Abdominal Surgery Decreases Food-reinforced Operant Responding in Rats

Background: Establishment of early oral nutrition after sur-gery is associated with a decrease in morbidity and mortality. The following studies were undertaken to determine how surgery in-fluences food-reinforced behavior in rats and to determine the relevance of afferent input from the incision site on this behavior. Methods: Rats were trained to press a lever for food pellets to assess the effects of various abdominal surgical manipulations. Operant requirements and food availability were also manipu-lated. The effects of wound infiltration with bupivacaine and denervation of the abdominal musculature in the area of the incision were similarly examined. Results: Incision of the skin and abdominal musculature pro-duced significant behavioral effects. Food pellets earned were significantly decreased, with gut manipulation producing ef-fects of greater magnitude and duration than incision alone