Behavioral and adrenocortical reactivity in female mice following individual or group housing.

Female "TO" strain mice were individually or group-housed for different durations (7-196 days). Behavioral reactivity was assessed for 3 days in an open field and an emergence test. Plasma samples were later collected after 5 min exposure to ethyl ether vapor; these generated "stress" corticosterone values. "Basal" corticosterone titers were obtained from similar untested and unanesthetized categories of mice. "Ether-stress" values were obtained from a limited number of mice subjected to ether anesthesia but no behavioral testing. Neither the basal nor the stress adrenocortical activities of the 2 housing categories differed. Open-field ambulation increased with longer durations of isolation, whereas for grouped mice it remained approximately constant. Individually housed mice had significantly lower defecation scores and longer emergence times than group-housed mice. In sum, little support was provided for the view that isolation is stressful.