Leptin, hunger, and body weight: Influence of gender, tobacco smoking, and smoking abstinence

Association of serum leptin and ghrelin levels with smoking status on body weight: a systematic review and meta-analysis

Background and aims

Smoking cigarettes is a major global health problem that affects appetite and weight. The aim of this systematic review was to determine how smoking affected plasma leptin and ghrelin levels.

Methods

A comprehensive search of PubMed, Scopus, Web of Science, and Ovid was conducted using a well-established methodology to gather all related publications.

Results

A total of 40 studies were included in the analysis of 11,336 patients. The overall effect showed a with a mean difference (MD) of -1.92[95%CI; -2.63: -1.20] and p = 0.00001. Subgroup analysis by study design revealed significant differences as well, but with high heterogeneity within the subgroups (I2 of 82.3%). Subgroup by sex showed that there was a significant difference in mean difference between the smoking and non-smoking groups for males (MD = -5.75[95% CI; -8.73: -2.77], p = 0.0002) but not for females (MD = -3.04[95% CI; -6.6:0.54], p = 0.10). Healthy, pregnant, diabetic and CVD subgroups found significant differences in the healthy (MD = -1.74[95% CI; -03.13: -0.35], p = 0.01) and diabetic (MD = -7.69[95% CI, -1.64: -0.73], p = 0.03). subgroups, but not in the pregnant or cardiovascular disease subgroups. On the other hand, the meta-analysis found no statistically significant difference in Ghrelin serum concentration between smokers and non-smokers (MD = 0.52[95% CI, -0.60:1.63], p = 0.36) and observed heterogeneity in the studies (I2 = 68%).

Conclusion

This study demonstrates a correlation between smoking and serum leptin/ghrelin levels, which explains smoking's effect on body weight.

Systematic review registration

https://www.crd.york.ac.uk/ prospero/display_record.php, identifier (Record ID=326680).

Early weight gain after stopping smoking: a predictor of overall large weight gain? A single-site retrospective cohort study

OBJECTIVES

Most people gain weight on stopping smoking but the extent of weight gain varies greatly. Interventions aimed at all quitters to prevent weight gain on cessation have proven unpopular but targeting people who have gained excess weight immediately after quitting may improve uptake and cost-effectiveness. We examined whether early large postcessation weight gain predicts overall large weight gain.

DESIGN

Retrospective cohort study.

SETTING

Primary care setting-smoking cessation centre in Prague, Czech Republic.

PARTICIPANTS

Out of 3537 patients treated between 2005 and 2013, 1050 were continuous abstainers (verified by carbon monoxide measurement) at 1-year follow-up and formed the cohort of the current report. 48.7% were women (n=511) with the mean age of 46 (±14.4) years.

METHODS

In this retrospective cohort study, all patients underwent usual tobacco dependence treatment using evidence-based methods. Weight was measured prior to smoking cessation and at each visit after quitting.

RESULTS

The mean weight gain in the first month (n=763) was 0.79% (±2.03%), in the second month (n=646) was 1.49% (±2.58%), for the third month (n=566) 2.33% (±3.44%) and 4.1% (±5.31%) after 1-year follow-up (n=1050). The regression coefficient per 1% rise in the first 3 months was +0.13% (95% CI -0.04% to 0.30%). A receiver operating curve analysis showed that patients gaining more than 0.98% of their baseline weight during first 3 months had a sensitivity of 66% and specificity of 44% for gaining 7% or more weight by 12 months. In addition, lower body mass index and an increase in appetite at 3 months after quitting were associated with greater weight gain, while using nicotine replacement therapy was associated with less weight gain at 1-year follow-up.

CONCLUSIONS

People who stop smoking and gain a larger amount of weight early after quitting are not more likely to gain excessively at 1 year.

Smoking cessation in European patients with coronary heart disease. Results from the EUROASPIRE IV survey: A registry from the European Society of Cardiology

OBJECTIVE

We investigated smoking cessation rates in coronary heart disease (CHD) patients throughout Europe; current and as compared to earlier EUROASPIRE surveys, and we studied characteristics of successful quitters.

METHODS

Analyses were done on 7998 patients from the EUROASPIRE-IV survey admitted for myocardial infarction, unstable angina and coronary revascularisation. Self-reported smoking status was validated by measuring carbon monoxide in exhaled air.

RESULTS

Thirty-one percent of the patients reported being a smoker in the month preceding hospital admission for the recruiting event, varying from 15% in centres from Finland to 57% from centres in Cyprus. Smoking rates at the interview were also highly variable, ranging from 7% to 28%. The proportion of successful quitters was relatively low in centres with a low number of pre- event smokers. Overall, successful smoking cessation was associated with increasing age (OR 1.50; 95% CI 1.09-2.06) and higher levels of education (OR 1.38; 95% CI 1.08-1.75). Successful quitters more frequently reported that they had been advised (56% vs. 47%, p < .001) and to attend (81% vs. 75%, p < .01) a cardiac rehabilitation programme.

CONCLUSION

Our study shows wide variation in cessation rates in a large contemporary European survey of CHD patients. Therefore, smoking cessation rates in patients with a CHD event should be interpreted in the light of pre-event smoking prevalence, and caution is needed when comparing cessation rates across Europe. Furthermore, we found that successful quitters reported more actions to make healthy lifestyle changes, including participating in a cardiac rehabilitation programme, as compared with persistent smokers.

[Factors associated with being underweight among elderly community-dwellers from seven Brazilian cities: the FIBRA Study]

The aim of this study was to assess the prevalence of being underweight among the elderly according to demographic and socioeconomic characteristics, health-related behaviors, diseases and health status. This was a cross-sectional multi-center study with 3,478 community-dwelling elders (≥ 65 years). The dependent variable was the prevalence of being underweight, classified by Body Mass Index < 22kg/m2. Adjusted prevalence rate ratios were estimated using multivariable Poisson regression. The mean age was 72.9 years and 12.0% of the elderly were underweight (CI95%:10.9-13.1). Aged elderly ≥ 80 years, former and current smokers, those who reported appetite loss and those classified as pre-frail or frail (PR=1.41; CI95%:1.09-1.82) presented a higher prevalence of being underweight. Individuals who received medical diagnosis of hypertension, diabetes and rheumatism had the lowest underweight prevalence observed. The results highlight the importance of nutritional status assessment and monitoring among the elderly, with emphasis on the most vulnerable subgroups, particularly the frail elderly, taking into account the health consequences of low weight.

Leptin and calorie intake among different nicotine dependent groups

BACKGROUND

Exposure to nicotine via tobacco smoking may influence leptin release and decrease food intake among smokers. However, the effect of nicotine exposure on leptin and food intake among different nicotine dependent groups is unclear.

OBJECTIVE

We aimed to measure leptin and calorie intake among different nicotine dependent groups.

DESIGN

Cross-sectional study.

SETTING

Research department in school of medical sciences.

PATIENTS AND METHODS

Subjects were selected by purposive (non-probability) sampling and categorized as having low, moderate and high nicotine dependency based on the Fagerstrom Test for Nicotine Dependence (FTND) score. Diet was recorded by interview. Anthropometry, blood pressure, body composition, lipid profile, and physical activity level were measured accordingly. Fasting serum leptin was measured using a commercial ELISA kit.

MAIN OUTCOME MEASURE(S)

Nicotine dependency, 24-hour diet, clinical anthropometric and clinical measurements.

RESULTS

In 107 Malay male smokers leptin concentration was inversely correlated with nicotine dependence. However, body weight, smoking period, blood pressure, body composition, lipid profile and physical activity level were not significantly different among low, moderately and highly dependent smoking groups. Leptin concentration and total calorie intake were also not significantly different among these groups.

CONCLUSION

Leptin concentration was inversely correlated with nicotine dependence, but leptin concentration and total calorie intake status were not significantly different among our different nicotine dependency subjects.

LIMITATIONS

Purposive sampling for subject recruitment and inaccurate information in the self-administered questionnaire.

Changes in circulating leptin levels during the initial stage of cessation are associated with smoking relapse

RATIONALE

Leptin has been linked to tobacco craving and withdrawal-related symptoms. Very few studies have examined leptin prospectively in both male and female nonsmokers and smokers.

OBJECTIVES

We examine leptin concentrations prospectively in both male and female nonsmokers and smokers to assess the associations of leptin with psychological symptoms and smoking relapse during ad libitum smoking, the first 48 h post quit, and 4 weeks post-cessation.

METHODS

Self-report psychological, anthropomorphic, and biological measures (cotinine, carbon monoxide, and plasma leptin) were collected before and after 48 h of smoking abstinence. Smokers were stratified at 28 days post quit as abstinent or relapsed if they had smoked daily for seven consecutive days at any point in the 28 days.

RESULTS

Leptin concentration (square root transformed ng/ml) increased over the 48-h abstinence, but only in female abstainers. In contrast, leptin was very stable across time for nonsmokers, relapsers, and males. Cox regression supported that increased leptin was associated with decreased risk of relapse. Leptin was correlated negatively with withdrawal symptoms for abstainers only. Females produce more leptin than males and this level increases from ad libitum smoking to 48-h post quit.

CONCLUSIONS

The current analysis indicates that a leptin increase early in cessation predicts abstinence. The increase in women, but not men, in response to abstinence provides further evidence of important gender differences. The negative correlation between leptin and withdrawal symptoms indicates a possible protective effect of leptin. Further research is ongoing to elucidate the psychological and biological determinants of this effect.

Circulating leptin and pain perception among tobacco-dependent individuals

Recent preclinical evidence suggests that leptin may modulate the stress response and may increase nociception. In this study, we examined for the first time the extent to which cigarette smoking is associated with leptin levels during an extended rest period and in response to noxious stimuli. Repeated blood samples were collected during a laboratory session from smokers and nonsmokers and assayed for leptin. Pain experiences, as well as neuroendocrine and cardiovascular measures, were collected across cold pressor and thermal heat pain tests. Both analysis of variance and correlations confirmed that smokers demonstrated dysregulations in leptin responsivity and association with pain relative to nonsmokers. The flat pattern of leptin release and the weak associations of this hormone with pain in smokers suggest a long-term effect of tobacco dependence on this regulatory hormone. In light of leptin's influence on reward pathways, further investigation of leptin's involvement in nicotine dependence is warranted.

Factors associated with weight changes in successful quitters participating in a smoking cessation program

OBJECTIVE

To identify possible predictors of post-cessation weight gain in smoking abstainers.

PATIENTS AND METHODS

A sample of 607 successful abstainers seen at the Centre for Tobacco-Dependent in Prague, Czech Republic, between 2005 and 2010, was included in this analysis. This sample was followed up for 1year and included 47.9% women (N=291) with the mean age of 48years (18-85).

FINDINGS

Post-cessation weight gain occurred in 88.6% of the 607 abstainers. The mean weight gain after one year post-quit was 5.1kg (95% confidence interval 4.7-5.5kg). Baseline characteristics associated with increased weight gain included a higher baseline smoking rate (p<0.001), more severe cigarette dependence (p=0.003), less physical activity (p=0.008), and a report of increased appetite on the baseline assessment of withdrawal symptoms (p<0.001).

CONCLUSIONS

Smokers who are more dependent and have minimal physical activity are at increased risk for post-cessation weight gain. For these smokers, incorporating interventions targeting the weight issue into tobacco dependence treatment is recommended. Further research should be done to identify reasons for this important quitting complication.

Prevalência e fatores associados à obesidade abdominal em indivíduos na faixa etária de 25 a 59 anos do Estado de Pernambuco, Brasil

Com o objetivo de estimar a prevalência de obesidade abdominal e avaliar os fatores associados em adultos do Estado de Pernambuco, Brasil, foi realizado, em 2006, um estudo transversal, de base populacional, envolvendo 1.580 indivíduos na faixa etária de 25-59 anos. A obesidade abdominal foi determinada pela circunferência da cintura ≥ 80cm para mulheres e ≥ 94cm para homens. O modelo conceitual considerou variáveis socioeconômicas, demográficas, reprodutivas e comportamentais. A prevalência de obesidade abdominal foi de 27,1% (IC95%: 23,8-30,7) no sexo masculino e 69,9% (IC95%: 66,8-72,8) no feminino (p < 0,001). A análise ajustada revelou maior prevalência em homens a partir de 50 anos, da região metropolitana, de maior renda, ex-fumantes e consumidores de bebidas alcoólicas. Entre as mulheres, foi mais prevalente a partir de 30 anos, em ex-fumantes e naquelas com a primeira gestação antes de 18 anos. Fica evidente a gravidade e a multifatorialidade do problema da adiposidade central no Estado de Pernambuco, além de ser possível destacar que os determinantes da obesidade são diferentes entre os sexos.

Effects of cigarette smoke exposure and its cessation on body weight, food intake and circulating leptin, and ghrelin levels in the rat

INTRODUCTION

Smoking is associated with loss of body weight (BW) and reduced appetite, while smoking abstinence with the opposite effect. The role of peripheral signaling by appetite-controlling hormones leptin and ghrelin is not clear. In the present study, the relationship of circulating leptin and ghrelin with BW and food intake rate (FIR) changes was studied during cigarette smoke exposure (CSE) and after its cessation in the rat.

METHODS

Male Wistar rats were subjected to CSE for 8 weeks by confinement to plexiglass chambers (Group S). Control animals were confined to identical chambers without smoke (Group C). During CSE and an equivalent follow-up period, BW and FIR was recorded and serum leptin and ghrelin levels were measured.

RESULTS

A sharp decrease in BW was noted during the first 4 weeks of CSE, while FIR, after a substantial decrease noted at Week 1, returned to control levels. Thereafter, rats started to regain their BW until they reached control levels by the 1st week postCSE. BW regain was accompanied by a rebound increase of FIR, which plateaued during the first 4 weeks postCSE and then normalized. Serum leptin was decreased in Group S during both periods, normalizing at the 7th week postCSE. Ghrelin levels did not differ between groups.

CONCLUSIONS

Circulating leptin could not explain by its own BW and FIR changes during the first few week of CSE in rats, in contrast to the rest of the CSE period as well as after its cessation. Serum ghrelin levels did not justify BW and FIR changes.

Sex differences in effects of cigarette smoking and 24-hr abstinence on plasma arginine vasopressin

The present study examined plasma arginine vasopressin (AVP) levels in 18 smokers (10 men, 8 women) and in 22 non-smokers (12 men, 10 women). Non-smokers came to the laboratory once, whereas smokers came twice: while smoking freely and following 24-hr abstinence. Plasma was collected for AVP assessment; salivary cotinine and expired carbon monoxide levels confirmed smoking status. Among non-smokers, men had higher AVP levels than did women (p<0.05). Among smokers, however, women displayed higher AVP levels than did men both while smoking and following abstinence (p's<0.05). Among men, smoking resulted in lower AVP levels compared to non-smoking men. In contrast, women who smoked displayed higher AVP levels compared to their non-smoking counterparts. AVP levels were not affected by 24-hr abstinence among smokers, regardless of sex, which suggests that dysregulation in AVP levels in tobacco smokers continues even following 24-hr abstinence. Findings are consistent with previous reports of elevated Th1/Th2 immune function among female smokers compared to male smokers and to male and female non-smokers. Data suggest sex-dependent AVP changes during smoking that could contribute to negative impact of smoking on cardiovascular health.

The rs1801278 G>A polymorphism of IRS-1 is associated with metabolic syndrome in healthy nondiabetic men. Modulation by cigarette smoking status

AIMS

To explore associations between IRS-1 rs1801278 G>A polymorphism and metabolic syndrome (MS).

METHODS

rs1801278 G>A was genotyped in 610 healthy Argentinian men.

RESULTS

GA carriers had lower risk of MS (OR=0.52, P=0.045), particularly among smokers (OR=0.10, P=0.006).

CONCLUSIONS

rs1801278 GA carriers had lower risk of MS, especially among smokers.

Salivary cytokines in cell proliferation and cancer

While the presence of multiple systemic steroids, amines and peptides in saliva has been reported, other hormones of the circulation do not appear in saliva. Substances present within saliva may be classified in different groups: first, those which passively display blood plasma concentrations and constitute a promising alternative to evaluate certain systemic parameters. Second, molecules which seem to play a more active, regulatory role within the upper gastrointestinal tract. Concerning the latter, a growing awareness, especially with regards to salivary peptides has been established. Up to now, understanding the distinct effects of salivary peptides known so far is in its infancy. Various publications, however, emphasize important effects of their presence. Salivary peptides can influence inflammatory processes and cell proliferation in epithelia of the upper digestive tract. These include transforming growth factors (TGFs), epidermal growth factors (EGFs), vascular endothelial growth factors (VEGFs) as well as amines such as melatonin. Of those, candidate cytokines like interleukin 8, tumor necrosis factors (TNFs) and leptin are involved in neoplastic activities of salivary glands and the oral cavity. The exact mechanisms of action are not yet completely understood, but their presence can be utilized for diagnostic purposes. Salivary gland tumors in patients may, in certain circumstances, be identified by saliva diagnostics. Saliva samples of the concerned patients, for instance, reveal significantly higher leptin concentrations than those of healthy individuals. Numerous studies postulate that, beside single indicators, the establishment of salivary hormone profiles may assist clinicians and researchers in detecting tumors and other pathologies of the oral cavity, including adjacent tissues, with high sensitivity and specificity.

Circulating leptin levels are associated with increased craving to smoke in abstinent smokers

The adipocyte hormone leptin regulates satiety and energy expenditure. Recent evidence suggests that leptin is associated with increased craving for alcohol and with shorter length of abstinence during alcohol treatment. This study examined leptin's associations with craving for cigarettes and smoking relapse among smokers interested in cessation. Participants (32 smokers; 14 women) attended a laboratory session 24h following their designated quit day where circulating leptin levels and craving for smoking were assessed. Other measures of withdrawal symptoms, affect, physical symptoms, as well as neuroendocrine and cardiovascular measures were collected before and after performing two stress tasks (public speaking and cognitive tasks). High circulating leptin levels were associated with increased craving, withdrawal symptoms, negative affect, physical symptoms, and reduced positive affect. Circulating leptin levels were not related to cardiovascular and neuroendocrine measures, responses to acute stressors, or to smoking relapse. These results indicate that circulating leptin is a promising biological marker of craving for smoking and warrant further investigation of the links between appetite regulation and nicotine dependence.

Tabagismo associado a outros fatores comportamentais de risco de doenças e agravos crônicos não transmissíveis

Foram entrevistados via ligação telefônica 1.410 indivíduos, amostra aleatória e representativa da população acima de 18 anos residente em domicílios conectados à rede de telefonia fixa. A prevalência de tabagismo foi de 21,8%, maior em homens (25%) e em indivíduos na faixa entre 18 e 29 anos. Tabagismo e sedentarismo juntos ocorrem em 13,9% dos homens e 14,2% das mulheres; tabagismo e baixo consumo de frutas em 12,9% dos homens e 12,3% das mulheres; e tabagismo e baixo consumo de legumes em 5,8% dos homens e 5,1% das mulheres. A associação de tabagismo e consumo excessivo de álcool foi observada apenas nos homens (em 3,5% deles) e, da mesma forma que verificada para tabagismo isoladamente, sua ocorrência concomitante a outros fatores comportamentais de risco de doenças e agravos crônicos não transmissíveis (DANT) associou-se inversamente à escolaridade. Os dados apontam indícios de efeito de aglomeração entre tabagismo e sedentarismo, tabagismo e álcool em excesso, tabagismo e dieta inadequada, justificando intervenções focadas na prevenção e redução concomitante dos principais fatores comportamentais de risco de DANT.

Measuring DHEA-S in saliva: time of day differences and positive correlations between two different types of collection methods

Background

The anabolic steroid, dehydroepiandosterone sulfate (DHEA-S), is secreted from the adrenal cortex. It plays a significant role in the body as a precursor to sex steroids as well as a lesser known role in the hypothalamic pituitary adrenal axis (HPA) response to stress. DHEA-S can be measured reliably in saliva, making saliva collection a valuable tool for health research because it minimizes the need for invasive sampling procedures (e.g., blood draws). Typical saliva collection methods include the use of plain cotton swab collection devices (e.g., Salivette^®) or passive drool. There has been some speculation that the plain saliva cotton collection device may interfere with determination of DHEA-S by enzyme immunoassay (EIA) bringing this saliva collection method into question. Because of the increasing popularity of salivary biomarker research, we sought to determine whether the cotton swab interferes with DHEA-S determination through EIA techniques.

Findings

Fifty-six healthy young adult men and women aged 18-30 years came to the lab in the morning (0800 hrs; 14 men, 14 women) or late afternoon (1600 hrs; 14 men, 14 women) and provided saliva samples via cotton Salivette and passive drool. Passive drool collection was taken first to minimize particle cross contamination from the cotton swab. Samples were assayed for DHEA-S in duplicate using a commercially available kit (DSL, Inc., Webster, TX). DHEA-S levels collected via Salivette and passive drool were positively correlated (r = + 0.83, p < 0.05). Mean DHEA-S levels were not significantly different between collection methods. Salivary DHEA-S levels were significantly higher in males than in females, regardless of saliva collection method (p < 0.05), and morning DHEA-S values were higher than evening levels (p < 0.05).

Conclusions

Results suggest that DHEA-S can be measured accurately using passive drool or cotton Salivette collection methods. Results also suggest that DHEA-S levels change across the day and that future studies need to take this time of day difference into account when measuring DHEA-S.

Influence of history of smoking on the physical capacity of older people

Among the elderly, smoking is related to death and it contributes to disability associated with chronic diseases. This study aims to verify the influence of a history of smoking on the physical capacity of elderly people, and its relationship with the gender. Elderly people beginning to practice physical activity reported questions about their smoking history and underwent a physical evaluation, consisted by hemodynamic data (blood pressure, heart rate and maximum oxygen consumption), body mass index (BMI), muscular strength, flexibility and balance. Mann-Whitney test and Spearman's test was used to data analysis. The sample consisted of 127 subjects, among whom 26.8% were ex-smokers. There were a higher number of nonsmoking women (p<0.001) than others, and women smoked fewer packets per day (p=0.047). Among the women, those ex-smokers were younger and more flexible in comparison with those nonsmokers (p<0.05). Among the men, the ex-smokers were older and walked more slowly than nonsmokers (p<0.05). There was a correlation between the BMI and duration of smoking time. Smoking cessation benefits the elderly, since the physical variables showed no long-term harm associated with the history of smoking when compared with those of elderly without this habit.

Do smokers know what we're talking about? The construct validity of nicotine dependence questionnaire measures

Few studies have examined whether nicotine dependence self-report questionnaires can predict specific behaviors and symptoms at specific points in time. The present study used data from a randomized clinical trial (N = 608; M. E. Piper et al., 2007) to assess the construct validity of scales and items from 3 nicotine dependence measures: the Fagerström Test for Nicotine Dependence (T. F. Heatherton, L. T. Kozlowski, R. C. Frecker & K.-O. Fagerström, 1991), the Nicotine Dependence Syndrome Scale (S. Shiffman, A. J. Waters, & M. Hickcox, 2004), and the Wisconsin Inventory of Smoking Dependence Motives (M. E. Piper et al., 2004). Scales from these measures were used to predict participants' reports on real-time measures of withdrawal symptoms and smoking behavior and retrospective self-report questionnaires to assess convergent and discriminative validity. The nicotine dependence measures' scales and items generally predicted the real-time measures of similar constructs, but the percent of variance accounted for was low. The nicotine dependence measures did, however, show evidence of discriminative validity. Thus, this study provides modest support for the construct validity of these nicotine dependence scales.

Sex-specific associations of body mass index with mood disturbance during smoking abstinence

OBJECTIVE

Previous reports have suggested an inverse relationship between body mass index (BMI) and negative mood in women. However, little is known about the potential association of these variables under stressful conditions, such as those experienced during smoking cessation. The current investigation examined the relationship of BMI and various indices of mood in a sample of male and female cigarette smokers undergoing cessation.

METHODS

Along with baseline assessments of variables such as depression and anxiety, total mood disturbance and perceived stress were assessed via self-report during both baseline (e.g. the smoking period) and the early phases of smoking cessation.

RESULTS

Among female participants, higher BMI was associated with lower levels of mood disturbance, perceived stress and depression. Similar analyses in male participants were non-significant.

CONCLUSIONS

The results of the current study confirm previous reports regarding the relationship of BMI and mood in women and extend these findings to the early stages of smoking cessation.

Sex differences in nicotine action

Accumulating evidence suggests that the antecedents, consequences, and mechanisms of drug abuse and dependence are not identical in males and females and that gender may be an important variable in treatment and prevention. Although there has been a decline in smoking prevalence in developed countries, females are less successful in quitting. Tobacco use is accepted to be a form of addiction, which manifests sex differences. There is also evidence for sex differences in the central effects of nicotine in laboratory animals. Although social factors impact smoking substantially in humans, findings from nonhuman subjects in controlled experiments provide support that sex differences in nicotine/tobacco addiction have a biological basis. Differences in the pharmacokinetic properties of nicotine or the effect of gonadal hormones may underlie some but not all sex differences observed. Laboratory-based information is very important in developing treatment strategies. Literature findings suggest that including sex as a factor in nicotine/tobacco-related studies will improve our success rates in individually tailored smoking cessation programs.

Lower leptin levels in young non-obese male smokers than non-smokers

Since the effect of smoking on plasma leptin has been divergent in clinical trials, which might have occurred due to selection of heterogeneous study populations, we investigated whether there is such an association in a group of healthy, non-obese, young male adults. A total of 54 smokers (mean age: 21.18+/-1.62; body mass index (BMI): 19.60+/-0.85) and 26 non-smokers (mean age 21.69+/-3.0; BMI: 21.59+/-1.39) with similar daily physical activities and diet and without any documented disease were enrolled, and their plasma leptin levels were determined for the comparison between the two groups. The mean BMI and plasma leptin of smokers were significantly lower than in non-smokers. Plasma leptin in the smokers group correlated inversely with BMI and the amount of daily smoking. Below BMI 20 kg/m(2) and between 20.0 and 20.9 kg/m(2) the plasma leptin levels in smokers were significantly lower when compared to non-smokers. Plasma leptin is decreased in healthy, young non-obese male smokers independently of the amount of body fat. High amount of smoking is associated with lower serum leptin as well.

[Smoking and changes in body weight: can physiopathology and genetics explain this association?]

Tobacco use is the leading preventable cause of death in most countries, including Brazil. Smoking cessation is an important strategy for reducing the morbidity and mortality associated with tobacco-related diseases. An inverse relationship between nicotine use and body weight has been reported, in which body weight tends to be lower among smokers than among nonsmokers. Smoking abstinence results in an increase in body weight for both males and females. On average, sustained quitters gain from 5 to 6 kg, although approximately 10% gain more than 10 kg. Pharmacological treatment for smoking cessation attenuates weight gain. The importance of smoking cessation as a contributing cause of the current obesity epidemic has been little studied. In the USA, the rate of obesity attributable to smoking cessation has been estimated at approximately 6.0 and 3.2% for males and females, respectively. Although the mechanisms are unclear, there is evidence that dopamine and serotonin are appetite suppressants. The administration of nicotine, regardless of the delivery system, acutely raises the levels of these neurotransmitters in the brain, reducing the need for energy intake and consequently suppressing appetite. In addition, nicotine has a direct effect on adipose tissue metabolism, influencing the rate of weight gain following smoking cessation. Leptin, ghrelin and neuropeptide Y are substances that might constitute factors involved in the inverse relationship between nicotine and body mass index, although their roles as determinants or consequences of this relationship have yet to be determined.

The effects of smoking on bone health

Osteoporotic fractures are a major public health problem in most developed countries and an increasing concern in much of the developing world. This healthcare burden will increase significantly worldwide over the next 20 years due to aging of the population. Smoking is a key lifestyle risk factor for bone loss and fractures that appears to be independent of other risk factors for fracture such as age, weight, sex and menopausal status. This review discusses the effects of smoking on bone health in pre-menopausal and post-menopausal women and men. Data from twin studies and the three main published meta-analyses are presented. Possible mechanisms by which smoking affects bone mass are reviewed. Despite smoking being a major lifestyle risk factor for osteoporosis, the mechanisms underlying smoking-associated bone loss and fracture risk remain poorly understood. The effect appears dose-dependent, and may be, at least partially, reversible. However, more work is required to confirm and characterize the reversibility of smoking-associated bone defects. Finally, strategies for quitting smoking are discussed. Encouragement of lifestyle alterations, including smoking cessation, should be a major component of any bone therapeutic programme.

Disruption in Th1/Th2 immune response in young adult smokers

Interferon (IFN)-gamma and IL-10 cytokines, measures of Th1 and Th2 immunity, were examined in 20 healthy nonsmokers (12 males, 8 females) and 19 smokers (11 males, 8 females), aged 19-41 years (23.46+/-0.82 years). Nonsmokers came to the laboratory once; smokers came to the laboratory after ad lib smoking and following 24-h smoking abstinence. Salivary cotinine and expired CO confirmed smoking status. Plasma was collected at the end of each lab session and assayed for peripheral IFN-gamma and IL-10 levels. Among smokers, peripheral IFN-gamma, IL-10, or IFN-gamma/IL-10 ratio levels did not change in response to 24-h smoking abstinence. IFN-gamma levels and IFN-gamma/IL-10 ratios were higher among female smokers while smoking and following 24-h abstinence compared to male smokers in both conditions and compared to male and female nonsmokers. There was no sex or smoking status difference in IL-10 levels. Results suggest that cigarette smoking may have at least short-term damaging effects on the body's normal immune balance, particularly for women.

Are smokers' reasons for smoking related to their body mass indices?

The current analyses addressed the relationship between body mass index and reasons for smoking in 69 cigarette smokers (39 male) enrolled in a smoking cessation study between 2000 and 2003 in a Midwestern metropolitan area. Multivariate analyses of variance were applied. Normal weight and overweight smokers exhibited differential patterns of responding on a questionnaire assessing reasons for smoking. Compared to the overweight group, the normal weight group endorsed smoking for relaxation as well as the sensation of having something to do with one's hands. While preliminary, pursuing body mass index (BMI) in relation to smokers' reasons for smoking may help tailor smoking cessation programs to the needs of these smokers. The study's limitations are noted.

Risk indicators of metabolic syndrome in young adults: A preliminary investigation on the influence of tobacco smoke exposure and gender

BACKGROUND

Metabolic syndrome is characterized by hypertension, dyslipidemia, insulin resistance, and obesity. Limited investigations have studied early indicators of metabolic syndrome in healthy young adults before diagnosis of disease.

PURPOSE

The purpose of this investigation is to identify shifts in cardiovascular (CV), metabolic, and immune variables consistent with metabolic syndrome but occurring before development of the disorder, and to determine whether these variables are influenced by gender or cigarette smoking.

METHODS

A pilot study of 41 subjects ages 18 to 39 years, with 20 smokers and 21 nonsmokers, was undertaken. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured to evaluate CV status; cholesterol, body mass index, leptin, percent glycated albumin, and homocysteine were measured to evaluate metabolic status; C-reactive protein, interleukin-1beta, and interleukin-10 were measured to evaluate immunologic status. Risk scores were assigned to each indicator, and total risk score was computed.

RESULTS

Men had higher SBP (P<.001), DBP (P=.046), and body mass index (P=.01), whereas women had higher leptin (P=.002). Total risk scores in men were greater (P=.02). There was no effect of smoking on risk score, related to the increase in two risks for smokers (SBP, P=.04, DBP; P=.027) reciprocated by a decrease in another (percentage of glycated albumin; P=.02).

CONCLUSION

Risk factors contributing to metabolic syndrome are present and highest in young men compared with women, whereas the effects of cigarette smoking on the syndrome are mixed. Early intervention to reduce modifiable risks may prevent full expression of disease.

Cigarette smoking may reduce plasma leptin concentration via catecholamines

BACKGROUND

Leptin might influence body weight among smokers.

DESIGN

(A) Screening of plasma leptin levels in 222 sedentary, smoking and non-smoking middle-aged men. (B) Double-blind, placebo-controlled smoking intervention on smokers (n=31). (C) Non-smokers (n=40) received chewing gum with nicotine (2mg nicotine, n=23) or without nicotine (n=19). (D) The effects of nicotine (0.05 and 0.5 microg/mL) were monitored on leptin secretion and mRNA levels in a human placental cell line (BeWo) expressing leptin, a murine adipocyte cell line (3T3-L1) and human adipose tissue explants.

RESULTS

(A) Plasma leptin levels in smoking men (8.4+/-8.4 ng/mL, n=100) was lower as compared to non-smokers (10.3+/-7.3 ng/mL, n=122) (P<0.001), even when adjusted for differences in body mass index (BMI) (P<0.001). (B) A significant reduction (P=0.02) in plasma concentration of leptin was found already after smoking one cigarette. Concomitant with the 3-5 fold increase in plasma nicotine concentration after the first cigarette, we observed increased plasma adrenaline levels (P=0.005). (C) There was no effect of nicotine on plasma leptin levels in non-smokers receiving nicotine-containing chewing gum, and plasma concentrations of catecholamines were unaltered. (D) There was no effect of nicotine on leptin mRNA expression after incubation with cells or adipose tissue.

CONCLUSION

Cigarette smoking reduced plasma leptin concentration in vivo, whereas nicotine had no direct effect on leptin expression in vitro. Nicotine might indirectly reduce leptin secretion via enhanced plasma catecholamine concentration.