nicotine
n. an alkaloid obtained primarily from the tobacco plant (Nicotiana tabacum). Today nicotine is one of the most widely used psychoactive drugs; it is the primary active ingredient in tobacco and accounts for both the acute pharmacological effects of smoking or chewing tobacco (e.g., a discharge of epinephrine; a sudden release of glucose; an increase in blood pressure, respiration, heart rate, and cutaneous vasoconstriction) and the dependence that develops (see nicotine dependence; nicotine withdrawal). The behavioral effects of the drug include enhanced alertness, decreased reaction time, improved attention, and feelings of calm. Nicotine produces multiple pharmacological effects on the central nervous system by activating nicotinic receptors as well as cannabinoid and other receptors, thus facilitating the release of several neurotransmitters, particularly dopamine (a reaction similar to that seen with
such drugs as cocaine and heroin). In large doses, it is highly poisonous, producing effects such as dizziness, diarrhea, vomiting, tremors, spasms, unconsciousness, heart attack, and potentially death via paralysis of the muscles of respiration. Nicotine was isolated from the tobacco plant in 1828 and was named for the French diplomat Jean Nicot, who introduced tobacco in France in 1560. —nicotinic
adj.