Biological determinants impact the neurovascular toxicity of nicotine and tobacco smoke: A pharmacokinetic and pharmacodynamics perspective

Health risks and toxicity mechanisms of medicinal and aromatic plants (MAPs): A comprehensive review of adverse effects on organ systems, genotoxicity and reproductive toxicity

The use of medicinal and aromatic plants (MAPs) requires careful evaluation due to their potential effects on human health. Assessing the risks, including toxicity and adverse effects, is essential to ensure their safe application. Our bibliometric analysis revealed a high prevalence of research focusing on MAPs' health impacts, with frequent mentions of "side effects" and "toxicity," emphasizing the need for further investigation into their active ingredients and mechanisms of action. The potential health effects of MAPs have been documented across various organ systems, including gastrointestinal (vomiting and diarrhea), renal (nephrotoxicity), hepatic (hepatotoxicity), and neurological (neurotoxicity). These effects arise from interactions between plant compounds and metabolic enzymes, cellular receptors, and signaling pathways, potentially leading to toxicity. The mechanisms discussed include oxidative stress, mitochondrial dysfunction, inhibition of metabolic enzymes, DNA damage (genotoxicity), and endocrine disruption, which may explain the diverse observed toxicological profiles. This review highlights the complex relationship between botanical substances and human health, integrating current applications while raising awareness of associated risks. It also underscores the importance of strict regulations and responsible use to ensure the safe and effective integration of MAPs into healthcare practices.

Repeated exposure to high-dose nicotine induces prefrontal gray matter atrophy in adolescent male rats

Incidences of seizure after e-cigarette use in adolescents and young adults have been reported, raising the concern about the risk of nicotine overconsumption. Few previous studies have investigated the effects of nicotine at high doses on brain and behavior in adolescent animals. In this study, the effects of a 15-day repeated nicotine treatment at a daily dose of 2 mg/kg body weight were investigated in adolescent and adult male rats. Nicotine treatment abolished body weight gain in the adults, but did not affect the body weight significantly in the adolescents. Only the nicotine-treated adolescents showed significant changes in brain anatomy 1 day post-treatment, which manifested as a significant reduction of whole-brain gray matter (GM) volume, a further reduction of regional GM volume in the medial prefrontal cortex (mPFC) and altered GM volume covariations between the mPFC and a number of brain regions. The mPFC of nicotine-treated adolescent rats did not exhibit evident signs of neuronal degeneration and reactive astrocytosis, but showed a significantly decreased expression of presynaptic marker synaptophysin (SYN), along with a significantly increased oxidative stress and a significantly elevated expressions of microglial marker ionized calcium binding adaptor molecule 1 (IBA1). Together, these results suggested that repeated nicotine overdosing may shift regional redox, modulate microglia-mediated pruning, and give rise to structural/connectivity deficits in the mPFC of adolescent male rats.

Evaluation of systemic and brain pharmacokinetic parameters for repurposing metformin using intravenous bolus administration

Metformin's potential in treating ischemic stroke and neurodegenerative conditions is of growing interest. Yet, the absence of established systemic and brain pharmacokinetic (PK) parameters at relevant preclinical doses presents a significant knowledge gap. This study highlights these PK parameters and the importance of using pharmacologically relevant preclinical doses to study pharmacodynamics in stroke and related neurodegenerative diseases. A liquid chromatography with tandem mass spectrometry method to measure metformin levels in plasma, brain, and cerebrospinal fluid was developed and validated. In vitro assays examined brain tissue binding and metabolic stability. Intravenous bolus administration of metformin to C57BL6 mice covered a low- to high-dose range maintaining pharmacological relevance. Quantification of metformin in the brain was used to assess brain PK parameters, such as unidirectional blood-to-brain constant (Kin) and unbound brain-to-plasma ratio (Kp, uu, brain). Metformin exhibited no binding in the mouse plasma and brain and remained metabolically stable. It rapidly entered the brain, reaching detectable levels in as little as 5 minutes. A Kin value of 1.87 ± 0.27 μL/g/min was obtained. As the dose increased, Kp, uu, brain showed decreased value, implying saturation, but this did not affect an increase in absolute brain concentrations. Metformin was quantifiable in the cerebrospinal fluid at 30 minutes but decreased over time, with concentrations lower than those in the brain across all doses. Our findings emphasize the importance of metformin dose selection based on PK parameters for preclinical pharmacological studies. We anticipate further investigations focusing on PKs and pharmacodynamics in disease conditions, such as stroke. SIGNIFICANCE STATEMENT: The study establishes crucial pharmacokinetic parameters of metformin for treating ischemic stroke and neurodegenerative diseases, addressing a significant knowledge gap. It further emphasizes the importance of selecting pharmacologically relevant preclinical doses. The findings highlight metformin's rapid brain entry, minimal binding, and metabolic stability. The necessity of considering pharmacokinetic parameters in preclinical studies provides a foundation for future investigations into metformin's efficacy for neurodegenerative disease(s).

Decoding the neurotoxic effects of propofol: insights into the RARα-Snhg1-Bdnf regulatory cascade

The potential neurotoxic effects of propofol, an extensively utilized anesthetic, underline the urgency to comprehend its influence on neuronal health. Insights into the role of the retinoic acid receptor-α, small nucleolar RNA host gene 1, and brain-derived neurotrophic factor (RARα-Snhg1-Bdnf) network can offer significant advancements in minimizing these effects. The study targets the exploration of the RARα and Snhg1 regulatory network's influence on Bdnf expression in the realm of propofol-induced neurotoxicity. Harnessing the Gene Expression Omnibus (GEO) database and utilizing JASPAR and RNA-Protein Interaction Prediction (RPISeq) database for projections, the study embarks on an in-depth analysis employing both in vitro and in vivo models. The findings draw a clear link between propofol-induced neurotoxicity and the amplification of RAR signaling pathways, impacting hippocampal development and apoptosis and leading to increased RARα and Snhg1 and decreased Bdnf. Propofol is inferred to accentuate neurotoxicity by heightening RARα and Snhg1 interactions, culminating in Bdnf suppression.NEW & NOTEWORTHY This study aimed to decode propofol's neurotoxic effects on the regulatory cascade, provide insights into the RARα-Snhg1-Bdnf interaction, apply extensive validation techniques, provide a detailed analysis and exploration of propofol's neurotoxicity, and offer a comprehensive approach to understanding molecular interactions.

Resting-state functional connectivity and structural differences between smokers and healthy non-smokers

Previous studies have shown an association between cigarette use and altered resting-state functional connectivity (rsFC) in many large-scale networks, sometimes complemented by measures of cortical atrophy. In this study, we aimed to further explore the neural differences between smokers and healthy non-smokers through the integration of functional and structural analyses. Imaging data of fifty-two smokers and forty-five non-smokers were analyzed through an independent component analysis for group differences in rsFC. Smokers showed lower rsFC within the dorsal attention network (DAN) in the left superior and middle frontal gyrus and left superior division of the lateral occipital cortex compared to non-smokers; moreover, cigarette use was found to be associated with reduced grey matter volume in the left superior and middle frontal gyrus and right orbitofrontal cortex, partly overlapping with functional findings. Within smokers, daily cigarette consumption was positively associated with increased rsFC within the cerebellar network and the default mode network and decreased rsFC within the visual network and the salience network, while carbon monoxide level showed a positive association with increased rsFC within the sensorimotor network. Our results suggest that smoking negatively impacts rsFC within the DAN and that changes within this network might serve as a circuit-based biomarker for structural deficits.

Correlation analysis between smoke exposure and serum neurofilament light chain in adults: a cross-sectional study

BACKGROUND

Smoke exposure is a prevalent and well-documented risk factor for various diseases across different organ systems. Serum neurofilament light chain (sNfL) has emerged as a promising biomarker for a multitude of nervous system disorders. However, there is a notable paucity of research exploring the associations between smoke exposure and sNfL levels.

METHODS

We conducted a comprehensive analysis of the National Health and Nutrition Examination Survey (NHANES) cross-sectional data spanning the years 2013 to 2014. Serum cotinine levels were classified into the following three groups: < 0.05, 0.05-2.99, and ≥ 3 ng/ml. Multiple linear regression models were employed to assess the relationships between serum cotinine levels and sNfL levels. Additionally, we utilized restricted cubic spline analyses to elucidate the potential nonlinear relationship between serum cotinine and sNfL levels.

RESULTS

A total of 2053 participants were included in our present research. Among these individuals, the mean age was 47.04 ± 15.32 years, and males accounted for 48.2% of the total study population. After adjusting the full model, serum cotinine was positively correlated with sNfl in the second group (β = 0.08, 95%CI 0.01-0.15) and in the highest concentration of serum cotinine (β = 0.10, 95%CI 0.01-0.19) compared to the group with the lowest serum cotinine concentrations. Current smokers, in comparison to non-smokers, exhibited a trend toward elevated sNfL levels (β = 0.07, 95%CI 0.01-0.13). Furthermore, subgroup analyses revealed interactions between serum cotinine levels and different age groups (P for interaction = 0.001) and gender stratification (P for interaction = 0.015) on sNfL levels.

CONCLUSION

The study suggested that serum cotinine was significantly and positively associated with sNfl levels in adult participants. Furthermore, current smokers tend to exhibit elevated sNfL levels. This research sheds light on the potential implications of smoke exposure on neurological function impairment and underscores the importance of further exploration in this area.

Folic acid supplementation improved nicotine withdrawal-induced of memory loss via affecting oxidative status, inflammatory response, cholinergic activity, BDNF and amyloid-B in adolescent male rat

BACKGROUND

The present study aimed to assess whether folic acid (FA) have potential to prevent memory impairment caused by nicotine (Nico) withdrawal in adolescent male rats.

METHODS AND MATERIALS

The experiments were divided into 7 groups: 1) vehicle, 2) Nico (Nico 2 mg/kg injection from 21 to 42 days of ages), 3-5) Nico FA5/10/15 mg/kg (received Nico from 21 to 42 days of ages and received FA at three doses 5, 10 and 15 mg/kg 43-63 days of ages), and 6) received normal saline from 21 to 42 days of age after that received FA 15 mg/kg by oral gavage from 43 to 63 days of age. At 64-69 days of ages, behavioral tests related to memory including Morris Water Maze (MWM) and Object Recognition Test (ORT) were performed and related biochemical analysis including the hippocampal levels of oxidative stress markers, inflammatory indices, brain-derived neurotrophic factor (BDNF), nitrite, amyloid-B and acetylcholinesterase [1] were measured.

RESULTS

Results showed that nicotine exposure in adolescence followed by withdrawal dramatically impaired learning and memory performance along with affecting a variety of biochemical markers in the hippocampal tissues. In addition, it was observed that administration of FA significantly ameliorated Nico withdrawal-induced adverse effects through restoration of the mentioned biochemical disturbances.

CONCLUSION

The present study and other relevant researches demonstrated that FA as a well-known, inexpensive, and safe supplement has strong potential to either prevent or ameliorate the detrimental effect of Nico withdrawal. However, further investigation is required to be more elucidated the precise mechanisms underlying memory impairment-induced by Nico withdrawal.

Alcohol consumption, smoking, and risk of dementia in community-dwelling Japanese people aged 40-74 years: The Murakami cohort study

OBJECTIVE

Alcohol drinking and tobacco smoking have impacts on lifestyle-related diseases, but their association with dementia remains a debated topic. This study aimed to examine longitudinal associations between alcohol consumption, smoking, and dementia risk in middle-aged and older Japanese people.

METHODS

This study used a cohort design with an 8-year follow-up. Participants were community-dwelling Japanese people (N = 13,802) aged 40-74 years. The baseline survey, including a self-administered questionnaire, was conducted in 2011-2013. Predictors were alcohol consumption and tobacco smoking. The outcome was incident dementia obtained from a long-term care insurance database. Covariates were demographics, lifestyle factors, body mass index, general health status, and history of stroke, diabetes, and depression.

RESULTS

Participant mean age was 59.0 years. The 1-149, 150-299, and 300-449 g ethanol/week groups had significantly lower adjusted hazard ratios (HRs) (0.62, 0.59, and 0.47, respectively) compared with the reference group, with no significant linear association. HRs increased toward 1 when past-drinkers and those with poor health status and a disease history were excluded (0.80, 0.66, and 0.82, respectively). Higher smoking levels were dose-dependently associated with a higher HR (adjusted P for trend = 0.0105), with the ≥20 cigarettes/day group having a significantly higher adjusted HR (1.80). Heavy drinkers (≥449 g ethanol/week) with smoking habits, but not those without smoking habits, had higher dementia risk (P for interaction = 0.0046).

CONCLUSION

Light-to-moderate alcohol consumption is associated with decreased dementia risk, and smoking is dose-dependently associated with increased dementia risk, with an interaction between high alcohol consumption and smoking on dementia risk.

Repeat Fall Risk in Geriatric Patients After Fall-Induced Head Trauma

Introduction There are many known risk factors for falls, with poor health and physiologic decreases in function as the major contributors to fall risk in older adults. However, risk factors for repeat falls after initial ED discharge are not well-described. This study seeks to prospectively investigate risk factors for short-term repeat falls in geriatric ED patients with fall-related head trauma who do not require hospital admission. Methods This is a prospective study of patients aged 65 years and older with fall-related head trauma who presented to the EDs of two community level I trauma centers. Patients were excluded for intracerebral hemorrhage, admission during initial ED visit, or death in the hospital. Patients were followed for 14 days. Patient characteristics, repeat ED visits, and reason for returns were noted. Results About 2,143 patients were identified as meeting the inclusion criteria. Within 14 days of the initial presentation, 14.1% of patients returned to the ED, with 8.3% presenting with a complaint related to the initial trauma and 2.6% with a new injury. Patients with comorbidities of dementia (OR 3.02, 95% CI, 1.72-5.33, p<0.001), stroke (OR 2.12, 95% CI, 1.05-4.27, p=0.031), and smoking (OR 4.27, 95% CI,1.76-10.37, p<0.001) were significantly more likely to sustain a new injury leading to a repeat ED visit within 14 days. Conclusions After an ED visit due to a fall, over one in 10 patients will re-present to the ED due to a new injury or sequelae from the initial fall. In the immediate period after a fall, enhanced outpatient follow-up or risk mitigation strategies should be considered to lessen return visits and decrease morbidity.

Impact of in-utero electronic cigarette exposure on neonatal neuroinflammation, oxidative stress and mitochondrial function

Introduction: Despite the prevalence of the perception that electronic cigarettes (e-cig) are a safer alternative to tobacco smoke, growing concern about their potential toxic impact warrants adequate investigation focusing on special populations like maternal and pediatric groups. This study evaluated the consequences of maternal e-cig use on neonatal neuroinflammation, oxidative stress, and mitochondrial function in primary cultured neurons and postnatal day (PD) 7 and 90 brain. Methodology: Pregnant CD1 mice were exposed to e-cig vapor (2.4% nicotine) from gestational day 5 (E5) till PD7, and the primary neurons were isolated from pups at E16/17. Cellular total reactive oxygen species (ROS) and mitochondrial superoxide were measured in primary neurons using CM-H2DCFDA and Mitosox red, respectively. Mitochondrial function was assessed by Seahorse XF Cell Mitostress analysis. The level of pro-inflammatory cytokines was measured in primary neurons and PD7 and PD90 brains by RT-PCR and immunobead assay. Western blot analysis evaluated the expression of antioxidative markers (SOD-2, HO-1, NRF2, NQO1) and that of the proinflammatory modulator NF-κB. Results: Significantly higher level of total cellular ROS (p < 0.05) and mitochondrial superoxide (p < 0.01) was observed in prenatally e-cig-exposed primary neurons. We also observed significantly reduced antioxidative marker expression and increased proinflammatory modulator and cytokines expression in primary neurons and PD7 (p < 0.05) but not in PD90 postnatal brain. Conclusion: Our findings suggest that prenatal e-cig exposure induces postnatal neuroinflammation by promoting oxidative stress (OS), increasing cytokines' levels, and disrupting mitochondrial function. These damaging events can alter the fetal brain's immune functions, making such offspring more vulnerable to brain insults.

Permeability of Metformin across an In Vitro Blood-Brain Barrier Model during Normoxia and Oxygen-Glucose Deprivation Conditions: Role of Organic Cation Transporters (Octs)

Our lab previously established that metformin, a first-line type two diabetes treatment, activates the Nrf2 pathway and improves post-stroke recovery. Metformin's brain permeability value and potential interaction with blood-brain barrier (BBB) uptake and efflux transporters are currently unknown. Metformin has been shown to be a substrate of organic cationic transporters (Octs) in the liver and kidneys. Brain endothelial cells at the BBB have been shown to express Octs; thus, we hypothesize that metformin uses Octs for its transport across the BBB. We used a co-culture model of brain endothelial cells and primary astrocytes as an in vitro BBB model to conduct permeability studies during normoxia and hypoxia using oxygen-glucose deprivation (OGD) conditions. Metformin was quantified using a highly sensitive LC-MS/MS method. We further checked Octs protein expression using Western blot analysis. Lastly, we completed a plasma glycoprotein (P-GP) efflux assay. Our results showed that metformin is a highly permeable molecule, uses Oct1 for its transport, and does not interact with P-GP. During OGD, we found alterations in Oct1 expression and increased permeability for metformin. Additionally, we showed that selective transport is a key determinant of metformin's permeability during OGD, thus, providing a novel target for improving ischemic drug delivery.

Antidiabetic Drugs Can Reduce the Harmful Impact of Chronic Smoking on Post-Traumatic Brain Injuries

Traumatic Brain Injury (TBI) is a primary cause of cerebrovascular and neurological disorders worldwide. The current scientific researchers believe that premorbid conditions such as tobacco smoking (TS) can exacerbate post-TBI brain injury and negatively affect recovery. This is related to vascular endothelial dysfunction resulting from the exposure to TS-released reactive oxygen species (ROS), nicotine, and oxidative stress (OS) stimuli impacting the blood-brain barrier (BBB) endothelium. Interestingly, these pathogenic modulators of BBB impairment are similar to those associated with hyperglycemia. Antidiabetic drugs such as metformin (MF) and rosiglitazone (RSG) were shown to prevent/reduce BBB damage promoted by chronic TS exposure. Thus, using in vivo approaches, we evaluated the effectiveness of post-TBI treatment with MF or RSG to reduce the TS-enhancement of BBB damage and brain injury after TBI. For this purpose, we employed an in vivo weight-drop TBI model using male C57BL/6J mice chronically exposed to TS with and without post-traumatic treatment with MF or RSG. Our results revealed that these antidiabetic drugs counteracted TS-promoted downregulation of nuclear factor erythroid 2-related factor 2 (NRF2) expression and concomitantly dampened TS-enhanced OS, inflammation, and loss of BBB integrity following TBI. In conclusion, our findings suggest that MF and RSG could reduce the harmful impact of chronic smoking on post-traumatic brain injuries.

Maternal e-cigarette use can disrupt postnatal blood-brain barrier (BBB) integrity and deteriorates motor, learning and memory function: influence of sex and age

Electronic nicotine delivery systems (ENDS), also commonly known as electronic cigarettes (e-cigs) are considered in most cases as a safer alternative to tobacco smoking and therefore have become extremely popular among all age groups and sex. It is estimated that up to 15% of pregnant women are now using e-cigs in the US which keeps increasing at an alarming rate. Harmful effects of tobacco smoking during pregnancy are well documented for both pregnancy and postnatal health, however limited preclinical and clinical studies exist to evaluate the long-term effects of prenatal e-cig exposure on postnatal health. Therefore, the aim of our study is to evaluate the effect of maternal e-cig use on postnatal blood-brain barrier (BBB) integrity and behavioral outcomes of mice of varying age and sex. In this study, pregnant CD1 mice (E5) were exposed to e-Cig vapor (2.4% nicotine) until postnatal day (PD) 7. Weight of the offspring was measured at PD0, PD7, PD15, PD30, PD45, PD60 and PD90. The expression of structural elements of the BBB, tight junction proteins (ZO-1, claudin-5, occludin), astrocytes (GFAP), pericytes (PDGFRβ) and the basement membrane (laminin α1, laminin α4), neuron specific marker (NeuN), water channel protein (AQP4) and glucose transporter (GLUT1) were analyzed in both male and female offspring using western blot and immunofluorescence. Estrous cycle was recorded by vaginal cytology method. Long-term motor and cognitive functions were evaluated using open field test (OFT), novel object recognition test (NORT) and morris water maze test (MWMT) at adolescence (PD 40-45) and adult (PD 90-95) age. In our study, significantly reduced expression of tight junction proteins and astrocyte marker were observed in male and female offspring until PD 90 (P < 0.05). Additionally, prenatally e-cig exposed adolescent and adult offspring showed impaired locomotor, learning, and memory function compared to control offspring (P < 0.05). Our findings suggest that prenatal e-cig exposure induces long-term neurovascular changes of neonates by disrupting postnatal BBB integrity and worsening behavioral outcomes.

Sex-Related Differences in Oxidative, Platelet, and Vascular Function in Chronic Users of Heat-not-Burn vs. Traditional Combustion Cigarettes

Smoking is still a major cardiovascular risk factor, despite many public awareness campaigns and dedicated interventions. Recently, modified risk products (MRP), e.g., heat-not-burn cigarettes (HNBCs), have been introduced as surrogates of traditional combustion cigarettes (TCCs). Although these products are promoted as healthier than TCCs, few studies have been conducted to assess it. This work is a sex-focused sub-study of a prospective observational study in which apparently healthy chronic TCC smokers were age-matched with regular HNBC users. Blood samples were collected for biochemical assays and blood pressure and flow-mediated dilation (FMD) were measured. Out of 60 subjects, 33 (55%) were women, and 27 (45%) men, with 11 (33%) vs. 9 (33%) non-smokers, respectively, 10 (30%) vs. 10 (37%) TCC smokers, and 12 (36%) vs. 8 (30%) HNBC smokers (p = 0.946). Bivariate and multivariable analyses showed no statistically significant between-sex differences in NO, H2O2, sCD40L, sNox2-dp, sP-selectin, platelet aggregation, cotinine or FMD, overall, in non-smokers, in TCC smokers, or in HNBC smokers (all p > 0.05). HNBCs appeared safer than TCCs when focusing on Nox2-dp (p = 0.026) and sP-selectin (p = 0.050) but had similar levels of the other measured markers. In conclusion, HNBCs have similar detrimental effects on women and men’s oxidative stress (H2O2: p = 0.49; sNox2-dp: p = 0.31) and platelet activation (sP-selectin: p = 0.33; platelet aggregation p = 0.87).