Five days before the test, rats were allowed 2-h daytime access to water. On the day of the experiment, rats were given access to 0.15% sodium saccharin rather than water for 30 min. Next, one experimental group was injected intraperitoneally with 0.15 mol/L lithium chloride (LiCl) in saline and subcutaneously with saline (vehicle). The second experimental group was injected intraperitoneally with saline and subcutaneously with nicotine. A third experimental group was injected intraperitoneally and subcutaneously with saline. Twenty-four hours later, rats were given a 2-h access to a two-bottle choice test of 0.15% saccharin versus water. Conditioned taste aversion (CTA) was expressed as percent saccharin preference ratio [100 × saccharin intake/(saccharin intake + water intake)]. A saccharin preference ratio <50% was considered as a signal of CTA (26).
