Activity Anorexia (AA) is a condition where rats begin to exercise excessively while simultaneously cutting down on their food intake, similar to human anorexia nervosa. When given free access to food and an exercise wheel rats develop a balance routine between exercise and food intake turning them into fit rats. However, if food intake is restricted and wheel access is unrestricted rats begin to exercise more and eat less resulting in excessive weight loss and ultimately death. The running cycles shift so that most of the running is done in hours before feeding is scheduled. In other conditions AA does not develop. Unrestricted food access and restricted wheel access will not cause any significant change in either feeding or exercise routine. Also if rats are restricted both in food intake and wheel access they will adjust accordingly. In fact if rats are first trained to the feeding schedule and then given unrestricted access to a running wheel they will not develop AA behavior. Results support that the running interfered with the adaptation to the new feeding schedule and is associated with the reward system in the brain. One theory is that running simulates foraging, a natural behavior in wild rats. Laboratory rats therefore run (forage) more in response to food shortages. The effect of semi-starvation on activity has also been studied in primates. Rhesus monkey males become hyperactive in response to long-term chronic food restriction.
Famous quotes containing the word activity:
“Humour is by far the most significant activity of the human brain.”
—Edward De Bono (b. 1933)