Adolescent and adult nicotine exposure differentially impacts oral nicotine and oral saccharin self-administration in mice.

•Adolescent nicotine exposure increased saccharin reinforcement in adulthood.•Adult nicotine re-exposure biased the sensitivity towards nicotine reward.•Both adolescent and adult nicotine exposure increased impulsive responding.•Adolescent and adult nicotine experience activated distinct behavioral mechanisms.•These mechanisms acted in concert to facilitate maladaptive nicotine taking.