Kaolin clay intake motivated by lactose ingestion in rats

Abstract

Abstract Adult rats learn to be shy away from a taste paired with the ingestion of lactose solution. This study thus aimed to elucidate the nature of this shyness learning. Specifically, by measuring kaolin clay consumption, which is as a good maker of nausea in rats, the study attempted to find out whether lactose produces nausea. Experiment 1 demonstrated that a lactose solution, as well as a lithium chloride sodium chloride cocktail, increased consumption of kaolin clay. Ingestion of a lactose solution increased kaolin consumption in Experiment 2A, while a similarly sweet sucrose solution did not changed it in Experiment 2B. The central results of Experiments 2A and 2B were replicated in Experiment 3 with a modified procedure, suggesting that lactose induces nausea in rats, which yields conditioned aversion (i.e., palatability downshift) of the paired taste.