Combined Exposure to Alcohol and Tobacco Smoke Changes Oxidative, Inflammatory, and Neurotrophic Parameters in Different Areas of the Brains of Rats

The impact of electronic cigarette aerosol exposure on spatial memory formation: Modulation by orally administered vitamin E

The use of electronic cigarettes (ECIGs) has grown exponentially among young adolescents. Tobacco smoking, in general and ECIG use in particular, has been linked to disruption of the oxidative system, resulting in organ damage. The current investigation intends to evaluate if orally administered Vitamin E (VitE) can protect from learning and cognitive impairment induced by ECIG aerosol exposure in a rat model. This effect was determined by studying behavioral and molecular targets for potential learning and memory impairment. Adult Wistar rats were assigned to the following groups (N= 12/group): Control, ECIG, VitE, and VitE+ECIG. The animals in the groups ECIG and VitE+ECIG were exposed to ECIG aerosol (1 hr/day, 6 days/week) for four weeks. The control group and VitE group were exposed to fresh air. At the same time, the VitE group and VitE+ECIG group were given Vitamin E 100 mg/kg/ day via gavage for the same period as the exposure. The control group and ECIG group were given the vehicle via gavage. Behavioral assessment was performed using the Radial Arm Water Maze. In addition, molecular measures (BDNF, SOD, GPx, GSH, and GSSG), were measured in rats' hippocampal tissues. The results showed that VitE prevented ECIG aerosol exposure-induced impairment of spatial short-term and long-term memory formation (p<0.05), decreased BDNF, and activities/levels of GPx, SOD, and GSH (p<0.05). Moreover, VitE protected against GSSG levels increases (p<0.05) associated with ECIG aerosol exposure. In summary, exposure to ECIGs resulted in spatial memory impairments, which could be mitigated by orally administered vitamin E.

Brain Glucose Metabolism as a Readout of the Central Nervous System Impact of Cigarette Smoke Exposure and Withdrawal and the Effects of NFL-101, as an Immune-Based Drug Candidate for Smoking Cessation Therapy

Neuroimaging biomarkers are needed to investigate the impact of smoking withdrawal on brain function. NFL-101 is a denicotinized aqueous extract of tobacco leaves currently investigated as an immune-based smoking cessation therapy in humans. However, the immune response to NFL-101 and its ability to induce significant changes in brain function remain to be demonstrated. Brain glucose metabolism was investigated using [18F]fluoro-deoxy-glucose ([18F]FDG) PET imaging in a mouse model of cigarette smoke exposure (CSE, 4-week whole-body inhalation, twice daily). Compared with control animals, the relative uptake of [18F]FDG in CSE mice was decreased in the thalamus and brain stem (p < 0.001, n = 14 per group) and increased in the hippocampus, cortex, cerebellum, and olfactory bulb (p < 0.001). NFL-101 induced a humoral immune response (specific IgGs) in mice and activated human natural-killer lymphocytes in vitro. In CSE mice, but not in control mice, single-dose NFL-101 significantly increased [18F]FDG uptake in the thalamus (p < 0.01), thus restoring normal brain glucose metabolism after 2-day withdrawal in this nicotinic receptor-rich region. In tobacco research, [18F]FDG PET imaging provides a quantitative method to evaluate changes in the brain function associated with the withdrawal phase. This method also showed the CNS effects of NFL-101, with translational perspectives for future clinical evaluation in smokers.

Endurance Exercise Training Attenuates the Waterpipe Smoke Inhaling-Induced Learning and Memory Impairment in Rats: Role of Neurotrophic Factors and Apoptotic System

INTRODUCTION

The increasing prevalence of waterpipe tobacco smoking (WTS) and its detrimental effects on memory function have been reported. This study was conducted to investigate the effect of moderate-intensity endurance exercise on the detrimental effects of WTS on learning and spatial memory in rats.

AIMS AND METHODS

Animals were divided into the Control group (CTL), the exercise group (Ex) which trained for 8 weeks, the WTS group (Wp) exposed to smoke inhalation (30 minutes per day, 5 days each week, and for 8 weeks), and the group that did exercise training and received waterpipe smoke together (Ex + Wp). Thereafter, learning and spatial memory were assessed by the Morris water maze test and hippocampal molecular measurements were done.

RESULTS

Waterpipe smoke significantly impaired learning and spatial memory, decreased expression of neurotrophic factors IGF-1 and BDNF (p < .01 and p < .05 vs. CTL group, respectively), increased BAX to BCL-2 ratio (p < .001 vs. CTL group) in hippocampal tissue, and increased the percent of damaged neurons in the hippocampal CA1 area (p < .05 vs. CTL group). Combination of exercise training with WTS prevented learning and spatial memory disturbances and recovered expression of neurotrophic factors IGF-1 (p < .05 vs. Wp group), decreased BAX to BCL-2 ratio (p < .001 vs. Wp group), and reduced percentage of damaged neurons (p < .05 vs. Wp group).

CONCLUSIONS

Findings suggest that moderate-intensity endurance exercise training can ameliorate learning and memory impairment caused by waterpipe smoke in rats. This effect partly results from increasing the expression of neurotrophic factors BDNF and IGF-1 and correcting pro/anti-apoptotic proteins balance in the hippocampal tissue.

IMPLICATIONS

The popularity of WTS especially among youth is increasing. We assessed the effect of hookah smoke with/without exercise on learning and memory. Hookah smoke leads to CA1-neural injury and impairs learning and memory in rats. A combination of exercise training with hookah smoke attenuates these complications. This positive effect of exercise is partially mediated by the balancing of brain-derived neurotrophic factor (BDNF) and Insulin-like growth factor-1 (IGF-1) and also the BAX to BCL-2 ratio, a significant predictor of cell susceptibility to apoptosis. Extrapolation of these positive findings to humans needs complementary studies.

Rhizophora mucronata Lam. (Mangrove) Bark Extract Reduces Ethanol-Induced Liver Cell Death and Oxidative Stress in Swiss Albino Mice: In Vivo and In Silico Studies

The bark extract of Rhizophora mucronata (BERM) was recently reported for its prominent in vitro protective effects against liver cell line toxicity caused by various toxicants, including ethanol. Here, we aimed to verify the in vivo hepatoprotective effects of BERM against ethanol intoxication with the prediction of potential targets employing in silico studies. An oral administration of different concentrations (100, 200 and 400 mg/kg body weight) of BERM before high-dose ethanol via intraperitoneal injection was performed in mice. On day 7, liver sections were dissected for histopathological examination. The ethanol intoxication caused liver injury and large areas of necrosis. The pre-BERM administration decreased the ethanol-induced liver damage marker tumor necrosis factor-alpha (TNF-α) expression, reduced hepatotoxicity revealed by nuclear deoxyribonucleic acid (DNA) fragmentation and decreased oxidative stress indicated by malondialdehyde and glutathione contents. Our in silico studies have identified BERM-derived metabolites exhibiting the highest predicted antioxidant and free radical scavenger activities. Molecular docking studies showed that most of the metabolites were predicted to be enzyme inhibitors such as carbonic anhydrase inhibitors, which were reported to stimulate the antioxidant defense system. The metabolites predominantly presented acceptable pharmacokinetics and safety profiles, suggesting them as promising new antioxidant agents. Altogether, the BERM extract exerts antioxidative activities and shows promising hepatoprotective effects against ethanol intoxication. Identification of related bioactive compounds will be of interest for future use at physiological concentrations in ethanol-intoxicated individuals.

Relationship between urinary dichlorophenols and cognitive function among people over 60 years old from NHANES

Studies have shown that exposure to dichlorophenols (DCPs) and their precursors might have potential neurotoxicity, which may be related to low cognitive function, but there are few large-scale, representative population data to explore the association between DCP exposure and cognitive function. We aimed to examine the relationship between urinary DCPs and cognitive function in the US older people. A total of 952 participants ≥ 60 years old from the National Health and Nutrition Examination Survey (NHANES) in two cycles (2011-2014) were enrolled. The Consortium to Establish a Registry for Alzheimer's disease Word Learning subtest (CERAD W-L), the Animal Fluency test (AFT), and the Digit Symbol Substitution test (DSST) were used to assess cognition. Multivariate logistic regression and restricted cubic spline (RCS) were used to evaluate the relationship between DCP exposure and cognitive function. A positive association between 2,5-DCP and the risk of bad performance of DSST was observed (P for trend = 0.024) after adjusting for the covariates. Compared to the lowest quartile, OR of DSST for the highest quartile of 2,5-DCP was 1.72 (95%CI:1.03-2.87, P = 0.039). There were no significant associations between DCPs and the other tests. The RCS plot showed an inverted J-shaped relationship between 2,5-DCP, 2,4-DCP, and the DSST score. The inflection points for the curves were found at 1.531 μg/L and 0.230 μg/L, respectively. On the right side of the inflection points, the DSST score dropped sharply. In subgroup analysis, those under 70 years old, smokers, and alcohol drinkers had a higher risk of bad performance in DSST when exposed to 2,5-DCP. The higher concentration of urinary DCPs is associated with a lower score of DSST in the US older people.

Low-cost apparatus for cigarette smoke exposure in rats

BACKGROUND

The effects of tobacco smoke on the central nervous system are usually studied with isolated nicotine, ignoring other compounds present in cigarette smoke. The few studies that use in vivo whole-body cigarette smoke exposure are usually performed in expensive commercial apparatus.

NEW METHOD

We presented a feasible, safe, and low-cost apparatus for cigarette smoke exposure in rodents.

RESULTS

Rats exposed to cigarette smoke in this apparatus showed cotinine levels similar to human active smokers. Additional results showed that cigarette smoke exposure increased glutamate and aspartic acid levels and decreased leucine, isoleucine, ornithine, phenylalanine, and tryptophan levels in the cerebrospinal fluid of rats.

COMPARISON WITH EXISTING METHOD(S)

Our apparatus is feasible, safe, and costs 67-fold less than a commercial automatized smoking machine. Beyond the low cost, it does not require specialized knowledge for building or maintenance.

CONCLUSIONS

We concluded that our low-cost apparatus is reliable and reproduces cigarette smoke use in humans.

Tobacco and Nervous System Development and Function-New Findings 2015-2020

Tobacco is a one of the most common addictive stimulants used by people around the world. The smoke generated during tobacco combustion is a toxic mixture of more than 5000 chemicals of which over 30 are known human carcinogens. While its negative effects on the human body are well understood, it remains a serious public health problem. One of the multiple effects of smoking is tobacco’s effect on the nervous system—its development and function. This review aims to summarize the progress made in research on the effects of tobacco on the nervous system both of the perinatal period and adults and both in animals and humans in 2015–2020. The 1245 results that corresponded to the keywords “tobacco, cigarette, nervous system, brain, morphology, function” were reviewed, of which 200 abstracts were considered significant. Most of those articles broadened the knowledge about the negative effects of smoking on the human nervous system. Tobacco has a significant negative impact on the development of nervous structures, neurotransmission and cognitive functions, and promotes the development of neurodegenerative diseases, insomnia and cerebrovascular diseases. The only exception is the protective effect of the dopaminergic system in Parkinson’s disease. In conclusion, in recent years much effort has been devoted to describing, revealing and uncovering new aspects of tobacco detrimental to human life. The nicotine contained in tobacco smoke affects the human body in a multidimensional way, including a serious impact on the broadly understood neurological health.

Hepatic and renal damage by alcohol and cigarette smoking in rats

Chronic use of alcohol and tobacco cigarettes is associated to millions of deaths per year, either by direct or indirect causes. However, few studies have explored the additional risks of the combined use of these drugs. Here we assessed the effect of the combined use of alcohol and cigarette smoke on liver or kidney morphology, and on biochemical parameters in chronically treated rats. Male Wistar rats were allocated to receive 2 g/kg alcohol orally, which was followed by the inhalation of smoke from six cigarettes during 2 h (ALTB group) for 28 days. Other groups received alcohol alone (AL) or were exposed to cigarette smoke (TB) alone and were compared to control (CT) rats, which received water followed by ambient air. On day 29, rats were euthanized and blood samples were collected for aminotransferase enzymes (AST and ALT), creatinine, and urea analysis. Liver and kidney were weighted, dissected, fixed, and stained with hematoxylin and eosin for morphological analysis. Our results showed that necrosis was elevated in the AL, TB, and mainly the ALTB group in both liver and kidney of rats. Serum levels of AST and ALT were reduced by cigarette smoke exposure, independently of alcohol use. Serum creatinine levels increased after tobacco smoke exposure. On the other hand, TB and AL groups decreased serum urea levels, and their association restored that decrease. Absolute liver and kidney weights were lower in the cigarette smoke exposure rats. Lastly, body weight gain was lower in TB group and combined use restored it. Thus, we may infer that the use of alcohol, exposure to tobacco cigarette smoke or, mainly, their association promotes liver and kidney injuries, and this damage is related with biochemical changes in rats.

Past Exposure to Cigarette Smoke Aggravates Cognitive Impairment in a Rat Model of Vascular Dementia via Neuroinflammation

Smoking is a risk factor for dementia. Cognitive function can be partially restored after quitting smoking, but still lower than never smoked group. The underlying mechanisms still remain unclear. The effects of smoking cessation combined with cerebral chronic hypoperfusion (CCH) on cognitive function have never been described. Here, we established a cigarette smoking cessation model, a CCH model, and a cigarette smoking cessation plus CCH model. We investigated cognitive function in these models and the mechanisms of the neuroinflammation, nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3(NLRP3)/cysteine aspartate-specific proteinase (caspase-1)/interleukin- 1β (IL-1β) pathway, and eucaryotic initiation factor 2α (eIF2α) /autophagy pathway. We used morris water maze (MWM) and novel object recognition (NOR) test to evaluate cognitive function in rats. Nissl staining was performed to observe cell morphology in the hippocampal CA1 area. A neuroinflammatory marker (glial fibrillary acidic protein, GFAP) was assessed by Western blot analysis and immunohistochemistry staining. IL-1β levels were detected by ELISA. The protein levels of NLRP3/caspase-1/ IL-1β and eIF2α/autophagy pathway were evaluated by Western blot analysis. LC3 was assessed by immunofluorescence staining. CCH can affect cognitive function by influencing neuroinflammation, NLRP3/caspase-1/IL-1β pathway, and eIF2α/autophagy pathway. Past exposure to cigarette smoke can also affect cognitive function by influencing neuroinflammation and NLRP3/caspase-1/IL-1β pathway, which may be induced by smoking and may not be alleviated after smoking cessation. Past exposure to cigarette smoke does not influence autophagy, which may be increased by smoking and then decrease to normal levels after smoking cessation. Past exposure to smoking can further aggravate cognitive impairment and neuroinflammation in VaD animals: cognitive impairment induced by CCH via neuroinflammation, NLRP3/caspase-1/IL-1β, and eIF2α/autophagy pathway and cognitive impairment induced by past exposure to cigarette smoke via neuroinflammation and NLRP3/caspase-1/IL-1β pathway. The combined group had the worst cognitive impairment because of harmful reasons.

Alcohol use disorders and associated factors among adults in rural communities in Enugu State, Nigeria: A cross-sectional survey

Evidence has shown increasing rate of alcohol abuse among rural dwellers. At the same time little is known about the association between alcohol use disorders (AUD) and factors peculiar to this group of people. A cross-sectional study design was adopted to determine the prevalence of AUD and associated factors among adults in rural communities in Enugu State, Nigeria. Multi-stage random sampling technique was used to select 2,996 respondents from six rural communities in Enugu State. Respondents' demographic, socioeconomic and clinical characteristics were documented. Data on alcohol use disorders were collected using the Alcohol Use Disorder Identification Test (AUDIT). AUDIT cutoff score of ≥ 8 signified presence of AUD. Logistic regression was used to determine the factors associated with the outcome variable, AUD calculating the crude and adjusted odds ratios and their respective confidence intervals (95% CI). The prevalence rates of alcohol use and AUD were 79.7% and 48.1%, respectively. The factors most strongly associated with AUD were eating once per day (OR= 8.59, 95% CI = 4.24-17.40), male gender (OR= 7.50, 95% CI = 6.30-8.93), being an artisan (OR= 5.92, 95% CI = 3.33-10.05), poor knowledge of health effects of alcohol abuse (OR= 4.26, 95% CI = 3.46-5.24), smoking (OR= 4.21, 95% CI = 3.24-5.47), low educational attainment and early age of alcohol initiation. Practicing Christianity, Islamic religion, being single and suffering from diabetes were some of the negative predictors of AUD. Multi-level interventions that encompass the associated factors are recommended to curtail harmful alcohol use in the rural communities.

Waterpipe smoking among university students in Hong Kong: a cross-sectional study

BACKGROUND

Waterpipe smoking has gained global popularity in recent years, especially among young people. However, there is a lack of empirical investigation into waterpipe smoking in East Asia. This study aimed to investigate the demographical and psycho-social characteristics and patterns of waterpipe smoking (WPS) among university students in Hong Kong.

METHODS

A cross-sectional survey was conducted via online questionnaires administered to 1288 Hong Kong university students (mean age: 22.4 [SD = 3.8]). Logistic regressions were used to compute adjusted odd ratios (aOR) for waterpipe ever-smoking in relation to respondents' characteristics. Moreover, multinomial logistic regression yielded adjusted RR (aRR) for four different smoking status (i.e., never, waterpipe-only, cigarette-only, and dual smoking) regarding the characteristics.

RESULTS

23.8% of participants reported having ever smoked a waterpipe (vs. cigarette ever-smoking: 21.1%). Factors including being female (aOR:1.57; 95% CI: 1.22-2.02), older age (≥24 years: 4.17; 1.35-12.93), frequent alcohol consumption (>monthly: 26.02; 10.91-62.09), and higher sensation-seeking behaviours (high level: 2.98;1.46-6.08) were associated with waterpipe ever-smokers. The study also identified that demographical and psycho-social characteristics were variably associated with students' smoking status. Particularly, more frequent alcohol consumption was most significantly associated with waterpipe-only smoking (aRR:45.73; 95% CI:11.44-182.73) (vs. cigarette-only smoking: 3.01; 1.76-5.14).

CONCLUSIONS

WPS is the most common form of tobacco smoking among university students in Hong Kong, and characteristics unique to the population were identified. There is no legislation of relevant policies on WPS despite its concerning significance in public health among young people, therefore immediate action to monitor and control WPS is needed in Hong Kong.