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Biomedical subjects

K A Perkins

Publications and source records attributed to K A Perkins.

At least 73 records · Page 4Linked to original sources
PubMed1992

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 nicotine's 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 micrograms/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 unexpectedly increased 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.

Adolescent↗
PubMed1992

Abstinence from smoking decreases habituation to food cues.

Smokers typically gain weight after cessation due, in part, to increased caloric intake. This increase may be due to enhanced responding to sensory characteristics of foods resulting from a failure to habituate to food cues. To test this possibility, salivation to eight presentations of strawberry yogurt was assessed in male smokers and nonsmokers in two sessions. To test stimulus specificity, on the ninth trial, subjects were presented either more strawberry yogurt or lemon yogurt. Smokers were studied under nonabstinent or abstinent conditions. Salivation for nonabstinent smokers and nonsmokers decreased over presentations, while abstinent smokers showed little change. Nonabstinent smokers and nonsmokers recovered salivation when the new flavor yogurt was presented, and showed greater consumption on the final trial for the different versus same flavor yogurt. Nonabstinent smokers participated in additional within-session smoking sessions to control for withdrawal. Nonabstinent subjects were not different across smoking or not smoking sessions, suggesting the effects are not due to the acute effects of withdrawal.

Adolescent↗
PubMed1992

"Paradoxical" effects of smoking on subjective stress versus cardiovascular arousal in males and females.

Cigarette smoking has sometimes been found to decrease subjective stress while simultaneously increasing cardiovascular arousal, contrasting effects referred to as the "nicotine paradox." The present study assessed acute effects of cigarette smoking on subjective stress vs. cardiovascular arousal in minimally deprived male and female smokers who smoked (n = 16) or sham smoked (unlit cigarette, n = 15) and a comparison group of male and female nonsmokers (n = 12) who sham smoked only. All subjects participated in two sessions (high- or low-challenge computer task) in which they smoked or sham smoked prior to each of two 20-min task trials. Results showed reduced subjective stress in smoking smokers compared with sham-smoking smokers during the high- but not low-challenge task. However, this stress reduction occurred only immediately after smoking and dissipated midway through each trial. In males, smoking appeared to reduce stress below that of nonsmokers, while smoking in females attenuated stress only partially to the level of nonsmokers. In contrast with the attenuated stress effects, cardiovascular arousal (especially heart rate) was increased immediately after smoking during both tasks and did not appear to be directly related to subjective changes. These findings suggest that the stress-reducing effects of smoking may be transient, situationally specific, partly gender dependent, and dissociated from the effects of smoking on cardiovascular arousal.

Adult↗
PubMed1992

Effects of nicotine on subjective arousal may be dependent on baseline subjective state.

The often disparate and contrasting effects of nicotine on subjective arousal in smokers may be due in part to differences in presmoking subjective state. In Study 1, on each of 2 days, 10 male smokers were divided into high- and low-baseline subgroups on the basis of median split of resting predrug baseline subjective arousal. Then, subjects received intermittent nicotine (15 mu/kg) or placebo via measured-dose nasal spray, with drug conditions counterbalanced between days. In Study 2, 32 male and female smokers were similarly divided into high- and low-baseline subgroups on subjective arousal prior to either smoking or sham-smoking (n = 16 each) during a single session. Results were virtually identical between studies in showing that subjective arousal responses to nicotine (Study 1) or smoking (Study 2) were significantly inversely related to baseline arousal level; those initially low in arousal showed large increases following nicotine or smoking whereas those high in arousal showed little change. No such baseline dependency of responses was seen following placebo or sham smoking. Baseline dependency of cardiovascular responses to nicotine or smoking was also evaluated in similar fashion to determine generalizability of these effects to nonsubjective responses. In each study, systolic blood pressure response was related to baseline level but there was no effect of baseline level on heart rate and diastolic blood pressure responses. Implications of these results for explaining differential rewarding effects of smoking are discussed.

Administration, Intranasal↗
PubMed1992

Nasal spray nicotine replacement suppresses cigarette smoking desire and behavior.

The effects of short-term nasal spray nicotine replacement in suppressing desire to smoke and ad libitum cigarette smoking behavior were evaluated in male and female smokers. In study I, 10 male and 10 female smokers received intermittent doses of 0, 7.5, 15, and 30 micrograms/kg nicotine by way of measured-dose nasal spray, with each dose on a separate day. Self-reported desire to smoke was significantly suppressed by each nicotine dose compared with placebo, but there were no significant differences among nicotine doses or between men and women. In study II, eight male and eight female smokers received 0, 15, and 30 micrograms/kg nicotine intermittently and were allowed to smoke their preferred brands of cigarettes ad libitum. Similar to study I, nicotine replacement significantly suppressed number of cigarettes smoked, number of puffs, and carbon monoxide boost and increased latency to smoking, but there were almost no significant differences between the two nicotine doses. Magnitude of smoking suppression attributable to 15 micrograms/kg tended to be greater in men than in women. However, plasma nicotine concentrations were significantly higher after 15 and 30 micrograms/kg versus placebo, suggesting only partial compensation in smoking behavior with short-term nasal nicotine replacement. These findings support the idea that short-term nicotine replacement decreases smoking desire and behavior, but the findings indicate that smoking behavior is partly influenced by factors other than nicotine regulation.

Administration, Intranasal↗
PubMed1992

Effects of tobacco smoking on caloric intake.

Reduced body weight due to smoking may be an important factor inhibiting smoking cessation and promoting relapse after cessation in some smokers. It is popularly believed that smoking decreases body weight by suppressing appetite. However, cross-sectional studies show that, despite their lower body weights, smokers do not eat less than non-smokers or ex-smokers and, in fact, tend to eat slightly more. Similarly, laboratory studies show no acute effects of smoking or nicotine intake via other means on caloric intake in smokers, although intake of non-smokers may be reduced after nicotine. In contrast, longitudinal studies show that eating consistently increases in the first weeks after stopping smoking, but may recede to pre-cessation levels with longer-term abstinence, while resumption of smoking after cessation is accompanied by a reduction in eating. A similar pattern of results is seen for self-reported hunger and some, but not all, constituents of diet. Thus, there appear to be no acute or chronic effects of smoking on eating in smokers maintaining regular smoking, but changes in eating are observed concomitant with changes in smoking status (i.e. cessation or relapse). Although tolerance to anorectic effects of nicotine is one potential explanation, these findings may be more parsimoniously explained by viewing changes in eating due to smoking as secondary to an alteration in the set point around which body weight is regulated. According to this notion, cessation is accompanied by increased eating only until a new, higher body weight set point is reached, while relapse (and perhaps initiation of smoking) decreases eating only until a lower set point is reached. Implications of these findings and a set point explanation for them are discussed.

Energy Intake↗
PubMed1992

Increased desire to smoke during acute stress.

Conditions which promote smoking urges, or desire to smoke, are believed to be important in maintaining smoking behaviour, yet little controlled research has examined acute situational factors which increase desire to smoke. In this study, 16 male and 16 female smokers either smoked or sham-smoked with an unlit cigarette after brief abstinence during two sessions, one involving a stressful computer task and the other a non-stress task. Desire to smoke was greater during the stress vs. non-stress task for sham-smokers (p less than 0.01). Furthermore, although smoking desire decreased markedly after smoking in the smoking smokers (p less than 0.001), even this group tended to report greater desire to smoke during stress (p less than 0.10). There were no differences between males and females. These findings indicate that exposure to stressors increases desire to smoke, and suggest that such situations may be influential in maintaining smoking behaviour in smokers not attempting to quit.

Adult↗
PubMed1992

Metabolic effects of cigarette smoking.

The inverse relationship between cigarette smoking and body weight, a potent obstacle to stopping smoking, may be due in part to effects of smoking on increasing whole body metabolism. Studies examining chronic and acute metabolic effects of smoking, as well as its constituent nicotine, are reviewed. Evidence suggests the absence of a chronic effect; most studies indicate that smokers and nonsmokers have similar resting metabolic rates (RMR) and that RMR declines very little after smoking cessation. Although an acute effect due to smoking is apparent, its magnitude is inconsistent across studies, possibly because of variability in smoke exposure or nicotine intake. In smokers at rest, the acute effect of smoking (and nicotine intake) appears to be significant but small (less than 10% of RMR) and transient (less than or equal to 30 min). However, the specific situations in which smokers tend to smoke may mediate the magnitude of this effect, inasmuch as smoking during casual physical activity may enhance it while smoking after eating may reduce it. Sympathoadrenal activation by nicotine appears to be primarily responsible for the metabolic effect of smoking, but possible contributions from nonnicotine constituents of tobacco smoke and behavioral effects of inhaling may also be important. Improved understanding of these metabolic effects may lead to better prediction and control of weight gain after smoking cessation, thus increasing the likelihood of maintaining abstinence.

Animals↗
PubMed1991

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 nicotine's 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 micrograms/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 afer 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.

Adult↗
PubMed1991

Behavioral economic analysis of smoking: money and food as alternatives.

The relative reinforcing value of smoking versus two nonpharmacological reinforcers, money and food, was evaluated in young female smokers in two experiments. In Experiment 1 eight smokers worked for access to smoking or money on concurrent progressive variable ratio schedules of reinforcement (VR4 to VR50) across two days of Smoking Deprivation or No Deprivation. During No Deprivation money was reliably chosen over smoking. During Deprivation subjects initially (VR4) chose smoking over money, but at subsequent comparisons allocated equal time to work for smoking or money. In Experiment 2 eight smokers were provided access to smoking or food across four conditions: No Deprivation, Smoking Deprivation, Food Deprivation and Smoking + Food Deprivation, using the same progressive variable ratio schedules as in Experiment 1. Results showed an increase in the reinforcing value of food after Food Deprivation and smoking after Smoking Deprivation. On the dual deprivation day, subjects initially (VR4) chose to work for food, showed equal preferences over the next three schedule comparisons (VR8-VR20), and from VR25-VR50 shifted their choice to smoking. An increase in percent of calories as fat was observed during all deprivation conditions. The results demonstrate the use of the concurrent schedule paradigm for assessing choice among pharmacological and nonpharmacological reinforcers, and shows the relative reinforcing value of smoking depends on recent deprivation, response demands to obtain the reinforcer and availability of alternative reinforcers.

Adolescent↗
PubMed1991

Conditioned tolerance to the anorectic and corticosterone-elevating effects of nicotine.

We have shown that tolerance to the behavioral effects of nicotine is partially dependent on conditioned environmental cues that predict drug delivery. The present research extends this finding to physiological effects of nicotine by assessing both the appetite-suppressing and adrenocortical-activating effects of nicotine, as measured by plasma corticosterone (CORT). In the first study, male rats on a 22-h food deprivation schedule were injected daily with 0.33 or 0.66 mg/kg (free base) of nicotine bitartrate or saline in a distinctive environment and tested for milk intake. Nicotine initially suppressed milk intake and tolerance developed over 10 days. Changing cues associated with drug administration partially reversed tolerance since injection of nicotine in a new environment reduced milk intake of tolerant animals. Similarly, animals who repeatedly received nicotine in one environment exhibited CORT levels lower than rats injected for the first time, and this tolerance also was partially reversed when administration occurred in the new environment. The second experiment indicated that the increased CORT of Experiment 1 was not a stress response associated with injecting animals in a different environment. These results indicate that tolerance to both behavioral and neuroendocrine effects of nicotine is influenced by conditioning.

Animals↗
PubMed1991

Conditioned tolerance to the heart rate effects of smoking.

This study extended our findings that behavioral tolerance to nicotine in animals can be influenced by conditioning to cardiovascular tolerance in humans. Subjects smoked one-half a cigarette during each of five trials. In the ten-minute intersmoking interval the contexts that preceded smoking were varied. Smokers in the Changing group attended to a different five-minute segment of a Sherlock Holmes radio mystery before each trial, while those in the Repeated group listened to the same segment of the tape. Presmoking heart rates were stable across the groups from trials 1 to 5. As predicted, heart rate for subjects who smoked in the same context showed tolerance to smoking from trials 1 to 5 (84.5 to 78 bpm), while subjects who smoked in in the same context showed tolerance to 83.9 bpm). COa levels increased equally for both groups over the five trials. The results of this study suggest tolerance to smoking can be influenced by learning.

Adult↗
PubMed1991

Effects of dose, gender, and level of physical activity on acute metabolic response to nicotine.

The acute thermogenic effect of nicotine was examined in cigarette smokers under conditions of rest and two levels of low-intensity physical activity comparable to that normally engaged in by sedentary adults. Male and female smokers (n = 10 each) each received 0 (placebo), 7.5, 15, or 30 micrograms/kg nicotine via measured-dose nasal spray once every 30 min for 90 min, with each dose presented on a separate occasion. After each dose presentation, subjects engaged in 10 min of rest or low-intensity activity at 30 or 60 watts (W) using a bicycle ergometer. For males, results indicated that expenditure attributable to nicotine was more than twice as large during 60-W activity compared with rest, while that during 30-W activity was intermediate. For females, expenditure attributable to nicotine was generally similar to that of males during rest and 30-W activity but was significantly lower during 60-W activity, indicating an apparent "inverted-U" relationship with activity intensity. The enhanced effect of nicotine was specific to energy expenditure, since heart rate showed dose-dependent changes that were generally similar regardless of activity level. These findings confirm a mediating influence of physical activity level on the acute metabolic effect of nicotine, especially in males, and may have implications for explaining individual differences in body weight changes due to tobacco smoking and cessation.

Adult↗
PubMed1991

Acute tolerance to the cardiovascular effects of nicotine.

Acute tolerance to cardiovascular effects of nicotine was examined by presenting to male smokers a single administration of each of three different doses of nicotine (0.5, 1.0, 2.0 mg) or a placebo (0 mg) in a brief series of nasal spray boluses to mimic nicotine intake via smoking. Each dose was presented on a separate occasion. Changes in heart rate, systolic and diastolic blood pressure, finger pulse amplitude (peripheral vasoconstriction) and, in a subsample, plasma nicotine concentration were assessed during and after dose administration. Acute tolerance to nicotine was determined by comparing responses at ascending plasma nicotine concentrations during dose administration with the responses at comparable descending plasma concentrations following administration. For each nicotine dose, there was substantial acute tolerance to blood pressure, but less tolerance to heart rate (except for 0.5 mg), and little tolerance to pulse amplitude responses. These findings indicate that cardiovascular adaptation to nicotine during cigarette smoking may be rapid but variable in magnitude depending on the response being measured.

Administration, Intranasal↗
PubMed1991

Smoking as a cue for subjective and behavioral responses to a stressor.

Smoking in conjunction with a repeated stressor may come to serve as a cue, or discriminative stimulus, for responses to the stressor. This study examined the effects of omitting a previously predictable smoking cue on subjective and behavioral responses to a stressor. Male smokers were instructed to smoke briefly on command immediately prior to ("smoke-pre", n = 10) or several minutes after ("smoke-post", n = 10) each of four acquisition trials of a mental arithmetic task. During two subsequent trials, both groups first engaged in the task without the smoking cue (Test Trial 1), a novel experience for smoke-pre, and then engaged in the task preceded by the smoking cue (Test Trial 2), a novel experience for smoke-post. Omission of the smoking cue during Test Trial 1 produced significantly poorer task performance and greater subjective stress in smoke-pre. Although not significant, insertion of the smoking cue during Test Trial 2 tended to produce poorer performance in smoke-post. Thus, a consistent pattern of smoking in association with a repeated stressor may subsequently lead to impaired responding to the stressor if smoking is omitted.

Adaptation, Psychological↗
PubMed1991

Effects of nicotine on perceived exertion during low-intensity activity.

Nicotine may decrease perceived exertion during physical work, which may be a potentially reinforcing effect of tobacco smoking. This study examined the effects of nicotine on ratings of perceived exertion (RPE) during low-intensity physical activity representative of activity normally engaged in by adult smokers. Ten male and 10 female smokers participated in four morning sessions, one for placebo and each of three nicotine doses (7.5, 15, and 30 micrograms.kg-1), which were administered by measured-dose nasal spray. Using a bicycle ergometer, subjects exercised at each of two lower power outputs (30 and 60 W) before and after nicotine dosing, while RPE and cardiovascular measures of heart rate and systolic and diastolic blood pressure were obtained. Results indicated no significant effect of nicotine on RPE for either males or females. In contrast, nicotine significantly increased each cardiovascular measure during activity, confirming that cardiovascular responses during exercise do not mediate RPE. Thus, nicotine did not influence perception of exertion during low-intensity physical activity.

Adult↗