Our lab has shown that neonatal treatment with quinpirole, a dopamine D2/D3 agonist, to rats resulted in an increase in dopamine D2-like receptor sensitivity that persists throughout the animal’s lifetime without a change in receptor number, consistent with schizophrenia. Approximately 80-85% of schizophrenics smoke cigarettes, and there is no delineated mechanism for this observation. Our lab has also shown more robust sensitization and accumbal dopamine release in response to nicotine in adolescent rats neontally treated with quinpirole compared to controls. This study analyzed whether environmental enrichment, known to reduce sensitization to psychostimulants, may also reduce or block enhanced sensitization to nicotine in this model. Male and female rats were treated with either quinpirole (1 mg/kg) or saline from postnatal day (P)1-21. After weaning at P21, animals were raised in either environmentally enriched or isolated housing throughout the experiment. Beginning on P33, animals were ip administered either nicotine (0.5 mg/kg free base) or saline 10 min before placement in a square locomotor arena and behavioral activity measured every second day from P33-49. Results revealed that animals given neonatal quinpirole treatment and reared in an enriched environment demonstrated more robust sensitization to nicotine than all other groups. Animals given neonatal quinpirole or saline treatment followed by nicotine in adolescence and raised in isolated housing conditions were equivalent, but demonstrated more robust sensitization compared to enriched rats neonatally treated with saline and administered nicotine in adolescence. Results here show that environmental enrichment enhanced nicotine sensitization in rats neonatally treated with quinpirole, which is in contrast to the blockade of sensitization to nicotine which has previously been shown in normal animals. Importantly, these results show that increases in D2 receptor sensitivity interacts with environmental enrichment differently than in normal animals and the manner in which the animal responds to nicotine, which may have implications towards smoking cessation in schizophrenia.

Schizophrenics are significantly more likely to smoke cigarettes than the general population. In Experiment 1, we analyzed the effects of a rewarding versus an aversive dose of nicotine using the neonatal quinpirole (QUIN; dopamine D2/D3 agonist) model of schizophrenia. In Experiment 2, we examined the effects of antipsychotic treatment upon the associative reward of nicotine within this same model. Neonatal QUIN treatment to rats results in increased dopamine D2 receptor sensitivity throughout the rat’s lifetime, consistent with schizophrenia. Rats were neonatally treated with QUIN (1 mg/kg dose) or saline from postnatal days (P)1-21. Animals were then raised to P41 without any further drug treatment. Subjects were administered two consecutive pre-conditioning drug free preference tests in a three chamber shuttle box on P41 and P42 to determine initial preference. In Experiment 1, beginning on P43, animals were conditioned with saline, a 0.6 mg/kg or a 1.8 mg/kg free base dose of nicotine for eight consecutive days. A drug free post-conditioning preference test was given on P51. Approximately 24 h following the post-conditioning test, brain tissue was harvested and analyzed for mammalian target of rapamycin (mTOR) and phosphorylated-CREB (pCREB) in the nucleus accumbens. In Experiment 2, animals were treated identically as in Experiment 1, but were conditioned with nicotine which was preceded by an injection of either a typical antipsychotic (haloperidol, 0.5 mg/kg dose) or an atypical antipsychotic (clozapine, 2.5 mg/kg dose) for a period of eight days which was followed by a drug free preference test. In both experiments, the difference between time spent in the paired context between pre-test and post-test was utilized as a measure of associative reward. Results revealed that neonatal QUIN enhanced the rewarding effects of nicotine, but neutralized the aversive effects compared to controls. Neonatal QUIN also significantly decreased accumbal mTOR and pCREB results will be presented. In Experiment 2, we found that treatment with clozapine reduced the enhancement of nicotine conditioned place preference, but haloperidol completely reduced nicotine place preference to control levels. These findings show that neonatal QUIN enhances the rewarding associative effects of nicotine, and that the typical antipsychotic haloperidol was more effective at eliminating the associative rewarding effects of nicotine likely due to its potent D2 antagonistic effects.

This study was designed to analyze the effects of adolescent exposure to methylphenidate (MPH; trade name: Ritalin) on nicotine self-administration, the motivation to obtain nicotine, and accumbal neuronal firing rate in female adolescent rats. MPH is the most commonly prescribed medication for Attention Deficit-Hyperactivity Disorder (ADHD) which is diagnosed in 3-5% of adolescents in the United States. However, this disorder is often misdiagnosed, and MPH is often prescribed to individuals not diagnosed with ADHD. Adolescent female Sprague-dawley rats were ip administered 1 mg/kg MPH or saline using a “school day” regimen of five days on, two days off, beginning on postnatal day (P)28 and this regimen was maintained throughout testing. A 1 mg/kg dose of MPH has been shown to result in brain plasma levels equivalent to clinical dosing in humans. Indwelling catheters were implanted in the jugular vein at P35, and one week later on P42, animals began nicotine self-administration. MPH (1 mg/kg) was administered each day approximately 6 h before each self-administration session began, which allows for nearly full plasma clearance of MPH (half-life = 1 h) before self-administration commenced. Rats were reduced to 85% of their free-feeding body weight and sipper tubes were made available to the rats in this paradigm, and responses to licking the tube produced an infusion of nicotine solution (15μg/kg) over a range of fixed ratio (FR) reinforcement schedules followed by a progressive ratio (PR) schedule, a measure of motivation. The schedule of reinforcement during 60 min sessions was increased from an FR5 to FR15 over approximately a three-week period. Results revealed that MPH pre-exposed rats self-administered significantly higher amounts of nicotine as compared to animals treated with saline throughout the FR5 and FR10 schedules. Further, MPH enhanced the motivation to self-administer nicotine on the PR schedule compared to controls, demonstrating an enhanced motivation to obtain nicotine produced by MPH. Finally, animals that had been pre-exposed to MPH and self-administered nicotine demonstrated a lower rate of basal accumbal firing as compared to controls, but a burst firing in response to nicotine that was higher than rats pre-exposed to saline. In conclusion, MPH altered the behavioral and neural response to nicotine in the nucleus accumbens.

Methylphenidate (MPH) is widely prescribed during childhood and adolescence for treatment of attention deficit and hyperactivity disorder. MPH is also one of the most commonly abused prescription drugs. However, the effects of MPH exposure and MPH abuse on incentive motivation are not well known. Moreover, MPH abuse during adolescence could increase sensitivity to the incentive motivational effects of other abused drugs such as nicotine in adulthood. Thus, the goals of this experiment were to investigate the effects of MPH exposure on the motivation to obtain sucrose during adolescence and to examine whether adolescent methylphenidate exposure altered the incentive motivational effects of nicotine (NIC) in adulthood. Incentive motivation was measured using an operant conditioning paradigm with sucrose available under a progressive ratio schedule of reinforcement (PR). Adolescent female rats were used because our previous studies have shown stronger sensitization to the locomotor stimulant effects of MPH. Rats arrived at post-natal day 21 (P21) and were shaped to respond for sucrose (20% w/v) on the PR schedule beginning on P24. After stable operant responding was established, rats were randomly assigned to receive either MPH (n=7) or SAL (n=6) injections (intraperitoneal) 30 min prior to test sessions, with the constraint that sucrose rewards earned did not differ between groups. Injection tests began on P36 and were carried out on alternating days for 10 total tests (P36-54). Although there was a trend for increased motivation for sucrose in the MPH group, it did not reach statistical significance. No further testing occurred until the rats reached adulthood (P55-P78). Over the next 5 days (P79-P84), all rats were pretreated with subcutaneous NIC injections (0.4 mg/kg base) 15 min before testing sessions. Following this initial ‘sensitization’ period, rats were tested with different NIC doses (0-1 mg/kg base) from P85-P92. During the sensitization period, NIC increased responding equally in both groups. However, during the dose-response testing, rats in the MPH group were more sensitive to the incentive motivational effects of NIC - the median effective dose was significantly lower for rats exposed to MPH in adolescence. The findings suggest that MPH may have limited reinforcement enhancing effects in adolescents. However, exposure to MPH during adolescents may increase the incentive motivational effects of NIC in adulthood.

abstract: Nicotine and tobacco use, whether it be through cigarette smoking or other devices, creates negative health conditions in pilots. The literature that was reviewed pertained to nicotine withdrawal symptoms and their negative impact on pilot performance. There have been studies conducted in order to explore how these symptoms impact pilot performance using cigarettes as the only nicotine device and does not specify the nicotine levels or the frequency of use. This thesis extends this work to examine the relationship between the nicotine withdrawal symptoms and the nicotine behaviors of pilots. It was hypothesized that the extent of withdrawal symptoms may differ by device and by nicotine levels and frequency of use, with higher levels and more frequent use being associated with more severe withdrawal symptoms. These behaviors included the device they use to take nicotine whether it be cigarettes, vaporizers, e-cigarettes, or smokeless tobacco. The behaviors also included exploration of how nicotine levels relate to withdrawal symptoms whether the nicotine level is as low as 3mg or high as 36mg. The last relationship that was explored was that between the withdrawal symptoms presented in pilots and how often they used nicotine, whether it be often as every day or less frequent as 1-2 times a year. It was found that there is no statistical relationship between nicotine withdrawal symptoms and the nicotine habits such as device used, nicotine level used, and frequency of use. / Dissertation/Thesis / Masters Thesis Engineering 2019

Background: Use of electronic cigarettes (EC) has dramatically increased in the United States since 2010 with a forecasted growth of 37% between 2014 and 2019. There is little research on e-liquid nicotine concentration from domestic manufacturers. However, limited research outside of the U.S. found wide inconsistencies between the labeled concentration of nicotine in e-liquids and the actual nicotine concentration. Methods: The seven most popular online manufacturers or distributors were identified. E-liquid samples of the five most popular flavors from each manufacturer were purchased in nicotine concentrations of 0 mg/ml and 18 mg/ml. Of the samples purchased (n=70), all were labeled as produced in the United States of America (USA). The researchers anonymized the samples before sending them to an independent university lab for testing. Results: The 35 e-liquid samples labeled 18 mg/ml nicotine measured between 11.6 and 27.4 mg/ml (M=18.7 SD=3.3) nicotine. The labeled 18 mg/ml samples measured as little as 35% less nicotine and as much as 52% greater nicotine. In the 35 samples labeled 0 mg/ml, nicotine was detected (>0.01 mg/ml) in 91.4% of the samples (Range = 0 to 23.9 mg/ml; M=2.9; SD=7.2). Six samples from two manufacturers labeled as 0 mg/ml were found to contain nicotine in amounts ranging from 5.7 mg/ml to 23.9 mg/ml. Conclusion: This study demonstrates the nicotine labeling inaccuracies present in current e-liquid solutions produced in the U.S. Incorrect labeling poses a significant risk to consumers and supports the recent regulation changes enacted by the FDA. Additional routine testing of nicotine concentrations should be conducted to evaluate the effectiveness of the regulations on future e-liquid production.

Negative affect plays a critical role in nicotine dependence. Smokers report feeling that negative affect is a primary motivation to keep smoking. This study examined the relationship between individual differences in emotional experience, in particular emotional clarity and differentiation (individuals' ability to understand, describe, and differentiate between emotions), and smoking motivation. We hypothesized that emotional clarity would be related to affect, craving, and smoking satisfaction. A second goal was to test the ability of an emotional-labeling intervention to reduce negative affect and smoking motivation resulting from a negative emotion induction. We also tested whether emotional clarity moderated the effect of the negative affect manipulation upon smoking-related variables. We hypothesized that emotional clarity would moderate the effect of the emotional-labeling manipulation upon affect, craving, and smoking satisfaction. A correlational and two-group between-subjects design was used. Participants (170 participants; 86 males) first completed baseline measures, then received a mood induction (via video). They then were randomized to one of two conditions (emotion labeling and writing control). Results indicate that emotional clarity was related to affect, craving, and smoking satisfaction ratings, such as those higher on emotional clarity reported more positive affect, less cravings, and having experienced aversive effects after smoking. We found no effect of the emotional labeling task. Although we replicated findings from previous studies showing a relationship between emotional clarity and mood, this study is the first to establish such a relationship with craving for a cigarette and aspects of smoking satisfaction.

Little is known about how electronic cigarette (EC) users manipulate device parameters, what factors drive their use, and how non-nicotine ingredients influence the stimulus effects of EC aerosols. The ingredients propylene glycol (PG) or vegetable glycerin (VG) serve as the base for virtually all electronic cigarette liquids, and information on how they affect the using experience would provide important groundwork for the study of other ingredients. In this dissertation, results from a survey and laboratory study focused on the stimulus effects of ECs, and the influence of PG and VG, will be discussed. A total of 522 regular EC users completed a survey comprised of an electronic cigarette dependence questionnaire, questions on tobacco and electronic cigarette use, and device and liquid preferences. This was followed by a laboratory study with sixteen electronic cigarette users completing five test days (one practice and four assessment days). In the laboratory study, following one hour of nicotine deprivation, two sampling puffs from liquid formulations containing 100/0, 75/25, 50/50, 25/75, and 0/100% PG/VG concentrations were administered in random order during five assessments, each separated by 20 min. Primary outcome measures were self-reported stimulus characteristics and breakpoint on a multiple-choice procedure. Survey results indicated that ability to change device voltage, and level of resistance, was significantly associated with level of nicotine dependence, as was amount of liquid consumed, nicotine concentration, and milligrams of nicotine used per week. Participants also rated 'good taste' as the most important consideration when purchasing and using liquids, and PG was associated with undesirable effects and VG with desirable effects. Laboratory results indicated that greater VG content was associated with greater reports of visibility of the exhalant (i.e. “cloud”). Liquids with mixtures of PG or VG were associated with conventional cigarette smoking sensations and greater reductions of systolic blood pressure compared to formulations with only PG or VG. There was no significant effect of liquid formulation on the multiple-choice procedure, but puffs were rarely chosen over even the smallest monetary option ($0.05), suggesting minimal reinforcing efficacy. In conclusion, survey data indicate that a wide range device parameter settings and liquid ingredients are preferred by daily e-cigarette users, and that individuals with greater nicotine dependence favor voltage control devices, and lower resistance heating elements. Survey data also indicated that taste is a key factor for EC liquid selection, and relative concentrations of propylene glycol and vegetable glycerin may have a significant impact on the reinforcing effects of liquids. In contrast, laboratory data suggests that PG or VG do not significantly impact the abuse liability of EC liquids, though reinforcing effects of these ingredients was unclear in the laboratory study.

Use of electronic cigarettes (e-cigarettes) is rapidly growing around the world. E-cigarettes are commonly used as an alternative nicotine delivery system, and have been advocated as generating lower levels of harmful chemicals compared to conventional cigarettes. Cigarette smoke-like aerosols are generated when e-cigarettes heat e-liquids. The main components of e-cigarette liquids are propylene glycol (PG) and glycerol (GL) in a varying ratio, plus nicotine and flavor chemicals. Both PG and GL are considered safe to ingest in foods and beverages, but the toxicity of these chemicals in aerosols is unknown. Current studies of e-cigarettes have mainly focused on dehydration and oxidation products of PG and GL. In this study, the other degradation products that can be generated during the vaping process are discussed. In addition, the gas/particle partitioning of chemicals in vaping aerosols is determined. This work finds that the formation of benzene in electronic cigarettes depends on the wattage, types of coils, and devices. To simulate commerical e-cigarette liquids, mixtures containing equal parts of PG and GL by volume were made with the following added components: benzoic acid (BA), benzoic acid with nicotine (Nic), benzaldehyde (BZ), band enzaldehyde with nicotine. PG only, GL only, and PG and GL mixtures were also made for comparison. The data presented here demonstrate that more benzene is generated as the wattage of a device increases. The results also seem to support the importance of ventilation in the generation of benzene. More benzene is generated from the mixtures containing benzoic acid when using the EVOD device with a smaller vent. However, benzaldehyde yields more benzene when using the Subtank Nano device with a larger vent. Findings also indicate that more benzene is produced from GL rather than PG. This thesis also addresses the chemical formation pathways of degradation compounds found in the aerosols formed from isotopically labeled e-cigarette liquids. Mixtures of both 13C-labeled and unlabeled PG as well as GL were made. The mixtures were vaped and gas-phase samples were collected to determine which chemicals were in the gas-phase portion of the aerosols. With the use of GC/MS methods, these isotopic labeling experiments provided evidence that the majority of the benzene, acetaldehyde, 2,3-butanedione, toluene, xylene, acrolein, and furan found in e-cigarette aerosols originates from GL in the PG plus GL mixtures. It was also shown that the majority of propanal is derived from PG: while hydroxyacetone can be formed from both PG and GL. Possible mechanisms for the formation of acetaldehyde, benzene, 2,3-butanedione, toluene, and xylene formation are proposed. Last, this study investigated the gas/particle partitioning of nicotine and flavor-related chemicals in e-cigarette fluids. The gas/particle partitioning behavior of chemicals in e-cigarettes fluids is highly dependent on the chemical volatility. A total of 37 compounds were examined. The target compounds were divided into 3 groups based on their vapor pressures: high, medium, and low. Headspace gas samples were collected and analyzed to determine the concentration of a compound in equilibrium with the liquid phase. The gas and liquid concentrations were used to calculate the gas/particle partitioning constant (Kp) for each compound. In an e-cigarette aerosol, volatile compounds have smaller Kp values and tend to be found in greater proportion in the gas-phase, whereas the less volatile compounds are likely to stay in the particle phase. General agreement with theory was found for compounds with known activity coefficients in PG and GL, indicating that theory can be used to predict Kp values for other compounds.

Smoking cigarettes is the most preventable cause of death in the US. Smokers are often unsuccessful at quitting because they are dependent. Reducing nicotine could be one way to reduce dependence. Currently, reducing cigarettes per day (CPD) is the most common strategy to reduce nicotine intake. However, some have proposed switching to very low nicotine content (VLNC) cigarettes to reduce nicotine and dependence. Both reducing CPD and switching to VLNC cigarettes aim to reduce nicotine but do so in different ways. I conducted a randomized trial to compare the degree to which switching to VLNC cigarettes vs reducing CPD 1) is more acceptable and 2) decreases dependence more among smokers not ready to quit. Sixty-eight adult smokers of ≥ 10 cigarettes/day who were not ready to quit smoked full nicotine study cigarettes ad-lib for 1 week (week 0). I provided all participants with nicotine replacement therapy (NRT) patches and instructions to gradually reduce over the next 4 weeks by either 1) switching to lower nicotine content VLNC cigarettes or 2) reducing the number of full nicotine CPD. I provided VLNC participants with their usual number of cigarettes throughout the study but cigarettes contained only 70% of their usual nicotine at week 1, 35% at week 2, 15% at week 3, and 3% at week 4. I provided CPD participants with full nicotine cigarettes throughout the study but only 70% of their usual number of cigarettes at week 1, 35% at week 2, 15% at week 3, and 3% at week 4. I instructed participants to attempt to smoke only study cigarettes and report use of all (study + non-study) cigarettes via nightly surveys. I used participants’ percent non-study cigarettes/day as a proxy for acceptability and the Nicotine Dependence Syndrome Scale as my primary measure of dependence. Participants completed self-report measures and provided breath and urine samples at weekly visits during the 5-week study period. I tested between-group differences, within-participant change over time, and group by time interactions using multi-level modeling. Switching to VLNC cigarettes was more acceptable than reducing CPD (F=5.0 p<.05). Acceptability declined over time for CPD participants as they were instructed to reduce more nicotine (F=42.2, p<.001) but this was not true for VLNC participants (F=29.5, p<.001). Dependence declined over time for both VLNC (F=10.5, p<001) and CPD (F=5.0, p<.01) participants but declined more over time for VLNC than CPD participants (F=3.2, p<.05). This is the first trial to directly compare switching to VLNC cigarettes vs reducing CPD. Large reductions were more acceptable and effective at decreasing dependence among participants who switched to VLNC cigarettes than those who reduced CPD when all were aided by NRT. My findings suggest that regulatory policy that promotes a gradual transition to VLNC cigarettes could be more acceptable and effective at decreasing dependence than the common strategy of reducing CPD. Furthermore, NRT-aided transitions to VLNC cigarettes could be a useful and acceptable component for clinical interventions to reduce nicotine dependence among smokers not ready to quit and thereby make it more likely for smokers to quit and succeed.