NicotineNicotinic AgonistsTobacco Use DisorderGanglionic StimulantsReceptors, NicotinicMecamylamineCotinineNicotinic AntagonistsChewing GumSubstance Withdrawal SyndromeTobacco Use Cessation ProductsSmoking CessationSmokingAdministration, CutaneousDihydro-beta-ErythroidineTarsSelf Administrationalpha7 Nicotinic Acetylcholine ReceptorAzocinesDose-Response Relationship, DrugAconitineConditioning, OperantRats, Sprague-DawleyQuinolizinesTobacco, SmokelessTobacco ProductsRewardTobaccoAnabasineBicyclo Compounds, HeterocyclicReinforcement (Psychology)Carbon MonoxideBehavior, AnimalSelf StimulationHexamethoniumDopamineBenzazepinesBungarotoxinsHexamethonium CompoundsTobacco Smoke PollutionVentral Tegmental AreaQuinoxalinesNitrosaminesSmokeAnalysis of VariancePyridinesMotor ActivityNucleus Accumbens