Effects of Maternal Stress on the Behavioral and HPA Responses of Offspring Exposed to the Predator or Non-Predator Odor in Brandt's Voles

Maternal stress influences offspring survival strategies under predation risk. This study investigated foraging behavior and the hypothalamic-pituitary-adrenal (HPA) responses of Brandt's vole (Lasiopodomys brandtii) offspring after their mothers had been repeatedly exposed to predator odors during pregnancy. We exposed pregnant Brandt's voles to distilled water (DW, the control), rabbit odor (RO, non-predator odor), or cat odor (CO, predator odor) for 18 days (60 min/day). Once the offspring matured into adults, we exposed them to either rabbit odor or cat odor and recorded their behavioral and hormonal responses, as well as hypothalamic c-fos mRNA expression, were measured. Female CO offspring exposed to cat odor spent more time hiding and less time foraging, accompanied by the highest levels of serum adrenocorticotropic hormone (ACTH), serum corticosterone (CORT), and hypothalamic c-fos mRNA, compared to RO and DW offspring. When exposed to rabbit odor, male RO offspring showed more alerting behaviors than females, while male CO offspring showed more exploring behaviors than females. CO offspring exposed to rabbit odor exhibited higher levels of serum ACTH, serum CORT, and c-fos mRNA than those in RO and DW offspring. Our findings indicate that maternal stress induced by predator odor is sufficient to induce an altered HPA response, and these changes may be associated with increased hiding behaviors but decreased foraging behaviors in adult female offspring. Predatorinduced maternal stress thus appears to be beneficial to increase the survival responses of vole offspring.