Social contact influences histological and behavioral outcomes following cerebral ischemia

Social interaction is neuroprotective following stroke, however, social housing introduces numerous social and sensory stimuli, and the individual contribution of these stimuli to stroke outcome is unknown. The current study was designed to investigate the role of physical contact in mediating the protective effect of social interaction in a rodent model of focal cerebral ischemia. Male mice were housed individually (socially isolated) or paired with an ovariectomized female in standard housing conditions, or in a cage separated by a grid partition that prevented physical contact. Implantable transmitters continuously recorded core body temperature and locomotor activity beginning 24 h before cerebral ischemia and continuing through 72 h of reperfusion. Among mice housed in standard cages, pair housing reduced infarct volume and led to a recovery of locomotor activity compared to social isolation. However, among mice that were pair housed in a partitioned cage that prevented social interaction throughout the experiment, infarct Volume was comparable to that of socially isolated mice. Further, locomotor activity did not fully recover by 72 h among paired mice that were separated by a partition. Core body temperature did not differ by housing condition in mice undergoing stroke. Taken together, these data suggest that the physical contact component of social interaction is an important mediator of social influences on stroke outcome. (C) 2009 Elsevier Inc. All rights reserved.