Postnatal Development of the Degu (Octodon degus) Endocrine Stress Response Is Affected by Maternal Care.

Maternal stress and care significantly affect offspring's future behavior and physiology. Studies in laboratory rats have shown that maternal stress decreases maternal care and that low rates of certain maternal behaviors cause offspring to develop hyperreactive stress responses. Plurally breeding rodents that practice communal care, such as degus (Octodon degus), may be able to buffer some of these effects since offspring receive care from multiple females. Directly after parturition, 0% (Control group), 50% (Mixed group), or 100% (CORT group) per cage of pair-housed female degus were implanted with 21-day release cortisol pellets. The amount of maternal care provided by females was determined from video recordings during the next 3 weeks. Females with cortisol implants did not alter rates of maternal care. However, females recently introduced to captivity had low rates of pup contact and pup retrievals compared to females of captive origin. When pups reached 4 weeks of age, we determined their baseline and stress-induced cortisol levels, in addition to assessing their negative feedback efficacy and adrenal sensitivity. Pups from mothers recently introduced to captivity had weak negative feedback. Within captive pups, those from CORT mothers weighed less compared to pups from either Control or Mixed mothers. Captive CORT pups also had weak adrenal sensitivity compared to captive Control pups. These findings demonstrate that maternal care and glucocorticoid elevation impact certain components of the degu pup stress response, but that plural breeding with communal care may buffer some of these effects.