Effect of Gestational Stress pa Maternal Behavior in Response to Cage Transfer and Handling of Pups in Two Strains of Rat

The influence of gestational stress was determined on the mother's behavior in two rat strains after a disturbance in her routine. Daily 10 min observations were made for 9 days post parturn in Sprague-Dawley (S-D) and Sabra (SB) rats after transfer of the maternal cage to another room or transient pup removal. In response to cage transfer, SB spent much more time than S-D rats in nursing, licking and sitting on their pups, but less time in individual activities. The direction of effect of gestational stress depended on the strain and particular behavior. The duration of nursing was increased in S-D but decreased in SB rats, while that of pup-licking was increased in SB and unchanged or decreased in S-D. Pup-removal reduced the total amount of pup-directed behavior in control and stressed mothers of both strains and eliminated any differences resulting from gestational stress seen in response to cage transfer. It is concluded that the degree and direction of effect of gestational stress on the partition of time by a nursing mother between pup-directed and other behaviors during the early postnatal period is strongly influenced by the strain of rat and the conditions under which it is assessed.