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

Abstract

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. In a previous study such bingeing was found when rats were given 4% sucrose solution; it also found that, following 1-in-4-days access for many weeks, intakes remained persistently higher than that of controls even when the conditions were changed to 1-in-2-days 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. However, when a maltodextrin solution was used, initial increased intakes produced by the 1-in-4-days schedule were not maintained when this was changed to a 1-in-2-days schedule. These results suggested 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-in-4-days 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.