Gestational stress: effects on open-field behaviour and heart rate reactivity in rat offspring.

Home-cage heart rate (HR) and open-field defecation, ambulation, rearing and HR, were recorded in the offspring of mothers who had been exposed to stress during gestation. Compared with controls, experimental animals showed no significant differences in ambulation and rearing, while defecation was significantly lower. The only significant finding on HR was an increase from home-cage level to open-field level in the experimental group. The results confirmed previous findings that illumination level is a useful independent variable in gestational stress studies, and suggested that different types of HR measure yield a similar picture of the HR/defecation relationship, which appears to be a negative function. These conclusions were discussed in the light of other findings in this area, and traditional assumptions about the emotionality construct were questioned.