Conditioned saccharin aversions in rats as a result of cutaneous nicotine or intraperitoneal nicotine administered in divided doses.

Nicotine base was used in a conditioned taste aversion (CTA) paradigm to avert male Sprague-Dawley rats to saccharin solution (0.1%, w/v). Experiments investigated different dose routes of nicotine administration and duration of action as determinants in nicotine-induced CTA. In Experiment 1 nicotine was injected intraperitoneally (IP) at doses of 0.5, 1.0, or 3.0 mg/kg 30 min after drinking saccharin solution. Using a two-bottle choice test, no CTA was observed, although all nicotine animals showed obvious symptoms of malaise including seizures in the highest dose group. Experiment 2 showed dose-related CTA when nicotine (10.0, 30.0, or 50.0 mg/kg) was cutaneously applied 30 min following saccharin drinking. Experiment 2B showed that the aversions were due to associative rather than nonassociative factors such as sensitization or enhanced neophobia. In Experiment 3, the following group treatments were begun 30 min after saccharin drinking to distribute identical total nicotine doses over an extended period of time: One IP injection of 2.0 mg/kg nicotine (in a saline vehicle) and four injections of saline solution, three injections of 0.67 mg/kg nicotine and two injections of saline, five injections of 0.40 mg/kg nicotine, or five injections of saline. All injections were spaced 30 min apart. Compared with saline-injected controls, CTA occurred in the rats receiving either three or five injections of nicotine but the group receiving one injection did not differ from the control group. There was no difference in CTA between the groups receiving three or five injections.

Saccharin aversions in hamsters as a result of nicotine injections.

Golden Syrian hamsters (males, N = 70) showed dose-related conditioned taste aversion (CTA) when saccharin drinking was followed by delayed nicotine injections. Baseline consisted of measuring amounts consumed after 20 minutes of daily access to tap water. Measures were taken for five days. The hamsters were then conditioned by offering them saccharin solution (0.1%, w/v) for 20 minutes; afterwhich a 30 minute delay was imposed. Subsequent to the delay, groups of 10 animals were treated as follows: nicotine injection (1.0, 3.0, or 9.0 mg/kg, IP), saline injection, lithium chloride injection (2% body weight of a 0.15 M solution), sham injection, or left in their cages as handling/stress controls. Following two recovery days with plain water available for 20 minutes, all animals were tested for CTA by offering them saccharin solution. Dose-related CTA was demonstrated in the nicotine animals as measured by a decrease in saccharin consumption compared to drinking measures obtained from animals injected with saline. Lithium chloride produced the same degree of CTA as 9 mg/kg of nicotine, and the aversions had extinguished in all groups by the third test day.