Oral Nicotine Administration Research Articles

Evaluating the Forensic Inferences of Oral Nicotine Ingestion: Autopsy Case Review, Animal Experimentation, and Legal Implications

Nicotine, a highly lipophilic alkaloid derived from Nicotiana tabacum and Nicotiana rustica, can be lethal even in small doses when ingested in concentrated forms like e-cigarette liquids. This study examined a murder case in South Korea where a 52-year-old man was allegedly killed by oral administration of nicotine. Despite the absence of typical signs, such as chemical burns or vomiting, the case posed questions about the lethal concentration of nicotine and the presence of gastrointestinal symptoms in nicotine poisoning. Through literature review, autopsy analysis, and animal experiments, this study evaluated the forensic evidence presented in court. The results indicated that lethal nicotine levels could be lower than established previously, and death could occur without gastrointestinal injury or vomiting. Our findings supported the court's conviction decision, emphasizing the variability of symptoms in nicotine toxicity and the importance of scientific evidence in legal proceedings. The results of this study highlight the role of forensic medicine in clarifying scientific uncertainties in judicial contexts, particularly in cases involving toxic substances.

Examination of empathy-like behaviour in nicotine-preferring rat lines

Aim Addiction is an important global health issue, impacting also addicts environment and society. Empathy plays crucial role in establishing successful social relationships and is a fundamental component of social life. The aim of this study is to investigate how nicotine preferring (NP) strain and oral forced nicotine administration affects empathy-like behaviour in rats, with gender differences. Materials and Methods Sprague-Dawley NP rats (10 males/10 females) and wild-type control rats (10 males/10 females) were used. Behavioural tests were administered to all rats before and after oral forced nicotine administration. The behavioural tests were completed in the fourth week of nicotine administration. Anxiety levels that could affect empathy-like behaviour were evaluated with open field, elevated plus maze tests and with blood cortisol levels. Oxytocin receptor and arginine vasopressin (AVP) levels, which have been shown to be related to empathy-like behaviour, were examined in the prefrontal cortex and amygdala regions using the enzyme-linked immunoassay method. Results It was observed that males from the NP strain showed less empathy-like behaviour than all other groups, and nicotine administration did not cause a significant change in the results. Higher levels of locomotor activity (LA) were found in control females than in all other groups. Blood nicotine and corticosterone levels were higher in NP rats. No significant differences were found in AVP and oxytocin receptor levels in the prefrontal cortex and amygdala. Conclusions It was found that coming from an addicted strain particularly reduces empathy-like behaviour in males.

The Effect of High Nicotine Dose on Maximum Anaerobic Performance and Perceived Pain in Healthy Non-Smoking Athletes: Crossover Pilot Study.

Background: In recent years, there has been intensive discussion about the positive effect of nicotine usage on enhancing sports performance. It is frequently applied through a non-burned tobacco form before physical activity. Nicotine is under the World Anti-Doping Agency (WADA) 2021 monitoring program. Therefore, study results that reveal either positive or negative effects are expected. This is the pilot study that reports the effect of 8 mg dose of nicotine on performance and perceived pain. Material and Methods: This research aimed to explore the oral intake effect of a high-nicotine dose (8 mg) on the maximum anaerobic performance and other selected physical performance parameters in healthy, well-trained adult athletes (n = 15, age 30.7 ± 3.6, BMI 25.3 ± 1.7). The cross-sectional study protocol included the oral administration of either sublingual nicotine or placebo tablets before the anaerobic load assessed by a standardized 30 s Wingate test of the lower limbs. Afterward, the Borg subjective perception of pain (CR 10) and Borg rating of perceived exertion (RPE) were evaluated. Wilcoxon signed-rank test was used for the analysis of data with a 0.05 level of significance. Results: The results revealed that oral administration of an 8 mg nicotine dose does not significantly improve any of the physical performance parameters monitored. We only reported the statistically significant positive effect in RPE (p = 0.03). Conclusion: Lower perception of pain intensity that we reported after nicotine application might be an important factor that affects performance. However, we did not report any improvement in physical performance parameters.

Nicotine Oral Administration Attenuates DSS-Induced Colitis Through Upregulation of Indole in the Distal Colon and Rectum in Mice.

Nicotine affects the gastrointestinal environment and modulates ulcerative colitis (UC). However, the associations among nicotine, gut metabolites, and UC are still largely unknown. We investigated whether orally administered nicotine affected gut metabolites and dextran sodium sulfate (DSS)-induced colitis. C57BL/6 male mice were orally administered nicotine solution in drinking water prior to inducing DSS-induced colitis. Short-chain fatty acids (SCFAs) and indole in gut contents and fecal samples were measured by GC-MS and hydroxylamine-based indole assays, respectively. Oral administration of nicotine increased indole concentration in feces, but, in contrast, SCFA values did not differ with nicotine administration. Indole levels were increased in the distal colon and rectum but not in the cecum and proximal colon. DSS-induced colitis was less severe clinically and histological changes were minimal in the rectum of orally nicotine-administered mice compared to mice drinking only water. 16S rRNA microbiome on the feces revealed an increasing in Clostridium and Porphyromonas in nicotine-administered mice. In conclusion, nicotine administration was associated with increased indole levels in the distal colon and rectum and attenuated DSS-induced colitis. Oral administration of nicotine may play a potential role in indole upregulation and prevention of UC.

Chronic oral nicotine administration and withdrawal regulate the expression of neuropeptide Y and its receptors in the mesocorticolimbic system

Neuropeptide Y (NPY) and its receptors are involved in the regulation of mood, stress, and anxiety. In parallel, NPY signaling may play a vital role in the negative affective state induced by drug withdrawal. This study examined the changes in the transcript levels of NPY, Y1, Y2, and Y5 receptors in the mesocorticolimbic system during chronic nicotine exposure and withdrawal. Rats were administered with nicotine (initial dose: 25 μg/ml, maintenance dose: 50 μg/ml, free base) in drinking water for 12 weeks. Control group received only tap water. In the final week of the study, some of the nicotine-treated animals continued to receive nicotine (0-W), whereas some were withdrawn for either 24 (24-W) or 48 (48-W) h. All animals were decapitated after the evaluation of somatic signs (frequency of gasps, eye blinks, ptosis, shakes, teeth chatter) and the duration of locomotor activity and immobility. mRNA levels of NPY, Y1, Y2, and Y5 receptors in the mesocorticolimbic system were measured by quantitative real-time PCR (qRT-PCR). Results showed that nicotine withdrawal increased overall somatic signs. Moreover, chronic nicotine treatment increased the duration of locomotor activity, whereas withdrawal increased the duration of immobility. qRT-PCR analysis revealed that chronic nicotine treatment increased NPY mRNA levels in the hippocampus. On the other hand, 24- and 48-h withdrawals increased NPY mRNA levels in the amygdala and medial prefrontal cortex (mPFC), Y1 and Y2 mRNA levels in the nucleus accumbens and mPFC, and Y5 mRNA levels in the mPFC. These findings suggest that nicotine withdrawal enhances NPY signaling in the mesocorticolimbic system, which could be an important mechanism involved in regulating the negative affective state triggered during nicotine withdrawal.

The Preventive Effects of Xanthohumol on Vascular Calcification Induced by Vitamin D3 Plus Nicotine

Vascular calcification (VC) is highly prevalent in patients with atherosclerosis, chronic kidney disease, diabetes mellitus, and hypertension. In blood vessels, VC is associated with major adverse cardiovascular events. Xanthohumol (XN), a main prenylated chalcone found in hops, has antioxidant effects to inhibit VC. This study aimed to investigate whether XN attenuates VC through in vivo study. A rat VC model was established by four weeks oral administration of vitamin D3 plus nicotine in Sprague Dawley (SD) rats. In brief, 30 male SD rats were randomly divided into three groups: control, 25 mg/kg nicotine in 5 mL corn oil and 3 × 105 IU/kg vitamin D3 administration (VDN), and combination of VDN with 20 mg/L in 0.1% ethanol of XN (treatment group). Physiological variables such as body and heart weight and drinking consumption were weekly observed, and treatment with XN caused no differences among the groups. In comparison with the control group, calcium content and alkaline phosphatase (ALP) activity were increased in calcified arteries, and XN treatment reduced these levels. Dihydroethidium (DHE) and 2′,7′-dichloroflurescin diacetate (DCFH-DA) staining to identify Superoxide and reactive oxygen species generation from aorta tissue showed increased production in VDN group compared with the control and treatment groups. Hematoxylin eosin (HE) and Alizarin Red S staining were determined to show medial vascular thickness and calcification of vessel wall. Administration of VDN resulted in VC, and XN treatment showed improvement in vascular structure. Moreover, overexpression of osteogenic transcription factors bone morphogenetic protein 2 (BMP-2) and runt-related transcription factor 2 (Runx2) were significantly suppressed by XN treatment in VC. Moreover, downregulation of vascular phenotypic markers alpha-smooth muscle actin (α-SMA) and smooth muscle 22 alpha (SM22α) were increased by XN treatment in VC. Furthermore, XN treatment in VC upregulated nuclear translocation of nuclear factor-E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expressions. Otherwise, Kelch-like ECH-associated protein 1 (Keap1) was alleviated by XN treatment in VC. In conclusion, our findings suggested that XN enhances antioxidant capacity to improve VC by regulating the Nrf2/Keap1/HO-1 pathway. Therefore, XN may have potential effects to decrease cardiovascular risk by reducing VC.

Inhaled aerosolized nicotine suppresses the lung eosinophilic response to house dust mite allergen.

Nicotine of unprecedented concentrations and purity is being inhaled by those using commercially available electronic nicotine delivery systems (ENDS). The consequences of this route of self-administration on the immunological response to inhaled allergens are not known. In mice, sensitization and inhalation challenge with the common environmental house dust mite (HDM) allergen is an experimental model of this response. When mice were exposed to aerosolized nicotine base (aeroNic) twice daily, 5 days/wk for 8 wk, the HDM-induced recruitment of eosinophils (EOS) was substantially reduced as measured in bronchial alveolar lavage fluid (BALF). Oral nicotine administration had no effect. HDM challenge in the presence of nicotinic receptor subtype α7 (α7)-specific type-1 positive allosteric modulators (PAMs) was alone sufficient to suppress EOS. RNA analysis of alveolar macrophages (AM) collected from BALF after HDM challenge of aeroNic revealed that α7 activation strongly suppresses initiation of Ccl24 (eotaxin 2) transcription. To examine possible cellular signaling mechanisms coupling α7 to Ccl24 transcription, an AM culture model system was used. In AM cultures of freshly collected BALF, Ccl24 transcription was robustly activated by a mixture of IL-4 and IL-10, and this was suppressed by coapplication of type-1 PAMs through a pathway that requires p38MAPK but is independent of Jak2. These results suggest that the EOS response to HDM inhaled allergen is subject to modulation through activation of the α7 receptor and suggest that the allergic response may be substantially modified in ENDS users.

Nicotine lowers TNF-α, IL-1b secretion and leukocyte accumulation via nAChR in rat stomach

Inflammatory suppressive effects of nicotine have been observed in inflammatory diseases. We aimed to investigate morphological damage and the changes in TNF-α, IL-1β, and IL-10 expression in the healthy stomach after long-term oral nicotine administration. Nicotine was added to the drinking water of Sprague Dawley rats for 6 weeks. Histological signs of damage, inflammatory cytokines, and nicotinic acetylcholine receptor (nAChR) levels were evaluated in the gastric tissues. There were no histological signs of inflammation in both groups. TNF-α and IL-1β were decreased in the nicotine-treated group. A positive correlation was found between TNF-α levels and infiltrated inflammatory cell count. nAChR levels were increased in the nicotine group. Long term nicotine administration upregulates and activates nAChR. The reduced TNF-α or with high activity nAChR affects the modulation of neutrophil functions and its entry into tissue. Nicotine may deteriorate host defence in non-inflammatory situations.

Four-week administration of nicotinemoderately impacts blood metabolic profile and gut microbiota in a diet-dependent manner

As the primary active component in tobacco, nicotine affects many aspects of human metabolism. Diet and gut microbiota are key factors that profoundly influence human lipid and glucose metabolism. However, the diet-based differential impacts of nicotine on blood lipid and glucose levels as well as on the gut microbiota are still largely unknown. Here we show that 4-week oral administration of nicotine (2 mg/kg) resulted in bodyweight and fat decrease in both normal-chow (NCD)- and high-fat diet (HFD)-fed mice. But nicotine showed little influence on the plasma levels of lipids, glucose and inflammatory cytokines in NCD-fed mice but moderately deteriorated these parameters in HFD-fed ones. 16S sequencing showed that nicotine perturbed bacterial diversity and community composition of gut microbiota more pronouncedly in HFD mice. At genus level, nicotine dramatically increased Ruminococcaceae UCG-009 in HFD condition but not in NCD feeding. Interestingly, co-treatment with antibiotics (ampicillin + norfloxacin) substantially abolished the lipid-enhancing effect of nicotine in HFD-fed mice, suggesting an important role of gut microbes in the lipid-modulatory effect of nicotine. Together, our results indicate that the harmful effects of nicotine on metabolism and systemic inflammation are diet-dependent. Chronic exposure to nicotine may alter the gut microbiota especially in HFD-fed animals.

The effects of oral nicotine administration and abstinence on sleep in male C57BL/6J mice.

Sleep disturbances are common in smoking cessation attempts and are predictive of relapse. Despite this knowledge, there is no established animal model to study the effect of nicotine abstinence on sleep and EEG parameters. The present study was conducted to characterize sleep and wakefulness in male C57BL/6J mice during periods of oral nicotine administration and abstinence. Male C57BL/6J mice were implanted with EEG/EMG recording devices. EEG/EMG data were recorded continuously for a period of 4weeks. At the beginning of week 2, 200μg/ml of nicotine was added to the 0.2% saccharin vehicle drinking solution. Following a 2-week period of oral nicotine administration, abstinence was initiated by excluding the nicotine from the 0.2% saccharin vehicle drinking solution. EEG/EMG were analyzed at pre-nicotine baseline, during nicotine administration, and on days 1, 2, and 5 of abstinence from nicotine. Oral nicotine administration decreased total sleep time during the active phase, consistent with the stimulant actions of nicotine. In contrast, NREM sleep quantity was increased during the active phase on nicotine abstinence day 1 and REM sleep was decreased during days 2 and 5 of abstinence. Further, sleep fragmentation was increased during the inactive phase on all days of abstinence. Oral nicotine administration and abstinence from nicotine also altered EEG relative power frequencies during the inactive and active phase. Both oral nicotine administration and abstinence lead to sleep disturbances in mice. Similarities between this model and human reports on the effect of nicotine/nicotine withdrawal on sleep support its utility in examining the molecular mechanisms that modulate the relationship between sleep, nicotine, and nicotine abstinence/withdrawal.

Abstract 397: Cotinine, but Not Nicotine, Increased ApoA-I Mediated HDL Synthesis in THP-1 Cells

Aim: Cotinine is known as a stable metabolite of nicotine, the plasma half-life is over 20-30 hrs. Here, we evaluated its characteristic properties on the apoA-I mediated HDL generation. Method: Cotinine (5.6 to 11.2μM), or nicotine (5 to 150μM) were supplemented to medium and co-incubated with apoA-I (10μg/mL) for 18 hrs with THP-1 cells to determine their effect on efflux activity. Cellular ACAT accessible cholesterol pool size was determined by [ 14 C]oleic acid labeling of cells for 60 min immediately after removal of the culture medium. The culture medium and the cellular lipids were extracted by organic solvents and cholesterol and phospholipids content were determined. Nicotine was administered orally as an aqueous solution (10 μM) to C57BL/6 mice for 10 days and the plasma lipoprotein profiles were measured by gel-HPLC (tandem TSK-lipopropak XL ) with online enzymatic lipid assay system (Skylight biotech, Inc.). Results: Supplementation of nicotine into the medium showed no effect on the apoA-I mediated cellular cholesterol release from THP-1 cells. On the other hand, cotinine increased apoA-I mediated cellular cholesterol efflux 2.8 fold. ACAT accessible cholesterol pool size was dramatically decreased to 80% and 58% of control with 5 and 10 μM cotinine treatment, respectively, indicating that cotinine effectively increased apoA-I/ABCA1 mediated cellular cholesterol efflux. Mice with oral nicotine administration showed increased plasma HDL by 11.4% (50.1±4.4 and 55.8±3.9 mg/dL for control and nicotine treatment, respectively). Conclusions: Cotinine increased apoA-I mediated cellular cholesterol efflux in THP-1 cells. The cellular ACAT accessible cholesterol pool size reduction is one of the early reactions of apoA-I/ABCA1 mediated cellular cholesterol efflux. Cotinine seemingly modifies cellular factor/factors to induce a change in cholesterol distribution. Mice administrated oral nicotine may convert the compound to cotinine by CYP2A6 and aldehyde oxidase activities in their liver, and which likely increased HDL generation. Further experiments are necessary to examine the direct effect of cotinine on the ABCA1 transporter for increasing HDL assembly system.

Glutathione and Inter-α-trypsin inhibitor heavy chain 3 (Itih3) mRNA levels in nicotine-treated Cd44 knockout mice.

Cluster of differentiation 44 (Cd44), a hyaluronan receptor, and the secreted hyaluronan-binding protein Inter-α-trypsin Inhibitor Heavy chain 3 (Itih3) play an important role in cancer and oxidative stress. Smoking of tobacco reduces Itih3 in the plasma and activates hyaluronan signaling through Cd44, but the impact of Cd44 on Itih3 expression is unknown. Here, we studied changes induced by the tobacco component nicotine on the glutathione (GSH) antioxidant system and Itih3 gene expression in Cd44 knockout mice. Cd44 deficiency decreased baseline total GSH and oxidized glutathione (GSSG) levels in the liver compared to wildtype mice. However, contrary to wildtype mice, chronic oral nicotine administration (200 μg/ml) failed to further reduce total GSH and GSSG in Cd44 mice. Sex differences with lowered glutathione levels in females was also detectable only in wildtype but not Cd44 knockout mice. Itih3 mRNA levels in the liver and hypothalamus were not affected by nicotine, Cd44 genotype or sex. Nonetheless, the correlation between Itih3 and total GSH levels in the liver (r = 0.42, p < 0.05) suggested a role of Itih3 in glutathione metabolism in WT mice. Again this effect was diminished in Cd44 knockout mice. The disappearance of nicotine effects, sex differences and correlations between Itih3 and total GSH in Cd44 knockout mice compared to wildtype animals suggests an interaction between nicotine, Cd44 and/or sex-dependent signaling in the regulation of glutathione metabolism.

Detrimental effects of nicotine on thioacetamide-induced liver injury in mice

Aim: Nicotine exerts a number of physiological effects. The purpose of this study was to determine the effects of nicotine on thioacetamide (TAA)-induced liver fibrosis in mice.Materials and methods: For in vivo experiments, hepatic fibrosis was induced by TAA (0.25 g/kg, i.p.) three times a week for 6 weeks. Mice of TAA treated groups were administered daily with distilled water and nicotine (50 or 100 μg/mL) via gastrogavage throughout the experimental period. For in vitro experiments, HepG2 (human liver cancer cell line) and LX-2 (human hepatic stellate cell line) were used to determine oxidative stress and fibrosis, respectively.Results: Compared to control groups, TAA treated groups had significantly differences in serum alanine transferase and aspartate aminotransferase levels and nicotine accentuated liver injury. Moreover, nicotine increased the mRNA levels of TAA-induced transforming growth factor-β (TGF-β) and collagen type I alpha 1 in the liver. Nicotine also increased TAA-induced oxidative stress. Histological examination confirmed that nicotine aggravated the degree of fibrosis caused by TAA treatment. Additionally, nicotine enhanced hepatic stellate cell activation via promoting the expression of α-smooth muscle actin.Conclusions: Oral administration of nicotine significantly aggravated TAA-induced hepatic fibrosis in mice through enhancing TGF-β secretion and TAA-induced oxidative stress. The increase in TGF-β levels might be associated with the strengthening of oxidative processes, subsequently leading to increased hepatic stellate cell activation and extracellular matrix deposition. These results suggest that patients with liver disease should be advised to abandon smoking since nicotine may exacerbate hepatic fibrosis.

Protective effect of Eruca sativa seed oil against oral nicotine induced testicular damage in rats.

Nicotine is a pharmacologically active component of the tobacco that adversely affects the male reproductive system and fertility. Nicotine administration in experimental animals was found to affect spermatogenesis, epididymal sperm count, motility and the fertilizing potential of sperms. The goal of this work is to assess the protective or ameliorative effect of Eruca Sativa seed oil against testicular damage induced by oral administration of nicotine in rats. Male adult Sprague-Dawley rats were used and divided into three groups; control, nicotine treated and nicotine and Eruca seed oil treated groups. After three weeks of treatment, the rats were weighed and sacrificed where testes were removed and weighed then calculating relative testis weights. The testes were processed for routine paraffin embedding and staining and the sections were examined for different morphometric and histopathological changes. The results show that nicotine administration had an effect on the body and testis weight and various morphometric parameters of the testis. It also induced varying degrees of structural damage to the seminiferous tubules, with shrinkage and absence of mature spermatids. Disorganized, vacuolization and loss of germinal cells were noticed in the basement membrane. The co-administration of Eruca Sativa seed oil led to improvement in the morphometric and histopathological changes of the seminiferous tubules. In conclusion, Eruca Sativa seed oil treatment in this study had a protective role by reversing, almost completely, all morphometric and histological changes in the testis induced by nicotine administration.

Nicotine induces resistance to erlotinib via cross-talk between α 1 nAChR and EGFR in the non-small cell lung cancer xenograft model.

Given our previously published study, α 1 nicotinic acetylcholine receptor (nAChR) plays an essential role in nicotine-induced cell signaling and nicotine-induced resistance to epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) in non-small cell lung cancer (NSCLC) PC9 cells. The aim of this study was to investigate the potential mechanism between nAChR and EGFR for nicotine-induced resistance to EGFR-TKI erlotinib in the NSCLC xenograft model. We identified the role of nicotine to EGFR/AKT/ERK pathways and to erlotinib-resistance in NSCLC PC9 and HCC827 cells by MTS assay and western blot. Then, we established the PC9 xenograft model with nicotine exposure and treated mice with erlotinib combined with vehicle or nicotine. We confirmed the effects of nicotine on EGFR/AKT/ERK pathways and determined nicotine's potential in preventing from the effect of erlotinib on NSCLC cells. Then, we showed that nicotine exposures can promote tumor growth and induce resistance to erlotinib in the PC9 xenograft model. Our results also indicated that chronic oral administration of nicotine can cause more significant erlotinib-resistance compared with acute i.v. injection of nicotine through activating α 1 nAChR and EGFR pathways. These results suggest that nicotine contributes to the progression and erlotinib-resistance of the NSCLC xenograft model via the cooperation between nAChR and EGFR.

Orally administered nicotine induces urothelial hyperplasia in rats and mice

Tobacco smoking is a major risk factor for multiple human cancers including urinary bladder carcinoma. Tobacco smoke is a complex mixture containing chemicals that are known carcinogens in humans and/or animals. Aromatic amines a major class of DNA-reactive carcinogens in cigarette smoke, are not present at sufficiently high levels to fully explain the incidence of bladder cancer in cigarette smokers. Other agents in tobacco smoke could be excreted in urine and enhance the carcinogenic process by increasing urothelial cell proliferation. Nicotine is one such major component, as it has been shown to induce cell proliferation in multiple cell types in vitro. However, in vivo evidence specifically for the urothelium is lacking. We previously showed that cigarette smoke induces increased urothelial cell proliferation in mice. In the present study, urothelial proliferative and cytotoxic effects were examined after nicotine treatment in mice and rats. Nicotine hydrogen tartrate was administered in drinking water to rats (52ppm nicotine) and mice (514ppm nicotine) for 4 weeks and urothelial changes were evaluated. Histopathologically, 7/10 rats and 4/10 mice showed simple hyperplasia following nicotine treatment compared to none in the controls. Rats had an increased mean BrdU labeling index compared to controls, although it was not statistically significantly elevated in either species. Scanning electron microscopic visualization of the urothelium did not reveal significant cytotoxicity. These findings suggest that oral nicotine administration induced urothelial hyperplasia (increased cell proliferation), possibly due to a mitogenic effect of nicotine and/or its metabolites.

Pharmacokinetic and Pharmacodynamics Studies of Nicotine After Oral Administration in Mice: Effects of Methoxsalen, a CYP2A5/6 Inhibitor

The use of novel oral nicotine delivery devices and compositions for human consumption and for animal research studies has been increasing in the last several years. Studies were undertaken to examine whether the systemic administration of methoxsalen, an inhibitor of human CYP2A6 and mouse CYP2A5, would modulate nicotine pharmacokinetics and pharmacological effects (antinociception in the tail-flick, and hot-plate tests, and hypothermia) in male ICR mouse after acute oral nicotine administration. Administration of intra peritoneal (ip) methoxsalen significantly increased nicotine's Cmax, prolonged the plasma half-life (fourfold decrease) of nicotine, and increased its area under the curve (AUC) compared with ip vehicle treatment. Methoxsalen pretreatment prolonged the duration of nicotine-induced antinociception and hypothermia (15mg/kg, po) for periods up to 6- and 24-hr postnicotine administration, respectively. Additionally, methoxsalen potentiated nicotine-induced antinociception and hypothermia as evidenced by leftward shifts in nicotine's dose-response curve. Furthermore, this prolongation of nicotine's effects after methoxsalen was associated with a parallel prolongation of nicotine plasma levels in mice. These data strongly suggest that variation in the rates of nicotine metabolic inactivation substantially alter pharmacological effects of nicotine given orally. We have shown that the pharmacological effects of inhibiting nicotine's metabolism after oral administration in mice are profound. Our results suggest that inhibiting nicotine metabolism can be used to dramatically enhance nicotine's bioavailability and its resulting pharmacology, which further supports this inhibitory approach for clinical development of an oral nicotine replacement therapy.

Behavioral effects of combined environmental enrichment and chronic nicotine administration in male NMRI mice

Environmental enrichment (EE) is an experimental paradigm which provides sensory, social, physical and cognitive stimulation for rodents. Experimental evidence indicates that this type of housing induces different neurobiological and behavioral changes. However, few studies have evaluated the consequences of combined exposure to an enriched environment and nicotine administration during a critical period of development such as adolescence. Taking into account previous studies, it can be hypothesized that a chronic treatment with nicotine would modulate the effects of rearing animals in enriched environments. In the current study, our main aim was to evaluate the effects of EE and chronic nicotine administration on physiological parameters (weight, fluid intake and cotinine levels), motor activity, exploratory behavior, anxiety and learning in male NMRI mice. Half of the mice (n=32) were exposed to an enriched environment (EE) and the other half (n=32) were housed in standard environments (SE) with or without oral nicotine administration (100μg/ml). After 3weeks, mice were evaluated in a behavioral battery that included an elevated plus-maze, a hole board, an actimeter and an inhibitory avoidance task. Blood cotinine levels were measured in an additional group of 32 mice in order to confirm nicotine intake. Results indicated that mice reared in an enriched environment gained less body weight and displayed higher fluid intake than those maintained in a standard environment. EE reduced motor activity, exploratory behavior and anxiety, whereas it enhanced inhibitory avoidance learning. In relation to the effects of chronic nicotine treatment, the data reflected a lower increase in body weight and a reduced fluid intake in nicotine-treated mice. In the elevated plus-maze, nicotine induced a reduction of total arm entries and rearings. Cotinine levels were higher in mice that received oral nicotine than in the control group. We conclude that the EE paradigm applied in this study induces physiological and behavioral changes in NMRI mice. Chronic nicotine treatment diminished motor activity displayed by mice in the elevated plus-maze but did not have significant effects on inhibitory avoidance learning. Future studies should explore in greater depth the interaction between environmental factors and nicotine administration using longer periods of EE, a wider range of doses and/or other cholinergic agonists, acute drug administration, and sequential exposure to nicotine and EE.

Prenatal ablation of nicotinic receptor alpha7 cell lineages produces lumbosacral spina bifida the severity of which is modified by choline and nicotine exposure

Lumbosacral spina bifida is a common debilitating birth defect whose multiple causes are poorly understood. Here, we provide the first genetic delineation of cholinergic nicotinic receptor alpha7 (Chrna7) expression and link the ablation of the Chrna7 cell lineage to this condition in the mouse. Using homologous recombination, an IRES-Cre bi-cistronic cassette was introduced into the 3′ noncoding region of Chrna7 (Chrna7:Cre) for identifying cell lineages expressing this gene. This lineage first appears at embryonic day E9.0 in rhombomeres 3 and 5 of the neural tube and extends to cell subsets in most tissues by E14.5. Ablation of the Chrna7:Cre cell lineage in embryos from crosses with conditionally expressed attenuated diphtheria toxin results in precise developmental defects including omphalocele (89%) and open spina bifida (SB; 80%). We hypothesized that like humans, this defect would be modified by environmental compounds not only folic acid or choline but also nicotine. Prenatal chronic oral nicotine administration substantially worsened the defect to often include the rostral neural tube. In contrast, supplementation of the maternal diet with 2% choline decreased SB prevalence to 38% and dramatically reduced the defect severity. Folic acid supplementation only trended towards a reduced SB frequency. The omphalocele was unaffected by these interventions. These studies identify the Chrna7 cell lineage as participating in posterior neuropore closure and present a novel model of lower SB that can be substantially modified by the prenatal environment. © 2012 Wiley Periodicals, Inc.

Effects of Oral Administrationof Nicotine on Blood Glucose, Electrolytes and Lipid Profile in Albino Rats

Effects of Oral Administrationof Nicotine on Blood Glucose, Electrolytes and Lipid Profile in Albino Rats