LAUSR

HighlightsChronic phase advance (CPA) does not interfere with the protective effect of behavioral control on the stress‐induced reduction in social exploration.CPA produces an escape‐learning deficit in the two‐way shuttlebox task and behavioral control does not rescue this impairment.CPA induces somatic alterations including increased weight gain, increased epidydmal adiposity, and decreased adrenal mass. Abstract In modern 24 h society, circadian disruption is pervasive, arising from night shift work, air travel across multiple time zones, irregular sleep schedules, and exposure to artificial light at night. Disruption of the circadian system is associated with many adverse health consequences, including mood disorders. Here we investigate whether inducing circadian misalignment using a phase advance protocol interferes with the ability to cope with a stressor, thereby increasing susceptibility to the negative consequences of stress. Male rats were maintained on a standard 12:12 light: dark (LD) cycle or subjected to a chronic phase advance (CPA) protocol involving 4 weekly 6 h phase shifts (earlier light onset) of the LD cycle. Rats were then exposed to escapable stress (ES), inescapable stress (IS), or no stress (home cage control; HC) and performance on juvenile social exploration and active escape learning in the two‐way shuttlebox test was assessed 24 h and 48 h following stress, respectively. CPA alone had no effect on pre‐stress juvenile social exploration, and it also did not interfere with the protective effect of ES on the stress‐induced reduction in juvenile social exploration. In contrast, CPA impaired escape learning in the two‐way shuttlebox to the same extent as IS in all subjects, regardless of stress history. Additionally, CPA produced somatic alterations that included increased body mass, increased epididymal adiposity, and decreased adrenal mass. These data indicate that CPA differentially modulated the stress‐protective effects of behavioral control depending on the type of affective behavior examined.