Repeated long separations from pups produce depression-like behavior in rat mothers.

Long maternal (LMS) versus brief maternal (BMS) daily separations of rat pups from their mothers have contrasting effects on their adult stress responses and maternal behavior by, respectively, decreasing and increasing licking received from their mothers. We hypothesized that LMS decreases pup-licking in mothers by inducing learned helplessness, creating a depression-like state. We subjected postpartum rats to LMS (3 h), BMS (15 min) or no separation (NMS) on postpartum days 2-14.