ROLE OF EXPERIMENTAL CONDITIONS IN DETERMINING DIFFERENCES IN EXPLORATORY-BEHAVIOR OF PRENATALLY STRESSED RATS

The effect of prenatal stress was determined on exploration in situati ons that induce different levels of fear. Dams (12) were stressed by n oise and light thrice weekly on an unpredictable basis throughout preg nancy, and 12 controls were left undisturbed. The time spent by differ ent groups of their adult offspring of both sexes in exploration was a ssessed during 4 min in a plus maze; large, well-lit open field (1), a nd open held (2) after prior exposure to a small, dark holebox. Prenat al stress resulted in a significant reduction in the number of arm ent ries in the plus maze and amount of time spent in the open arms. Locom otion and rearing were also reduced in Open Field 1 and 2, but these a ctivities and hole poking were unchanged in the holebox. It is conclud ed that prenatal stress renders the animal more fearful to a novel, in timidating environment,which may be expressed as a suppression of expl oratory activity. (C) 1996 John Wiley & Sons, Inc.