:psychology
D003345:Corticosterone