Increase In Nicotine Concentration Research Articles

Evaluating trends in recruitment challenges in vape shop research, e-cigarette product characteristics and use among shop customers from 2019 to 2023: A mixed-methods study.

Brick-and-mortar vape shops specialize in the sale of e-cigarettes and remain a primary source for purchasing emerging e-cigarette products. New regulatory policies have been implemented at local-, state- and federal-level; the retail environment at vape shops and product preferences among vape shop customers shifted accordingly. From 2019 to 2023, we collected anonymous interview data from vape shop customers (n=572) from 83 vape shops in Southern California. We aggregated the data by month and treated each month as the unit of analysis to document changes in recruitment efforts among the vape shops in relation to major policy implementations over 4 years. We also examined the systematic fluctuations and trends in customers' e-cigarette product preferences and nicotine content in these products. The monthly average shop-level consent rate was 52.9% (SD=8.7), with an overall decreasing trend over time. It was necessary for our data collection team to approach a greater number of vape shops to obtain consent with implementation of various state and federal tobacco regulations and following COVID-19. We observed an increase in the purchase of disposable products and nicotine concentrations in the products, while the average use frequency remained the same. Our findings demonstrated that user preferences, product characteristics and challenges in research involving vape shops are closely associated to changes in regulations. We documented a dramatic increase in nicotine concentration in products. Future policies restricting the amount of nicotine in tobacco products at the federal level are necessary to protect consumers from further nicotine addiction. This study provides documentation over time of the drastic increases in nicotine concentration among e-cigarette users as a result of the fluctuations in the product market. Regulating nicotine content in tobacco products could safeguard against further unsafe modifications in e-cigarettes and other types of tobacco products.

Associations of Electronic Cigarette Nicotine Concentration With Subsequent Cigarette Smoking and Vaping Levels in Adolescents

Research indicates that electronic cigarette (e-cigarette) use (vaping) among adolescents is associated with the initiation and progression of combustible cigarette smoking. The reasons for this association are unknown. To evaluate whether use of e-cigarettes with higher nicotine concentrations is associated with subsequent increases in the frequency and intensity of combustible cigarette smoking and vaping. In this prospective cohort study involving students from 10 high schools in the Los Angeles, California, metropolitan area, surveys were administered during 10th grade in the spring (baseline) and 11th grade in the fall (6-month follow-up) of 2015 to students who reported using e-cigarettes within the past 30 days and the nicotine concentration level they used at baseline. Self-report of baseline e-cigarette nicotine concentration of none (0 mg/mL), low (1-5 mg/mL), medium (6-17 mg/mL), or high (≥18 mg/mL) typically used during the past 30 days. Frequency of combustible cigarette smoking and e-cigarette use within the past 30 days (0 days [none], 1-2 days [infrequent], or ≥3 days [frequent]) and daily intensity of smoking and vaping (number of cigarettes smoked per day, number of vaping episodes per day, and number of puffs per vaping episode) at the 6-month follow-up. The analytic sample included 181 students (96 boys [53.0%] and 85 girls [47.0%]; mean [SD] age, 16.1 [0.4] years). Each successive increase in nicotine concentration (none to low, low to medium, and medium to high) vaped was associated with a 2.26 (95% CI, 1.28-3.98) increase in the odds of frequent (vs no) smoking and a 1.65 (95% CI, 1.09-2.51) increase in the odds of frequent (vs no) vaping at follow-up after adjustment for baseline frequency of smoking and vaping and other relevant covariates. Use of e-cigarettes with high (vs no) nicotine concentration was associated with a greater number of cigarettes smoked per day at follow-up (adjusted rate ratio [RR], 7.03; 95% CI, 6.11-7.95). An association with a significantly greater number of vaping episodes per day was found with use of low (adjusted RR, 3.32; 95% CI, 2.61-4.03), medium (adjusted RR, 3.32; 95% CI, 2.54-4.10), and high (adjusted RR, 2.44; 95% CI, 1.63-3.24) nicotine concentrations (vs no nicotine) at baseline. Similar results were found for the number of puffs per vaping episode for low (adjusted RR, 2.05; 95% CI, 1.41-2.70), medium (adjusted RR, 3.39; 95% CI, 2.66-4.11), and high (adjusted RR, 2.23; 95% CI, 1.42-3.03) nicotine concentrations. The results of this study provide preliminary evidence that use of e-cigarettes with higher nicotine concentrations by youths may increase subsequent frequency and intensity of smoking and vaping.

Alteration of adolescent aversive nicotine response and anxiety-like behavior in nicotine-exposed rats during late lactation period

Early nicotine exposure is an important cause of further habitual tobacco smoking. Although nicotine has not only rewarding but also aversive properties, the effects of early nicotine exposure on the distinct properties of nicotine are not well known. To reveal the effects of early adolescent nicotine exposure on further persistent tobacco smoking, we demonstrated developmental changes in nicotine-related appetitive and aversive behaviors of rats exposed to nicotine during the late lactation period. Sprague–Dawley rats were injected with saline or nicotine (2, 6 and 12mg/kg). We performed a two bottle free-choice test using escalating doses of nicotine (25, 50 and 100μg/ml), saccharin and quinine and the open field test in both adolescent and adult rats. The rats’ aversive response to nicotine was increased according to the increase in nicotine concentration. Adolescent rats showed higher nicotine preference and consumption behaviors than did adult rats at an aversive dose of nicotine. Nicotine-exposed rats increased adolescent nicotine consumption when the nicotine concentration was 12mg/kg. We observed significant increases in anxious behaviors in adolescent nicotine-injected rats compared to saline-injected rats, but there were no alterations in adult rats. In both adolescent and adult rats, saccharin and quinine intake were not significantly different between groups. Taken together, it suggests that repeated nicotine exposure in late lactation period affect changes in aversive nicotine responses and anxious behaviors during adolescence but there is no difference in adults.

Rats quit nicotine for a sweet reward following an extensive history of nicotine use.

Drug use may be exacerbated in environments which lack alternative means of engaging in rewarding behaviour. When alternative rewards are available, drug use may decrease-an effect that can be harnessed for therapeutic benefit. This idea is particularly well-supported by recent preclinical evidence demonstrating that a majority of rats will readily choose a potent non-drug reward over cocaine or heroin. Here we examine whether the same holds true for nicotine, a drug considered to have one of the highest addiction liabilities amongst drugs of abuse. Rats were trained to nose-poke separately for saccharin or nicotine on alternate days. Using a discrete-trial, forced-choice procedure, rats were then allowed to choose between nicotine and saccharin. This was followed by choice testing after a decrease in saccharin concentration (0.2-0%), omission of the fluid reward, an increase in nicotine concentration and following an extended nicotine self-administration history. All rats demonstrated a clear and immediate preference for saccharin at all times. This was despite variations in reward concentrations, or after an extensive nicotine history. Notably, rats preferred to nose-poke for water over nicotine and would omit responses when no fluid was delivered, rather than resume responding for nicotine. Overall, this study confirms and extends to nicotine previous research on other drugs of abuse, including cocaine and heroin. The ease with which rats quit nicotine in the present study contrasts with the well-known difficulty of humans to quit tobacco smoking. Possible factors that could explain this apparent discrepancy are discussed.

Tobacco plants can use nitrogen taken up before mechanical wounding to synthesize nicotine afterwards

Mechanical wounding stimulates nicotine synthesis in tobacco plants. In the practice of tobacco production, most nitrogen (N) is taken up before removal of the shoot apex, while nicotine is mainly synthesized afterwards. Since N is required for nicotine synthesis, it is interesting to know whether plants can use N taken up before removal of the shoot apex to synthesize nicotine after wounding. To address this question, a hydroponics culture experiment was carried out, in which N was supplied as NH4NO3 at two levels (1 mM and 6 mM) in pre-culture, and N was either withdrawn or replaced by 15N after removing the shoot apex for the next 7 days. Removal of the shoot apex caused a marked increase in nicotine concentration in various organs, also when plants grew under low-N conditions and showed symptoms of N deficiency. Increased nicotine accumulation even occurred when N was withdrawn from the growth medium before the apex was removed, indicating that tobacco plants can use N taken up previously to synthesize nicotine after mechanical wounding. The amount of N used for nicotine synthesis accounted for 5-6% of the total N, irrespective of treatment. Although most of the nicotine in intact plants and plants with the apex removed was synthesized de novo, as evidenced by the data when N was replaced by 15N-labeled NH4NO3, a large amount of the N absorbed before the N replacement was incorporated into the newly formed nicotine. The proportion of nicotine-15N to total nicotine-N was almost the same as that of 15N to total N in various organs. The results show the utilization of remobilized N taken up before excision of the shoot apex for nicotine synthesis afterwards, and highlight the importance of N cycling within plants, both when grown under N-sufficient and N-deficient conditions.

Nicotine synthesis in Nicotiana tabacum L. induced by mechanical wounding is regulated by auxin

The effects of different kinds of mechanical wounding on nicotine production in tobacco plants were compared, with sand or hydroponics culture under controlled conditions. Both removal of the shoot apex and damage of the youngest unfolded leaves nos 1 and 2 by a comb-like brusher with 720 punctures caused an increase in nicotine concentration in whole plants at day 3, and reached its highest level at day 6. The nicotine concentration induced by excision of the shoot apex was much higher than that induced by leaf wounding. Both treatments also caused an increase in jasmonic acid (JA) concentration within 90 min in the shoot, followed by an increase in the roots (210 min), in which the JA concentration induced by leaf wounding was significantly higher than that induced by excision of the shoot apex. The increase in nicotine concentration occurred throughout the whole plant, especially in the shoot, while the increase in JA concentration in the shoot was restricted to the damaged tissues, and was not observed in the adjacent tissues. Removal of the lateral buds that emerged after excision of the shoot apex caused a further increase in nicotine concentrations in the plant tissues. Removal of mature leaves, however, did not cause any changes in nicotine concentration in the plant, even though the degree of wounding in this case was comparable with that occurring with apex removal. The results suggest that the nicotine production in tobacco plants was not correlated with the degree of wounding (cut-surface or punctures), but was highly dependent on the removal of apical meristems and hence on the major sources of auxin in the plant. Furthermore, immediate application of 1-naphthylacetic acid (NAA) on the cut surface after removing the shoot apex completely inhibited the increase both in nicotine in whole plants and in JA in the damaged stem segment and roots. Application of an auxin transport inhibitor around the stem directly under the shoot apex of intact plants also caused an increase in nicotine concentration in the whole plant. The results strongly suggest that auxin serves as a negative signal to regulate nicotine synthesis in roots of tobacco plants.

Photothermal detection of nicotine-induced apoptotic effects in pancreatic cancer cells

The objective of this study was to evaluate the capability of a photothermal (PT) assay in determining the effects of graded doses of nicotine in a pancreatic acinar cell line (AR42J). The cellular response to nicotine was detected through the monitoring of PT signals from light-absorbing endogenous cellular structures that have been used as natural indicators for nicotine's action. It was demonstrated that introducing nicotine to cultured acinar cells in vitro leads to changes in cellular absorbing structures, thereby altering the microstructure of PT cell images and the temporal shape of PT signals. The results showed that the dependence of specific PT parameters was almost proportional to nicotine concentrations ranging from 1 nM to 100 μM, with the saturation maximum at and around 100 μM – 1 mM; thereafter, PT signals decreased rapidly to control levels and even lower, in the range of 1 – 50 mM. Conventional fluorescent tests (Annexin V – Propidium Iodide) performed in parallel showed no effect with nicotine at a concentration <1 μM (three orders of magnitude greater than the sensitivity threshold of the PT assay). With an increase in nicotine concentration from 1 mM to 50 mM, rapidly growing apoptotic and necrotic cells were detected. Thus, the PT assay demonstrated the capability for high-sensitivity detection of nicotine's impact, which may be related to a change in cell metabolism, apoptosis, or necrosis, depending on nicotine concentration.

Effects of nicotine on sperm attachment and penetration of zona-free hamster eggs.

A previous study from this laboratory showed that nicotine in vitro has deleterious effects on sperm motion characteristics. This study was conducted to evaluate the effects of nicotine on the ability of human spermatozoa to attach and penetrate zona-free hamster eggs. Spermatozoa from fertile donors, washed free of seminal plasma, were incubated with medium (control) and 0.1, 1, 5, and 10 mM concentrations of nicotine (concentrations estimated to approximate residual concentrations of nicotine in the testes of heavy smokers) for 18 h at 37 degrees C in a humid 5% carbon dioxide incubator. The sperm preparations were then mixed with enzymatically denuded hamster eggs and incubated for 3 h at 37 degrees C. The oocytes were examined by phase-contrast microscopy to enumerate the rates of sperm attachment and penetration. The data were analyzed by a paired t test and repeated measures analysis of variance using the arcsine transformation of the percentages. The percentages of eggs with attached spermatozoa significantly declined in a dose-dependent manner, the highest inhibition being at 10 mM (F = 24). The rate of sperm penetration was even more significantly decreased with the increase in nicotine concentrations in the following order: 10 mM (F = 56) > 5 mM (F = 30) > 1 mM (F = 44) > 0.1 mM (F = 12). Nicotine concentrations of 0.1 mM and above negatively affected sperm penetration of zona-free hamster eggs.

Interaction of nitrate and sulfate reduction in tobacco

Abstract A series of experiments was conducted to study the effects of apical meristem removal on sulfate and nitrate reduction in ‘Ky14’ tobacco plants (Nicotiana tabacum L.). Apical meristem removal is expected to modify N metabolism since it causes an increase in the synthesis of nicotine in the roots and its accumulation in shoots. There may not be any such complementary effect on S metabolism. Further, the experiments were designed to study the effects of apical meristem removal on the interaction of nitrate (NO3) and sulfate (SO4) reduction. Activities of ATP sulfurylase and NO3 reductase, the first steps of SO4 and NO3 reduction, respectively, have been considered indicators of the state of regulation of the assimilatory pathways of SO4 and NO3. The effect of apical meristem removal on the activities of the above enzymes in the leaf tissue and the interrelationship between them was examined. Removal of the apical meristem resulted in a large increase in nicotine concentration, a large increase in t...

Interaction of nitrate and sulfate reduction in tobacco

A series of experiments was conducted to study the effects of apical meristem removal on sulfate and nitrate reduction in ‘Ky14’ tobacco plants (Nicotiana tabacum L.). Apical meristem removal is expected to modify N metabolism since it causes an increase in the synthesis of nicotine in the roots and its accumulation in shoots. There may not be any such complementary effect on S metabolism. Further, the experiments were designed to study the effects of apical meristem removal on the interaction of nitrate (NO3) and sulfate (SO4) reduction. Activities of ATP sulfurylase and NO3 reductase, the first steps of SO4 and NO3 reduction, respectively, have been considered indicators of the state of regulation of the assimilatory pathways of SO4 and NO3. The effect of apical meristem removal on the activities of the above enzymes in the leaf tissue and the interrelationship between them was examined. Removal of the apical meristem resulted in a large increase in nicotine concentration, a large increase in t...