Behavioural and intestinal responses to novelty in rats selected for diverging reactivity in the open field test

There are indications that the severity of functional gastrointestinal disturbances in humans is linked to individual coping styles. In rodents, the open field test can be used to assess individual differences in behavioural responsivity to novel challenges. Two groups of Wistar rats were selected for high (HA) and low (LA) locomotor activity in a novel open field and fitted with electrodes on the proximal colon. During subsequent exposure to a novel box, a smaller locomotor activation in LA was accompanied by a greater increase in colonic spike burst activity compared to HA rats, even though this novel stressful challenge did not result in a clear defecation response in either group. In contrast, no marked behavioural differences between HA and LA were seen in the shock prod paradigm. Although detection of divergent behavioural responsivity in HA and LA rats may depend on stimulus quality or intensity, combined use of behavioural selection and intestinal motility recording in freely moving rats may offer a model to study individual vulnerability to stress-related disturbances of intestinal function.