Joan E. Sexton

Subjective and cardiovascular responses to nicotine combined with alcohol in male and female smokers

Nicotine and alcohol are often consumed concurrently by smokers. Each drug alone produces significant subjective and cardiovascular responses, but the effects of the two drugs in combination have rarely been examined. Smokers who were moderate alcohol drinkers (n = 18, 9 males and 9 females) participated in four sessions, involving acute administration of nicotine/placebo and alcohol/no alcohol. Subjects abstained overnight from tobacco and alcohol prior to each session. Nicotine (20 µg/kg per presentation) or placebo was administered by measured-dose nasal spray every 30 min for 2 h following consumption of diet tonic water with or without alcohol (0.5 g/kg). Subjective (visual analog scales, Profile of Mood States, Addiction Research Center Inventory) and cardiovascular (heart rate, systolic and diastolic blood pressure) responses were assessed after each nicotine/placebo administration. Nicotine increased head rush, dizzy, and most stimulant effects (i.e. jittery, tension, and arousal and decreased fatigue and relaxed), while alcohol increased intoxication, head rush, dizzy, and jittery, with no other stimulant effects. Nicotine and alcohol generally produced additive subjective and cardiovascular effects when consumed together, although nicotine attenuated sedating and intoxicating effects of alcohol alone. Furthermore, there were several interaction effects on subjective measures involving gender. Nicotine plus alcohol tended to attenuate some subjective effects due to one drug or the other alone in men but enhanced the effects of either alone in women. These findings indicate that nicotine and alcohol generally have additive subjective and cardiovascular effects, but that men and women differentially respond on some subjective measures to the combination of alcohol and nicotine.

Acute effects of nicotine on hunger and caloric intake in smokers and nonsmokers

The inverse relationship between smoking and body weight may be due in part to nicotines effects on reducing hunger and eating. Male smokers and nonsmokers (n=10 each), abstinent overnight from smoking and food, participated in four sessions, involving consumption of a liquid caloric load or water followed by nicotine (15 µg/kg) or placebo via nasal spray every 20 min for 2 h. Hunger and satiety (“fullness”) ratings were obtained prior to each dose presentation. At the end of the two sessions involving the caloric load (simulating breakfast), subjects were also presented with typical lunch/snack food items varying in sweet taste and fat content for ad lib consumption. Results indicated that, for both smokers and nonsmokers, the hunger-reducing effects of nicotine occurred only following caloric load consumption, and there was no effect of nicotine on hunger after water consumption. Smokers unexpectedly reported greater satiation than nonsmokers following the caloric load regardless of nicotine or placebo condition. Nicotine also resulted in less caloric intake during the meal, and the decrease was not specific to consumption of sweet, high-fat foods. These results indicate that nicotine reduces appetite, possibly helping to explain the influence of smoking on body weight.

Subjective and cardiovascular responses to nicotine combined with caffeine during rest and casual activity

Although nicotine and caffeine have separately been shown to acutely increase subjective arousal, their combined effects are unclear. Furthermore, their effects during casual physical activity, the condition under which individuals usually experience nicotine and caffeine, are unknown. Smokers who were regular coffee drinkers (n=19, 9 males, 10 females) participated in eight morning sessions, involving nicotine/placebo, caffeine/no caffeine, and rest/physical activity (i.e. 2×2×2 within-subjects design). Nicotine (15 µg/kg) or placebo was given via measured-dose nasal spray intermittently after consumption of decaf coffee with or without added caffeine (5 mg/kg), followed by subjective [Profile of Mood States (POMS), Stress-Arousal Checklist, visual analog scales] and cardiovascular (heart rate, blood pressure) measures. Casual physical activity was standardized by low-intensity bicycle riding while sitting comfortably. Results indicated significant subjective and cardiovascular effects of nicotine and caffeine individually, with the combination of nicotine and caffeine generally producing additive or greater than additive effects for each measure. However, activity mediated some of the subjective effects of nicotine, as nicotine appeared to be “stimulating” during rest but not during activity. There were no differences between males and females. These findings suggest that nicotine per se and caffeine generally have additive subjective and cardiovascular effects, and that nicotine may influence subjective stimulation differentially depending on whether a smoker is resting or engaged in casual activity.

Perception and hedonics of sweet and fat taste in smokers and nonsmokers following nicotine intake

Nicotines effects on reducing perception and/or hedonics of sweet and fat taste may lead to less intake of sweet tasting, high-fat foods by smokers, helping to explain their generally lower body weights. Smokers and nonsmokers (n = 10 males each) rated perception (intensity and sensitivity) and hedonics (liking) of sweet/fat taste in milk samples varying both in sucrose (0, 5, 10, 20% w/w) and fat (0.1, 3.5, 11.7, 37.6% w/w) concentration on two occasions, once following intermittent presentation of nicotine (15 micrograms/kg) via measured dose nasal spray and the other following placebo. Nicotine significantly reduced perceived intensity of fat but not sweet taste and had no effect on sensitivity to either taste. There was no effect of nicotine on hedonics of sweet/fat taste. On the other hand, although there were no differences between smokers and nonsmokers in perception of sweet or fat, hedonics of sweet/fat taste was reduced in smokers regardless of nicotine or placebo intake. Thus, nicotine may acutely decrease fat taste perception without influencing sweet/fat hedonics, while long-term exposure (i.e., being a smoker) may produce chronically decreased taste hedonics without altering perception.

Effects of nicotine on hunger and eating in male and female smokers

We tested whether the inverse relationship between smoking and body weight may be due in part to nicotines acute effects on reducing hunger and eating. On four mornings, male and female smokers (n=10 each), abstinent overnight from smoking and food, received one of three nicotine doses (7.5, 15, and 30 µg/kg) or placebo (0) via nasal spray every 30 min for 2 h. Self-reported hunger and satiety (“fullness”) and craving for cigarettes were obtained after each dose presentation. Subjects subsequently ate ad lib from a large array of food items varying in sweet taste and fat content. For both males and females, nicotine had no effect on self-reported hunger, but cigarette craving was decreased. Rather than being decreased, caloric intake during the meal was unexpectedlyincreased following nicotine compared with placebo. Cigarette craving increased after the meal, and this increase was unaffected by nicotine dose. There were virtually no differences between males and females in any effects of nicotine. These results indicate that nicotine may not acutely suppress appetite in fasting smokers and suggest that other actions of nicotine or smoking may account for the lower body weights of smokers.

Behavioral performance effects of nicotine in smokers and nonsmokers

Performance on finger-tapping and handsteadiness, tasks opposite in response requirements, was compared between male smokers and nonsmokers (n = 10 each) on two occasions, once following intake of nicotine (15 micrograms/kg) by measured-dose nasal spray and once following placebo. Compared with nonsmokers, smokers had significantly greater increase in finger-tapping speed due to nicotine. On the other hand, smokers tended to have improved performance on handsteadiness (i.e., less involuntary movement) due to nicotine, while nonsmokers had impaired performance, although this difference was not significant. Nicotine-induced changes in performance on each task were inversely related, suggesting specificity of the behavioral effects of nicotine depending on task demands, rather than a generalized effect. These effects of nicotine on behavioral performance may be important in understanding the reinforcing value of nicotine intake, and differences in effects as a function of smoking history may suggest chronic adaptation to nicotine.

Acute thermogenic effects of nicotine and alcohol in healthy male and female smokers

Nicotine intake is associated with lower body weight in both women and men. Despite its energy content, alcohol consumption is also associated with lower body weight in women but not in men. Each drug may reduce weight by acutely increasing thermogenesis. During four sessions, nicotine (20 micrograms/kg per dosing) or placebo was given to male and female smokers (n = 9 each) via measured-dose nasal spray every 30 min for 2 h after consumption of diet tonic water with or without alcohol (0.5 g/kg). Each nicotine/placebo dosing was followed by assessment of energy expenditure by indirect calorimetry. Alcohol alone induced no significant effect in men or women, whereas nicotine alone and combined with alcohol induced a significant thermogenic effect in men but not women. These results are consistent with other research suggesting a reduced thermogenic responsiveness to drugs in women and indicate that nicotine must act via appetite suppression to reduce body weight in women. Similarly, these findings do not support the notion that alcohol is inversely related to body weight in women because of excessive acute thermogenesis.

Effects of smoking cessation on consumption of alcohol and sweet, high-fat foods.

Smoking cessation may have significant effects on consumption of certain foods and other substances which may influence health. This study of seven young female smokers examined consumption of alcohol, coffee, soda, and sweets (sweet, high-fat foods) across 3 weeks, involving baseline ad lib smoking (week 1), complete cessation (week 2), and resumption of smoking (week 3). TV watching (i.e., nondietary activity) and subjective measures of craving and tension-anxiety also were assessed. Results showed increased intake of sweets and, to a lesser extent, alcohol after cessation which was reversed upon resumption of smoking. There were no significant changes across weeks in other substances. The changes in alcohol and sweet intake did not appear to be related directly to the subjective changes. These findings indicate that smoking cessation, a behavior change which promotes health, may lead to alterations in consumption of other substances, which may have adverse effects on health risk.

Effects of smoking status on content of caloric intake and energy expenditure

The present study compared daily caloric and nutrient intake, participation in leisure time activities, and resting metabolic rate (RMR) following overnight smoking abstinence between male smokers (n=29) and nonsmokers (n=21), with groups equated on age, body weight, and fitness

Influence of aerobic fitness, activity level, and smoking history on the acute thermic effect of nicotine

Individual variability in sensitivity to the acute thermic effects of nicotine has been difficult to study because of methodological limitations in the use of smoking to manipulate nicotine dose. This study examined the influence of smoking history, body composition, and, in a subset of subjects, aerobic fitness and physical activity on the thermic effect of nicotine using a measured-dose nasal spray procedure. Following overnight fasting and smoking abstinence, 38 healthy male smokers were intermittently administered a nicotine dose corrected for body weight (15 micrograms/kg, approx. 1.1 mg for average subject) or placebo on separate occasions in a within-subjects study. Indirect calorimetry was used to assess resting energy expenditure (REE) before and after dosing. Acute thermic response to nicotine ranged from -4.3 to +10.8 kcal/h (-5.4% to +12.6% of REE). Thermic response to nicotine was correlated significantly with aerobic fitness (r = 0.58, p < 0.005), physical activity (r = 0.44, p < 0.05), and number of pack-years of smoking (r = 0.43, p < 0.01). Thermic response was marginally correlated with percent body fat (r = -0.23, p < 0.10), but not with body weight (r = 0.04), percent of ideal weight for height (r = -0.10), or lean body mass (r = 0.05). These results indicate that male smokers higher in fitness and activity and with greater smoking exposure histories may experience greater increases in energy expenditure as a result of nicotine intake via smoking. Consequently, variability in these characteristics could help account for some of the variability in weight gain after stopping smoking.