Preventive effects of caffeine on nicotine plus high-fat diet-induced hepatic steatosis and gain weight: a possible explanation for why obese smokers with high coffee consumption tend to be leaner.

Non-alcoholic fatty liver disease (NAFLD) is a prevalent liver disorder, affecting approximately 25 % of the population. Coffee-drinking obese smokers exhibit lower body weights and decreased NAFLD rates, but the reasons behind this remain unclear. Additionally, the effect of nicotine, the main component of tobacco, on the development of NAFLD is still controversial. Our study aimed to explore the possible reasons that drinking coffee could alleviate NAFLD and gain weight and identify the real role of nicotine in NAFLD of obese smokers. A NAFLD model in mice was induced by administering nicotine and a high-fat diet (HFD). We recorded changes in body weight and daily food intake, measured the weights of the liver and visceral fat, and observed liver and adipose tissue histopathology. Lipid levels, liver function, liver malondialdehyde (MDA), superoxide dismutase (SOD), serum inflammatory cytokine levels and the expression of hepatic genes involved in lipid metabolism were determined. Our results demonstrated that nicotine exacerbated the development of NAFLD and caffeine had a hepatoprotective effect on NAFLD. The administration of caffeine could ameliorate nicotine-plus-HFD-induced NAFLD by reducing lipid accumulation, regulating hepatic lipid metabolism, alleviating oxidative stress, attenuating inflammatory response and restoring hepatic functions. These results might explain why obese smokers with high coffee consumption exhibit the lower incidence rate of NAFLD and tend to be leaner. It is essential to emphasise that the detrimental impact of smoking on health is multifaceted. Smoking cessation remains the sole practical and effective strategy for averting the tobacco-related complications and reducing the risk of mortality.

The effect of Cornus mas extract on nicotine-induced oxidative stress and intratesticular damage in male rats.

The role of oxidative stress in disease pathogenesis has been extensively investigated. Researchers have gathered sufficient evidence related to oxidative stress-mediated intratesticular damage. The aim of this was study to evaluate the effects of Cornus Mas (CM) extract on intratesticular changes in rats exposed to nicotine. Thirty Wistar albino rats were divided into four groups. The groups and the administrated agents for 35 days were as follows; Control group (n=6): 0.9% saline, intraperitoneally; Nicotine group (n=7): 4 mg/kg nicotine, subcutaneous; CM group (n=7): 1000 mg/kg CM extract in 0.5 ml saline, via gavage; Nicotine + CM Group (n=8): 4 mg/kg Nicotine, subcutaneous + 1000 mg/kg CM extract via gavage. One rat each from the groups Nicotine and CM died.  In spermatogenetic and histopathological examination, significant positive changes were detected in nicotine + CM group regarding seminal parameters, apoptotic cells, Factor VIII and Johnsen score as compared to nicotine group. Oxidative stress markers were higher in nicotine group as compared to the control group. OSI and MDA levels were found to be reduced in nicotine + CM group than nicotine group. Nicotine induced a significant increase in TNF-α and IL-6 levels compared to the control group; however, CM effectively counteracted this increase. We have shown that nicotine increases testicular damage, causes apoptosis of testicular cells and adversely affects spermatogenesis by increasing inflammation. We concluded that CM extract exerted beneficial effects on spermatogenesis and minimized testicular parenchymal damage, apoptosis and angiogenesis. Rapidly increasing understanding of the complexity of oxidative stress in intratesticular is the key to unlocking the potential of ROS-targeting therapies.

Alterations of auditory sensory gating in mice with noise-induced tinnitus treated with nicotine and cannabis extract.

Tinnitus is a phantom sound perception affecting both auditory and limbic structures. The mechanisms of tinnitus remain unclear and it is debatable whether tinnitus alters attention to sound and the ability to inhibit repetitive sounds, a phenomenon also known as auditory gating. Here we investigate if noise exposure interferes with auditory gating and whether natural extracts of cannabis or nicotine could improve auditory pre-attentional processing in noise-exposed mice. We used 22 male C57BL/6J mice divided into noise-exposed (exposed to a 9-11 kHz narrow band noise for 1 h) and sham (no sound during noise exposure) groups. Hearing thresholds were measured using auditory brainstem responses, and tinnitus-like behavior was assessed using Gap prepulse inhibition of acoustic startle. After noise exposure, mice were implanted with multi-electrodes in the dorsal hippocampus to assess auditory event-related potentials in response to paired clicks. The results showed that mice with tinnitus-like behavior displayed auditory gating of repetitive clicks, but with larger amplitudes and longer latencies of the N40 component of the aERP waveform. The combination of cannabis extract and nicotine improved the auditory gating ratio in noise-exposed mice without permanent hearing threshold shifts. Lastly, the longer latency of the N40 component appears due to an increased sensitivity to cannabis extract in noise-exposed mice compared to sham mice. The study suggests that the altered central plasticity in tinnitus is more sensitive to the combined actions on the cholinergic and the endocannabinoid systems. Overall, the findings contribute to a better understanding of pharmacological modulation of auditory sensory gating.

Omega-3 fatty acids prevent nicotine withdrawal-induced impairment of learning and memory via affecting oxidative status, inflammatory response, cholinergic activity, BDNF and amyloid-B in rat hippocampal tissues.

In the present study, the main objective was to reveal whether treatment by Omega-3 fatty acids could prevent the adverse effects of adolescent nicotine withdrawal on spatial and avoidance memory in male rats. For this purpose, Morris water maze and passive avoidance tests were performed on male Wistar rats and the hippocampal levels of oxidative stress markers, inflammatory indices, brain-derived neurotrophic factor, nitrite, amyloid-B and acetylcholinesterase (AChE) were measured. Moreover, density of dark neurons were assessed in CA1 and CA3 regions. Results showed that adolescent nicotine exposure followed by a period of drug cessation exacerbates the behavioral indices of learning and memory through affecting a variety of biochemical markers within the hippocampal tissues. These changes lead to elevation of oxidative and inflammatory markers, reduction of neurotrophic capacity and increased AChE activity in hippocampal tissues. In addition, it was observed that co-administration of nicotine with Omega-3 fatty acids significantly prevents nicotine withdrawal-induced adverse effects through restoration of the mentioned biochemical disturbances. Therefore, we suggest administration of Omega-3 fatty acids as a safe, inexpensive and effective therapeutic strategy for prevention of memory dysfunctions associated with nicotine abstinence during adolescence.

Electronic cigarettes can damage lingual papillae and taste buds. Can vitamins C and E supplementation reverse this damage?

AIMS: This histological study focuses on the impact of electronic cigarette liquid (EC) on lingual papillae, especially taste buds, compare it to nicotine, and investigates the potential of vitamins in reversing these unwanted changes. MAIN METHODS: 40 adult male rats were allocated into 5 groups. Control injected saline intraperitoneally, electronic cigarettes group injected EC-liquid containing nicotine of dose (0.75 mg/kg), electronic cigarette group injected EC-liquid then supplemented orally with vitamins C and E, nicotine group injected pure nicotine of dose (0.75 mg/kg) and lastly nicotine group injected with pure nicotine of dose (0.75 mg/kg) then supplemented orally with vitamins C and E. Keratin surface area and the ratio between taste buds and its epithelial covering surface areas in fungiform papillae were measured. KEY FINDINGS: Histological examination of EC group revealed abnormal epithelial stratification and mitotic figs. EC plus V group showed intact basal cell layer. N group showed better histological stratification than EC group. Fungiform and circumvallate papillae in EC and N groups showed distorted appearance of taste buds. Histomorphometry analysis showed a significant decrease in taste buds to epithelium surface areas in EC, nicotine, and EC plus V groups, p-value (<0.05). There was no significant difference between control and N plus V groups. SIGNIFICANCE: Administration of vitamins C and E showed preservation of normal histological features of the lingual mucous membrane. EC caused striking damage to taste buds even after the administration of vitamins. The negative effects of electronic cigarettes are not confined only to the presence of nicotine.

Salvia officinalis L. Methanolic Extract Reduces Lead and Nicotine-Induced Sperm Quality Degeneration in Male Rats.

Most heavy metals and industrial chemicals such as nicotine and lead cause harm to the reproduction process through a decrease in sperm motility, fertilization process, and sperm binding to the oocyte. Salvia officinalis L. (sage) has been reported to enhance serum testosterone levels and other certain biochemical enzymes. Thus, the current study is aimed at evaluating the potential health benefits of S. officinalis L. methanol extract on lead and nicotine hydrogen tartrate-induced sperm quality degeneration in male rats and also identifying some of the non-polar volatile bioactive compounds that might be attributed to the bioactivity of S. officinalis extract using gas chromatography-mass spectrometry (GC/MS). In the study, fifty-four mature male albino rats of about 220-250 g [were divided randomly and equally into 9 groups (n=6)]. Sperm quality degeneration was induced through the oral administration of 1.5 g/L of lead acetate in drinking water or peritoneal injection of 0.50 mg/kg (animal weight) nicotine hydrogen tartrate for sixty days. Two doses (200 & 400 mg/kg b.w.) of S. officinalis L. were used. The rats were anesthetized after the experimental period and then sacrificed. Blood samples were collected while the epididymis, testicle, and accessory sex organs (prostates and seminal vesical) were taken for histopathological studies. Twelve major compounds were identified through the GC/MS analysis of S. officinalis L. methanol extract. Lead and nicotine toxicity had a great effect on the rats' sperm quality causing a significant (p<0.05) decrease in the quantity of sperm and sperm motility as well as an upsurge in the abnormalities of the sperm and a reduction in the length & diameter of seminiferous tubules and size & weight of sexual organs (accessory sex glands, epididymis, and testis). The administration of S. officinalis L. methanol extract, however, had a positive impact on the sexual organ weights, semen quality & quantity, and rats' fertility, thus, ameliorating the adversative effects of both lead and nicotine. Further evaluation and isolation of the bioactive components are recommended as potential drug leads.

Omega-3 fatty acids prevent nicotine withdrawal-induced exacerbation of anxiety and depression by affecting oxidative stress balance, inflammatory response, BDNF and serotonin metabolism in rats.

Adolescents are known to be more vulnerable than adults to the adverse effects of nicotine dependence. In the present study, we aimed to investigate whether adolescent nicotine exposure, followed by a period of abstinence, could affect the anxiety- and depressive-like behaviors in rats. For this purpose, behavioral assessments were carried out using open field test, elevated plus maze and forced swimming test in male rats received chronic nicotine intake during adolescence followed by a period of abstinence in adulthood, compared to their control counterparts. In addition, O3 pre-treatment was done at three different doses to reveal whether it could prevent nicotine withdrawal effects. Then, animals were euthanized and the cortical concentrations of oxidative stress markers, inflammatory indices, brain-derived neurotrophic factor, serotonin and the enzymatic activity of monoamine oxidase-A were measured. Results indicated that nicotine withdrawal exacerbates the behavioral signs of anxiety through alteration of the brain oxidative stress balance, inflammatory response and serotonin metabolism. Moreover, we found that omega 3 pre-treatment significantly prevents the nicotine withdrawal-induced complications by restoration of changes in the mentioned biochemical indices. Moreover, the improving effects of O3 fatty acids were found to be dose-dependent in all experiments. Taken together, we would like to suggest the O3 fatty acids supplementation as a safe, inexpensive and effective strategy for prevention or amelioration of detrimental effects induced by nicotine withdrawal at cellular and behavioral levels.

Enhanced tolerance of Cupriavidus necator NCIMB 11599 to lignocellulosic derived inhibitors by inserting NAD salvage pathway genes.

Polyhydroxybutyrate (PHB) is a bio-based, biodegradable and biocompatible plastic that has the potential to replace petroleum-based plastics. Lignocellulosic biomass is a promising feedstock for industrial fermentation to produce bioproducts such as polyhydroxybutyrate (PHB). However, the pretreatment processes of lignocellulosic biomass lead to the generation of toxic byproducts, such as furfural, 5-HMF, vanillin, and acetate, which affect microbial growth and productivity. In this study, to reduce furfural toxicity during PHB production from lignocellulosic hydrolysates, we genetically engineered Cupriavidus necator NCIMB 11599, by inserting the nicotine amide salvage pathway genes pncB and nadE to increase the NAD(P)H pool. We found that the expression of pncB was the most effective in improving tolerance to inhibitors, cell growth, PHB production and sugar consumption rate. In addition, the engineered strain harboring pncB showed higher PHB production using lignocellulosic hydrolysates than the wild-type strain. Therefore, the application of NAD salvage pathway genes improves the tolerance of Cupriavidus necator to lignocellulosic-derived inhibitors and should be used to optimize PHB production.

Supplemental treatment to atropine improves the efficacy to reverse nerve agent induced bronchoconstriction.

Exposure to highly toxic organophosphorus compounds causes inhibition of the enzyme acetylcholinesterase resulting in a cholinergic toxidrome and innervation of receptors in the neuromuscular junction may cause life-threatening respiratory effects. The involvement of several receptor systems was therefore examined for their impact on bronchoconstriction using an ex vivo rat precision-cut lung slice (PCLS) model. The ability to recover airways with therapeutics following nerve agent exposure was determined by quantitative analyses of muscle contraction. PCLS exposed to nicotine resulted in a dose-dependent bronchoconstriction. The neuromuscular nicotinic antagonist tubocurarine counteracted the nicotine-induced bronchoconstriction but not the ganglion blocker mecamylamine or the common muscarinic antagonist atropine. Correspondingly, atropine demonstrated a significant airway relaxation following ACh-exposure while tubocurarine did not. Atropine, the M3 muscarinic receptor antagonist 4-DAMP, tubocurarine, the ß2-adrenergic receptor agonist formoterol, the Na+-channel blocker tetrodotoxin and the K+ATP-channel opener cromakalim all significantly decreased airway contractions induced by electric field stimulation. Following VX-exposure, treatment with atropine and the Ca2+-channel blocker magnesium sulfate resulted in significant airway relaxation. Formoterol, cromakalim and magnesium sulfate administered in combinations with atropine demonstrated an additive effect. In conclusion, the present study demonstrated improved airway function following nerve agent exposure by adjunct treatment to the standard therapy of atropine.

Anti-inflammatory activity of nicotine isolated from Brassica oleracea in rheumatoid arthritis.

OBJECTIVES: Rheumatoid arthritis (RA) is an autoimmune disease, associated with chronic inflammation of synoviocytes. Tumor necrosis factor α (TNF-α) plays a crucial role in the pathogenesis of RA through pro-inflammatory cytokines. Nicotine, an alkaloid used as herbal medicine, often worked as an anti-inflammatory agent. In the present study, we tried to uncover the anti-inflammatory impact of nicotine against RA. MATERIALS AND METHODS: Nicotine was isolated from Brassica oleracea, purified by high profile/phase liquid chromatography (HPLC). In-silico docking was carried out using bioinformatics tools SwissADME (absorption, distribution, metabolism and excretion), PASS, and Drug-induced Gene Expression Profile (DIGEP)-Pred to determine drug likeliness of nicotine. The in-vitro study was performed in TNFα-induced SW982 synoviocytes by qPCR. mRNA expression of pro-inflammatory cytokines (TNF, IL6, IL1ß) and proteins (TRAF2, P50, P65) were analyzed followed by validation of P65 (RELA), pP65, IkBα by Western blot analysis. RESULTS: Nicotine compound was extracted from Brassica oleracea and purified by HPLC method (Rt values at 2.67 min). The physicochemical, pharmacokinetic properties and drug-likeliness of nicotine were studied by in-silico analysis. In-vitro studies revealed that nicotine lowers the expression of inflammatory cytokines (TNF, IL6, IL1ß) and proteins (TNF receptor-associated factor 2 (TRAF2), P50, P65) at 1 µg/ml in TNFα-induced SW982 cells. CONCLUSION: Nicotine from natural sources (Brassica oleracea) has been found to be an effective anti- inflammatory compound at a low dosage; thus, identifying the role of nicotine present in the natural sources as a therapeutic option for RA, may be recommended as remedial drug instead of synthetic drug.

Ginseng alleviates folliculogenesis disorders via induction of cell proliferation and downregulation of apoptotic markers in nicotine-treated mice.

BACKGROUND: Ginseng is a powerful phytoestrogen with high antioxidant properties. OBJECTIVE: This study aimed to evaluate the effect of Panax Ginseng (PG) on folliculogenesis, proliferation, and apoptosis in the ovary impaired by nicotine. METHODS: Forty adult mice were divided into five groups. Control, sham, and nicotine groups, and co-treated groups of nicotine and ginseng in doses of 0.5 and 1 g/kg. Folliculogenesis was assessed via histopathology and serum evaluation of estradiol, progesterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) by ELISA. Lipid peroxidation and antioxidant enzyme activities both in homogenate tissue and serum were assayed by colorimetric analysis. Apoptotic markers of cytochrome c (Cyt c), Bax, and Bcl-2 were evaluated by RT-PCR. Proliferative index was studied by the Ki-67 immunostaining procedure. RESULTS: In comparison to the control or sham groups, nicotine significantly reduced the levels of FSH, LH, and estradiol hormones. An insignificant reduction was observed in the progesterone hormone. Nicotine reduced all healthy follicle numbers, except primordial (P = 0.001). Malondialdehyde (MDA) was increased in tissue and serum in the nicotine group (P = 0.01). Serum catalase (CAT) and enzymatic activity of superoxide dismutase (SOD) both were reduced in tissue and the serum, in the nicotine group. Nicotine induced a reduction in the proliferative indexes of granulosa and theca cells in pre-antral and antral follicles (P = 0.001). However, its effect on the proliferative index of stroma cells was not significant. Apoptotic markers were elevated in the nicotine group (P = 0.001). Co-treatment with ginseng elevated all sex hormones, increased healthy follicles, and reduced tissue or serum lipid peroxidation, compared with the nicotine group (p < 0.05). Co-Treatment with ginseng also reduced the expression of apoptotic markers and increased the proliferative indexes in granulosa and theca cells in pre-antral and antral follicles and also in stroma cells, in comparison to the nicotine group (P = 0.001). All above-mentioned alterations following treatment with ginseng were remarkable, especially in the dose of 1 g/kg. CONCLUSION: This study showed ginseng protects folliculogenesis via alteration of hypothalamic- pituitary-gonadal (HPG) axis, induction of proliferation in ovarian somatic cells, reduction of lipid peroxidation, and downregulation of apoptotic markers in the mouse ovary, treated with nicotine.

Ginkgo biloba L. flavonoids inhibit CYP 2A5; potential dietary supplement for nicotine replacement therapy enhancement.

Smoking is a public health concern, and even though smoking cessation methods exist, nicotine replacement therapy (NRT) is often ineffective. Smoking behavior is related to the nicotine metabolizing enzyme (NME) P450 2A6 (mouse 2A5) polymorphisms. Accordingly, fast metabolizers are nicotine dependent, and have low quitting rates compared to slow metabolizers. In this study we examined the ability of Ginkgo biloba L (GB) and its constituents to inhibit the NME, using mouse liver microsomes containing the 2A5 enzyme. Our results indicate that GB can inhibit 2A5 (25% inhibition at 5%v/v), with the flavonoids quercetin, isorhamnetin, and kaempferol being responsible for this inhibition (23.5%, 10.7%, 25.2% inhibition at 60 ng/µL, respectively). Importantly, the flavonoids inhibited 2A5 via mechanism based inhibition (for quercetin 30 ng/µl inhibition increased from 20.8% to 26.9% within 15 minutes). Our results suggest that GB if consumed on a regular basis can help NRT enhancement particularly in fast nicotine metabolizers.

Intrahippocampal co-administration of nicotine and O-acetyl-L-carnitine prevents the H-89-induced spatial learning deficits in Morris water maze.

OBJECTIVES: H-89 (a protein kinase AII [PKA II] inhibitor) impairs the spatial memory in the Morris water maze task in rats. In the present study, we aimed to study the protective effects of nicotine and O-acetyl-L-carnitine against H-89-induced spatial memory deficits. METHODS: Spatial memory impairment was induced by the bilateral intrahippocampal administration of 10 µM H-89 (dissolved in dimethyl sulfoxide, DMSO) to rats. The rats then received bilateral administrations of either nicotine (1 µg/µL, dissolved in saline) or O-acetyl-L-carnitine (100 µM/side, dissolved in deionized water) alone and in combination. Control groups received either saline, deionized water, or DMSO. RESULTS: The H-89-treated animals showed significant increases in the time and distance travelled to find hidden platforms, and there was also a significant decrease in the time spent in the target quadrant compared to DMSO-treated animals. Nicotine and O-acetyl-L-carnitine had no significant effects on H-89-induced spatial learning impairments alone, but the bilateral intrahippocampal co-administration of nicotine and O-acetyl-L-carnitine prevented H-89-induced spatial learning deficits and increased the time spent in the target quadrant in comparison with H-89-treated animals. CONCLUSIONS: Our results indicated the potential synergistic effects of nicotine and O-acetyl-L-carnitine in preventing protein kinase AII inhibitor (H-89)-induced spatial learning impairments.

Levo-tetrahydropalmatine inhibits α4ß2 nicotinic receptor response to nicotine in cultured SH-EP1 cells.

Nicotine, a major component of tobacco, is highly addictive and acts on nicotinic acetylcholine receptors (nAChRs) to stimulate reward-associated circuits in the brain. It is well known that nAChRs play critical roles in mediating nicotine reward and addiction. Current FDA-approved medications for smoking cessation are the antidepressant bupropion and the nicotinic partial agonist varenicline, yet both are limited by adverse side effects and moderate efficacy. Thus, development of more efficacious medications with fewer side effects for nicotine addiction and smoking cessation is urgently needed. l-Tetrahydropalmatine (l-THP) is an active ingredient of the Chinese medicinal herb Corydalis ambigua that possesses rich neuropharmacological actions on dopamine (DA) receptors in the mesocorticolimbic dopaminergic reward pathway. L-THP has been explored as anti-addiction treatments for drug abuse including nicotine. However, the targets and mechanisms of l-THP-caused anti-nicotine effects are largely unknown. In this study we address this question by elucidating the effects of l-THP on human neuronal nAChRs using patch-clamp recordings. Human neuronal α4ß2-nAChRs were heterologously expressed in SH-EP1 human epithelial cells. Bath application of nicotine (0.1-100 µM) induced inward currents, co-application of l-THP (3 µM) inhibited nicotine-induced currents in the transfected cells. L-THP-caused inhibition was concentration-dependent (the EC50 values for inhibiting the peak and steady-state current were 18 and 2.1 µM, respectively) and non-competitive. Kinetic analysis of the whole-cell currents showed that l-THP slowed rising time and accelerated decay time constants. L-THP specifically modulated α4ß2-nAChRs, as it did not affect α7-nAChRs or α1*-nAChRs (muscle type). Interestingly, two putative α4ß2-nAChR isoforms, namely sazetidine A-activated, high-sensitive one (α42ß23-nAChR) and cytisine-activated, low-sensitive one (α43ß22-nAChR) were pharmacologically separated, and the low-sensitive one was more susceptible to l-THP inhibition than the high-sensitive one. In conclusion, we demonstrate that l-THP blocks neuronal α4ß2-nAChR function, which may underlie its inhibition on nicotine addiction.

The Reassessed Impact of Nicotine against Neurotoxicity in Mesencephalic Dopaminergic Cell Cultures and Neuroblastoma N18TG2 Cells.

Neuroprotective effects of nicotine are still under debate, so further studies on its effectiveness against Parkinson's disease are required. In our present study, we used primary dopaminergic cell cultures and N18TG2 neuroblastoma cells to investigate the effect of nicotine and its neuroprotective potential against rotenone toxicity. Nicotine protected dopaminergic (tyrosine hydroxylase immunoreactive) neurons against rotenone. This effect was not nAChR receptor-dependent. Moreover, the alkaloid at a concentration of 5 µM caused an increase in neurite length, and at a concentration of 500 µM, it caused an increase in neurite count in dopaminergic cells exposed to rotenone. Nicotine alone was not toxic in either cell culture model, while the highest tested concentration of nicotine (500 µM) caused growth inhibition of N18TG2 neuroblastoma cells. Nicotine alone increased the level of glutathione in both cell cultures and also in rotenone-treated neuroblastoma cells. The obtained results may be helpful to explain the potential neuroprotective action of nicotine on neural cell cultures.

Prepulse inhibition based grouping of rats and assessing differences in response to pharmacological agents.

Schizophrenia modeling by disrupting prepulse inhibition (PPI) is one of the most frequently used psycho-pharmacological methods by administering pharmacological agents to stimulate disruption. However, since PPI is also a biological indicator of schizophrenia, it is possible to classify subjects based on their basal PPI values and group them as "low inhibition" and "high inhibition without taking any pharmacological agent. Therefore this study was conducted to show that rats can be divided into groups in terms of susceptibility to schizophrenia according to basal PPI values. It was also observed that these groups might give different responses to different pharmacological agents (apomorphine, amphetamine, MK-801, scopolamine, nicotine, caffeine). Male Sprague Dawley rats (250-350 g) were used in the study. To examine the effects of different pharmacological agents on the groups, apomorphine (0.5 mg/kg and 1 mg/kg), amphetamine (4 mg/kg), MK-801 (0.05 mg/kg and 0.15 mg/kg), scopolamine (0.4 mg/kg), nicotine (1 mg/kg) and caffeine (10 mg/kg and 30 mg/kg) were used. Amphetamine showed a disruptive effect on PPI in both low and high inhibitory groups, while apomorphine, MK-801, scopolamine, and nicotine showed PPI decrease only in the high inhibitory group. Besides, caffeine decreased PPI levels at two doses in the high inhibitory group; however, 10 mg/kg dose caffeine was increased only in the low inhibitory group. According to the data obtained from this study, rats can be grouped with baseline inhibition values by using PPI, and response differences of pharmacological agents to groups may vary.

APOE genotype influences P3b amplitude and response to smoking abstinence in young adults.

RATIONALE: There is strong evidence that nicotine can enhance cognitive functions and growing evidence that this effect may be larger in young healthy APOE ε4 carriers. However, the moderating effects of the APOE ε4 allele on cognitive impairments caused by nicotine deprivation in chronic smokers have not yet been studied with brain indices. OBJECTIVE: We sought to determine whether young female carriers of the APOE ε4 allele, relative to noncarriers, would exhibit larger abstinence-induced decreases in P3b amplitude during a two-stimulus auditory oddball task. METHODS: We compared parietal P3bs in female chronic smokers with either APOE ε3/ε3 (n = 54) or ε3/ε4 (n = 20) genotype under nicotine-sated conditions and after 12-17-h nicotine deprivation. RESULTS: Nicotine deprivation significantly reduced P3b amplitudes in APOE ε4 carriers, but not in APOE-ε3/ε3 individuals, such that the difference seen prior to nicotine deprivation was eliminated. CONCLUSIONS: The results suggest that subjects with the APOE ε4 allele are more sensitive to nicotine, which could influence smoking patterns, the risk for nicotine dependence, and the cognitive effects of nicotine use in these individuals.

Methionine Supplementation Abolishes Nicotine-Induced Place Preference in Zebrafish: a Behavioral and Molecular Analysis.

In zebrafish, nicotine is known to regulate sensitivity to psychostimulants via epigenetic mechanisms. Little however is known about the regulation of addictive-like behavior by DNA methylation processes. To evaluate the influence of DNA methylation on nicotine-induced conditioned place preference (CPP), zebrafish were exposed to methyl supplementation through oral L-methionine (Met) administration. Met was found to reduce dramatically nicotine-induced CPP as well as behaviors associated with drug reward. The reduction was associated with the upregulation of DNA methyltransferases (DNMT1 and 3) as well as with the downregulation of methyl-cytosine dioxygenase-1 (TET1) and of nicotinic receptor subunits. Met also increased the expression of histone methyltransferases in nicotine-induced CPP groups. It reversed the nicotine-induced reduction in the methylation at α7 and NMDAR1 gene promoters. Treatment with the DNMT inhibitor 5-aza-2'-deoxycytidine (AZA) was found to reverse the effects of Met in structures of the reward pathway. Interestingly, Met did not modify the amount of the phospho-form of CREB (pCREB), a key factor establishing nicotine conditioning, whereas AZA increased pCREB levels. Our data suggest that nicotine-seeking behavior is partially dependent on DNA methylation occurring probably at specific gene loci, such as α7 and NMDAR1 receptor gene promoters. Overall, they suggest that Met should be considered as a potential therapeutic drug to treat nicotine addiction.

Chronic exposure to cigarette smoke extract upregulates nicotinic receptor binding in adult and adolescent rats.

Heavy smokers display increased radioligand binding of nicotinic acetylcholine receptors (nAChRs). This "upregulation" is thought to be a contributing factor to tobacco dependence. Although cigarette smoke contains thousands of constituents that can contribute to nicotine dependence, it is not well understood whether non-nicotine constituents contribute to nAChR upregulation. In this study, we used an aqueous cigarette smoke extract (CSE), which contains nicotine and soluble constituents of cigarette smoke, to induce nAChR upregulation in adult and adolescent rats. To do this, male rats were exposed to nicotine or CSE (1.5 mg/kg/day nicotine equivalent, intravenously) daily for ten days. This experimental procedure produces equivalent levels of brain and plasma nicotine in nicotine- and CSE-treated animals. We then assessed nAChR upregulation using quantitative autoradiography to measure changes in three nAChR types. Adolescents were found to have consistently greater α4ß2 nAChR binding than adults in many brain regions. Chronic nicotine exposure did not significantly increase nAChR binding in any brain region at either age. Chronic CSE exposure selectively increased α4ß2 nAChR binding in adolescent medial amygdala and α7 binding in adolescent central amygdala and lateral hypothalamus. CSE also increased α3ß4 nAChR binding in the medial habenula and interpeduncular nucleus, and α7 binding in the medial amygdala, independent of age. Overall, this work provides evidence that cigarette smoke constituents influence nAChR upregulation in an age-, nAChR type- and region-dependent manner.

Protective Effects of Pinus halepensis Bark Extract and Nicotine on Cigarette Smoke-induced Oxidative Stress in Keratinocytes.

BACKGROUND/AIM: Cigarette smoke (CS) is a major environmental health threat. The oxidative stress induced by CS on keratinocytes and the possible protective effect of nicotine, its receptor inhibitors, and Pinus halepensis bark extract in relation to known antioxidants were investigated. MATERIALS AND METHODS: Primary mouse keratinocytes were exposed to cigarette smoke in the presence and absence of Pinus halepensis bark extract (1 µg/ml), rutin (50 µM) and ascorbic acid (250 µM), nicotine (1 µM) with or without mecamylamine (5 µM) and α-bungarotoxin (0.1 µM). Keratinocyte viability and oxidative stress were evaluated by MTT and fluorescence assays. RESULTS: Pinus halepensis bark extract decreased the oxidative stress and increased the viability of keratinocytes, and moreover, these effects were more pronounced compared to the mixture of rutin and L-ascorbic acid. Nicotine significantly enhanced the viability potentiation of the beneficial effect induced by Pinus halepensis bark extract. Mecamylamine and α-bungarotoxin showed no specific effect. CONCLUSION: Pinus halepensis bark extract in combination with nicotine may successfully reverse skin damage induced by cigarette smoke.