Individual housing does not influence the adaptation of the pituitary-adrenal axis and other physiological variables to chronic stress in adult male rats

Although the influence of housing conditions on the physiological response to stress has been extensively studied for several years, no attempts have been made to investigate the effect of this variable on the capacity for adaptation to chronic stress. To this end, adult male rats were housed either individually or in groups of four per cage and subjected to 2 hr of daily immobilization stress for 14 days. Housing did not influence any of the physiological variables measured either in unstressed or in stressed rats except the corticosterone response to stress which was higher in individually housed rats. Of the behavioral measures, individual housing significantly decreased defecation rate in the novel environment. Other behavioral measures were not influenced by housing. Chronic stress significantly reduced ambulation but no significant interaction between housing and chronic stress was observed. Taken together, these data indicate that a short period of individual housing did not affect the physiological and behavioral consequences of repeated exposure to chronic stress. © 1989.