Prenatal Exposure to Predictable and Unpredictable Novelty Stress and Oxytocin Treatment Affects offspring Development and Behavior in Rats

Abstract

Prenatal stress in rats usually results in behavioral and developmental changes in offspring. This experiment assessed body weight during the first three weeks postpartum and subsequent behavior of the offspring when tested as adults. Pregnant females allocated to the stress condition were exposed during the third week of pregnancy to either predictable (NOV1) or unpredictable (NOV2) psychological novelty stress. At this time, pregnant rats were also treated with various doses of oxytocin or vehicle solution. The exposure to unpredictable novelty stress during the third week of pregnancy resulted in pups which were significantly heavier at birth than either control animals or those which had received predictable exposure to the novelty stress. In contrast, oxytocin treatment appeared to lower body weight of offspring compared to control animals. This effect was observed right up until Day 21 postpartum for animals exposed to the larger dose (11.6 I.U.) of oxytocin. When tested as adults, NOV1 and NOV2 offspring were found to defecate more in the open field setting suggesting the they were more emotional than control animals. It was concluded that psychological stress during pregnancy has a subtle effect on development and subsequent effects on later emotionality of the offspring when tested as adults.

Key Words:

• prenatal psychological stress
• oxytocin
• bodyweight
• openfield
• Rattus Norvegicus