CHRONIC AND ACUTE TOLERANCE TO SUBJECTIVE EFFECTS OF NICOTINE

Tolerance to subjective effects of nicotine may induce novice smokers to increase the magnitude and frequency of their nicotine self-dosing. In this study, smokers (n = 8) and nonsmokers (n = 7) participated in three sessions involving presentation of 0, 7.5, or 15 mug/kg nicotin e 30 min for 2 h via measured-dose nasal spray, with different doses p resented on separate days. Subjective responses were assessed using vi sual analog scales (VASs) of jittery, light-headed, relaxed, dizzy, an d head rush, and the Profile of Mood States (POMS) scales of vigor, co nfusion, fatigue, tension, and the composite scale of arousal. Smaller responses in smokers vs. nonsmokers were viewed as evidence for chron ic tolerance. In addition, on each day subjects received a fifth, chal lenge dose of 30 mug/kg 30 min after the previous dosing. Smaller resp onses to the challenge dose as a function of increasing prior nicotine dosing during Trials 1-4 were viewed as evidence for acute tolerance. Results showed significant changes in most measures as a function of nicotine dose, and the dose-response curves for most VAS and POMS scal es tended to be shifted to the right, or dampened, in smokers relative to nonsmokers, consistent with chronic tolerance. However, smokers an d nonsmokers tended to respond to nicotine in opposite directions for POMS scales of vigor and arousal, perhaps reflecting withdrawal relief in smokers. Acute tolerance on a few selected VAS and POMS scales was apparent for both smokers and nonsmokers. These results support the n otions that chronic use of nicotine is associated with chronic toleran ce to some subjective effects of nicotine and that repeated nicotine e xposure during a single day elicits progressively smaller responses on selected measures.