Induced preference or conditioned aversion for sodium chloride in rats with chronic bile duct ligation

We examined whether a learned aversion to saline could account for the reduction in saline intake produced by bile duct ligation (BDL) in rats and whether increased saline intake by BDL rats was associated with hypotension. In three experiments, rats were given continuous access to water in choice with saline after surgery. In Experiment 1, rats were deprived of food and fluid for 24 h and then given 2-h access to either 0.15 or 0.3 M saline. Rats received a BDL or sham-ligation immediately (paired) or 48 h after (nonpaired) the 2-h bout of saline ingestion. The results show that nonpaired BDL rats increased their daily saline intake relative to nonpaired sham-ligated or paired BDL rats approximately 1-4 weeks after surgery. In Experiment 2, when water and either cherry or grape Kool-Aid (0.05% w/v) dissolved in 0.15 M saline to distinguish the flavor of the solution was offered prior to surgery, BDL rats reduced their ingestion of grape-flavored saline after surgery regardless of whether they were exposed to grape- or cherry-flavored saline prior to surgery. In Experiment 3, when rats were offered water and 0.3 M saline 48 h after surgery, BDL rats ligated for 4 weeks increased their saline intake relative to sham-ligated controls and this elevation in saline intake by BDL rats was associated with hypotension. The results suggest that the symptoms associated with the BDL surgery can serve as effective unconditioned stimuli in the acquisition of learned flavor aversions, and that hypotension may play a role in the elevated intake of saline by BDL rats.