Effectiveness of pharmacologic therapies on smoking cessation success: three years results of a smoking cessation clinic

Effectiveness of smoking cessation interventions for smokers with Crohn's disease: a systematic review

Aims

Smoking cessation (SC) in Crohn's disease (CD) is widely accepted to be the most important modifiable factor to improve outcomes in these patients. We aimed in this review to provide a summary of the evidence base regarding the effectiveness of SC interventions in patients with CD.

Materials & methods

The following databases were systematically searched from inception to February 2022: PubMed, Google Scholar and Cochrane Library.

Results

Overall, five articles met the research criteria. Studies sample size ranged from 17 to 474 patients. At the outcome level, the abstinence rates ranged from 14.8 to 42% and was ≤25% in four studies. The three studies with control groups did not report statistically higher SC rates in the intervention groups. No predictors of interventions success were identified in this review.

Conclusion

Implementation and evaluation of tailored SC interventions for CD patients must be promptly addressed in further studies.

Exploring the barriers and facilitators to the uptake of smoking cessation services for people in treatment or recovery from problematic drug or alcohol use: A qualitative systematic review

BACKGROUND

Smoking prevalence and the associated poor health and mortality is significantly higher among people with/recovering from problematic drug or alcohol (PDA) use in comparison with the general population. Evidence from existing systematic reviews shows smoking cessation enhances rather than compromises long-term abstinence from alcohol or drug use. However, these systematic reviews lack important contextual detail around the reasons why uptake of, and successful engagement with existing stop smoking services remains low for people in treatment or recovery from PDA use. This systematic review explores qualitative data on the barriers and facilitators to the uptake of smoking cessation services for people in treatment or recovery from PDA use. This key objective addresses the limited inclusion of qualitative studies in previous systematic reviews on this issue.

METHODS

A qualitative systematic review was conducted with searches across four electronic databases (PubMed, Embase, PsycINFO and Cumulative Index to Nursing and Allied Health Literature [CINAHL]). All studies that had a qualitative component about free smoking cessation/reduction programmes for people in treatment or recovery from PDA use were included. Studies that examined electronic smoking or services that required a fee were excluded. Study quality was assessed using National Institute for Health and Care Excellence checklist. Qualitative synthesis involved inductive thematic analysis. (PROSPERO Registration number: CRD42022298521).

RESULTS

8809 potentially eligible articles were identified, 72 full texts were screened and ten articles were included for full review. Barriers to uptake and engagement with existing stop smoking services centered on three key themes: perception of public health importance, programme structure, and intervention elements. Facilitators included supportive treatment environment and optimization of support/staff resources for smoking cessation service delivery.

CONCLUSION

Recommendations included influencing a change in the way people perceive the importance of smoking cessation activities during PDA use treatment or recovery. There was also some emphasis on the need to create the right environment for sustained adherence to treatment or recovery plans, and deliver the interventions within the health system as comprehensive care. The limited qualitative evidence on community-based and outpatient services highlights a research gap.

Efficacy and Safety of Cytisine in Combination with a Community Pharmacists' Counselling for Smoking Cessation in Thailand: A Randomized Double-Blinded Placebo-Controlled Trial

BACKGROUND

Cytisine is a prospective pharmacological alternative for community pharmacy smoking cessation services. However, it has not yet been licensed because of a lack of efficacy and safety information in Thailand.

OBJECTIVE

The aim of this study was to evaluate the efficacy of cytisine in combination with community pharmacists' counselling on smoking cessation in a community pharmacy in ThailandDesign. Setting, participants, and interventions: A double-blinded randomized placebo-controlled trials was carried out. Participants aged >18 years old who smoked >10 tobaccos/day were randomly assigned to receive cytisine or placebo and five sessions of counselling by a community pharmacist. The primary outcome was a continuous abstinence rate (CAR) at week 48. The CAR was also measured at weeks 2, 4, 12, and 24. Adverse events were monitored.

RESULTS

A total of 132 participants were included, with 67 receiving cytisine and 65 receiving a placebo. Approximately 95% of participants were male. The CARs were determined to be 14.93% and 6.15% for cytisine and placebo, respectively, at week 48. The relative risk (RR) was 2.41 (95% confidence interval (CI); 0.80-7.35, p = 0.102). The RRs for CAR at weeks 2, 4, 12, and 24 were 2.43, 2.91, 2.50, and 1.78, respectively. Only the RRs for weeks 2, 4, and 12 were statistically significant. Common and non-serious gastrointestinal and neurological adverse events were observed.

CONCLUSION

Cytisine, when combined with community pharmacists' counselling, did not statistically improve the CAR at week 48, although it did improve the CAR at weeks 2, 4, and 12. Adverse events of cytisine were common and non-serious (registration number: TCTR20180312001).

Pharmacological smoking cessation of adults aged 30-50 years with COPD

The prevalence of active smokers has remained relatively stable around 20% for several years in Denmark despite knowledge of the harmful effects. Smoking cessation is the most effective way to limit progression and reduce mortality of chronic obstructive pulmonary disease (COPD). Therefore, smoking cessation is particularly important among adults with COPD. The aim of this study was to determine the extent to which adults 30–50 years of age with COPD redeem pharmacotherapy for smoking cessation, and to identify demographic factors that influence the use of smoking cessation medication. We conducted a national retrospective non-interventional registry study, including all Danish patients with COPD (ICD-10 code J.44: chronic obstructive pulmonary disease) aged 30–50 years in the period 2009–2015. We identified 7734 cases, who were matched with controls (15,307) 1:2 on age, sex, and geography. Smoking status was not registered. We found that 18% of cases (with an estimated smoking prevalence at 33–50%) redeemed pharmacological smoking cessation medication in the study period compared to 3% of the controls (with an estimated smoking prevalence at 23%). The OR for cases collecting pharmacological smoking cessation medication was 5.92 [95% CI 5.24–6.70]. Male sex, being unemployed, and receiving social benefits were factors associated with less probability of redeeming pharmacological smoking cessation medication. Our study indicates that attention is needed on smoking cessation in adults aged 30–50 years with COPD, especially if unemployed or receiving social benefits, as these individuals are less likely to redeem pharmacological smoking cessation medication.

Nationwide implementation of the self-management program "Living well with COPD": Process and effectiveness evaluation using a mixed-methods approach

OBJECTIVE

To evaluate the nationwide implementation of the "Living well with COPD" program by the Swiss Lung Association in various cantons in Switzerland.

METHODS

For the process evaluation, we used qualitative (interview, focus group) and quantitative (questionnaires, documentation analysis) methods to assess the implementation outcomes reach, dose, fidelity and acceptability. For the effectiveness, we performed a pre-post analysis of patient data collected at baseline and program end (after 14 months).

RESULTS

Seven Cantonal Lung Associations implemented the program into their services according to plan, conducted it 13 times and included 122 COPD patients. Patients' attendance rate was 81% and coaches' fidelity to protocol 94%. Acceptance and satisfaction of all involved persons was high. Integration of the coaches' additional workload, uncertainties regarding roles and responsibilities and sustainable reimbursement were major challenges. Patients significantly improved in COPD specific quality of life and increased exercise capacity with on average 3.2 more repetitions in the 1-minute sit-to-stand test.

CONCLUSION

The program was successfully implemented throughout Switzerland with high acceptability and positive association with patients' quality of life.

PRACTICE IMPLICATIONS

Our findings support the broader multiplication throughout Switzerland and serves the international community since it is one of the first nationwide implementations beyond study settings.

Evaluating level of adherence to nicotine replacement therapy and its impact on smoking cessation: a systematic review and meta-analysis

Background

Nicotine replacement therapy (NRT) has proven effect in assisting smoking cessation. However, its effectiveness varies across studies and population groups. This may be due to differences in the rate of adherence. Hence, this review aims to examine the level of adherence to NRT and to assess if the level of adherence to NRT affects success of smoking cessation.

Methods

A systematic review and meta-analysis was conducted using studies retrieved from five electronic databases (MEDLINE, Scopus, EMBASE, Web of science, and PsycINFO) and grey literature. Pooled analysis was conducted using Stata version 16 software. Methodological quality and risk of bias were assessed using the NIH Quality Assessment Tool. Analyses were done among those studies that used similar measurements to assess level of adherence and successful smoking cessation. Heterogeneity of studies was assessed using the Higgins’ I² statistical test. Funnel plots and Egger’s regression asymmetry test were used to affirm presence of significant publication bias.

Results

A total of 7521 adult participants of 18 years old and above from 16 studies were included in the analysis. Level of adherence to NRT among participants of randomised controlled trials were found to be 61% (95% CI, 54–68%), p-value of < 0.001 and I² = 85.5%. Whereas 26% of participants were adherent among participants of population-based studies with 95% CI, 20–32%, p-value of < 0.001 and I² = 94.5%. Level of adherence was the lowest among pregnant women (22%) with 95% CI, 18–25%, p-value of 0.31 and I² = 15.8%. Being adherent to NRT doubles the rate of successful quitting (OR = 2.17, 95% CI, 1.34–3.51), p-value of < 0.001 and I² = 77.6%.

Conclusions

This review highlights a low level of adherence to NRT among participants of population-based studies and pregnant women as compared to clinical trials. Moreover, the review illustrated a strong association between adherence and successful smoking cessation. Hence, it is recommended to implement and assess large scale interventions to improve adherence. Health programs and policies are recommended to integrate the issue of adherence to NRT as a core component of smoking cessation interventions.

Trial registration

PROSPERO registration number: CRD42020176749. Registered on 28 April 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13690-021-00550-2.

Mandatory Nicotine Cessation for Elective Orthopedic Hip Procedures Results in Reduction in Postoperative Nicotine Use

Purpose

To determine the efficacy of mandatory preoperative nicotine cessation on postoperative nicotine use, and to identify independent predictors of nicotine use relapse in subjects undergoing hip preservation surgery or total hip arthroplasty by a single fellowship-trained orthopedic surgeon.

Methods

Consecutive subjects that underwent hip surgery from November 2014 to December 2017 were reviewed. Subjects who self-reported nicotine use, quit prior to surgery, and completed a minimum one-year follow-up were included. Multiple linear regression models were constructed to determine the effect of independent variables on nicotine use relapse following surgery.

Results

Sixty subjects were included in the study (mean follow-up 35.1 months (17-57 months), mean age 44.9 years (20-82 years), and 23 (38.3%) males). Twenty-eight subjects (46.7%) remained nicotine-free at final follow-up. The mean number of cigarettes per day decreased from 13.4 preoperatively to 8.4 postoperatively in the subjects who relapsed (P=0.002). The mean time to return to nicotine postoperatively was 2.4 months. The number of preoperative cigarettes per day was the only independent predictor of tobacco use relapse (P=0.005).

Conclusion

Mandatory preoperative nicotine cessation prior to elective hip surgery demonstrates a 46.7% nicotine-free survivorship at final follow-up with the number of preoperative cigarettes per day found to be the only independent predictor of nicotine use relapse.

Level of evidence

The level of evidence of this research study is Level III since it is a non-experimental study with a cohort of patients.

The effect of a multidisciplinary approach for smoking cessation in patients with Crohn's disease: Results from an observational cohort study

INTRODUCTION

Cigarette smoking is the most important risk factor for Crohn’s disease (CD). The effectiveness of smoking cessation programs (SCPs) in patients with CD is still poorly understood.

METHODS

This was a retrospective, observational, single-centre, cohort study of 136 active smokers with mean age 55 years (SD=11), 58% males, including 27 (19.8%) patients with CD who entered the multidisciplinary SCP of the Luigi Sacco University Hospital of Milan from January 2017 through January 2019. A pulmonologist was responsible for the clinical and pharmacological management, while a psychiatrist and a psychologist conducted the counselling and assessed the motivation to quit, anxiety and depression using the Brief Psychiatric Rating Scale (BPRS) and the nicotine dependence with the Fagerström test. Patients were defined as quitters after 12 months.

RESULTS

Demographic and clinical characteristics, and Fagerström score, did not differ in patients with and without CD. At baseline, patients with CD had a higher BPRS (median: 27, IQR: 22–32; vs 25 and 22–28.5; p=0.03), and a lower motivation to quit score (median: 10, IQR: 9–13; vs 14 and 12–15; p<0.001). After 12 months, the quitting rate of smokers with CD was significantly lower (14.8% vs 36.7%; p<0.022) and the chance of quitting was negatively associated with the baseline BPRS (r=-0.256; p<0.003). Varenicline and nicotine replacement therapy tended to be less effective in patients with CD.

CONCLUSIONS

The lower efficacy of SCPs in patients with CD might be secondary to a higher prevalence of anxiety and depression. Psychological issue recognition and support should be enhanced to increase SCP effectiveness in CD.

Comparison of monoamine oxidase inhibition by cigarettes and modified risk tobacco products

The adverse effects of cigarette smoking are well documented, and the two main strategies for reducing smoking prevalence are prevention of smoking initiation and promotion of smoking cessation. More recently, a third and complementary avenue, tobacco harm reduction has emerged, which is aimed to reduce the burden of smoking-related diseases. This has been enabled by the development of novel products such as electronic cigarettes (e-cigarettes) and heated tobacco products, designed to deliver nicotine with significantly reduced levels of the toxicants that are emitted by cigarettes. Several potential modified risk tobacco products (pMRTP) have been reported to emit significantly less toxicants than cigarettes and significantly reduce toxicant exposure in smokers who switch completely to such products. These are two prerequisites for pMRTPs to reduce harm and the risk of smoking-related disease. However, concerns remain regarding the addictive nature of these products. Smoking addiction is a complex phenomenon involving multiple pharmacological and non-pharmacological factors. Although the main pharmacological substance associated with smoking addiction is nicotine, accumulating evidence suggests that nicotine mostly acts as a primary reinforcer and that other factors are involved in establishing smoking addiction. Inhibition of monoamine oxidases (MAO)-mammalian flavoenzymes with a central role in neurotransmitter metabolism-has also been suggested to be involved in this process. Therefore, we aimed to comparatively investigate the ability of several types of pMRTPs and cigarette smoke (3R4F) to inhibit MAO activity. The results showed that the heated tobacco product Tobacco Heating System (THS) 2.2 and the MESH 1.1 e-cigarette possessed no MAO inhibitory activity while 3R4F significantly inhibits the levels of MAO activity (3R4F MAO-A and B; > 2 μM nicotine). Snus products have similar inhibition profiles as 3R4F but for larger nicotine concentrations (snus MAO-A; ∼68-fold, snus MAO-B; ∼23-fold higher compared to 3R4F). These observations were confirmed by analytical datasets of potential MAO inhibitors emitted by these products. In conclusion, we have demonstrated that specific pMRTPs, namely THS 2.2 and MESH 1.1, have a significantly lower MAO-inhibitory activity than 3R4F. These findings provide a basis for further investigation of the role of MAO inhibitors in cigarette addiction as well as the implications of the findings for abuse liability of pMRTPs in comparison with cigarettes.

Healthcare Costs of Smokers Using Varenicline Versus Nicotine-Replacement Therapy Patch in the United States: Evidence from Real-World Practice

Introduction

Varenicline (VAR) is an effective smoking-cessation therapy compared to the commonly used nicotine-replacement therapy patch (NRT-P). However, comparative real-world evidence on smoking-cessation therapies is limited, especially for economic outcomes.

Methods

Using national claims databases (2012–2016) in the United States (US), adults initiating VAR or NRT-P without use of any other smoking-cessation products were followed for up to 1 year on a quarterly basis. Outcomes included smoking-attributable (SA) (cardiovascular, diabetes, pulmonary diseases, and smoking cessation) and all-cause costs (2017 US dollars). Adjusted mean costs were estimated from multivariable regressions, with baseline characteristics and propensity scores as covariates. Annual adjusted costs were calculated from quarterly averages.

Results

The VAR cohort (n = 209,284) was younger (mean age 46.7 vs. 49.0 years) and had fewer comorbidities [mean Charlson Comorbidity Index (CCI): 0.8 vs. 1.6] than the NRT-P cohort (n = 34,593). After adjustment, VAR cohort had lower SA and all-cause medical costs than NRT-P cohort in Quarters 1–4 (Q1–Q4) of follow-up, and had lower SA and all-cause total costs in Q2–Q4. Annually, VAR cohort had higher SA total costs ($307) and lower all-cause costs (− $2089) than NRT-P cohort. Annual medical costs were lower in VAR cohort (− $640 for SA and − $2876 for all-cause), and pharmacy costs were higher ($762 for SA and $777 for all-cause). In adherent patients (VAR: n = 38,744; NRT-P: n = 2702), VAR patients had lower annual medical costs (− $794 for SA and − $1636 for all-cause) and higher pharmacy costs ($1175 for SA and $1269 for all-cause); differences in SA and all-cause total costs were not statistically significant between treatment groups.

Conclusions

Lower SA and all-cause medical costs associated with the use of VAR versus NRT-P resulted in savings in all-cause total costs and, among adherent patients, potentially offset the high pharmacy costs of VAR.

Funding

Pfizer, Inc.

Electronic supplementary material

The online version of this article (10.1007/s12325-018-0858-y) contains supplementary material, which is available to authorized users.

Tobacco Control Policies in Turkey in Terms of MPOWER

Tobacco consumption is a worldwide health problem threatening all, making no differentiation between gender, age, race, and cultural or educational background. Tobacco is responsible for 7 million deaths each year. Over 6 million deaths are directly related to tobacco consumption, and over 890.000 deaths involve non-smokers exposed to tobacco smoke. Although the harmful effects of cigarettes on human health have been confirmed repeatedly, still over 1 billion people worldwide are tobacco consumers, and according the World Health Organization (WHO), unless a strict action plan is implemented, tobacco-related deaths will rise to more than 8 million per year by 2030. The WHO published the Framework Convention on Tobacco Control in 2003, which could form a common policy to guide countries in the struggle against tobacco. Tobacco control in the Convention is defined as "a range of supply, demand and harm reduction strategies that aim to improve the health of a population by eliminating or reducing their consumption of tobacco products and exposure to tobacco smoke." This agreement was adopted by Turkey in 2004 with the Law No. 5261. In 2008, the WHO published the MPOWER package, containing the following six basic strategies, which are parallel with the Tobacco Framework Convention measures and practices: Monitor tobacco use.Protect people from tobacco smoke.Offer help to quit tobacco use.Warn about the dangers of tobacco.Enforce bans on tobacco advertising and promotion.Raise taxes on tobacco products. In the 2013 Global Tobacco Control Report by the WHO, Turkey was announced as the first country achieving a high level of success in the six MPOWER strategies, and other countries were advised to adopt the Turkish policies. Here we review Turkey's MPOWER tobacco control strategies one by one.

Effects of lorcaserin (Belviq®) on nicotine- and food-maintained responding in non-human primates

BACKGROUND

Accumulating evidence suggests that the FDA-approved serotonin 5-HT2C receptor agonist, lorcaserin (Belviq®), may be a promising candidate for the management of substance use disorders, including nicotine addiction. The present study was conducted to determine the efficacy and selectivity of acute or continuous lorcaserin treatment for decreasing the reinforcing effects of nicotine in a primate species.

METHODS

Adult rhesus monkeys (n=4) with a history of nicotine self-administration (>2years) responded for injections of nicotine (0.32-100μg/kg IV) or food pellets under a fixed-ratio schedule of reinforcement during daily 100-min sessions. When responding was stable, lorcaserin was administered either as an acute pretreatment (0.1-1.0mg/kg, IM) or by continuous infusion (0.1mg/kg/hr, SC for 3-5days). Daily activity patterns were also monitored immediately following experimental sessions.

RESULTS

Results indicate that acute lorcaserin pretreatment produced significant and dose-dependent decreases in nicotine-maintained responding across a >100-fold range of self-administered nicotine doses. Continuous lorcaserin treatment decreased intake of 10μg/kg/inj nicotine to about 50% of baseline values. Food-maintained responding was only moderately decreased in 3 of 4 subjects after acute administration and unaffected in all subjects during continuous treatment. Daily activity also was significantly decreased-to ≤50% of control values-following experimental sessions in which acute lorcaserin was administered.

CONCLUSIONS

These data indicate that lorcaserin reduces IV self-administration of nicotine at a dose that decreases motoric activity but less consistently disrupts food-maintained responding. Further research into lorcaserin's potential utility for the management of nicotine dependence is warranted.

Gender differences in the real-world effectiveness of smoking cessation medications: Findings from the 2010-2011 Tobacco Use Supplement to the Current Population Survey

BACKGROUND

Meta-analyses of clinical trial data have identified clinically relevant gender differences in the efficacy of smoking cessation pharmacotherapy. It is unclear whether these findings are generalizable to smokers quitting in real-world contexts.

METHODS

Using Tobacco Use Supplement to the Current Population Survey (TUS-CPS) 2010-2011 cross-sectional data, we generated propensity score matched samples of smokers who quit either unassisted by medication, using only varenicline, or using only transdermal nicotine patch (TNP). We used generalized estimating equations to estimate gender differences in the comparative effectiveness of these cessation options for achieving 30-days of abstinence, adjusting for potential confounders.

RESULTS

When stratified by gender, TNP was significantly more effective than unassisted quit attempts for men (OR=1.37; 95%CI=1.02,1.83; p=0.03), but not for women (OR=0.96; 95%CI=0.71,1.31; p=0.82). Varenicline was significantly more effective than unassisted quit attempts for women (OR=1.63; 95%CI=1.16, 2.31; p=0.005), but not men (OR=1.35; 95%CI=0.94,1.96; p=0.11). Varenicline was also more effective than TNP for women (OR=1.51; 95%CI=0.12,2.05; p=0.007) but not men (OR=0.92; 95%CI=0.65,1.31; p=0.64). A significant gender by medication interaction was found only for the comparison of varenicline to TNP (OR=1.64; 95%CI=1.04,2.61; p=0.04).

CONCLUSIONS

Findings for varenicline vs. TNP were consistent with clinical trial data, showing greater differences in effectiveness for women compared to men. Results lend support to the generalizability of clinical trial findings, highlighting the importance of considering gender when offering treatment for smoking cessation.

Increasing awareness of sex differences in airway diseases

There is growing epidemiologic data demonstrating sex differences with respect to prevalence and progression of airway diseases, including asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF) and non-CF-related bronchiectasis. In asthma, for example, young boys have increased exacerbations and higher morbidity than girls which distinctly reverses after adolescence and into adulthood. In COPD, a disease that was historically considered an illness of men, the number of women dying per year is now greater than in men. Finally, women with CF-related bronchiectasis have a decreased median life expectancy relative to men and a higher risk of respiratory infections despite equal prevalence of the disease. A number of studies now exist demonstrating mechanisms behind these sex differences, including influences of genetic predisposition, sex hormones and comorbidities. The notable sex disparity has potential diagnostic, therapeutic and prognostic implications and for the practicing respiratory or general physician, a familiarity with these distinctions may augment effective management of patients with airway diseases. This review seeks to concisely summarize the data regarding gender-based differences in airway diseases, outline the current understanding of contributing factors and discuss therapeutic implications for clinicians.

Seven-day continuous abstinence rate from smoking at 1, 2, or 3 years after the use of varenicline

BACKGROUND

Varenicline, a selective partial agonist/antagonist of the α4β2 nicotinic receptor, has proven effectiveness for smoking cessation by several randomized, controlled trials. Because few studies have evaluated the long-term efficacy of varenicline, we tried to evaluate the smoking status of varenicline users up to 3 years after the initial prescription of the drug.

METHODS

We interviewed varenicline users who were prescribed the drug from June 2007 to May 2010 by telephone, from June 2010 to May 2011.

RESULTS

One-hundred and thirty-three of 250 varenicline users (53.2%) were available for the survey. Seven-day continuous abstinence from smoking was adhered to by 17 of 39 respondents (43.6%) at 1 year, and 11 of 36 (30.6%) and 19 of 58 (32.8%) at 2 and 3 years since the first use of varenicline, respectively. Compared to current smokers, successful quitters were older (55.0 years vs. 49.9 years, p=0.01), had better compliance to the 12-week course (27.7 vs. 9.3%, p=0.01), and had taken varenicline longer (10.1 vs. 5.9 weeks, p=0.01). Fifty-four of 71 current smokers (76.1%) were willing to stop smoking in the near future. The preferred ways to cease smoking were will-power (48.1%), varenicline (25.9%), nicotine replacement therapy (11.1%), and others (14.9%).

CONCLUSION

Smokers should be encouraged to stick to the proven way for recommended period of time for successful cessation of smoking.

Key systemic and environmental risk factors for implant failure

Dental implants are an important treatment option for patients interested in replacing lost or missing teeth. Although a robust body of literature has reviewed risk factors for tooth loss, the evidence for risk factors associated with dental implants is less well defined. This article focuses on key systemic risk factors relating to dental implant failure, as well as on perimucositis and peri-implantitis.

Neuroanatomical circuitry mediating the sensory impact of nicotine in the central nervous system

Direct actions of nicotine in the CNS appear to be essential for its reinforcing properties. However, activation of nicotinic acetylcholine receptors (nAChRs) on afferent sensory nerve fibers is an important component of addiction to, and withdrawal from, cigarette smoking. The aim of the present study was to identify the neuroanatomical substrates activated by the peripheral actions of nicotine and to determine whether these sites overlap brain structures stimulated by direct actions of nicotine. Mouse brains were examined by immunohistochemistry for c-Fos protein after intraperitoneal injection of either nicotine hydrogen tartrate salt (NIC; 30 and 40 μg/kg) or nicotine pyrrolidine methiodide (NIC-PM; 20 and 30 μg/kg). NIC-PM induced c-Fos immunoreactivity (IR) at multiple brain sites. In the brainstem, c-Fos IR was detected in the locus coeruleus, laterodorsal tegmental nucleus, and pedunculotegmental nucleus. In the midbrain, c-Fos IR was observed in areas overlapping the ventral tegmental area (VTA), which includes the paranigral nucleus, parainterfascicular nucleus, parabrachial pigmental area, and rostral VTA. Other structures of the nicotine brain-reward circuitry activated by NIC-PM included the hypothalamus, paraventricular thalamic nucleus, lateral habenular nucleus, hippocampus, amygdala, accumbens nucleus, piriform cortex, angular insular cortex, anterior olfactory nucleus, lateral septal nucleus, bed nucleus of stria terminalis, cingulate and medial prefrontal cortex, olfactory tubercle, and medial and lateral orbital cortex. NIC, acting through central and peripheral nAChRs, produced c-Fos IR in areas that overlapped NIC-PM-induced c-Fos-expressing sites. These neuroanatomical data are the first to demonstrate that the CNS structures that are the direct targets of nicotine are also anatomical substrates for the peripheral sensory impact of nicotine.