Doses Of Nicotine Research Articles

Melanin-concentrating hormone receptor antagonism differentially attenuates nicotine experience-dependent locomotor behavior in female and male rats

Nicotine is a significant public health concern because it is the primary pharmacological agent in tobacco use disorder. One neural system that has been implicated in the symptoms of several substance use disorders is the melanin-concentrating hormone (MCH) system. MCH regulates various motivated behaviors depending on sex, yet little is known of how this interaction affects experience with drugs of abuse, particularly nicotine. The goal of this study was to determine the effect of MCH receptor antagonism on experience-dependent nicotine-induced locomotion after chronic exposure, particularly on the expression of locomotor sensitization. Adult female and male Wistar rats were given saline then cumulative doses of nicotine (0.1, 0.32, 0.56, and 1.0 mg/kg) intraperitoneally to determine the acute effects of nicotine (day 1). Next, rats were treated with 1.0 mg/kg nicotine for 6 days, given an identical series of cumulative doses (day 8), and then kept in a drug-free state for 6 days. On day 15, rats were pretreated with vehicle or the MCH receptor antagonist GW803430 (10 or 30 mg/kg) before another series of cumulative doses to assess response to chronic nicotine. After vehicle, male rats increased nicotine locomotor activation from day 1 to day 15, and both sexes showed a sensitized response when normalized to saline. The lower dose of GW803430 decreased locomotion compared to vehicle in females, while the higher dose decreased locomotion in males. Both sexes showed nicotine dose-dependent effects of GW803430, strongest at lower doses of nicotine. Controlling for sex-based locomotor differences revealed that females are more sensitive to GW803430. The high dose of GW803430 also decreased saline locomotion in males. Together, the results of our study suggest that MCH is involved in the expression of nicotine locomotor sensitization, and that MCH regulates these nicotine behavioral symptoms differently across sex.

Antioxidant Activity of Fermented Red Bean Extract on Sperm Quality of Mice Exposed to Cigarette Smoke

Smoking has a negative effect on fertilization as it decreases sperm quality. The current research aimed to investigate the effect of fermented red bean (Phaseolus vulgaris L.) extract on sperm motility, viability, and plasma membrane integrity of white mice (Mus musculus) exposed to cigarette smoke. The red beans were subjected to a 36-hour fermentation process using Rhizopus spp. Then, methanol was extracted by maceration method for 24 hours until maceration was obtained. In this study, 25 male white mice aged 3 months were randomly divided into 5 groups of 5 mice. Group C (negative control) was given 0.5 mL of carboxymethyl cellulose natrium (CMC Na) 1% solution orally without unfiltered cigarette smoke exposure, and group C+ (positive control) was given 0.5 mL of CMC Na 1% solution orally and unfiltered cigarette smoke exposure. Treatment groups T1, T2, and T3 were orally given fermented red bean extract at doses of 26 mg/kg Body weight (BW), 52 mg/kg BW, and 104 mg/kg BW, respectively, and then were exposed to unfiltered cigarette smoke. For 36 days, treatment groups (except the negative control) were subjected to the inhalation of smoke from an unfiltered cigarette containing a nicotine dose of 2.2 mg. The exposure period lasted for 20 minutes each day. Each group was put into a cigarette smoke-exposing box. The sperm motility (observing the forward movement of spermatozoa), the sperm viability (examining the color of the sperm head), and the sperm plasma membrane integrity (observing the tail shape using the hypoosmotic swelling test) were then evaluated. The findings indicated significant differences in sperm motility, viability, and plasma membrane integrity of each group with positive control. A dose of 104 mg/kg BW of fermented red bean extract had the best potential to maintain sperm motility (70%), viability (82.13%), and plasma membrane integrity (61.93%) of mice exposed to unfiltered cigarette smoke.

Pharmacological and electronic cigarette interventions for smoking cessation in adults: component network meta-analyses.

Pharmacological and electronic cigarette interventions for smoking cessation in adults: component network meta-analyses.

Experimenter administered Δ9-THC decreases nicotine self-administration in a rat model

BackgroundThe co-use of nicotine and cannabis has been steadily rising in the United States. Rodent studies suggest that delta-9-tetrahydrocannabinol (THC) could increase addictive qualities of nicotine, but whether repeated THC exposure alters self-administration of nicotine has not been tested. We hypothesized that THC would increase the reinforcing effects of nicotine and alter nicotine intake. MethodsAdult male and female Sprague-Dawley rats were treated with THC (0, 3, 30 mg/kg) daily for 14 days prior to and during training for intravenous self-administration of nicotine. Rats were allowed to self-administer nicotine for several weeks, then tested for sensitivity to nicotine dose through multiple determinations of a nicotine dose-effect curve with or without THC pretreatment. A separate set of rats were trained on fixed ratio responding for sucrose and assessed for THC effects on behavior. ResultsPost-session THC decreased nicotine self-administration in male and female rats throughout acquisition and maintenance and increased the latency to stable rates of nicotine intake during acquisition. Post-session THC shifted nicotine dose-effect curves downward, and pre-session THC suppressed responding at higher nicotine doses. Unlike nicotine, responding for sucrose was not affected by post-session THC. Pre-session THC decreased responding for sucrose, particularly for THC-naïve rats. ConclusionsRepeated post-session THC decreased nicotine-taking behaviors but did not alter sucrose responding. Thus, post-session THC may alter sensitivity to nicotine. Pre-session THC treatment decreased lever pressing in both sucrose and nicotine studies, indicating this effect was nonspecific. These studies show that THC modulates patterns of nicotine intake in rat models.

Chronic exposure to cigarette smoke extract increases nicotine withdrawal symptoms in adult and adolescent male rats.

The aim of the current study was to determine whether non-nicotine constituents of cigarette smoke contribute to nicotine dependence in adolescent and adult male Sprague Dawley rats. For 10days animals were given three times daily intravenous injections of nicotine (1.5mg/kg/day) or cigarette smoke extract (CSE) containing an equivalent dose of nicotine. Both spontaneous and mecamylamine-precipitated withdrawal were then measured. Chronic treatment with CSE induced significantly greater somatic and affective withdrawal signs than nicotine in both adolescents and adults. Mecamylamine-precipitated somatic signs were similar at both ages. In contrast, animals spontaneously withdrawn from chronic drug treatment exhibited significant age differences: whereas adolescents chronically treated with nicotine did not show somatic signs, those treated with CSE showed similar physical withdrawal to those of adults. Mecamylamine did not precipitate anxiety-like behavior at either age. However, both adolescents and adults showed significant anxiety in a light-dark box test 18h after spontaneous withdrawal. Anxiety-like behavior was still evident in an open field test 1month after termination of drug treatment, with adolescents showing significantly greater affective symptoms than adults. Our findings indicate that non-nicotine constituents of cigarette smoke do contribute to dependence in both adolescents and adults and emphasize the importance of including smoke constituents with nicotine in animal models of tobacco dependence.

Nicotine modifies cocaine responding in a concurrent self-administration model

BackgroundPreclinical models of cocaine use disorder (CUD) have not yielded any FDA-approved pharmacotherapies, potentially due to a focus on cocaine use in isolation, which may not fully translate to real-world drug taking patterns. Cocaine and nicotine are commonly used together, and clinical research suggests that nicotine may increase the potency and reinforcing strength of cocaine. In this study, we sought to determine whether and how the addition of nicotine would alter ongoing intravenous cocaine self-administration and motivation to take cocaine in rats. MethodsMale Sprague-Dawley rats self-administered cocaine alone on a long access, Fixed Ratio one (FR1) schedule, and then switched to a combination of cocaine and nicotine. Finally, rats responded on a Progressive Ratio (PR) schedule for several doses of cocaine alone and in combination with a single dose of nicotine. ResultsUnder long access conditions, rats co-self-administering cocaine and nicotine responded less and with decreased response rates than for cocaine alone and did not escalate responding. However, under PR conditions that test motivation to take drugs, the dose response curve for the combination was shifted upwards relative to cocaine alone. ConclusionsTogether, these results suggest that nicotine may enhance the reinforcing strength of cocaine, increasing PR responding for cocaine across the dose response curve.

Caffeic Acid Phenethyl Ester Reduces the Adverse Effects of Nicotine on the Endometrium.

Tobacco smoke contains various toxins that negatively affect the human reproductive system. Caffeic acid phenethyl ester (CAPE), a potent antioxidant, has protective effects on the reproductive system against oxygen-free radicals, methotrexate, and pesticides. Herein, the effect of CAPE on some key markers of endometrial receptivity has been evaluated. A cross-sectional study was conducted during 2018-2019 in the Department of Clinical Biochemistry, School of Medicine, Fasa University of Medical Sciences (Fasa, Iran). Primary endometrial cells were divided into five groups, namely control, nicotine, CAPE, vehicle, and nicotine+CAPE. Real-time polymerase chain reaction (PCR) and methylation-specific PCR were performed to evaluate gene expressions and methylation, respectively. Appropriate doses of CAPE and nicotine were determined using the MTT assay. Data were analyzed using SPSS software (version 16.0) with a one-way analysis of variance. P<0.01 was considered statistically significant. The fold change was calculated using the 2-∆ΔCT method. Treatment of cells with nicotine significantly reduced the expression of C-X-C motif chemokine ligand 12 (CXCL12), fibroblast growth factor 2 (FGF2), and vascular endothelial growth factor A (VEGF-A) genes (P<0.0001). However, the expression levels increased significantly when treated with nicotine+CAPE (P<0.0001). Despite the reduced CXCL12 gene expression in cells treated with nicotine, CXCL12 was unmethylated in all study groups, indicating that the methylation status of the CXCL12 gene was not affected by nicotine or CAPE. CAPE can be a suitable agent to protect female smokers from the harmful effects of nicotine. This manuscript is available as a preprint on the Research Gate website.

The Impact of High or Low Doses of Nicotine in a Mouse Model of Vapor Self-Administration.

A wide variety of nicotine concentrations and formulations are available to users of electronic nicotine delivery systems (ENDS). This is increasingly true when considering the many flavors available with ENDS products. To date, there have been few preclinical investigations into the impact of nicotine doses, with and without flavors, on vaping-related behaviors. This present study evaluated how nicotine concentrations relevant to tank-based and pod-based ENDS, with and without flavors, impact reinforcement-related behavior in a mouse model. Adult male and female C57/BL6J mice were used in vapor-inhalation self-administration assays. Mice were assigned e-liquids containing 6 mg/mL or 60 mg/mL nicotine. Additional mice were assigned these nicotine doses with green apple or menthol flavorants. Mice were trained on fixed-ratio 1 for 10, 2-hour sessions, then five sessions at FR3, three progressive ratio sessions, and two FR3 sessions. We observed male mice exhibited higher reinforcement-related behavior to menthol-flavored 6 mg/mL nicotine when compared to female mice. Males were only observed to have a menthol-induced enhancement of self-administration at 6 mg/mL nicotine and not 60 mg/mL nicotine. However, female mice exhibited significant menthol-induced increases in reinforcement-related behaviors with 60 mg/mL nicotine. These data provide evidence that males and females exhibit different dose sensitivities to nicotine. These sex-dependent differences in nicotine sensitivity also indicate that flavor-induced enhancement in nicotine intake is dependent on the different doses for each sex. There has been much discussion recently regarding the impact of flavors on vaping-related behavior. Our current study may support prior investigations that suggest flavors enhance the palatability of nicotine-containing products. However, this current study provides evidence that males and females exhibit different sensitivities to nicotine.

Cigarette smoking exposure disrupts the regenerative potential of dental pulp stem cells.

Smoking is known to alter the regenerative and immunomodulatory properties of many types of mesenchymal stem cells (MSCs). This study investigates the impact of cigarette smoke exposure on the regenerative potential of dental pulp stem cells (DPSCs). DPSCs were treated with various doses of cigarette smoke condensate (CSC) or nicotine. Cell proliferation and survival were evaluated by a water-soluble tetrazolium salt (WST-1) and a survival assay. DPSC migration, cytokine expression, mutagenesis, and the signaling pathway were also measured during CSC and nicotine treatment. Low concentrations of CSC and nicotine did not impair cell proliferation, but higher concentrations reduced cell proliferation. CSC and nicotine could impede DPSC survival and migration in a dose-dependent manner. In addition, the cytokine secretion expression profile was altered with CSC or nicotine treatments. In particular, secretion of IL-6, TNF-α, and IL-10 significantly increased, while TGF-β1 levels showed different patterns after exposure to CSC or nicotine, as shown by ELISA and quantitative PCR. Nicotine treatment increased AKT (also known as protein kinase B) and extracellular signal-regulated kinase (ERK) phosphorylation. Finally, CSC induced higher levels of mutagenicity than nicotine, as shown by the Ames test. These findings suggest that cigarette smoke exposure alters the regenerative abilities of DPSCs in various ways. Future studies are warranted to further characterize the underlying molecular mechanisms of smoking-mediated damage to DPSCs, which will guide the personalized stem cell treatment plan for smoking patients.

The effect of nicotine on antidepressant and anxiolytic responses induced by citalopram and citicoline in mice.

The effect of nicotine on both anxiety and depression has been broadly studied. Moreover, citalopram and citicoline play a role in the modulation of anxiety and depression. This study was designed to examine the effects of nicotine on the antidepressant and anxiolytic responses induced by citalopram and citicoline in mice. Anxiety‑ and depression‑related behaviors were assessed with the elevated plus maze and forced swim test, respectively. The results showed that subcutaneous administration of nicotine decreased open‑arm time (OAT) and open‑arm entries (OAE) but increased immobility time, suggesting anxiogenic‑like and depressive‑like effects. Intraperitoneal administration of citalopram increased OAT but decreased immobility time, indicating that citalopram induced anxiolytic‑like and antidepressant‑like responses. Additionally, an injection of citicoline increased OAE but decreased immobility time, revealing anxiolytic‑like and antidepressant‑like effects. Interestingly, the subthreshold dose of nicotine potentiated the citalopram and citicoline effects on OAT and immobility time, which revealed anxiolytic‑like and antidepressant‑like behaviors. Locomotor activity was not significantly changed by any doses of the drugs. In conclusion, these findings suggest that interactions between nicotine and citalopram or citicoline occur upon induction of anxiolytic and antidepressant responses in mice.

Assessing the effects of prenatal poly-drug exposure on fetal brain vasculature using optical coherence angiography.

Maternal exposure to drugs during pregnancy is known to have detrimental effects on the fetus. Alcohol (ethanol) and nicotine are two of the most commonly co-abused substances during pregnancy, and prenatal poly-drug exposure is common due, in part, to the prevalence of unplanned pregnancies. The second trimester is a critical period for fetal neurogenesis and angiogenesis. When drug exposure occurs during this time, fetal brain development is affected. Several behavioral, morphological, and functional studies have evaluated the changes in fetal brain development due to exposure to these drugs individually. However, research on the combined effects of ethanol and nicotine is far more limited, specifically on fetal vasculature changes and development. We use correlation mapping optical coherence angiography (cm-OCA) to evaluate acute changes in fetal brain vasculature caused by maternal exposure to a combination of ethanol and nicotine. Ethanol (16.6% v/v, at a dose of ) and nicotine (at a dose of ) were administered to pregnant mice after initial cm-OCA measurements in utero. Subsequent measurements were taken at 5-min intervals for a total period of 45min. Results from these experiments were compared to results from our previous studies in which the mother was exposed to only ethanol (dose: ) or nicotine (dose: ). While results from exposure to ethanol or nicotine independently showed vasoconstriction, no significant change in vasculature was observed with combined exposure. Results suggested antagonistic effects of ethanol and nicotine on fetal brain vasculature.

Nicotine Delivery of a Menthol-Flavored Heat-not-Burn Tobacco Product During Directed Use.

IQOS was authorized by the U.S. Food and Drug Administration (FDA) as a modified-risk tobacco product. We conducted a pharmacokinetic study evaluating the nicotine delivery and subjective effects of IQOS use among current menthol cigarette smokers to better understand if IQOS is an acceptable cigarette alternative in light of the proposed menthol cigarette ban. Participants were adult smokers of >4 menthol cigarettes per day. After 14-hour nicotine abstinence, participants were provided an IQOS device and menthol heatstick to puff every 20 seconds for a total of 14 puffs. Blood samples were collected at baseline and during active use to calculate nicotine boost from baseline to peak concentration. Nicotine withdrawal symptoms were collected before and after IQOS use. In addition, a modified Product Evaluation Scale for IQOS was collected after use. Participants (n = 8) were a mean age of 43.9 years, 63% were female, 88% identified as White, and they smoked a mean of 17.1 menthol cigarettes per day. After IQOS use, the mean nicotine boost obtained was 15.96 ng/mL (SD = 6.91) (range 9.31 to 30.55 ng/mL). Most (75%) participants reported enjoying use of the product "a lot" or greater and more than half (62.5%) reported reduced cigarette cravings. Most participants reported no side effects after use; however, two experienced dry mouth, three experienced dizziness, one experienced throat irritation, and one experienced headache. We found that directed use (14 puffs) of menthol IQOS delivered a mean nicotine boost of 15.96 ng/mL which reduced craving for a cigarette. The majority of participants enjoyed use of IQOS and reported mild side effects. Menthol IQOS delivered a sufficient dose of nicotine perceived as satisfying by menthol cigarette smokers and it reduced craving with mild side effects. Menthol IQOS has potential to serve as a less harmful alternative for menthol cigarette smokers. The availability of modified risk products like IQOS should be considered by FDA's Comprehensive Plan for Tobacco and Nicotine Regulation.

EFFECTS OF TURMERIC (CURCUMA LONGA L.) RHIZOME EXTRACT ONLUNGHISTOLOGICAL STRUCTUREIN MICE(MUSMUSCULUSL) INDUCEDNICOTINE

Nicotine is an alkaloid compound found in tobacco leaves. The use of nicotine in a long period can cause lung damage.The aim of this study was to determine the effect of giving turmeric extract (Curcuma longa L.) on lung histological structure in nicotine-induced mice. In this study, 25 male mice were divided into 5 groups. Group 1 was a negative control group without nicotine-induced and turmeric extract. Group 2 was a positive control group induced by nicotine without turmeric rhizome extract, groups 3, 4 and 5 were groups exposed to nicotine followed by giving turmeric extract at doses of 0,98, 19,6 dan 29,4 mg/kg BW. The dose of nicotine given was 2.5 mg/kg BW, given intraperitoneally for 28 days. Turmeric extract was given as gavage for 14 days. The results showed that nicotine exposure resulted in an increase in mucosal thickness of the bronchioles and alveolar septa of mice. The administration of turmeric rhizome extract resulted in a decrease in the thickness of the bronchial mucosa and alveolar septa. Giving turmeric extract at a dose of 29,4 mg/kg BW resulted in a decrease in the thickness of the bronchial mucosa and alveolar septa. The conclusion of this study is that the 29,4 mg/kg BW dose of turmeric extract is effective in repairing histological damage to lung tissue in mice.

Effect of eucalyptol on matrix metalloproteinase-9 and its tissue inhibitor in hypertensive rats.

Effects of eucalyptol, a key component of eucalyptus globules, on matrix metalloproteinase-9 (MMP-9) and its tissue inhibitor (TIMP-1), compared with lisinopril, were investigated in a model of hypertension induced by chronic intraperitoneal (IP) injection of low dose nicotine in rats. The hypertensive rats were randomly allocated to 4 groups (n=8): Positive control (PC, untreated), eucalyptol-treated group (1.0 mg/kg, IP), lisinopril-treated group (10 mg/kg, IP), and eucalyptol+lisinopril-treated group. Systolic blood pressure and plasma levels of MMP-9 and TIMP-1 were measured. All treatments decreased the elevated blood pressure and plasma levels of MMP-9 and TIMP-1 most significantly with the combination group which showed non-significant differences from the normal control group. Lisinopril reduced plasma levels of MMP-9 and TIMP-1 more significantly than eucalyptol. In conclusion, eucalyptol significantly decreased the increased plasma levels of MMP-9 and TIMP-1 in nicotine-induced hypertension in rats. Moreover, its combination with lisinopril exerted more significant effects compared to each drug alone. This makes this combination particularly useful in hypertension and related cardiovascular disorders where suppression of MMP-9 and TIMP-1 activities decreases the related complications and improves the overall morbidity and mortality. To our knowledge, the current data are novel, and may open the way for development of a co-delivery system of both drugs which could be beneficial in treatment of hypertension in chronic smokers.

The relative reinforcing efficacy of nicotine in an adolescent rat model of attention-deficit hyperactivity disorder.

Attention-deficit/hyperactivity disorder (ADHD) is an independent risk factor for tobacco use disorder. Individuals with ADHD are more likely to begin smoking at a younger age, become a daily smoker sooner, smoke more cigarettes per day, and exhibit greater nicotine dependence than individuals without ADHD. It is unclear whether these findings are due to the reinforcing efficacy of nicotine per se being greater among individuals with ADHD. The purpose of the present study was to examine this issue using an animal model of ADHD, the spontaneously hypertensive rat (SHR) strain. Adolescent SHR and Wistar (control) rats were given access to a typically reinforcing nicotine unit dose (30 μg/kg), a threshold reinforcing nicotine dose (4 μg/kg), or saline under an FR 1 (week 1) and FR 2 (week 2) schedule during 23 h sessions to examine acquisition of self-administration. Behavioral economic demand elasticity was then evaluated at the 30 μg/kg dose through an FR escalation procedure. At the 30 μg/kg dose, SHR rats exhibited a lower average response rate, lower mean active to inactive lever discrimination ratio, and lower proportion of rats acquiring self-administration compared to control rats. During demand assessment, SHR rats showed no significant difference from Wistars in demand intensity (Q0) or elasticity (α; i.e., reinforcing efficacy). In addition, no strain difference in acquisition measures were observed at the 4 μg/kg dose. These findings suggest that the increased risk of tobacco use disorder in adolescents with ADHD may not be attributable to a greater reinforcing efficacy of nicotine, and that other aspects of tobacco smoking (e.g., non-nicotine constituents, sensory factors) may play a more important role. A policy implication of these findings is that a nicotine standard to reduce initiation of tobacco use among adolescents in the general population may also be effective among those with ADHD.

Investigating the Co-administration of Ghrelin and Nicotine into the Medial Septum and Its Influencing on Morphine Amnestic Effect

Introduction: Evidence indicates that medial septum nicotinic receptors regulate cognitive processes. Ghrelin is a gut hormone that regulates energy homeostasis. Ghrelin is also produced in the brain and is involved in cognitive function. This study aims to evaluate the effects of medial septal administration of ghrelin on the amnestic effect of morphine in rats.In addition, the possible relationship between the medial septal ghrelin and acetylcholine nicotinic receptors on the amnestic effect of morphine is evaluated. Methods: The rats were implanted at the medial septum area and were microinjected with ghrelin and nicotinic receptor agents. The step-through type inhibitory avoidance apparatus was used for memory retrieval assessment. Results: The results showed that the administration of morphine after the training phase impaired memory consolidation. Post-training intra-septal injection of the same doses of either ghrelin or nicotine did not change memory performance; however, their co-application with morphine (significant dose: 7.5 mg/kg subcutaneous injection) increased the step-through latency and improved memory consolidation. Moreover, post-training co-application of low doses of the two agonists could not affect morphine-induced memory impairment. Conclusion: These results indicated no interaction between medial septal ghrelin and nicotinic receptors on the amnestic effect of morphine in rats.

Comparison of a Daily Smartphone App and Retrospective Questionnaire Measures of Adherence to Nicotine Replacement Therapy Among Pregnant Women: Observational Study.

Few studies have investigated how to best measure adherence to smoking cessation medications, but continuous usage measures are recommended. In this first study of its kind, we compared methods for measuring adherence to nicotine replacement therapy (NRT) among pregnant women, investigating the completeness and validity of data collected from daily assessments using a smartphone app versus data collected from retrospective questionnaires. Women aged ≥16 years who were daily smokers and <25 weeks pregnant were offered smoking-cessation counseling and encouraged to use NRT. For 28 days after setting a quit date (QD), women were asked to report NRT use daily to a smartphone app and to questionnaires administered in person or remotely at 7 and 28 days. For both data collection methods, we provided up to £25 (~US $30) as compensation for the time taken providing research data. Data completeness and NRT use reported to the app and in questionnaires were compared. For each method, we also correlated mean daily nicotine doses reported within 7 days of the QD with Day 7 saliva cotinine concentrations. Of the 438 women assessed for eligibility, 40 participated and 35 accepted NRT. More participants (31/35) submitted NRT usage data to the app by Day 28 (median 25, IQR 11 days) than completed the Day 28 questionnaire (24/35) or either of the two questionnaires (27/35). Data submitted to the app showed a lower reported duration of NRT use compared to that indicated in the questionnaire (median for app 24 days, IQR 10.25; median for questionnaire 28 days, IQR 4.75; P=.007), and there appeared to be specific cases of overreporting to the questionnaire. Mean daily nicotine doses between the QD and Day 7 were lower when calculated using app data (median for app 40 mg, IQR 52.1; median for questionnaire 40 mg, IQR 63.1; P=.001), and some large outliers were evident for the questionnaire. Mean daily nicotine doses, adjusted for cigarettes smoked, were not associated with cotinine concentrations for either method (app rs=0.184, P=.55; questionnaire rs=0.031, P=.92), but the small sample size meant that the analysis was likely underpowered. Daily assessment of NRT use via a smartphone app facilitated more complete data (a higher response rate) than questionnaires, and reporting rates over 28 days were encouraging among pregnant women. App data had better face validity; retrospective questionnaires appeared to overestimate NRT use for some participants.

Threshold for the pleasurable effects of nicotine are lower than its reinforcing effects during self-administration.

A recent study demonstrated that during a single sampling period, 0.1 mg of intravenous (IV) nicotine (vs. placebo) was found to be the threshold for subjective and physiological drug effects. The present study is a secondary analysis evaluating whether the threshold for subjective and physiological effects is similar when the subject has repeated opportunities to choose blinded doses of nicotine versus placebo. We also examined whether cigarette craving, withdrawal, and rate of nicotine metabolism affected nicotine reinforcement, defined by a greater number of nicotine choices than placebo. Young adult (n = 34; 68% male), daily smokers had five laboratory sessions after overnight abstinence. After sampling an IV dose of nicotine (0.0125, 0.025, 0.05, 0.1, or 0.2 mg/70 kg) versus saline (placebo), participants completed a nicotine self-administration (NSA) procedure that included 10 opportunities to self-administer IV dose of nicotine or placebo. The threshold for subjective positive effects of nicotine during the NSA was equal to or lower than the sampling period, 0.05-0.1 mg versus 0.1 mg. The threshold for nicotine-induced heart rate increase was higher during the NSA than during the sampling period (0.2 mg vs. 0.1 mg). Higher baseline craving and nicotine metabolite ratio (NMR) were associated with nicotine reinforcement at 0.2 mg and 0.1 mg doses, respectively (p < .05). The results suggest that subjective effects during NSA are reported at doses lower than the sampling period. Taken together, tobacco products thought to be subthreshold for reinforcement should be carefully evaluated for their subjective effects, including their discriminative stimulus effects. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Post-weaning social isolation increases the incentive value of nicotine-related contexts and decreases the accumulation of ΔFosB in nucleus accumbens in adolescent rats

Adolescent social conditions profoundly affect vulnerability to drug abuse. Preclinical studies have shown that preventing social interactions during adolescence increases the rewarding effects of drugs like alcohol, cocaine, or amphetamines, however, little data exist regarding the impact of social isolation on nicotine effects. The current study evaluated the effects of differential rearing conditions during adolescence (isolation or group rearing) on (1) conditioned place preference induced by low nicotine doses (0.1 or 0.3 mg/kg) and (2) sensitization to the locomotor effects of nicotine after sub-chronic administration (3) and accumulation of ΔFosB in nucleus accumbens (NAc). Results showed that nicotine induced place preference in isolated and grouped rats, but the effect was more persistent for the rats reared in isolation. Isolated reared rats also exhibited lower levels of ΔFosB accumulation in NAc. No differences were found in the behavioral sensitization to nicotine effects between rearing conditions. The results suggest that isolation engenders a more robust incentive value of nicotine-related contexts. This effect could be related to the basal expression of ΔFosB: lower levels of this transcription factor seem to impair the motivation of isolated reared rats and increase their vulnerability to the effects of drugs like nicotine.

Examining racial differences in smoking outcomes among smokers enrolled in an intravenous nicotine infusion study

IntroductionLarge racial disparities exist in the prevention and treatment of smoking-related diseases, and minoritized populations carry a heavier burden of smoking-related morbidity and mortality. To date, most studies investigating smoking-related illnesses have been conducted in samples in which the majority, or totality, self-identified as White or Caucasian. While Black individuals who smoke tend to have a lower rate of nicotine clearance, in part due to the use of mentholated cigarettes, less is known about how slower clearance affects their acute subjective and physiologic responses in response to either overnight abstinence or subsequent nicotine administration. This study aimed to investigate differences between the experiences of Black and White individuals who smoke across these outcomes after a period of short-term abstinence and after IV nicotine infusion. MethodsThe study included 206 smokers (N = 103 Black, N = 103 White, by self-report). The study investigated self-report, physiological, and biochemical smoking-related outcomes following confirmed overnight abstinence followed by IV nicotine infusion. The outcome measures were separately analyzed with repeated-measures mixed-models. ResultsBlack individuals had lower rates of nicotine clearance and were more likely to smoke mentholated cigarettes than White individuals. Despite these differences, no differences in withdrawal, cravings, or physiological outcomes were observed between the two groups. There were some trends toward differences in subjective experiences, in that an interaction with trend level significance between race and dose was observed for negative subjective drug effects, with White smokers trending towards endorsing higher levels of negative affect after abstinence and nicotine infusion. We also observed that Black individuals trended towards experiencing more negative drug effects in response to initial nicotine delivery than to saline, whereas White individuals had no differences in negative drug effects across saline or nicotine doses. ConclusionsDespite slower nicotine clearance, Black participants exhibited withdrawal and urges to smoke as severe as White participants, and did not have blunted physiological responses to overnight abstinence or administration of nicotine, which were contrary to our hypotheses. Our findings suggest minimal differences across races in the acute pharmacologic effects of nicotine. We observed trend-level differences in subjective and affective responses to nicotine. Greater insight into these differences may lead to improved prevention and treatment strategies for smoking-related illnesses for Black individuals who smoke.