Abnormal patterns of maternal behavior in a genetic animal model of depression

The Flinders Sensitive Line (FSL) model is considered a genetic animal model of depression. Among other characteristics, FSL rats express stress-induced anhedonia and an abnormal dopaminergic system. Our hypothesis was that FSL rats would show abnormal maternal behaviors, especially reduced motivation to reach and care for pups and reduced licking and non-nutritive contact, based on their anhedonic characteristics. Mother-infant interactions were assessed by time limited observations in FSL and Sprague-Dawley (SD) controls. In study 1, differences were found in consummatory behaviors: FSL dams compared to SD dams showed less licking and significant decrease in non-nutritive contact from the first to the third postpartum weeks. In addition, shorter duration of nursing postures was seen in FSL compared to SD dams in the first week postpartum, and this difference was significantly increased by the third week postpartum. In study 2, after exposure to acute swim stress, differences emerged in appetitive behaviors: latencies to reach and care for pups were longer in FSL dams compared to controls, suggesting a stress-induced motivational deficit in FSL dams. Possible explanations, especially regarding the FSL dams' reward system are discussed.