Induction of nicotine-metabolizing CYP2B1 by ethanol and ethanol-metabolizing CYP2E1 by nicotine: summary and implications

Effects of excessive alcohol drinking on nicotine biotransformation in rats

Alcohol and nicotine (tobacco smoke) are often used together, and taking both addictive substances is associated with an increased risk of certain diseases. It is extremely important to understand the pharmacodynamic and pharmacokinetic mechanisms of the interaction between nicotine and ethanol, which are still not fully understood. The study aimed to evaluate the influence of chronic alcohol consumption on nicotine biotransformation in ethanol-preferring and non-preferring male and female rats. Rats were divided into four groups depending on their alcohol preferences and gender. Nicotine, nornicotine, nicotine N-oxide, cotinine, trans-3'-hydroxycotinine, and cotinine N-oxide in rats plasma were determined by LC-MS/MS after five days of exposure to tobacco smoke. A non-compartmental analysis of nicotine and its metabolites was used for pharmacokinetic parameters calculation. Our experimental results showed that the rate of nicotine elimination depends on gender, regardless of alcohol preferences (significantly slower in females than in males). Mean residence timeof nornicotine, cotinine, and trans-3'-hydroxycotinine were significantly higher in alcohol-preferring male rats than in alcohol preferring female rats. In non-alcohol preferring female rats compared to ethanol-preferring female rats, significantly more nicotine N-oxide (fivefold) and trans-3'-hydroxycotinine (twofold) reached the general circulation unchanged. Drinking ethanol influenced the elimination of nornicotine and cotinine in male rats. Ethanol consumption was identified as a modifier of nicotine pharmacokinetics and this was gender-dependent.

Scrutinizing pathways of Nicotine effect on renal Alpha-7 Nicotinic Acetylcholine receptor and Mitogen-activated protein kinase (MAPK) expression in Ehrlich ascites carcinoma-bearing Mice: role of Chlorella vulgaris

Nicotine is one of several physiologically stable and active chemicals found in tobacco. The mechanism through which nicotine causes kidney damage is still obscure. As a result, the goal of this research was to investigate how oral nicotine intake can lead to kidney damage. Naturaly occurring superfood green algae are immense supplements help us using extra chemicals during cancer prevalence if the patient is exposed to nicotine. Hence, the mitigating role of Chlorella vulgaris extract (CVE) against nicotine-nephrotoxic impact in Ehrlich ascites carcinoma (EAC)-bearing mice was studied. For this purpose, four groups of Swiss female mice were assigned, nicotine group (NIC) (100 µg/ml/kg), CVE group (100 mg/kg), CVE+Nicotine, and a control group. Renal dysfunction was evaluated by estimating serum biomarkers ofrenal damage. The expression pattern of Nf-_KB, MAPK, P53, and α7-nAchR, lipid peroxidation biomarker, and antioxidant enzyme activities were evaluated in kidney tissue. Also, micro-morphometric examination and apoptosis immunohistochemical reactivity of kidney tissue were applied. The obtained results indicated up-regulation of all estimated genes and oxidative stress. Moreover, a significant (P<0.05) increment in the apoptotic marker Caspase-3 and declined BCL-2 proteins were recorded. In serum, a significant (P<0.05) elevation of urea, creatinine, TNF-α, IL-1β, and Kim-1 were evident. Histological investigation reinforced the aforementioned data, revealing structural changes involving the tubules, glomeruli, and interstitium of mice kidneys. CVE may be a strong contender for protecting renal tissue damage since it reduces renal tissue injury and oxidative stress. Cancer patients who regularly use nicotine through direct smoking or second-hand exposure can benefit from CVE usage as a dietary supplement.

The impact of adolescent nicotine exposure on alcohol use during adulthood: The role of neuropeptides

Nicotine and alcohol abuse and co-dependence represent major public health crises. Indeed, previous research has shown that the prevalence of alcoholism is higher in smokers than in non-smokers. Adolescence is a susceptible period of life for the initiation of nicotine and alcohol use and the development of nicotine-alcohol codependence. However, there is a limited number of pharmacotherapeutic agents to treat addiction to nicotine or alcohol alone. Notably, there is no effective medication to treat this comorbid disorder. This chapter aims to review the early nicotine use and its impact on subsequent alcohol abuse during adolescence and adulthood as well as the role of neuropeptides in this comorbid disorder. The preclinical and clinical findings discussed in this chapter will advance our understanding of this comorbid disorder's neurobiology and lay a foundation for developing novel pharmacotherapies to treat nicotine and alcohol codependence.

Diallyl disulfide prevents cigarette smoke-induced emphysema in mice

INTRODUCTION

Cigarette smoke (CS) is the main risk factor for the development of chronic obstructive pulmonary disease (COPD) and pulmonary emphysema. The use of antioxidants has emerged as a potential therapeutic strategy to treat airway inflammation and lung diseases. In the current study, we investigated the potential therapeutic impact of diallyl disulfide (Dads) treatment in a murine model of CS-induced emphysema.

METHODS

C57BL/6 mice were exposed to CS for 60 consecutive days and treated with vehicle or Dads (30, 60 or 90 mg/kg) by oral gavage for the last 30 days, three times/week. The control group was sham-smoked and received vehicle treatment. All mice were euthanized 24 h after day 60; bronchoalveolar lavage (BAL) was performed and lungs were processed for further experimentation. Histological (HE stained sections, assessment of mean linear intercept (Lm)), biochemical (nitrite, superoxide dismutase (SOD), glutathione transferase (GST), and malondialdehyde (MDA) equivalents), and molecular biology (metalloproteinase (MMP) 12, SOD2, carbonyl reductase 1 (CBR1), nitrotyrosine (PNK), 4-hydroxynonenal (4-HNE), and CYP2E1) analyses were performed.

RESULTS

Treatment with Dads dose-dependently reduced CS-induced leukocyte infiltration into the airways (based on BAL fluid counts) and improved lung histology (indicated by a reduction of Lm). Furthermore, CS exposure dramatically reduced the activity of the antioxidant enzymes SOD and GST in lung tissue and increased nitrite and MDA levels in BAL; these effects were all effectively counteracted by Dads treatment. Western blot analysis further confirmed the antioxidant potential of Dads, showing that treatment prevented the CS-induced decrease in SOD2 expression and increase in lung damage markers, such as CBR1, PNK, and 4-HNE. Furthermore, increased MMP12 (an important hallmark of CS-induced emphysema) and CYP2E1 lung protein levels were significantly reduced in mice receiving Dads treatment.

CONCLUSION

Our findings demonstrate that treatment with Dads is effective in preventing multiple pathological features of CS-induced emphysema in an in vivo mouse model. In addition, we have identified several proteins/enzymes, including 4-HNE, CBR1, and CYP2E1, that are modifiable by Dads and could represent specific therapeutic targets for the treatment of COPD and emphysema.

Genetic and epigenetic modifications of F1 offspring's sperm cells following in utero and lactational combined exposure to nicotine and ethanol

It is well established that maternal lifestyle during pregnancy and lactation affects the intrauterine programming of F1 offspring. However, despite the co-use of alcohol and nicotine is a common habit, the effects of exposure to both substances on the reproductive system of F1 male offspring and the underlying mechanisms of developmental programming have not been investigated. The present study aimed to examine pre- and postnatal concurrent exposure to these substances on genetic and epigenetic alterations of sperm cells as well as testis properties of F1 offspring compared with exposure to each substance alone. Pregnant dams in the F0 generation randomly received normal saline, nicotine, ethanol, and combinations throughout full gestation and lactation periods. Sperm cells and testes of F1 male offspring were collected at postnatal day 90 for further experiments. High levels of sperm DNA fragmentation were observed in all exposed offspring. Regarding epigenetic alterations, there was a significant increase in the relative transcript abundance of histone deacetylase 1 and 2 in all exposed sperm cells. Moreover, despite a decrease in the expression level of DNA methyltransferase (DNMT) 3A, no marked differences were found in the expression levels of DNMT1 and 3B in any of the exposed sperm cells compared to non-exposed ones. Interestingly, combined exposure had less prominent effects relative to exposure to each substance alone. The changes in the testicular and sperm parameters were compatible with genetic and epigenetic alterations. However, MDA level as an oxidative stress indicator increased in all exposed pups, which may be responsible for such outputs. In conclusion, maternal co-exposure to these substances exhibited epigenotoxicity effects on germline cells of F1 male offspring, although these effects were less marked relative to exposure to each substance alone. These counteracting effects may be explained by cross-tolerance and probably less impairment of the antioxidant defense system.

Suppressed hepatocyte proliferation via a ROS-HNE-P21 pathway is associated with nicotine- and cotinine-enhanced alcoholic fatty liver in mice

CYP2A5 is a major enzyme responsible for nicotine and cotinine metabolism in mice. Nicotine and cotinine enhance alcoholic fatty liver in wild type (WT) mice but not in CYP2A5 knockout (KO) mice, and reactive oxygen species (ROS) generated during the CYP2A5-mediated metabolism contributes to the enhancing effect. In combination with ethanol, nicotine and cotinine increased lipid peroxidation end product 4-hydroxynonenal (HNE) in WT mice but not in KO mice. In ethanol-fed KO mice, only 5 and 10 genes were regulated by nicotine and cotinine, respectively. However, in ethanol-fed WT mice, 59 and 104 genes were regulated by nicotine and cotinine, respectively, and 7 genes were up-regulated by both nicotine and cotinine. Plin 2 and Cdkn1a are among the 7 genes. Plin2 encodes adipose differentiation-related protein (ADRP), a lipid droplet-associated protein, which was confirmed to be increased by nicotine and cotinine in WT mice but not in KO mice. Cdkn1a encodes P21 and elevated P21 in nuclei was also confirmed. HNE can increase P21 and P21 inhibit cell proliferation. Consistently, hepatocyte proliferation markers proliferating cell nuclear antigen (PCNA) and Ki67 were decreased in WT mice but not in KO mice by nicotine/ethanol and cotinine/ethanol, respectively. These results suggest that inhibition of liver proliferation via a ROS-HNE-P21 pathway is involved in nicotine- and cotinine-enhanced alcoholic fatty liver.

Nicotine pre-treatment reduces sensitivity to the interoceptive stimulus effects of commonly abused drugs as assessed with taste conditioning paradigms

BACKGROUND

Drug pre-exposure attenuates sensitivity to the interoceptive stimulus properties of additional subsequently administered drugs in drug-induced conditioned taste avoidance (CTA) and conditioned place preference (CPP) paradigms. Specifically, nicotine, commonly used in conjunction with other addictive substances, attenuates acquisition of ethanol and caffeine CTAs and morphine-induced CPP.

METHODS

Because nicotine use is comorbid with a number of substance use disorders, we systematically examined the effects of nicotine pre-exposure on two different conditioning paradigms involving integration of the interoceptive stimulus properties of multiple commonly abused drugs, in male and female rats, designed to examine both the aversive and reinforcing properties of these drugs.

RESULTS

Nicotine dose-dependently interfered with acquisition of CTA to passively administered morphine, ethanol, and cocaine, but not lithium chloride, demonstrating that the effects of nicotine are not simply a matter of reduced orosensory processing or an inability to learn such associations. Moreover, nicotine-treated rats required higher doses of drug in order to develop CTA and did not show increased acceptance of the taste of self-administered ethanol compared with saline-treated rats.

CONCLUSIONS

These data demonstrate that nicotine pre-exposure attenuates sensitivity to the stimulus effects of multiple drugs in two conditioning paradigms, in a manner which is consistent with a reduced ability to integrate the interoceptive properties of abused drugs. Through reducing these stimulus properties of drugs of abuse, concomitant nicotine use may result in a need to increase either the frequency or strength of doses during drug-taking, thus likely contributing to enhanced addiction liability in smokers.

Renoprotective effect of Spirulina platensis extract against nicotine-induced oxidative stress-mediated inflammation in rats

BACKGROUND

Nicotine is an important factor in the pathogenesis of renal injury in smokers.

PURPOSE

The purpose of the present study was to investigate the renoprotective effect of Spirulina platensis extract (SP) against chronic nicotine administration in rats.

METHODS

Nicotine intoxication was induced with 0.5 mg/kg BW. Rats received 500 mg SP/kg BW by gastric gavage over 4 weeks.

RESULTS

Our data revealed that nicotine induced renal dysfunction manifested by significant abnormal levels of kidney function markers (creatinine and urea) accompanied by increased levels of oxidative stress biomarker (malondialdehyde) and inflammatory markers (nitric oxide, Interleukin-6 and tumor necrosis factor-α) while antioxidant status as glutathione level and glutathione S-transferase activity were found to be decreased significantly as compared with controls. It is worthy to note that nicotine toxicity induced significant increments in the protein expression levels of nuclear factor kappa B as well as caspase-3. Histopathological observations showed tubular necrosis and congestion in the endothelial lining glomerular tuft and epithelial lining renal tubules with nicotine intoxication. Interestingly, our data demonstrated that SP supplementation significantly improved the nicotine-induced kidney dysfunction, alleviated the induced-lipid peroxidation, inflammatory, apoptotic protein markers, and boosted the enzymatic/non-enzymatic antioxidants. Moreover, it attenuated the nicotine-induced histopathological alterations of the kidney architecture.

CONCLUSION

Thus, it is tempting to recommend dietary approaches with Spirulina platensis extract for smokers to minimize the deleterious effect of chronic nicotine consumption and smoke exposure-related problems towards kidney injury via the antioxidant, anti-inflammatory and antiapoptotic properties of Spirulina platensis.

Nicotine enhances alcoholic fatty liver in mice: Role of CYP2A5

Tobacco and alcohol are often co-abused. Nicotine can enhance alcoholic fatty liver, and CYP2A6 (CYP2A5 in mice), a major metabolism enzyme for nicotine, can be induced by alcohol. CYP2A5 knockout (cyp2a5^-/-) mice and their littermates (cyp2a5^+/+) were used to test whether CYP2A5 has an effect on nicotine-enhanced alcoholic fatty liver. The results showed that alcoholic fatty liver was enhanced by nicotine in cyp2a5^+/+ mice but not in the cyp2a5^-/- mice. Combination of ethanol and nicotine increased serum triglyceride in cyp2a5^+/+ mice but not in the cyp2a5^-/- mice. Cotinine, a major metabolite of nicotine, also enhanced alcoholic fatty liver, which was also observed in cyp2a5^+/+ mice but not in the cyp2a5^-/- mice. Nitrotyrosine and malondialdehyde (MDA), markers of oxidative/nitrosative stress, were induced by alcohol and were further increased by nicotine and cotinine in cyp2a5^+/+ mice but not in the cyp2a5^-/- mice. Reactive oxygen species (ROS) production during microsomal metabolism of nicotine and cotinine was increased in microsomes from cyp2a5^+/+ mice but not in microsomes from cyp2a5^-/- mice. These results suggest that nicotine enhances alcoholic fatty liver in a CYP2A5-dependent manner, which is related to ROS produced during the process of CYP2A5-dependent nicotine metabolism.

Exposure to acrylamide and the risk of cardiovascular diseases in the National Health and Nutrition Examination Survey 2003-2006

BACKGROUND

Long-term exposure to acrylamide (AA) from diet sources may induce oxidative stress and chronic inflammation. However, the association between AA exposure and the prevalence of cardiovascular diseases (CVD) remains unclear.

OBJECTIVES

We aimed to examine the association between blood exposure levels of AA biomarkers and the prevalence of main types of CVD in a general population of US adults.

METHODS

We analyzed the associations between AA hemoglobin biomarkers [hemoglobin adducts of acrylamide (HbAA) and glycidamide (HbGA), sum of HbAA and HbGA (HbAA+HbGA), and ratio of HbGA to HbAA (HbGA:HbAA)] and self-reported diagnosis of CVD in 8290 adults (≥20 years of age) from the National Health and Nutrition Examination Survey (NHANES) 2003-2006. Multivariable logistic regression models were employed for estimating the associations in three groups classified by the combination of smoking status and serum cotinine levels.

RESULTS

In people exposed to environmental tobacco smoke (n = 4670), HbGA, HbAA+HbGA, and HbGA:HbAA were significantly and inversely associated with the prevalence of total CVD (p < 0.0001, p = 0.0155, and p = 0.0014 for trend, respectively) after adjusting for various covariates. The odd ratios (ORs) for total CVD in the highest quartiles of HbGA, HbAA+HbGA, and HbGA:HbAA were 0.311 [95% confidence interval (CI): 0.193-0.500], 0.664 (95% CI: 0.485-0.911), and 0.495 (95% CI: 0.326-0.752) when compared with the individual lowest quartiles. In active smokers (n = 2432), HbAA was positively associated with CVD risk (p = 0.0088 for trend), while HbGA:HbAA was inversely related to total CVD (p = 0.0137 for trend). However, no significant associations of any AA hemoglobin biomarker with total and individual CVD prevalence were observed in the nonsmoking group (n = 1188).

CONCLUSIONS

AA hemoglobin biomarkers are significantly associated with CVD in the active smoking group and the group exposed to environmental tobacco smoke but not in the nonsmoking group. Further prospective studies should clarify the causal relationship between HbAA and HbGA and the prevalence of CVD.

Cytochrome P450s and Alcoholic Liver Disease

Alcohol consumption causes liver diseases, designated as Alcoholic Liver Disease (ALD). Because alcohol is detoxified by alcohol dehydrogenase (ADH), a major ethanol metabolism system, the development of ALD was initially believed to be due to malnutrition caused by alcohol metabolism in liver. The discovery of the microsomal ethanol oxidizing system (MEOS) changed this dogma. Cytochrome P450 enzymes (CYP) constitute the major components of MEOS. Cytochrome P450 2E1 (CYP2E1) in MEOS is one of the major ROS generators in liver and is considered to be contributive to ALD. Our labs have been studying the relationship between CYP2E1 and ALD for many years. Recently, we found that human CYP2A6 and its mouse analog CYP2A5 are also induced by alcohol. In mice, the alcohol induction of CYP2A5 is CYP2E1-dependent. Unlike CYP2E1, CYP2A5 protects against the development of ALD. The relationship of CYP2E1, CYP2A5, and ALD is a major focus of this review.

Interactions between ethanol and cigarette smoke in a mouse lung carcinogenesis model

Both ethanol and cigarette smoke are classified as human carcinogens. They can synergize, especially in tissues of the upper aerodigestive tract that are targeted by both agents. The main objective of the present study was to evaluate the individual and combined effects of ethanol and smoke in the respiratory tract, either following transplacental exposure and/or postnatal exposure. We designed two consecutive studies in mouse models by exposing Swiss H mice to oral ethanol and/or inhaled mainstream cigarette smoke for up to 4 months, at various prenatal and postnatal life stages. Clastogenic effects and histopathological alterations were evaluated after 4 and 8 months, respectively. Ethanol was per se devoid of clastogenic effects in mouse peripheral blood erythrocytes. However, especially in mice exposed both transplacentally throughout pregnancy and in the postnatal life, ethanol administration was associated not only with liver damage but also with pro-angiogenetic effects in the lung by stimulating the proliferation of blood vessels. In addition, these mice developed pulmonary emphysema, alveolar epithelial hyperplasias, microadenomas, and benign tumors. On the other hand, ethanol interfered in the lung carcinogenesis process resulting from the concomitant exposure of mice to smoke. In fact, ethanol significantly attenuated some smoke-related preneoplastic and neoplastic lesions in the respiratory tract, such as alveolar epithelial hyperplasia, microadenomas, and even malignant tumors. In addition, ethanol attenuated cigarette smoke clastogenicity. In conclusion, preclinical studies provide evidence that, in spite of its pulmonary toxicity, ethanol may mitigate some noxious effects of cigarette smoke in the respiratory tract.

Modulation by Ethanol of Cigarette Smoke Clastogenicity in Cells of Adult Mice and of Transplacentally Exposed Fetuses

Cigarette smoke (CS) and ethanol (EtOH) are known to synergize in the causation of cancers of the upper aerodigestive tract and of the liver. Little is known about possible interactions between these agents in other organs. These premises prompted us to evaluate the clastogenic effects resulting from the inhalation for 3 weeks of mainstream CS and oral administration of EtOH, which were tested either individually or in combination in cells of adult BDF1 mice and their fetuses. CS exerted clastogenic effects in haematopoietic cells of adult male mice by increasing the frequency of micronucleated erythroid cells both in bone marrow and in peripheral blood as well as the frequency of micronucleated and polynucleated pulmonary alveolar macrophages. Likewise, exposure to CS of pregnant mice resulted in a clastogenic damage in maternal bone marrow cells and in the liver and peripheral blood of their fetuses. Under all experimental conditions, EtOH was consistently devoid of clastogenic effects when given alone. In adult mice, EtOH exhibited a mild stimulating effect on the clastogenicity of CS in haematopoietic cells, while an opposite effect was observed in the respiratory tract, where EtOH attenuated the cytogenetic alterations induced by CS in pulmonary alveolar macrophages. At variance with the mild synergism observed in haematopoietic cells of adult mice, EtOH inhibited the clastogenicity of CS in the liver and peripheral blood cells of transplacentally exposed fetuses. Therefore, the effects of EtOH in CS-exposed mice show different trends depending both on the life stage and on the cells analyzed.

Predictors of Third Trimester Blood Trihalomethanes and Urinary Trichloroacetic Acid Concentrations among Pregnant Women

Prenatal exposure to disinfection byproducts (DBPs) has been associated with a variety of adverse birth outcomes. However, little is known about predictors of prenatal biomarkers of exposure to DBPs among pregnant women. We aimed to identify predictors of third trimester blood trihalomethanes (THMs) and urinary trichloroacetic acid (TCAA) concentrations, two biomarkers of exposure to DBPs, among pregnant women. Blood samples, urine samples, and questionnaires on individual characteristics and water-use activities were collected from 893 pregnant women in a Chinese cohort study. Maternal blood THM [chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)] and urinary TCAA concentrations were measured. We used multivariable linear regression to identify the predictors of third trimester blood THM and creatinine-adjusted urinary TCAA concentrations. The geometric mean of blood TTHM (sum of TCM, BDCM, DBCM, and TBM) and creatinine-adjusted urinary TCAA concentrations were 51.90 ng/L and 9.66 μg/g creatinine, respectively. Study city was the strongest significant predictors of blood THM and creatinine-adjusted urinary TCAA concentrations. Prenatal body mass index (BMI) was associated with decreased blood THM and decreased creatinine-adjusted urinary TCAA concentrations. Age was associated with increased blood Br-THM (sum of BDCM, DBCM, and TBM) concentrations. Intake of boiled water and passive smoking were associated with lower blood THM concentrations. The predictors of blood THM and urinary TCAA concentrations identified in this study provide potential health implications on how to reduce DBP exposure during pregnancy.

Oxidative damage and histopathological changes in lung of rat chronically exposed to nicotine alone or associated to ethanol

Smoking is the most important preventable risk factor of chronic obstructive pulmonary disease and lung cancer. This study was designed to investigate oxidative damage and histopathological changes in lung tissue of rats chronically exposed to nicotine alone or supplemented with ethanol. Twenty-four male Wistar rats divided into three groups were used for the study. The nicotine group received nicotine (2.5mg/kg/day); the nicotine-ethanol group was given simultaneously same dose of nicotine plus ethanol (0.2g/kg/day), while the control group was administered only normal saline (1 ml/kg/day). The treatment was administered by subcutaneous injection once daily for a period of 18 weeks. Chronic nicotine administration alone or combined to ethanol caused a significant increase in malondialdehyde (MDA) level, superoxide dismutase (SOD) activity and catalase (CAT) activity in lung tissue compared to control rats suggesting an oxidative damage. However, these increases were mostly prominent in nicotine group. The histopathological examination of lung tissue of rats in both treated groups revealed many alterations in the pulmonary structures such as emphysema change (disappearance of the alveolar septa, increased irregularity and size of air sacs) and marked lymphocytic infiltration in perivascular and interstitial areas. However, the changes characterized in the nicotine group (pulmonary congestion, hemorrhage into alveoli and interstitial areas, edema) were more drastic than those observed in the nicotine-ethanol group, and they can be attributed to a significant degree of capillary endothelial permeability and microvascular leak. Conversely, the ethanol supplementation caused an appearance of fatty change and fibrosis in pulmonary tissue essentially due to a metabolism of ethanol. Finally, the lung damage illustrated in nicotine group was more severe than that observed in the nicotine-ethanol group. We conclude that the combined administration of nicotine and ethanol may moderate the effect of nicotine administered independently by counteractive interactions between these two drugs.

Influence of tobacco smoke exposure on pharmacokinetics of ethyl alcohol in alcohol preferring and non-preferring rats

BACKGROUND

A vast majority of people who abuse alcohol are also defined as "heavy smokers". Tobacco smokes induces CYP1A1, CYP1A2, CYP2A6 isoenzymes, but on the other hand, ethanol activates CYP2E1, which can be important during combined, chronic use of both of them. The aim of the study was to evaluate the influence of tobacco smoke xenobiotics on ethanol pharmacokinetics and the level of its metabolites in alcohol preferring and non-preferring rats.

METHODS

Ethanol, acetaldehyde, methanol, n-propanol and n-butanol were determined in whole blood by means of gas chromatography. Cotinine in serum was determined by LC-MS/MS. A non-compartmental analysis (cotinine, acetaldehyde) and Widmark equation (ethanol) were used for pharmacokinetic parameters calculation.

RESULTS

Ethanol levels were lower in animals exposed to tobacco smoke compared to rats receiving this xenobiotic, without a prior exposure to tobacco smoke. Lower values of the studied pharmacokinetic parameters were observed in the alcohol preferring males compared to the non-alcohol preferring rats. Both n-propanol and n-butanol had higher values of the pharmacokinetic parameters analyzed in the animals exposed to tobacco smoke and ethanol compared to those, which ethanol was administered only once.

CONCLUSIONS

An increase in maximum concentration and the area under concentration-time curve for ethanol after its administration to rats preferring alcohol and exposed to tobacco smoke are accompanied by a decrease in the volume of distribution. The changes in the volume of distribution may be caused by an increase in the first-pass effect, in the intestinal tract and/or in the liver. The acetaldehyde elimination rate constant was significantly higher in alcohol-preferring animals.

Toxicity of aerosols of nicotine and pyruvic acid (separate and combined) in Sprague-Dawley rats in a 28-day OECD 412 inhalation study and assessment of systems toxicology

Toxicity of nebulized nicotine (Nic) and nicotine/pyruvic acid mixtures (Nic/Pyr) was characterized in a 28-day Organization for Economic Co-operation and Development 412 inhalation study with additional transcriptomic and lipidomic analyses. Sprague-Dawley rats were nose-only exposed, 6 h/day, 5 days/week to filtered air, saline, nicotine (50 µg/l), sodium pyruvate (NaPyr, 33.9 µg/l) or equimolar Nic/Pyr mixtures (18, 25 and 50 µg nicotine/l). Saline and NaPyr caused no health effects, but rats exposed to nicotine-containing aerosols had decreased body weight gains and concentration-dependent increases in liver weight. Blood neutrophil counts were increased and lymphocyte counts decreased in rats exposed to nicotine; activities of alkaline phosphatase and alanine aminotransferase were increased, and levels of cholesterol and glucose decreased. The only histopathologic finding in non-respiratory tract organs was increased liver vacuolation and glycogen content. Respiratory tract findings upon nicotine exposure (but also some phosphate-buffered saline aerosol effects) were observed only in the larynx and were limited to adaptive changes. Gene expression changes in the lung and liver were very weak. Nic and Nic/Pyr caused few significant changes (including Cyp1a1 gene upregulation). Changes were predominantly related to energy metabolism and fatty acid metabolism but did not indicate an obvious toxicity-related response. Nicotine exposure lowered plasma lipids, including cholesteryl ester (CE) and free cholesterol and, in the liver, phospholipids and sphingolipids. Nic, NaPyr and Nic/Pyr decreased hepatic triacylglycerol and CE. In the lung, Nic and Nic/Pyr increased CE levels. These data suggest that only minor biologic effects related to inhalation of Nic or Nic/Pyr aerosols were observed in this 28-day study.

Association between in vivo alcohol metabolism and genetic variation in pathways that metabolize the carbon skeleton of ethanol and NADH reoxidation in the alcohol challenge twin study

BACKGROUND

Variation in alcohol metabolism affects the duration of intoxication and alcohol use. While the majority of genetic association studies investigating variation in alcohol metabolism have focused on polymorphisms in alcohol or aldehyde dehydrogenases, we have now tested for association with genes in alternative metabolic pathways that catalyze the carbon skeleton of ethanol (EtOH) and NADH reoxidation.

METHODS

Nine hundred fifty single nucleotide polymorphisms (SNPs) spanning 14 genes (ACN9, ACSS1, ACSS2, ALDH1A1, CAT, CYP2E1, GOT1, GOT2, MDH1, MDH2, SLC25A10, SLC25A11, SLC25A12, SLC25A13) were genotyped in 352 young adults who participated in an alcohol challenge study. Traits tested were blood alcohol concentration (BAC), breath alcohol concentration (BrAC), peak alcohol concentration, and rates of alcohol absorption and elimination. Allelic association was tested using quantitative univariate and multivariate methods.

RESULTS

A CYP2E1 promoter SNP (rs4838767, minor allele frequency 0.008) exceeded the threshold for study-wide significance (4.01 × 10(-5) ) for 2 early BAC, 8 BrAC measures, and the peak BrAC. For each phenotype, the minor C allele was related to a lower alcohol concentration, most strongly for the fourth BrAC (p = 2.07 × 10(-7) ) explaining ~8% of the phenotypic variance. We also observed suggestive patterns of association with variants in ALDH1A1 and on chromosome 17 near SLC25A11 for aspects of blood and breath alcohol metabolism. An SNP upstream of GOT1 (rs2490286) reached study-wide significance for multivariate BAC metabolism (p = 0.000040).

CONCLUSIONS

Overall, we did not find strong evidence that variation in genes coding for proteins that further metabolize the carbon backbone of acetaldehyde, or contribute to mechanisms for regenerating NAD from NADH, affects alcohol metabolism in our European-descent subjects. However, based on the breath alcohol data, variation in the promoter of CYP2E1 may play a role in preabsorptive or early hepatic alcohol metabolism, but more samples are required to validate this finding.

Impact of repeated nicotine and alcohol coexposure on in vitro and in vivo chlorpyrifos dosimetry and cholinesterase inhibition

Chlorpyrifos (CPF) is an organophosphorus insecticide, and neurotoxicity results from inhibition of acetylcholinesterase (AChE) by its metabolite, chlorpyrifos-oxon. Routine consumption of alcohol and tobacco modifies metabolic and physiological processes impacting the metabolism and pharmacokinetics of other xenobiotics, including pesticides. This study evaluated the influence of repeated ethanol and nicotine coexposure on in vivo CPF dosimetry and cholinesterase (ChE) response (ChE- includes AChE and/or butyrylcholinesterase (BuChE)). Hepatic microsomes were prepared from groups of naive, ethanol-only (1 g/kg/d, 7 d, po), and ethanol + nicotine (1 mg/kg/d 7 d, sc)-treated rats, and the in vitro metabolism of CPF was evaluated. For in vivo studies, rats were treated with saline or ethanol (1 g/kg/d, po) + nicotine (1 mg/kg/d, sc) in addition to CPF (1 or 5 mg/kg/d, po) for 7 d. The major CPF metabolite, 3,5,6-trichloro-2-pyridinol (TCPy), in blood and urine and the plasma ChE and brain acetylcholinesterase (AChE) activities were measured in rats. There were differences in pharmacokinetics, with higher TCPy peak concentrations and increased blood TCPy AUC in ethanol + nicotine groups compared to CPF only (approximately 1.8- and 3.8-fold at 1 and 5 mg CPF doses, respectively). Brain AChE activities after ethanol + nicotine treatments showed significantly less inhibition following repeated 5 mg CPF/kg dosing compared to CPF only (96 ± 13 and 66 ± 7% of naive at 4 h post last CPF dosing, respectively). Although brain AChE activity was minimal inhibited for the 1-mg CPF/kg/d groups, the ethanol + nicotine pretreatment resulted in a similar trend (i.e., slightly less inhibition). No marked differences were observed in plasma ChE activities due to the alcohol + nicotine treatments. In vitro, CPF metabolism was not markedly affected by repeated ethanol or both ethanol + nicotine exposures. Compared with a previous study of nicotine and CPF exposure, there were no apparent additional exacerbating effects due to ethanol coexposure.

The investigation into CYP2E1 in relation to the level of response to alcohol through a combination of linkage and association analysis

BACKGROUND

A low level of response to alcohol during an individual's early experience with alcohol is associated with an increase risk of alcoholism. A family-based genome-wide linkage analysis using sibling pairs that underwent an alcohol challenge where the level of response to alcohol was measured with the Subjective High Assessment Scale (SHAS) implicated the 10q terminal (10qter) region. CYP2E1, a gene known for its involvement with ethanol metabolism, maps to this region.

METHODS

Variance component multipoint linkage analysis was performed on a combined map of single-nucleotide polymorphism (SNP) and microsatellite data. To account for the heterogeneity evident in the dataset, a calculation assuming locus heterogeneity was made using the Heterogeneity Log of Odds (HLOD) score. Association between SNP marker allele counts and copy number and SHAS scores were evaluated using a logistic regression model.

RESULTS

Linkage analysis detected significant linkage to CYP2E1, which was diminished because of apparent locus heterogeneity traced to a single family with extreme phenotypes. In retrospect, circumstances recorded during testing for this family suggest that their phenotype data are likely to be unreliable. Significant allelic associations were detected for several CYP2E1 polymorphisms and the SHAS score. DNA sequencing from families that contributed the greatest evidence for linkage did not detect any changes directly affecting the primary amino acid sequence. With the removal of a single family, combined evidence from microsatellites and SNPs offers significant linkage between the level of response to alcohol and the region on the end of chromosome 10.

CONCLUSION

Combined linkage and association indicate that sequence changes in or near CYP2E1 affect the level of response to alcohol providing a predictor of risk of alcoholism. The absence of coding sequence changes indicates that regulatory sequences are responsible. Implicating CYP2E1 in the level of response to alcohol allows inferences to be made about how the brain perceives alcohol.

Hepatic Drug-Metabolizing Enzyme Induction and Implications for Preclinical and Clinical Risk Assessment

Hepatic drug metabolizing enzyme (DME) induction complicates the development of new drugs owing to altered efficacy of concomitant treatments, reduction in exposure resulting from autoinduction, and potential generation of toxic metabolites. Risk assessment of DME induction during clinical evaluation is confounded by several uncertainties pertaining to hazard identification and dose response analysis. Hepatic DME induction rarely leads to clinical evidence of altered metabolism and toxicity in the patient, which typically occur only if the DME induction is relatively severe. High drug doses are associated with a greater likelihood of hepatic DME induction and downstream effects; therefore, drugs of low potency requiring higher dosing tend to lead to a greater risk of drug–drug interactions. Vigilance in clinical trials for increased or diminished drug effect and, specifically, pharmacokinetic studies in the presence of other drugs and concomitant diseases are necessary for a drug risk assessment profile.

Efforts to remove hepatic DME-inducing drugs from development can be facilitated with current in vitro and in vivo assessments and will improve with the development of newer technologies. A carefully tailored case-by-case approach will lead to the development of efficacious drugs with an acceptable risk/benefit profile available to patients.

Nicotine: alcohol reward interactions

It is well established that the continued intake of drugs of abuse is reinforcing-that is repeated consumption increases preference. This has been shown in some studies to extend to other drugs of abuse; use of one increases preference for another. In particular, the present review deals with the interaction of nicotine and alcohol as it has been shown that smoking is a risk factor for alcoholism and alcohol use is a risk factor to become a smoker. The review discusses changes in the brain caused by chronic nicotine and chronic alcohol intake to approach the possible mechanisms by which one drug increases the preference for another. Chronic nicotine administration was shown to affect nicotine receptors in the brain, affecting not only receptor levels and distribution, but also receptor subunit composition, thus affecting affinity to nicotine. Other receptor systems are also affected among others catecholamine, glutamate, GABA levels and opiate and cannabinoid receptors. In addition to receptor systems and transmitters, there are endocrine, metabolic and neuropeptide changes as well induced by nicotine. Similarly chronic alcohol intake results in changes in the brain, in multiple receptors, transmitters and peptides as discussed in this overview and also illustrated in the tables. The changes are sex and age-dependent-some changes in males are different from those in females and in general adolescents are more sensitive to drug effects than adults. Although nicotine and alcohol interact-not all the changes induced by the combined intake of both are additive-some are opposing. These opposing effects include those on locomotion, acetylcholine metabolism, nicotine binding, opiate peptides, glutamate transporters and endocannabinoid content among others. The two compounds lower the negative withdrawal symptoms of each other which may contribute to the increase in preference, but the mechanism by which preference increases-most likely consists of multiple components that are not clear at the present time. As the details of induced changes of nicotine and alcohol differ, it is likely that the mechanisms of increasing nicotine preference may not be identical to that of increasing alcohol preference. Stimulation of preference of yet other drugs may again be different -representing one aspect of drug specificity of reward mechanisms.

Metabolism of nicotine in rat lung microvascular endothelial cells

The aim of this study was to examine whether cultured rat lung microvascular endothelial cells (LMECs), which constitute the gas-blood barrier, have the ability to metabolize nicotine. Nicotine was biotransformed to cotinine and nicotine N′-oxide by cytochrome 450 (CYP) and flavin-containing monooxyganase (FMO), respectively, in rat LMECs. The intrinsic clearance (Vmax1/Km1) for the cotinine formation was about 20 times as high as that for the trans-nicotine N′-oxide formation in the low-Km phase, indicating that oxidation by CYP was much higher than that by FMO. On the other hand, as shown in Eadie-Hofstee plots, the formation of cis-nicotine N′-oxide was monophasic, whereas the plot for the trans-nicotine N′-oxide formation was clearly biphasic. These results suggest that nicotine N′-oxide was stereoselectively metabolized to cis and trans forms. However, in the high-Km phase there was no significant difference in N′-oxidation between the cis and trans forms. Moreover, we suggest that CYP2C11 and CYP3A2 are key players in the metabolism to cotinine of nicotine in rat LMECs using the respective enzyme inhibitors (tranylcypromine and troleandomycine). On the other hand, methimazole (5 μm) caused 73 and 45% decreases in the formation of N′-oxides of cis- and trans- enantiomers, respectively, demonstrating the presence of FMO in rat LMECs. These results suggest that rat LMEC enzymes can convert substrates of exogenous origin such as nicotine for detoxication, indicating LMECs are an important barrier for metabolic products, besides hepatic cells.

The influence of a chronic adolescent nicotine exposure on ethanol withdrawal severity during adulthood in C3H mice

Animal and human studies have shown tolerance, consumption, relapse, and behavioral interactions between ethanol and nicotine, but little is understood about their interaction, especially as it relates to ethanol withdrawal in adulthood for subjects who have an adolescent history of using these drugs. This study investigated nicotine's influence on ethanol withdrawal seizures in two different age groups of male C3H mice. Adolescent and adult male C3H mice, beginning at postnatal day 28 or 70, respectively, were subjected to a 7-day chronic exposure to ethanol only, ethanol plus nicotine, nicotine only, or vehicle treatment. Six weeks later, all the groups were subjected to chronic exposure to ethanol vapors and the severity of their ethanol withdrawal seizures was assessed by handling-induced convulsions. An adolescent exposure to chronic nicotine resulted in an exacerbation of ethanol withdrawal seizures in adulthood. Given this, adolescence may contain a neurophysiological critical period that is sensitive to nicotine and which may result in an altered response to ethanol dependency in adulthood. These findings have serious implications for the long-term consequences following co-abuse of these drugs during adolescence.

Effect of gene polymorphisms and ethanol consumption on micronucleus frequency in human reticulocytes: a preliminary study

OBJECTIVE

Results from previous studies suggest that alcohol consumption can be genotoxic on peripheral lymphocytes. The aim of our study was to examine the association of alcohol consumption and its genotoxic effect on hematopoietic stem cells in vivo.

METHODS

We investigated 156 healthy Japanese males in a cross-sectional study. Lifestyles, including alcohol drinking behavior and cigarette smoking status, were investigated by means of a self-completed questionnaire. Polymorphisms of ADH1B and ALDH2 were identified by PCR-restriction fragment length polymorphism (RFLP) analysis. The presence of micronuclei in transferrin-positive reticulocytes (MN-RET) was detected with a single-laser flow cytometer. Associations between the genetic polymorphisms, lifestyle factors, and MN-RET frequency were statistically analyzed.

RESULTS

We found a significant difference in the mean frequencies of MN-RET between habitual drinkers and non-habitual drinkers (P = 0.043), and between the ALDH2*1/*1 and ALDH2*2/*2 genotype (P = 0.015). The ADH1B*2 and ALDH2*2 haplotype was estimated to have a significantly higher influence on MN-RET frequency than the ADH1B*2 and ALDH2*1 haplotype (P = 0.00035), and the frequency of alcohol consumption played a significant role in MN-RET frequency on the background of the ADH1B*2 and ALDH2*1 haplotype (P = 0.012).

CONCLUSION

The results of our study suggest a possible association between the ADH1B and ALDH2 polymorphism and the genotoxic effects of alcohol drinking on hematopoietic stem cells.

Ethanol and tobacco smoke increase hepatic steatosis and hypoxia in the hypercholesterolemic apoE(-/-) mouse: implications for a "multihit" hypothesis of fatty liver disease

Although epidemiologic studies indicate that combined exposure to cigarette smoke and alcohol increase the risk and severity of liver diseases, the molecular mechanisms responsible for hepatotoxicity are unknown. Similarly, emerging evidence indicates a linkage among hepatic steatosis and cardiovascular disease. Herein, we hypothesize that combined exposure to alcohol and environmental tobacco smoke (ETS) on a hypercholesterolemic background increases liver injury through oxidative/nitrative stress, hypoxia, and mitochondrial damage. To test this, male apoE(-/-) mice were exposed to an ethanol-containing diet, ETS alone, or a combination of the two, and histology and functional endpoints were compared to filtered-air-exposed, ethanol-naïve controls.Whereas ethanol consumption induced a mild steatosis, combined exposure to ethanol + ETS resulted in increased hepatic steatosis, inflammation, alpha-smooth muscle actin, and collagen. Exposure to ethanol + ETS induced the largest increase in CYP2E1 and iNOS protein, as well as increased 3-nitrotyrosine, mtDNA damage, and decreased cytochrome c oxidase protein, compared to all other groups. Similarly, the largest increase in HIF1alpha expression was observed in the ethanol + ETS group, indicating enhanced hypoxia. These studies demonstrate that ETS increases alcohol-dependent steatosis and hypoxic stress. Therefore, ETS may be a key environmental "hit" that accelerates and exacerbates alcoholic liver disease in hypercholesterolemic apoE(-/-) mice.

Differential induction of ethanol-metabolizing CYP2E1 and nicotine-metabolizing CYP2B1/2 in rat liver by chronic nicotine treatment and voluntary ethanol intake

Alcohol and nicotine are frequently co-used and co-abused, and use of both drugs alone can affect hepatic drug metabolism. We investigated the influences of chronic nicotine treatment and voluntary ethanol intake on the induction of rat hepatic cytochrome P450 (CYP) enzymes that metabolize ethanol and nicotine. Rats were trained to voluntarily drink ethanol (6% v/v, 1 h) with nicotine pretreatment for 10 days. Another group of rats were treated with the same nicotine doses alone. Hepatic CYP2E1, CYP2B1/2 and CYP2D1 proteins were assessed by immunoblotting. Nicotine pretreatment (0.4, 0.8 and 1.2 mg/kg) increased voluntary ethanol intake on day 10 by 1.8, 2.0, and 1.4 fold respectively compared to saline pretreatment (P<0.01-0.3). CYP2E1 was increased 1.7, 1.8, and 1.4 fold by the three doses of nicotine alone (P<0.02-0.21); CYP2E1 levels were increased by voluntary ethanol intake alone and a further 2.4, 2.2, and 1.8 fold by 0.4, 0.8, and 1.2 mg/kg nicotine respectively versus saline pretreatment (P<0.002-0.06). CYP2B1/2 proteins were not induced by nicotine alone, but were increased by 2.2-2.5 fold by ethanol drinking (P<0.05). CYP2E1 (r=0.67, P<0.001) and CYP2B1/2 levels (r=0.49, P=0.007) correlated with alcohol consumption on day 10. There was no change in CYP2D1. Chronic nicotine increased voluntary ethanol intake thereby enhancing CYP2E1 and CYP2B1/2 levels. Thus CYPs are regulated not only directly by nicotine and ethanol, but also indirectly via an increase in the ethanol consumption in the presence of nicotine pretreatment. Together this may contribute to the co-abuse of these drugs and alter the metabolism of clinical drugs and endogenous substrates.

Growth retardation of fetal rats exposed to nicotine in utero: possible involvement of CYP1A1, CYP2E1, and P-glycoprotein

To elucidate the possible metabolic mechanism of intrauterine growth retardation induced by nicotine, this study determines the effects of prenatal nicotine exposure on fetal development and cytochrome P4501A1 (CYP1A1), CYP2E1, and P-glycoprotein (Pgp) expression in maternal liver and placenta. Pregnant rats were given 1.0 mg/kg nicotine subcutaneously twice a day from gestational day (GD) 8 to GD 15, 18, or 21. In nicotine-treated groups, fetal developmental parameters including body weight were significantly lower. The activities of CYP1A1 and CYP2E1 in maternal liver microsomes in nicotine-treated groups increased significantly with progressing gestation when compared with the corresponding control, but returned to the level similar to the control in late pregnancy. Nicotine-treated groups induced pathological changes and increased malondialdehyde (MDA) content in the placenta when compared with the control. The gene expressions of CYP1A1 and CYP2E1 in the placenta increased significantly in nicotine-treated groups on GD 15 and GD 18, but returned to the level similar to the corresponding control on GD 21. In nicotine group, there was a decrease of mdr1a expression on GD 15, GD 18, and GD 21, with the most significant decrease on GD 15. In contrast, no significant difference was found in mdr1b mRNA expression between the nicotine-treated animals and the corresponding control. In comparison with the corresponding control, the placental Pgp protein significantly decreased on GD 15 and GD 18. Our results showed that prenatal nicotine exposure resulted in inhibition of fetal growth significantly. The induction of CYP2E1 and CYP1A1 gene expression by nicotine in the maternal liver and placenta may be involved with the observed increase in oxidative stress and lipid peroxidation. The inhibition of the placental Pgp expression by nicotine may also contribute to an increased susceptibility of the fetus to environmental toxins.

Effects of nicotine exposure on in vitro metabolism of chlorpyrifos in male Sprague-Dawley rats

The routine use of tobacco products may modify key metabolizing systems, which will further impact the metabolism of environmental contaminants. The objective of this study was to quantify the effect of repeated in vivo exposures to nicotine, a major pharmacologically active component of cigarette smoke, on in vitro metabolism of chlorpyrifos (CPF). CPF is an organophosphorus (OP) insecticide that is metabolized by cytochrome P-450 (CYP450) to its major metabolites, chlorpyrifos-oxon (CPF-oxon) and 3,5,6-trichloro-2-pyridinol (TCP). Male Sprague-Dawley rats were dosed subcutaneously with 1 mg nicotine/kg for 1, 7, or 10 d. Rats were sacrificed 4 or 24 h after the last nicotine treatment, and liver microsomes were prepared. The microsomes were incubated with varying concentrations of CPF and the production of the metabolites CPF-oxon and TCP were measured. The metabolism of CPF to the active oxon metabolite did not show significant changes following repeated nicotine treatments, evidenced by the unchanged pseudo first-order clearance rate of V(max)/K(mapp). The V(max) describing the metabolism of CPF to the inactive metabolite, TCP was increased in 24-h postdosing groups, after both single and repeated treatments of nicotine. In contrast, the metabolism to TCP was unchanged in groups evaluated at 4 h (single or repeated) post nicotine dosing. Some basic marker substrate activities were also investigated to ensure that nicotine exerted effects on CYP450 activities. Total P450 reduced spectra were not altered by nicotine treatment, but marker substrate activities for CYP1A and CYP2E1 were increased at 24 h after the single treatment, and marker substrate activity for CYP2B was decreased 4 h after 7 d of treatment. Results of this in vitro study suggest that repeated nicotine exposure may result in altered metabolism of CPF. Future in vivo experiments based on these results need to be conducted to ascertain the impact of in vivo nicotine exposures on CPF metabolism in rats.

Structural requirements for inhibitors of cytochromes P450 2B: Assessment of the enzyme interaction with diamondoids

The series of diamondoids: adamantane, diamantane, triamantane, 2-isopropenyl-2-methyladamantane and 3-isopropenyl-3-methyldiamantane (3-IPMDIA), were employed to elucidate the molecular basis of their interaction with the active site of cytochromes P450 (CYP) of a 2B subfamily. These potent inhibitors of CYP2B enzymes were docked into the homology model of CYP2B4. Apparent dissociation constants calculated for the complexes of CYP2B4 with docked diamandoids agreed closely with the experimental data showing inhibition potency of the compounds and their binding affinity to CYP2B4. Superimposed structures of docked diamondoids mapped binding site residues. As they are mainly non-polar residues, the hydrophobicity plays the major role in the binding of diamondoids. Overlapping structure of diamondoids defined an elliptical binding cavity (5.9A inner diameter, 7.9A length) forming an angle of approximately 43 degrees with the heme plane. CYP2B specific diamondoids, namely 3-IPMDIA, showing the highest binding affinity, should be considered for a potential clinical use.

Renal function in male Sprague-Dawley rats concurrently exposed to long-term nicotine (3-{1-methyl-2-pyrrolidinyl}pyridine) and methylated spirits (methyl alcohol)

Abuse of nicotine and methylated spirits is a global problem. The current study determined the concurrent influence of nicotine and methylated spirits on renal hemodynamics. Two series of experimental protocols were designed: conscious and anesthetized vehicle loading. Conscious animals received nicotine (0.1 mg x kg(-1) bwt, 0.26-0.30 mL), methylated spirits (1.0 g x kg (-1) bwt, 0.26-0.30 mL), combined nicotine and methylated spirits, and control animals (water, 0.26-0.30 mL). Anesthetized animals were challenged with a continuous jugular infusion of 0.077M NaCl. Plasma nicotine concentration was significantly elevated in combined conscious treatments by comparison with animals infused nicotine alone. Plasma arginine vasopressin was significantly attenuated in combined conscious groups, and those infused methylated spirits alone. Aldosterone was elevated in all conscious groups. Both plasma ethanol and methanol concentrations were elevated in rats concurrently administered nicotine and methylated spirits compared with those given methylated spirits alone. Urinary Na(+) levels were significantly elevated in all anesthetized groups associated with attenuated aldosterone concentrations. Plasma nicotine concentrations were increased in combined treatments. Plasma ethanol levels were significantly reduced and elevated in rats concurrently exposed to nicotine and methylated spirits, respectively. The present study suggests that chronic exposure to methylated spirits alone and in combination with nicotine increases urinary Na(+) loss. The renal toxicity is manifested hypothetically via elevations in plasma nicotine and methanol concentrations. This implies that people who concurrently consume methylated spirits and smoke cigarettes have an increased risk of renal failure by being predisposed to fluid and electrolyte disturbances.

Smoking status relationships with the food and fluid intakes of free-living humans

OBJECTIVE

The relation of cigarette smoking to food and fluid intakes was studied.

METHODS

Ninety-nine smoking and 551 non-smoking free-living adult humans provided a detailed record of their eating and drinking in 7-d diaries.

RESULTS

Cigarette smoking was associated with significant changes in overall intakes and meal pattern. Smokers had higher intakes of fluids in the form of drinks due to higher levels of alcohol and coffee/tea consumption. Smokers were less hungry but more responsive to social facilitation and time of day. There were also substantial gender differences in smoking relations to intake, with male smokers tending to have higher overall and meal intakes particularly of fats than non-smokers, whereas female smokers tended to have lower overall intakes, fewer meals, and lower amounts of carbohydrates than non-smokers. Male smokers tended to be less responsive to their before-meal stomach content, their level of hunger, and the palatability of the meal than non-smokers, whereas females tend to be more responsive to all of these influences on meal size.

CONCLUSION

These results suggest that smoking has very few direct simple effects on intake but rather influences intake indirectly through its covariation with alcohol and caffeine intakes and with dietary restraint and that smoking has different, sometimes opposite, influences in males and females.

Distribution of alcohol-metabolizing enzyme genotypes in trauma patients with excessive alcohol consumption in the emergency department

OBJECTIVES

The objective of this study was to investigate the distribution of genetic polymorphisms of alcohol-metabolizing enzymes in trauma patients with excessive alcohol consumption in the emergency department (ED).

DESIGN AND METHODS

A total of 100 trauma patients and age-matched control subjects composed of 98 participants were enrolled in this study. The activities of liver enzymes and genotypes of alcohol-metabolizing enzymes, including ADH2, ALDH2, and CYP2E1, were analyzed with the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis.

RESULTS

There was a significant difference in the allele frequencies of ALDH2 between the two groups. For the genotypes, there were significant differences in the genotype frequencies of ADH2 and ALDH2. There was also a significantly lower frequency in patients with the ALDH2*2 phenotype than those of the controls. For the activities of liver enzymes, there were significant differences between the two groups. For ADH2 and ALDH2, there were significantly higher ORs (odds ratios) in trauma patients with normal activity than those with weak or intermediate activity but there were no significant difference in CYP2E1 genotype between two groups. To investigate the interaction of alcohol-metabolizing enzyme genotypes, we have estimated the odds ratios in two alcohol-metabolizing pathways. The ORs of the combined genotypes of ADH2 (*1/*1+*1/*2) and ALDH2 (*1/*1) and the combined genotypes of either CYP2E1 (*c1/*c1) or CYP2E1 (*c1/*c2+*c2/*c2) and ALDH2 (*1/*1) were significantly higher than that of the reference group in the major and the minor pathway, respectively.

CONCLUSIONS

Genetic variation of alcohol-metabolizing enzymes, especially ALDH2, may play an important role on the occasions of alcohol problems in the emergency department.

Non-Nicotinic Therapies for Smoking Cessation

Cigarette smoking is the primary cause of numerous preventable diseases; as such, the goals of smoking cessation are both to reduce health risks and to improve the quality of life. Currently, the first-line smoking cessation therapies include nicotine replacement products and bupropion. The nicotinic receptor partial agonist varenicline has recently been approved by the FDA for smoking cessation. A newer product currently under development and seeking approval by the FDA are nicotine vaccines. Clonidine and nortriptyline have demonstrated some efficacy but side effects may limit their use to second-line therapeutic products. Other therapeutic drugs that are under development include rimonabant, mecamylamine, monoamine oxidase inhibitors, and dopamine receptor D3 antagonists. Inhibitors of nicotine metabolism are also promising candidates for smoking reduction and cessation. In conclusion, promising new therapeutic products are emerging and they will provide smokers additional options to assist in achieving smoking cessation.

Comorbidity between alcohol dependence and illicit drug dependence in adolescents with antisocial behavior and matched controls

BACKGROUND

Knowledge regarding the causes of comorbidity among substance use disorders can have significant impact on future research examining the etiology of these disorders. Unfortunately, the conclusions of past studies examining the comorbidity among substance use disorders are conflicting; some studies emphasize familial influences common to multiple substances, while others emphasize substance-specific influences. Discrepancies in results may reflect different analytical approaches or differences in the samples. Here, we examine the causes of comorbidity between alcohol dependence and illicit drug dependence in adolescents.

METHODS

We ascertained a clinical sample of adolescents treated for antisocial behavior and substance use disorders and their siblings and a matched control sample. A model fitting approach was used to test 13 alternative hypotheses for the causes of comorbidity.

RESULTS

The best supported hypothesis for the comorbidity between alcohol dependence and illicit drug dependence was a model hypothesizing that comorbid disorders are alternate forms of a single underlying liability. The next best fitting models were two of the correlated liabilities models (correlated risk factors and reciprocal causation).

DISCUSSION

The results suggest that the best hypotheses explaining the comorbidity between alcohol and illicit drug dependence in adolescents are that alcohol dependence and illicit drug dependence are manifestations of a single general liability to develop substance dependence or that there are separate liabilities that are highly correlated.

Regional and cellular distribution of CYP2E1 in monkey brain and its induction by chronic nicotine

CYP2E1 is expressed in liver and extrahepatic tissues, including brain. It metabolizes ethanol and other drugs and toxins, such as acetaminophen, chlorzoxazone and tobacco-derived nitrosamines. Hepatic CYP2E1 is inducible by nicotine, and cigarette smoke accelerates chlorzoxazone metabolism. Smokers have higher levels of brain CYP2E1 expression than non-smokers, but the specific regions and cell types which have the higher expression differ from nicotine-induced rat brain. We therefore investigated the expression and distribution of brain CYP2E1 in a non-human primate, the African green monkey, and determined the effect of nicotine treatment. CYP2E1 levels varied among saline-treated monkey brain regions (P < 0.01) and expression was cell-type specific. Chronic nicotine treatment induced CYP2E1 expression in the frontal cortex (1.5-fold, P < 0.05) and cerebellum (1.5-fold, P < 0.01), specifically in cortical pyramidal neurons and cerebellar Purkinje cells but no change was seen in temporal cortex (P = 0.20), hippocampus (P = 0.29), putamen (P = 0.26) and thalamus (P = 0.08). CYP2E1 expression pattern in monkey brain following chronic nicotine treatment is similar to that in smokers, suggesting that nicotine may be the primary component in cigarette smoke that induces CYP2E1. Increased CYP2E1 in brain may contribute to oxidative stress and alter localized metabolism, and resulting pharmacology, of centrally acting drugs metabolized by CYP2E1.

Nicotine increases alcohol self-administration in non-dependent male smokers

BACKGROUND

Alcohol and tobacco are commonly co-administered, yet little is known about the effects of acute nicotine administration on alcohol consumption in humans. This study sought to determine how nicotine delivered by tobacco smoke influences alcohol intake in humans using a double-blind placebo controlled repeated measures design.

METHODS

During two randomized 120 min sessions 15 male occasional smokers smoked four nicotine-containing or four de-nicotinized cigarettes at 30 min intervals. Throughout the session, subjects could earn units of their preferred alcoholic beverage and glasses of water using a progressive-ratio (PR) task.

RESULTS

Wilcoxon signed-rank tests indicated that nicotine increased alcohol self-administration in a significant proportion of participants (P<or=0.03) without affecting water consumption (P>or=0.16). A two-way ANOVA supported this observation further, and, compared to de-nicotinized cigarettes, the nicotine-containing cigarettes increased PR breakpoints for alcohol but not water, as reflected by a Cigarettex Beverage interaction (P<or=0.055).

CONCLUSIONS

The present data suggest that acute nicotine administration increases alcohol consumption in at least a subset of smokers.

Herbal interactions involving cytochrome p450 enzymes: a mini review

The metabolism of a drug can be altered by another drug or foreign chemical, and such interactions can often be clinically significant. Cytochrome P450 (CYP) enzymes, a superfamily of enzymes found mainly in the liver, are involved in the metabolism of a plethora of xenobiotics and have been shown to be involved in numerous interactions between drugs and food, herbs and other drugs. The observed induction and inhibition of CYP enzymes by natural products in the presence of a prescribed drug has (among other reasons) led to the general acceptance that natural therapies can have adverse effects, contrary to the popular beliefs in countries where there is an active practice of ethnomedicine. Herbal medicines such as St. John's wort, garlic, piperine, ginseng, and gingko, which are freely available over the counter, have given rise to serious clinical interactions when co-administered with prescription medicines. Such adversities have spurred various pre-clinical and in vitro investigations on a series of other herbal remedies, with their clinical relevance remaining to be established. Although the presence of numerous active ingredients in herbal medicines, foods and dietary supplements complicate experimentation, the observable interactions with CYP enzymes warrant systematic studies, so that metabolism-based interactions can be predicted and avoided more readily. This article highlights the involvement of CYP enzymes in metabolism-related drug-herb interactions and the importance of gaining a mechanism-based understanding to avoid potential adverse drug reactions, in addition to outlining other contributory factors, such as pharmacogenetics and recreational habits that may compound this important health issue.

Effects of light and dark beer on hepatic cytochrome P-450 expression in male rats receiving alcoholic beverages as part of total enteral nutrition

BACKGROUND

Alcoholic beverages contain many congeners in addition to ethanol. Therefore, consumption of alcoholic beverages may have considerably different effects on expression of hepatic microsomal monooxygenases than the relatively selective induction of cytochrome P-450 (CYP) 2E1 observed after consumption of pure ethanol.

METHODS

: In the current study, we compared the effects of two beers: lager (a light roasted beer) and stout (a dark roasted beer) with those of an equivalent amount of pure ethanol on hepatic CYP expression. Beer or pure ethanol was part of a complete total enteral nutrition diet that was infused intragastrically into male Sprague Dawley rats for 21 days. At the end of the infusion period, rats were euthanized, and liver and intestinal microsomes were prepared. Expression and activity of CYP1A1/2, CYP2B1, CYP2E1, CYP3A, and CYP4A were assessed by Western immunoblotting and by using CYP enzyme-specific substrates, respectively.

RESULTS

mRNA and protein levels of CYP4A1 were elevated only in stout-treated animals. However, lauric acid 12-hydroxylase activity (a CYP4A-specific activity) was reduced (p < or = 0.05) in microsomes from lager- and stout-fed rats. After oxidation with potassium ferricyanide, this activity was significantly increased in microsomes from stout-fed animals. The relative expression of CYP2E1 and CYP2B1 and the activities toward p-nitrophenol, pentoxyresorufin, or benzyloxyresorufin did not differ between beers or compared with pure ethanol or controls. However, the mean expression of CYP1A2, CYP3A, and CYP4A apoproteins was greater in liver microsomes from stout-infused rats than in those from lager-infused rats, ethanol-infused rats, and diet controls (p < or = 0.05). In addition, although no significant differences were observed in ethoxyresorufin O-dealkylase (EROD), methoxyresorufin O-dealkylase (MROD), midazolam, or testosterone hydroxylase activities between groups, stout-infused rats had greater hepatic microsomal erythromycin N-demethylase activity than other groups (p < or = 0.05).

CONCLUSIONS

Stout contains components other than ethanol that interact in a complex fashion with the monooxygenase system.

Tobacco smoke-dependent changes in cytochrome P450 1A1, 1A2, and 2E1 protein expressions in fetuses, newborns, pregnant rats, and human placenta

Tobacco smoke (TS) was described as a mixture of numerous cytochrome P450 (P450) substrates, inducers, and inhibitors. These inducers and inhibitors may modify drug clearance and xenobiotic or endogenous metabolism affecting P450s expression. In the present study, the effect of gestation and TS on: (1) cytochrome P450 CYP1A1, CYP1A2, and CYP2E1 protein expressions, and (2) cytochrome P450-linked microsomal enzyme activities, were studied in fetal rat liver, rat, and human placenta and in newborn and adult rat hepatic and extrahepatic tissues. Non-pregnant and pregnant 4-month-old female Wistar rats were exposed to TS (500, 1,000, or 1,500 mg carbon monoxide per m(3) air) in a toxicological chamber for 3 weeks (6 h daily, 5 days weekly). Human placentas were sampled from non-smoking, passive smoking, or active smoking primiparas. The efficacy of exposure was assessed by measuring urine cotinine levels. The TS-dependent inductory effect on the expression of CYP1A1 and 1A2 and related monooxygenase activities, and the inhibitory/inductory effect on CYP2E1 expression in rat tissues were observed. Pregnancy was associated with decreased levels of constitutive CYP1A1 and 2E1 in hepatic and extrahepatic tissues, TS-inducible CYP1A2 expression in the liver, and CYP1A1 expression in lungs and heart, but had no inhibitory effect on TS-inducible CYP1A1 and 2E1 expression, EROD, and P450-cooperated enzyme activities in the liver, kidney, and, in the latter case, in the heart. The presence of TS-induced CYP1A1 protein was confirmed in rat and human placenta and showed in newborn liver and lungs. CYP1A2 and 2E1 proteins were detectable in fetal rat liver. It was concluded that the expression of CYP1A1, 1A2, and 2E1, which metabolize some drugs and activate carcinogens, is controlled by age-, pregnancy-, and tissue-specific regulatory mechanisms in rats. Gestational differences in the regulation of expression of CYP1A subfamily members are not excluded. CYP1A1 and 2E1, but not CYP1A2 inductory mechanisms seem to be functional in fetal liver at day 21 of pregnancy but they appeared to be uninducible under a TS exposure. In TS-exposed pregnant females and fetuses the effects of metabolic activation of CYP1A1 and 1A2 substrates might be reduced because of lower CYP expressions or poor induction, respectively.