A cross-fostering study in a genetic animal model of depression: maternal behavior and depression-like symptoms.

Connections between maternal behavior and childhood depression were examined by using a "genetic animal model"; Flinder Sensitive Line--(FSL) rats, and cross-fostering the offspring with the control strain, Sprague Dawley (SD) rats. The control procedure was "in-fostering", where the foster dam and her pups were from the same strain. Contribution of pups' characteristics/genotype to maternal behavior was examined. After weaning, we measured male offspring's body weight, immobility in the swim test, and basal corticosterone (CORT) and adrenocorticotropin (ACTH) levels at the prepubertal age of 35 days. While maternal behavior (of "depressive-like" dams and their controls) was not altered significantly by the pups' strain, the adoption procedure per se appeared to have more adverse effects on "depressive-like" symptoms of the SD prepubertal rats than on the FSL pups. Nevertheless, the combination between abnormal maternal behavior and genetic predisposition affected the hormonal stress responses of the offspring in a more severe manner than genetic predisposition or abnormal maternal behavior per se.