Altered mRNA Levels of Stress-Related Peptides in Mouse Hippocampus and Caudate-Putamen in Withdrawal after Long-Term Intermittent Exposure to Tobacco Smoke or Electronic Cigarette Vapour

Chronic Nicotine Consumption and Withdrawal Regulate Melanocortin Receptor, CRF, and CRF Receptor mRNA Levels in the Rat Brain

Alterations in the various neuropeptide systems in the mesocorticolimbic circuitry have been implicated in negative effects associated with drug withdrawal. The corticotropin-releasing factor (CRF) and α-melanocyte-stimulating hormone are two peptides that may be involved. This study investigated the regulatory effects of chronic nicotine exposure and withdrawal on the mRNA levels of melanocortin receptors (MC3R, MC4R), CRF, and CRF receptors (CRFR1 and CRFR2) expressed in the mesocorticolimbic system. Rats were given drinking water with nicotine or without nicotine (control group) for 12 weeks, after which they continued receiving nicotine (chronic exposure) or were withdrawn from nicotine for 24 or 48 h. The animals were decapitated following behavioral testing for withdrawal signs. Quantitative real-time PCR analysis demonstrated that nicotine exposure (with or without withdrawal) increased levels of CRF and CRFR1 mRNA in the amygdala, CRF mRNA in the medial prefrontal cortex, and CRFR1 mRNA in the septum. Nicotine withdrawal also enhanced MC3R and MC4R mRNA levels in different brain regions, while chronic nicotine exposure was associated with increased MC4R mRNA levels in the nucleus accumbens. These results suggest that chronic nicotine exposure and withdrawal regulate CRF and melanocortin signaling in the mesocorticolimbic system, possibly contributing to negative affective state and nicotine addiction.

Investigating Behavioral and Neuronal Changes in Adolescent Mice Following Prenatal Exposure to Electronic Cigarette (E-Cigarette) Vapor Containing Nicotine

A substantial percentage of pregnant smokers stop using traditional cigarettes and switch to alternative nicotine-related products such as e-cigarettes. Prenatal exposure to tobacco increases the risk of psychiatric disorders in children. Adolescence is a complex phase in which higher cognitive and emotional processes undergo maturation and refinement. In this study, we examined the behavioral and molecular effects of first-trimester prenatal exposure to e-cigarettes. Adult female mice were divided into normal air, vehicle, and 2.5%-nicotine-exposed groups. Our analyses indicated that the adolescents in the 2.5%-nicotine-exposed group exhibited a significant lack of normal digging behavior, elevated initial sucrose intake, and reduced recognition memory. Importantly, we identified a substantial level of nicotine self-administration in the 2.5%-nicotine-exposed group. At a molecular level, the mRNAs of metabotropic glutamate receptors and transporters in the nucleus accumbens were not altered. This previously undescribed work indicates that prenatal exposure to e-cigarettes might increase the risk of nicotine addiction during adolescence, reduce cognitive capacity, and alter normal adolescent behavior. The outcome will aid in translating research and assist healthcare practitioners in tackling addiction and mental issues caused by toxicological exposure. Further, it will inform relevant policymaking, such as recommended taxation, labeling e-cigarette devices with more detailed neurotoxic effects, and preventing their sale to pregnant women and adolescents.

Electronic nicotine delivery systems (ENDS): A convenient means of smoking?

Electronic nicotine delivery systems (ENDS), which are becoming increasingly popular in many parts of the world, have recently become more sophisticated in terms of their more active content and better controlled vaporisation. This review begins by describing how cigarette smoking led to the development of ENDS as a means of combatting nicotine addiction. ENDS are usually categorised as belonging to one of only three main generations, but a fourth has been added in order to differentiate the latest, most powerful, most advanced and innovative that have improved heating efficiency. Descriptions of the principal substances contained in ENDS are followed by considerations concerning the risk of toxicity due to the presence of albeit low concentrations of such a variety of compounds inhaled over a long time, and the increasingly widespread use of ENDS as a means of smoking illicit drugs. We also review the most widely used pharmacotherapeutic approaches to smoking cessation, and recent epidemiological data showing that ENDS can help some people to stop smoking. However, in order to ensure their appropriate regulation, there is a need for higher-quality evidence concerning the health effects and safety of ENDS, and their effectiveness in discouraging tobacco smoking.

Beyond the label: current evidence and future directions for the interrelationship between electronic cigarettes and mental health

Electronic cigarette use has dramatically increased over the last decade. With this recent technological development and wide range of constituents in various products, putative adverse effects on the brain and body have been largely unexplored. Here, we review current evidence linking electronic nicotine cigarette use with potential health consequences and provide evidence supporting an association between drug use and depression in humans. We also examine the biological effects of individual constituents in electronic cigarette aerosols, which include labeled ingredients, such as propylene glycol, vegetable glycerin, nicotine, and flavorants, as well as unlabeled ingredients found in the aerosols, such as carbonyls and heavy metals. Lastly, we examine the effects of electronic cigarette use on endogenous metabolism via changes in cytochrome P450 enzymes, which can thereby impact therapeutic outcomes. While the current evidence offers insight into the potential effects of electronic cigarette use on biological processes, further studies are necessary to determine the long-term clinical relevance of aerosol inhalation.

Switching from tobacco cigarettes in very early pregnancy: The effects of in utero e-cigarette exposure on mouse offspring neurodevelopment and behaviour

INTRODUCTION

Electronic cigarettes (e-cigarettes) are often perceived to be safer than smoking, which has led to some women switching to e-cigarettes during pregnancy. However, the effects of switching from smoking to e-cigarettes on both pregnancy outcomes and the foetus are largely unknown. This study aimed to investigate the effects of switching from tobacco smoking to e-cigarette use in very early pregnancy on birth outcomes, neurodevelopment and behaviour of the offspring.

METHODS

Female BALB/c mice were exposed to cigarette smoke for up to two weeks before being mated. Mated dams were then allocated to one of four treatment groups: (i) continued exposure to cigarette smoke (ii) exposure to e-cigarette aerosol with nicotine, (iii) or without nicotine, or (iv) medical air. Pregnant mice were exposed for 2 h per day for the duration of pregnancy. Gestational outcomes including litter size and sex ratio were assessed, in addition to early-life markers of physical- and neuro- development. At 8 weeks of age, motor coordination, anxiety, locomotion, memory and learning of the adult offspring were assessed.

RESULTS

Gestational outcomes and early markers of physical- and neuro- development were unaffected by in utero exposure, as well as locomotion, anxiety-like behaviour, and object recognition memory during adulthood. However, both e-cigarette groups displayed increased spatial recognition memory compared to air exposed controls. Maternal exposure to nicotine containing e-cigarette aerosol was found to increase offspring bodyweight and impair motor skill learning.

CONCLUSIONS

These results suggest there may be some benefits as well as negative effects of switching to e-cigarettes in early pregnancy.

Increased Expression of Autophagy-Related Genes in Alzheimer's Disease-Type 2 Diabetes Mellitus Comorbidity Models in Cells

The association between Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) has been extensively demonstrated, but despite this, the pathophysiological mechanisms underlying it are still unknown. In previous work, we discovered a central role for the autophagy pathway in the common alterations observed between AD and T2DM. In this study, we further investigate the role of genes belonging to this pathway, measuring their mRNA expression and protein levels in 3xTg-AD transgenic mice, an animal model of AD. Moreover, primary mouse cortical neurons derived from this model and the human H4Swe cell line were used as cellular models of insulin resistance in AD brains. Hippocampal mRNA expression showed significantly different levels for Atg16L1, Atg16L2, GabarapL1, GabarapL2, and Sqstm1 genes at different ages of 3xTg-AD mice. Significantly elevated expression of Atg16L1, Atg16L2, and GabarapL1 was also observed in H4Swe cell cultures, in the presence of insulin resistance. Gene expression analysis confirmed that Atg16L1 was significantly increased in cultures from transgenic mice when insulin resistance was induced. Taken together, these results emphasise the association of the autophagy pathway in AD-T2DM co-morbidity, providing new evidence about the pathophysiology of both diseases and their mutual interaction.

Anxiety and Depression: What Do We Know of Neuropeptides?

In modern society, there has been a rising trend of depression and anxiety. This trend heavily impacts the population’s mental health and thus contributes significantly to morbidity and, in the worst case, to suicides. Modern medicine, with many antidepressants and anxiolytics at hand, is still unable to achieve remission in many patients. The pathophysiology of depression and anxiety is still only marginally understood, which encouraged researchers to focus on neuropeptides, as they are a vast group of signaling molecules in the nervous system. Neuropeptides are involved in the regulation of many physiological functions. Some act as neuromodulators and are often co-released with neurotransmitters that allow for reciprocal communication between the brain and the body. Most studied in the past were the antidepressant and anxiolytic effects of oxytocin, vasopressin or neuropeptide Y and S, or Substance P. However, in recent years, more and more novel neuropeptides have been added to the list, with implications for the research and development of new targets, diagnostic elements, and even therapies to treat anxiety and depressive disorders. In this review, we take a close look at all currently studied neuropeptides, their related pathways, their roles in stress adaptation, and the etiology of anxiety and depression in humans and animal models. We will focus on the latest research and information regarding these associated neuropeptides and thus picture their potential uses in the future.

GLP-1 mediates the neuroprotective action of crocin against cigarette smoking-induced cognitive disorders via suppressing HMGB1-RAGE/TLR4-NF-κB pathway

Cigarette smoking (CS) has been associated with an increased risk of cognitive disorders. Although HMGB1 has been connected to various neurological ailments, its role in the pathogenesis of CS-induced cognitive impairments is undefined. With the ability of GLP-1 to lower HMGB1 expression and improve learning and memory performance, we sought to assess the potential neuroprotective efficacy of Crocin (Cro) as a GLP-1 stimulator against CS-induced cognitive impairments, with a focus on the HMGB1-RAGE/TLR4-NF-κB pathway. Fifty adult rats were specified into: Control; Cro (30 mg/kg); CS; Cro then CS and CS concurrently with Cro. Cognitive functions were assessed by MWM, EMP, and passive avoidance tests. Hippocampal levels of GLP-1, HMGB1, pro-inflammatory cytokines, and apoptotic markers were detected using ELISA, western blotting, and immunohistochemistry. Hippocampal oxidant/antioxidant status was evaluated via colorimetric determination of MDA and TAC. The results revealed that Cro either before or along with CS produced a significant improvement in learning and memory. Cro markedly hindered HMGB1-RAGE/TLR4-NF-κB pathway through enhancing GLP-1 level and expression, which in turn suppressed TNF-α and IL-1β levels and alleviated CS-induced neuroinflammation. Cro significantly counteracted CS-triggered oxidative stress as evidenced by reducing MDA level and raising TAC. Histopathologically, Cro lessened neuronal apoptosis by lowering Bax/Bcl-2 ratio at hippocampal CA2 region. These findings confirmed a GLP-1-dependent neuroprotective action of Cro against CS-induced cognitive disorders via suppressing HMGB1-RAGE/TLR4-NF-κB axis.