Chronic voluntary nicotine drinking enhances nicotine palatability in rats.
The response of rats to nicotine solutions was examined with the brief-exposure, taste reactivity test and a two-bottle, 24-hr preference test. In Experiment 1, naive nondeprived rats were administered intraoral infusions (0.8 ml infused during 1 min) of distilled water and 1 microgram/ml, 5 micrograms/ml, 10 micrograms/ml, 25 micrograms/ml, 50 micrograms/ml, and 100 micrograms/ml nicotine. The oral motor, taste reactivity (TR) responses of the rats were recorded during the infusion. Nicotine solutions up to a concentration of 50 micrograms/ml elicited a number of ingestive TR responses similar to that by water. Ingestive responses significantly decreased and aversive TR responses significantly increased in response to 100 micrograms/ml nicotine. On the basis of these results, two-bottle preferences for water versus 1 microgram/ml, 5 micrograms/ml, and 0 microgram/ml (water control group) nicotine were measured in three groups of naive rats. Rats initially showed an equal preference for 0 microgram/ml and 1 microgram/ml nicotine. After 16 days of exposure, however, rats developed a significant preference for 1 microgram/ml nicotine. The preference ratio for 5 micrograms/ml nicotine significantly increased during the experiment, but the preference ratio remained significantly less than that for 1 microgram/ml and 0 microgram/ml nicotine solutions. Last, TR responses elicited by intraoral infusions of 1 microgram/ml and 5 micrograms/ml nicotine were then measured in these rats having had the two-bottle experience. Rats showing a two-bottle preference for the 1 microgram/ml nicotine solution displayed significantly more ingestive TR responses to 1 microgram/ml and 5 micrograms/ml nicotine than did the control rats.(ABSTRACT TRUNCATED AT 250 WORDS)
Flynn
F W
FW
Department of Psychology, University of Wyoming, Laramie 82071.
Webster
M
M
Ksir
C
C
D000818:Animals; D001245:Association Learning / Q000187:drug effects*; D001362:Avoidance Learning / Q000187:drug effects; D002755:Choice Behavior / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects*; D007858:Learning / Q000187:drug effects*; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013649:Taste / Q000187:drug effects*
D009538:Nicotine