Effect of stress on feeding behavior in rats: individual differences

The experiment was conducted to study individual differences in stress-induced changes of food intake in rats and to examine concomitant changes of non-eating behaviors. Eating and non-eating behaviors were measured during five consecutive test sessions under stressful noise (95 dB white noise, n=18) and control conditions (60 dB white noise, n=18). Two thirds of the stressed rats were classified as normophagic, one third showed hypophagic responses. Hypophagic rats spent less time eating and more time grooming and resting than normophagic and control rats. Hypophagic rats also showed an increased tendency of scanning movements during eating and an increased tendency to leave the food area. Their eating speed was significantly lower than that of the normophagic rats. Hypophagic rats were characterized by a heightened reactivity to stressors which may have counteracted the adaptation to the stressful feeding situation. Results point to a role of biological factors for individual differences in stress-induced changes of eating.