The effects of mild maternal stress during pregnancy on the behavior of rat pups.

Mild maternal stress in the form of chronic daily subcutaneous injections of saline or the vehicle for diazepam to pregnant rats was shown to result in some long term, subtle but reliable, changes in the behavior of the offspring. The same vehicle given for the same period of time in the dam's drinking water, without injection had no effect on the development of later behavior of rat pups. Chronic prenatal injections of saline or vehicle for diazepam, used in many experiments as controls for the evaluation of drug effects were shown to have some long lasting behavioral effects in the offspring of the treated dams. The series of experiments reported here compared the offspring of saline or vehicle injected dams to those of uninjected dams on a variety of developmental measurements, an open field behaviour and on learning performance in a complex brightness discrimination maze.