Stress-induced Eating in Rats

Mild tail pinch (TP) in rats resulted in 72% of animals displaying ingestive behavior with 20% demonstrating gnawing behavior without food ingestion and 8% demonstrating licking behavior only. The animals ate steadily over 5 min with a maximum rate occurring at 1 min (0.5 +/- 0.2 g). There was a circadian rhythm of TP-induced behavior with the peak food ingestion occurring at 24 h. A mild increase in blood glucose occurred 120 s after commencement of TP (115 +/- 4 mg/dl). Common satiety signals such as stomach distension and glucose decreased food ingestion. Parenteral administration of glucagon, cholecystokinin-octapeptide, bombesin, and thyrotropin-releasing hormone resulted in suppression of TP-induced food ingestion. Chronic TP (12 5-min TP periods/day) resulted in a fall in spontaneous food intake with the total intake remaining similar to food intake prior to the chronic TP period. We suggest that TP serves as an excellent model for eating behavior because 1) it correlates well with starvation-induced eating; 2) it precludes the necessary deprivation of food and water to adrenalectomized animals; and 3) animals subjected to TP continue chewing in the face of decreased food intake allowing one to exclude the possibility that the effects of an anorectic are secondary to nausea.