Determinants of the voluntary consumption of nicotine by rats.

The 2-bottle free-choice method was used to study the voluntary consumption of nicotine by rats. Rats consumed nicotine voluntarily at different, albeit quite consistent, amounts. Voluntary intakes were higher in younger than older rats, but were not affected by gender. A previously forced nicotine intake had no effect on a subsequent voluntary intake of nicotine in older but increased it in younger rats. Forced exposure to nicotine of pregnant and lactating rats did not increase the voluntary intake by their offsprings. Established free-choice drinking patterns of nicotine were not affected by a temporary forced intake of this substance. The 2-bottle choice proved to be a reliable method to study the voluntary intake of nicotine, and results suggest that nicotine is not 'addictive' per se, but that its use is apparently determined by the response of an individual rat to this substance. Copyright 2000 S. Karger AG, Basel