Rewarding Effects Of Nicotine Research Articles

Attenuation of nicotine-induced rewarding and antidepressant-like effects in male and female mice lacking regulator of G-protein signaling 2

Nicotine-induced rewarding and mood altering effects contribute to the continued use of nicotine and the subsequent development of nicotine dependence. The goal of this study was to assess the role of two specific regulators of G-protein signaling (RGS) proteins namely RGS2 and RGS4 in the above described effects of nicotine. Male and female mice lacking either RGS2 (RGS2 KO) or RGS4 (RGS4 KO), and their respective wildtype (WT) littermates were used in this study. The rewarding effects of nicotine (0.5 mg/kg, base; s.c.) were assessed using the conditioned place preference model. Nicotine-induced anxiolytic-like (0.1 mg/kg, base; i.p.) and antidepressant-like (1 mg/kg, base; i.p.) effects were assessed using the elevated plus maze and tail suspension test, respectively. We also assessed effects of nicotine (0, 0.05, 0.1 & 0.5 mg/kg, base; s.c.) on spontaneous locomotor activity. Nicotine-induced rewarding and antidepressant-like effects were observed in both male and female RGS2 WT mice, but not in mice lacking RGS2 compared to respective controls. In contrast, nicotine-induced rewarding and antidepressant-like effects were observed in both male and female mice lacking RGS4 and their WT littermates. Interestingly, deletion of RGS4 facilitated antidepressant-like effect of nicotine in male, but not female mice compared to respective WT littermates. Nicotine-induced anxiolytic-like effect was not influenced by deletion of either RGS2 or RGS4, irrespective of sex. Nicotine (0.5 mg/kg) decreased locomotor activity in both WT and KO mice compared to respective saline, irrespective of genotype and sex. Taken together, these data provide evidence that RGS2, but not RGS4, plays a role in mediating the rewarding and antidepressant-like effects of nicotine. Further research is required to explore the role of RGS2 after chronic exposure to nicotine.

Significant association of mu-opioid receptor 1 haplotype with tobacco smoking in healthy control subjects but not in patients with schizophrenia and alcohol dependence

Tobacco smoking is highly prevalent in patients with schizophrenia and alcohol dependence. The underlying neurobiology of nicotine addiction is complex. Rewarding effects of nicotine from cigarettes are associated, among others, with mu-opioid receptors encoded by the OPRM1 gene. The aim of the study was to evaluate the association between two OPRM1 gene polymorphisms, rs1799971 and rs510769, and tobacco smoking in Caucasian patients with schizophrenia, alcohol dependence, and healthy control subjects. The study included 1058 Caucasians (277 patients with schizophrenia, 359 patients with alcohol dependence, and 422 healthy control subjects), subdivided according to the nicotine dependence into smokers (i.e. current smokers) and non-smokers. A significant association was found between the GC haplotype (OPRM1 rs1799971 and rs510769) and smoking in healthy controls, but not in patients with schizophrenia and alcohol dependence. A nominal association was detected in all cases/controls, but this significance did not survive the correction for the multiple testing. This is the first study to reveal that nicotine dependence is associated with the GC haplotype of the OPRM1 rs1799971 and rs510769 in all subjects or specifically in healthy controls. These results did not confirm the strong connection between OPRM1 polymorphisms and nicotine dependence in schizophrenia or alcohol dependence.

Behavioural and pharmacological profiles of zebrafish administrated pyrrolidinyl benzodioxanes and prolinol aryl ethers with high affinity for heteromeric nicotinic acetylcholine receptors.

Prolinol aryl ethers and their rigidified analogues pyrrolidinyl benzodioxanes have a high affinity for mammalian α4β2 nicotinic acetylcholine receptors (nAChRs). Electrophysiological studies have shown that the former are full agonists and the latter partial agonists or antagonists of human α4β2 receptors, but their in vivo effects are unknown. As α4β2 nAChRs play an important role in the cognition and the rewarding effects of nicotine, we tested the effects of two full agonists and one antagonist on spatial learning, memory and attention in zebrafish using a T-maze task and virtual object recognition test (VORT). The effect of a partial agonist in reducing nicotine-induced conditioned place preference (CPP) was also investigated. In comparison with the vehicle alone, the full agonists MCL-11 and MCL-28 induced a significant cognitive enhancement as measured by the reduced running time in the T-maze and increased attention as measured by the increased discrimination index in the VORT. MCL-11 was 882 times more potent than nicotine. The two compounds were characterised by an inverted U-shaped dose-response curve, and their effects were blocked by the co-administration of the antagonist MCL-117, which alone had no effect. The partial agonist MCL-54 induced CPP and had an inverted U-shaped dose-response curve similar to that of nicotine but blocked the reinforcing effect of co-administered nicotine. Binding studies showed that all of the compounds have a higher affinity for heteromeric [3H]-epibatidine receptors than [125I]-αBungarotoxin receptors. MCL-11 was the most selective of heteromeric receptors. These behavioural studies indicate that full agonist prolinol aryl ethers are very active in increasing spatial learning, memory and attention in zebrafish. The benzodioxane partial agonist MCL-54 reduced nicotine-induced CPP, and the benzodioxane antagonist MCL-117 blocked all agonist-induced activities.

Regulators Of G‐Protein Signaling 2 And 4 Differentially Regulate the Rewarding Effects of Nicotine and Cocaine

Addiction to nicotine and cocaine is a major cause of preventable premature morbidity and mortality. The reinforcing effects of nicotine and cocaine are primarily mediated by increasing dopamine in the mesolimbic reward pathway. The effects of neurotransmitters like dopamine in this pathway are mediated by G protein‐coupled receptors (GPCRs). Interestingly, regulator of G protein‐signaling (RGS) proteins negatively regulate the functioning of GPCRs. In this study we specifically focused on the role of RGS2 and RGS4, which are extensively distributed in the mesolimbic reward pathway. This study evaluated the effects of RGS2 and RGS4 in the rewarding effects of nicotine (0.5 mg/kg; s.c.; base) and cocaine (15 mg/kg; i.p.) using conditioned place preference procedure (CPP) in mice lacking either RGS2 (i.e. RGS2 KO) or RGS4 (RGS4 KO) and their wildtype counterparts. Because a role of sex has been reported in the effects mediated by different RGS proteins, both male and female mice lacking either RGS2 or RGS4 were studied while assessing the rewarding effects of cocaine and nicotine. Cocaine and nicotine‐induced CPP was observed in all wildtype mice irrespective of genotype and sex. Cocaine‐induced rewarding effects were attenuated in male RGS4 KO mice, but not male RGS2 KO mice compared to respective saline controls. In contrast, nicotine‐induced rewarding effects were attenuated in male RGS2 KO mice, but not in male RGS4 KO mice compared to respective saline controls. Interestingly, knockout of either RGS2 or RGS4 in female mice had no effect on nicotine or cocaine‐induced rewarding effects, respectively. Thus, these data suggest both genotype and sex‐dependent differential effects of RGS2 and RGS4 in the rewarding effects of nicotine and cocaine. Clinically, the data support a role for targeting RGS2 and RGS4 for the treatment nicotine and cocaine addiction, respectively.Support or Funding InformationThis work was supported by a Bower, Bennett and Bennett grant awarded to Dr. Manoranjan S. D’Souza by the Raabe College of Pharmacy, Ohio Northern University (ONU), Ada, Ohio.

Examination of nicotine and saccharin reward in the Goto-Kakizaki diabetic rat model

Morbidity and mortality attributed to type 2 diabetes have exponentially increased in the US. At exceptionally high risk is a subpopulation of persons with type 2 diabetes who smoke, which are shown to have decreased success rates of smoking cessation than euglycemic smokers. Preclinical research in our laboratory has shown that the rewarding effects of nicotine are enhanced in the streptozotocin and high-fat diet rodent model of diabetes. It is presently unclear whether this enhancement of nicotine reward can be demonstrated in other insulin resistant rat models. This study aimed to determine if a similar increase in nicotine reward is found in Goto-Kakizaki (GK) rats, a model of the spontaneous formation of insulin resistance in an inbred sub-strain of Wistar rat. Nicotine conditioned place preference (CPP) was examined in Sprague-Dawley (SD), Wistar, and GK rats. A robust nicotine CPP was found in SD and Wistar rats, but nicotine CPP was not detected in GK rats. Locomotor activity was also evaluated in all three strains, and GK rats demonstrated significantly less activity as compared to SD and Wistar rats. To further assess reward behavior in GK rats, consumption of saccharin solution was measured over a 48 -h period. GK rats showed a significant increase in saccharin intake compared to SD rats. These findings suggest that GK rats experience an enhanced hedonic processing as compared to SD rats. The lack of nicotine CPP in GK rats may be due to deficits in learning and memory, thus hindering their ability to acquire or express a place preference.

Cytisine as an alternative smoking cessation product for Pacific smokers in New Zealand

ABSTRACT 
 Introduction: Pacific people in New Zealand have one of the highest rates of smoking. Cytisine is a plant-based alkaloid that has proven efficacy, effectiveness and safety compared to a placebo and nicotine replacement therapy (NRT) for smoking cessation. Cytisine, like varenicline, is a partial agonist of nicotinic acetylcholine receptors, and blocks the rewarding effects of nicotine. Cytisine is naturally found in some plants in the Pacific region, and so may appeal to Pacific smokers wanting to quit. This paper investigates the acceptability of cytisine as a smoking cessation product for Pacific smokers in New Zealand, using a qualitative study design.
 Methods: In December 2015, advertisements and snowball sampling was used to recruit four Pacific smokers and three Pacific smoking cessation specialists in Auckland, New Zealand. Semi-structured interviews where undertaken, whereby participants were asked about motivations to quit and their views on smoking cessation products, including cytisine (which is currently unavailable in New Zealand). Interviews were recorded and transcribed verbatim, with thematic analysis conducted manually.
 Findings: Pacific smokers reported wanting to quit for loved ones and family, but did not find currently available smoking cessation products effective. Almost all participants had not previously heard of cytisine, but many of the Pacific smokers were keen to try it. Participants identified with cytisine on a cultural basis (given its natural status), but noted that their use would be determined by the efficacy of the medicine, its cost, side-effects, and accessibility. They were particularly interested in cytisine being made available in liquid form, which could be added to a “smoothie” or drunk as a “traditional tea”. Participants thought cytisine should be promoted in a culturally-appropriate way, with packaging and advertising designed to appeal to Pacific smokers.
 Conclusions: Cytisine is more acceptable to Pacific smokers than other smoking cessation products, because of their cultural practices of traditional medicine and the natural product status of cytisine.

N-Oleoyl-glycine reduces nicotine reward and withdrawal in mice

Cigarette smokers with brain damage involving the insular cortex display cessation of tobacco smoking, suggesting that this region may contribute to nicotine addiction. In the present study, we speculated that molecules in the insular cortex that are sensitive to experimental traumatic brain injury (TBI) in mice might provide leads to ameliorate nicotine addiction. Using targeted lipidomics, we found that TBI elicited substantial increases of a largely uncharacterized lipid, N-acyl-glycine, N-oleoyl-glycine (OlGly), in the insular cortex of mice. We then evaluated whether intraperitoneal administration of OlGly would alter withdrawal responses in nicotine-dependent mice as well as the rewarding effects of nicotine, as assessed in the conditioned place preference paradigm (CPP). Systemic administration of OlGly reduced mecamylamine-precipitated withdrawal responses in nicotine-dependent mice and prevented nicotine CPP. However, OlGly did not affect morphine CPP, demonstrating a degree of selectivity. Our respective in vitro and in vivo observations that OlGly activated peroxisome proliferator-activated receptor alpha (PPAR-α) and the PPAR-α antagonist GW6471 prevented the OlGly-induced reduction of nicotine CPP in mice suggests that this lipid acts as a functional PPAR-α agonist to attenuate nicotine reward. These findings raise the possibility that the long chain fatty acid amide OlGly may possess efficacy in treating nicotine addiction.

Associations of rare nicotinic cholinergic receptor gene variants to nicotine and alcohol dependence.

Nicotine's rewarding effects are mediated through distinct subunits of nAChRs, encoded by different nicotinic cholinergic receptor (CHRN) genes and expressed in discrete regions in the brain. In the present study, we aimed to test the associations between rare variants at CHRN genes and nicotine dependence (ND), and alcohol dependence (AD). A total of 26,498 subjects with nine different neuropsychiatric disorders in 15 independent cohorts, which were genotyped on Illumina, Affymetrix, or PERLEGEN microarray platforms, were analyzed. Associations between rare variants (minor allele frequency (MAF) <0.05) at CHRN genes and nicotine dependence, and alcohol dependence were tested. The mRNA expression of all Chrn genes in whole mouse brain and 10 specific brain areas was investigated. All CHRN genes except the muscle-type CHRNB1, including eight genomic regions containing 11 neuronal CHRN genes and three genomic regions containing four muscle-type CHRN genes, were significantly associated with ND, and/or AD. All of these genes were expressed in the mouse brain. We conclude that CHRNs are associated with ND (mainly) and AD, supporting the hypothesis that the full catalog of ND/AD risk genes may contain most neuronal nAChRs-encoding genes. © 2016 Wiley Periodicals, Inc.

Insight into the Potential Factors That Promote Tobacco Use in Vulnerable Populations

It is presently unclear why certain populations are more vulnerable to tobacco use and less responsive to smoking cessation interventions. This review considers the contribution of nicotine reward and withdrawal in populations that appear to be more susceptible to tobacco use. Our focus is on populations that have been modeled in rodents including, adolescents, females, and persons with metabolic disorders, such as diabetes. A common feature across these rodent models is heightened nicotine reward, suggesting that vulnerable populations may experience strong rewarding effects of nicotine that promote tobacco use. One distinguishing factor among these rodent models of at-risk populations is with regard to the magnitude of nicotine withdrawal, which is lower during adolescence. These groups also differ with regard to expression of the physical signs versus affective states produced by withdrawal, suggesting that these distinct facets of withdrawal differentially contribute to tobacco use in vulnerable populations. Thus, we may need to apply different diagnostic criteria and/or specialized treatments that target the unique factors that promote tobacco use in different vulnerable populations.

A test of the aversive versus the rewarding effects of nicotine in rats neonatally treated with quinpirole

A test of the aversive versus the rewarding effects of nicotine in rats neonatally treated with quinpirole

Strain-dependent performance in nicotine-induced conditioned place preference.

Nicotine addiction is most likely a result of a combination of factors including the rewarding effects of the drug; these effects, however, might be influenced by genetic background. Using a conditioned place preference (CPP) paradigm and 8 inbred mouse strains, we conducted an initial examination of the role of genetic background in the rewarding effects of nicotine. Following habituation and initial place preference test, inbred strains (A/J, BALB/cByJ, C3H/HeJ, C57BL/6J, CBA/J, DBA/1J, DBA/2J, and 129/SvEv) were trained and tested in CPP for nicotine (0.35 mg/kg). Although several strains (C57BL/6J, CBA/J, and 129/SvEv) showed nicotine-induced CPP, 1 strain (DBA/1J) showed conditioned place aversion (CPA), and other strains (A/J, BALB/cByJ, C3H/HeJ, and DBA/2J) did not show CPP. Overall, these results indicate that nicotine's rewarding effects tested in CPP are differentially affected by the genetic background, and this trait has a relatively high heritability (42%-57%). This initial investigation lays the foundation for future studies examining the genetic substrates of nicotine reward.

Mu Opioid Receptor Binding Correlates with Nicotine Dependence and Reward in Smokers.

The rewarding effects of nicotine are associated with activation of nicotine receptors. However, there is increasing evidence that the endogenous opioid system is involved in nicotine's rewarding effects. We employed PET imaging with [11C]carfentanil to test the hypotheses that acute cigarette smoking increases release of endogenous opioids in the human brain and that smokers have an upregulation of mu opioid receptors (MORs) when compared to nonsmokers. We found no significant changes in binding potential (BPND) of [11C]carfentanil between the placebo and the active cigarette sessions, nor did we observe differences in MOR binding between smokers and nonsmokers. Interestingly, we showed that in smokers MOR availability in bilateral superior temporal cortices during the placebo condition was negatively correlated with scores on the Fagerström Test for Nicotine Dependence (FTND). Also in smokers, smoking-induced decreases in [11C]carfentanil binding in frontal cortical regions were associated with self-reports of cigarette liking and wanting. Although we did not show differences between smokers and nonsmokers, the negative correlation with FTND corroborates the role of MORs in superior temporal cortices in nicotine addiction and provides preliminary evidence of a role of endogenous opioid signaling in frontal cortex in nicotine reward.

The Absence of Blocking Innicotine High-Responders as a Possible Factor in the Development of Nicotine Dependence?

Rationale: The importance of reward-associated cues in eliciting behavior is well established, with stimuli associated with drugs of abuse known to play a crucial role in recidivism. Recently, Redish (2004) proposed that drugs, acting as unconditional stimuli (US), remain associable even after being fully predicted by a conditional stimulus (CS), meaning that they are not susceptible to the blocking effect (1); if correct, this may represent a possible mechanism to explain exaggerated cue-controlled drug-seeking and reinstatement in nicotine dependence and substance dependence problems in general. Objectives: We tested whether pairings between nicotine and an environmental CS would convey conditioned reinforcement properties onto the CS, even when nicotine's rewarding effects were already fully predicted by another cue (whether there was an absence of the blocking effect). Methods: 134 male Long-Evans rats were implanted with jugular catheters and assigned to either food- or nicotine-reward (0.06 mg/kg/inf) conditions. Each group was exposed to paired or unpaired presentations of their respective reward with one CS in 10 daily sessions; subsequently, they were exposed to 4 more daily sessions of paired presentations of the reward paired with a compound CS composed of the original CS and a second CS. Tests of the conditioned reinforcing value of both CSs using the active-lever-presses to total-presses ratio as an outcome were conducted following training. Results: Pressing for a blocked second CS (µ = 0.59, SD = 0.21) was significantly lower than pressing for an unblocked second CS (µ = 0.69, SD = 0.14) in the food-reward condition, but not in nicotine-rewarded animals, verifying the hypothesis that nicotine, but not food, is resilient to the blocking effect. Conclusion: The absence of blocking when nicotine is the reward may explain the powerful role for cues in supporting tobacco dependenceby allowing for the extension of nicotine's rewarding value across numerous associated cues.

Initiating buprenorphine maintenance for opiate-dependent hospitalized patients: A randomized trial

Initiating buprenorphine maintenance for opiate-dependent hospitalized patients: A randomized trial

KK-92A, a novel Gaba B receptor positive modulator, attenuates the rewarding effects of nicotine in rat

KK-92A, a novel Gaba B receptor positive modulator, attenuates the rewarding effects of nicotine in rat

An fMRI study of nicotine-deprived smokers' reactivity to smoking cues during novel/exciting activity.

Engaging in novel/exciting (“self-expanding”) activities activates the mesolimbic dopamine pathway, a brain reward pathway also associated with the rewarding effects of nicotine. This suggests that self-expanding activities can potentially substitute for the reward from nicotine. We tested this model among nicotine-deprived smokers who, during fMRI scanning, played a series of two-player cooperative games with a relationship partner. Games were randomized in a 2 (self-expanding vs. not) x 2 (cigarette cue present vs. absent) design. Self-expansion conditions yielded significantly greater activation in a reward region (caudate) than did non-self-expansion conditions. Moreover, when exposed to smoking cues during the self-expanding versus the non-self-expanding cooperative games, smokers showed less activation in a cigarette cue-reactivity region, a priori defined [temporo-parietal junction (TPJ)] from a recent meta-analysis of cue-reactivity. In smoking cue conditions, increases in excitement associated with the self-expanding condition (versus the non-self-expanding condition) were also negatively correlated with TPJ activation. These results support the idea that a self-expanding activity promoting reward activation attenuates cigarette cue-reactivity among nicotine-deprived smokers. Future research could focus on the parameters of self-expanding activities that produce this effect, as well as test the utility of self-expansion in clinical interventions for smoking cessation.

1H-Nuclear magnetic resonance-based metabolomic analysis of brain in mice with nicotine treatment

BackgroundNicotine is rapidly absorbed from cigarette smoke and therefore induces a number of chronic illnesses with the widespread use of tobacco products. Studies have shown a few cerebral metabolites modified by nicotine; however, endogenous metabolic profiling in brain has not been well explored.ResultsH NMR-based on metabonomics was applied to investigate the endogenous metabolic profiling of brain hippocampus, nucleus acumens (NAc), prefrontal cortex (PFC) and striatum. We found that nicotine significantly increased CPP in mice, and some specific cerebral metabolites differentially changed in nicotine-treated mice. These modified metabolites included glutamate, acetylcholine, tryptamine, glucose, lactate, creatine, 3-hydroxybutyrate and nicotinamide-adenine dinucleotide (NAD), which was closely associated with neurotransmitter and energy source. Additionally, glutathione and taurine in hippocampus and striatum, phosphocholine in PFC and glycerol in NAc were significantly modified by nicotine, implying the dysregulation of anti-oxidative stress response and membrane metabolism.ConclusionsNicotine induces significant metabonomic alterations in brain, which are involved in neurotransmitter disturbance, energy metabolism dysregulation, anti-oxidation and membrane function disruptions, as well as amino acid metabolism imbalance. These findings provide a new insight into rewarding effects of nicotine and the underlying mechanism.

Impact of Nicotine Metabolism on Nicotine’s Pharmacological Effects and Behavioral Responses: Insights from a Cyp2a(4/5)bgs-Null Mouse

Nicotine metabolism is believed to affect not only nicotine's pharmacological effects but also nicotine addiction. As a key step toward testing this hypothesis, we have studied nicotine metabolism and nicotine's pharmacological and behavioral effects in a novel knockout mouse model [named Cyp2a(4/5)bgs-null] lacking a number of cytochrome P450 genes known to be or possibly involved in nicotine metabolism, including two Cyp2a and all Cyp2b genes. We found that, compared with wild-type mice, the Cyp2a(4/5)bgs-null mice showed >90% decreases in hepatic microsomal nicotine oxidase activity in vitro, and in rates of systemic nicotine clearance in vivo. Further comparisons of nicotine metabolism between Cyp2a(4/5)bgs-null and Cyp2a5-null mice revealed significant roles of both CYP2A5 and CYP2B enzymes in nicotine clearance. Compared with the behavioral responses in wild-type mice, the decreases in nicotine metabolism in the Cyp2a(4/5)bgs-null mice led to prolonged nicotine-induced acute pharmacological effects, in that null mice showed enhanced nicotine hypothermia and antinociception. Furthermore, we found that the Cyp2a(4/5)bgs-null mice developed a preference for nicotine in a conditioned place preference test, a commonly used test of nicotine's rewarding effects, at a nicotine dose that was 4-fold lower than what was required by wild-type mice. Thus, CYP2A/2B-catalyzed nicotine clearance affects nicotine's behavioral response as well as its acute pharmacological effects in mice. This result provides direct experimental support of the findings of pharmacogenetic studies that suggest linkage between rates of nicotine metabolism and smoking behavior in humans.

Extinction Burst after Varenicline Titration: A Case Report

Background: The mechanism of action of varenicline as a partial agonist may make it useful for cigarette reduction as smokers experience reduced craving and withdrawal at the same time their cigarettes provide reduced reinforcement value.Case Description: The current case report describes a 51-year-old African American woman using varenicline to reduce her cigarette use. After making a substantial reduction in cigarettes per day (from 25 to 8), the patient unexpectedly began smoking considerably more (from 8 to 20) after 11 days treatment with varenicline.Conclusions: The temporary increase in smoking while taking varenicline was likely the result of an ‘extinction burst’ where the extinction of a reward (e.g., nicotine's rewarding effects after smoking a cigarette) was temporarily associated with an increase in the behaviour usually associated with the reward (e.g., smoking a cigarette). Once explaining to her that no amount of cigarettes would overcome the feeling of reduced reward she likely felt while taking varenicline, she was able to reduce her smoking again.

CC4, a dimer of cytisine, is a selective partial agonist at α4β2/α6β2 nAChR with improved selectivity for tobacco smoking cessation.

Many of the addictive and rewarding effects of nicotine are due to its actions on the neuronal nicotinic ACh receptor (nAChR) subtypes expressed in dopaminergic mesocorticolimbic cells. The partial agonists, cytisine and varenicline, are helpful smoking cessation aids. These drugs have a number of side effects that limit their usefulness. The aim of this study was to investigate the preclinical pharmacology of the cytisine dimer1,2-bisN-cytisinylethane (CC4). The effects of CC4 on nAChRs were investigated using in vitro assays and animal behaviours. When electrophysiologically tested using heterologously expressed human subtypes, CC4 was less efficacious than cytisine on neuronal α4β2, α3β4, α7 and muscle-type receptors, and had no effect on 5-hydroxytryptamine3 receptors. Acting through α4β2 and α6β2 nAChRs, CC4 is a partial agonist of nAChR-mediated striatal dopamine release and, when co-incubated with nicotine, prevented nicotine's maximal effect on this response. In addition, it had low affinity for, and was less efficacious than nicotine and cytisine on the α3β4 and α7-nAChR subtypes. Like cytisine and nicotine, CC4-induced conditioned place preference (CPP), and its self-administration shows an inverted-U dose-response curve. Pretreatment with non-reinforcing doses of CC4 significantly reduced nicotine-induced self-administration and CPP without affecting motor functions. Our in vitro and in vivo findings reveal that CC4 selectively reduces behaviours associated with nicotine addiction consistent with the partial agonist selectivity of CC4 for β2-nAChRs. The results support the possible development of CC4 or its derivatives as a promising drug for tobacco smoking cessation.