Bingeing in rats: Persistence of high intakes of palatable solutions induced by 1-day-in-4 intermittent access

When animals are given access to a palatable food or drink on some days but not on others, the amount they consume can far exceed the daily amounts consumed by controls given daily access. A previous study demonstrated such bingeing when rats were given 4% sucrose solution. Importantly, it also found that, following 1-dayin-4 access for many weeks, intakes remained persistently higher than that of controls even when the conditions were changed to 1-day-in-2 access for both groups. One aim of the three experiments reported here was to test whether such persistent bingeing could be found for other solutions. This was confirmed in rats for a saccharin solution and a highly palatable saccharin-plus-glucose solution. When a maltodextrin solution was used, the 1-day-in-4 schedule initially produced higher intakes than controls given daily access. However, the difference between these groups was not maintained when both were switched to a 1-day-in-2 schedule. These results suggest that the hedonic value of a solution is more important than its caloric content in determining whether it will support persistent bingeing. A second aim was to test for evidence that the 1-day-in-4 procedure induced an addiction to the target solution. No such evidence was found using multiple measures including instrumental responding and anxiety-like behavior on the elevated plus-maze for craving and withdrawal respectively.