Individual versus group housing affects nociception independently of housing status during development

Abstract

Individually housed rats displayed longer nociceptive latencies than did group-housed animals both before and after very brief, mild electric shocks. The lack of effect of mild shock in changing latencies indicates that individual housing did not result in a stress-induced hypoalgesia rein-stateable by a mild stressor, itself insufficient to cause hypoalgesia in normal animals. The longer latencies were entirely a function of the housing condition current at the time of testing. No carryover effects occurred from the housing condition that was in effect immediately after weaning. Therefore, it is likely that no critical period exists for nociceptive sensitivity. The longer latencies support the hypothesis that individual housing is stressful in rats. These results may be of interest to those planning experiments or comparing results across laboratories on stress-induced hypoalgesia.