Flavor avoidance expressed in grooming by pine voles (Microtus pinetorum): importance of context and hormonal factors

Pine voles (Microtus pinetorum) were given sipper tubes containing saccharin solution, and after drinking, were injected with 0.15 M LiCl. Subsequently, two-sipper tests were given to assure the presence of conditioned flavor avoidance (CFA), and then animals were presented with saccharin in carboxymethyl-cellulose on their own fur (autogrooming), or on the fur of cagemates (allogrooming). CFA was expressed in two-sipper tests, and during allogrooming of material from a cagemate's fur, but not during autogrooming. Failure to express CFA during autogrooming was associated with high circulating levels of corticosterone and cortisol, steroids implicated in behavioral arousal. These results are consistent with previous work showing that rats and mice will ingest flavors while grooming that they would otherwise avoid. We speculate that our findings provide a plausible explanation for the successful use of grooming to increase the ingestion of unpalatable toxicants.