In separate studies, nonsmoking nicotine-naive subjects (11 young and middle-aged normal volunteers and 11 nonsmoking patients with Alzheimer's disease) received up to three doses of intravenous nicotine bitartrate (0.125, 0.25, and 0.5 micrograms/kg/min) and placebo for 60 min. Measurement of plasma ACTH, cortisol, and prolactin showed that nicotine produced in both groups a dose-dependent increase in cortisol, with ACTH in both groups and prolactin in the Alzheimer's group significantly elevated only by the 0.5 micrograms dose. Physiologic measures showed dose-dependent increases that were consistent with previous reports of nicotinic cholinergic stimulation. Behavioral effects included increases in anxiety and decreases in mood, especially following the 0.5 micrograms dose. Physical side effects were modest. The results indicate that nicotinic cholinergic stimulation can activate pituitary hormonal secretion in the human and suggest that nicotinic cholinergic stimulation may constitute an important part of cholinesterase inhibitor-induced endocrine stimulation and behavioral activation.