Nicotine: From Discovery to Biological Effects

Metabolomic Analysis of Nicotine-Induced Metabolic Disruptions and Their Amelioration by Resveratrol

This study investigates the metabolic disruptions caused by nicotine (NIC) exposure, with a particular focus on amino acid and lipid metabolism, and evaluates resveratrol (RSV) as a potential protective agent. Mice were divided into four groups: control (CON), NIC-exposed, NIC + RSV-treated, and RSV-only. NIC exposure resulted in significant weight loss, elevated glucose levels, altered lipid profiles, and organ damage, particularly in the liver and kidneys. Increased inflammation was evidenced by elevated levels of IL-6 and CRP. In contrast, RSV treatment mitigated these effects by improving lipid profiles, glycemic indices, and reducing inflammatory markers. Histopathological analysis confirmed reduced tissue damage in the NIC + RSV group compared to the NIC-alone group. Metabolomics analysis using LC-MS/MS revealed significant dysregulation in lipid, amino acid, and nucleotide metabolism in NIC-exposed mice. Fold-change analysis identified altered metabolites, including sphingomyelin 36:1;02 (p < 0.001), valine (p < 0.001), triacylglycerol 4:0-18:1 (p < 0.001), and ceramide 32:1;02 (p < 0.001). Amino acids such as arginine, phenylalanine, glutamic acid, tyrosine, and lysine, as well as NIC metabolites like nornicotine and cotinine, were identified, underscoring molecular fragmentation analysis findings. RSV treatment partially restored metabolic balance, highlighting its role as a metabolic modulator. This study underscores the therapeutic potential of RSV in alleviating NIC-induced metabolic dysfunctions by restoring lipid homeostasis and reducing inflammation. Additionally, it emphasizes the importance of RSV in addressing NIC-related metabolic impairments and the need for noninvasive biomarkers for early disease detection.

Recent highlights in the synthesis and biological significance of pyrazole derivatives

Aza-heterocyclic scaffolds are privileged cores in the composition of their potential therapeutic profiles and versatile synthetic intermediates. Pyrazole is one of the frequently studied compounds of "azole" family and consists of nitrogen in a 1,2 linking sequence. These motifs possess a wide-spectrum of applications in the field of pharmaceuticals, agrochemicals, polymer chemistry, cosmetics, food industries and more. In addition, functionalized pyrazole derivatives are frequently used as ligands in coordination chemistry and metal-catalysed reactions. As exemplified by numerous recent reports, pyrazoles are highly promising pharmacophores with excellent therapeutic applications. Owing to their aromaticity, the ring structures have many reactive positions, where electrophilic, nucleophilic, alkylation and oxidative reactions might occur. The structural adroitness and diversity of pyrazole cores further emanated numerous fused bicyclic skeletons with various biological applications. In this review, we highlight the recent synthetic methods developed for the preparation of functionalized pyrazole derivatives (From 2017 to present). In addition, we have also covered the notable biological activities (anti-cancer, anti-inflammatory, anti-bacterial and anti-viral) of this ubiquitous core. Herein, we emphasised the synthesis of pyrazoles from variety of precursors such as, alkynes, α,β-unsaturated carbonyl compounds, diazo reagents, nitrile imines, diazonium salts, 1,3-dicarbonyl compounds and etc. Moreover, the recent synthetic methodologies focusing on the preparation of pyrazolines and pyrazolones and variously fused-pyrazoles are also included. Authors expect this review could significantly help the researchers in finding elegant novel tools to synthesize pyrazole skeletons and expand their biological evaluation.

The Effect of a Caffeine and Nicotine Combination on Nicotine Withdrawal Syndrome in Mice

Nicotine dependence is an important cause of excessive exposure to tobacco combustion compounds in most smokers. Nicotine replacement therapy is the main method to treat nicotine dependence, but it still has its shortcomings, such as the inability to mitigate withdrawal effects and limited applicability. It has been hypothesized that a combination of low-dose nicotine and caffeine could achieve the same psychological stimulation effect as a high dose of nicotine without causing nicotine withdrawal effects. To establish a model of nicotine dependence, male C57BL/6J mice were subcutaneously injected four times a day with nicotine (2 mg/kg) for 15 days and fed with water containing nicotine at the same time. They were randomly divided into four groups. After 24 h of withdrawal, different groups were injected with saline, nicotine (0.25 mg/kg or 0.1 mg/kg), or nicotine (0.1 mg/kg) and caffeine (20 mg/kg). Behavioral and physiological changes were evaluated by an assessment of physical signs, open field tests, elevated plus maze experiments, forced swimming tests, hot plate tests, and new-object-recognition tests. The changes in dopamine release in the prefrontal cortex (PFC) and ventral tegmental area (VTA) in the midbrain were analyzed using ELISA. The results showed that a combination of caffeine and nicotine could effectively relieve nicotine withdrawal syndrome, increase movement ability and pain thresholds, reduce anxiety and depression, enhance memory and cognitive ability, and increase the level of dopamine release in the PFC and VTA. Thus, caffeine combined with nicotine has potential as a stable and effective treatment option to help humans with smoking cessation.

Increased PHLPP1 expression through ERK-4E-BP1 signaling axis drives nicotine induced oxidative stress related damage of cardiomyocytes

Nicotine, a key constituent of tobacco/electronic cigarettes causes cardiovascular injury and mortality. Nicotine is known to induce oxidative stress and mitochondrial dysfunction in cardiomyocytes leading to cell death. However, the underlying mechanisms remain unclear. Pleckstrin homology domain leucine-rich repeat protein phosphatase (PHLPP) is a member of metal-dependent protein phosphatase (PPM) family and is known to dephosphorylate several AGC family kinases and thereby regulate a diverse set of cellular functions including cell growth, survival, and death. Our lab has previously demonstrated that PHLPP1 removal reduced cardiomyocyte death and cardiac dysfunction following injury. Here, we present a novel finding that nicotine exposure significantly increased PHLPP1 protein expression in the adolescent rodent heart. Building upon our in vivo finding, we determined the mechanism of PHLPP1 expression in cardiomyocytes. Nicotine significantly increased PHLPP1 protein expression without altering PHLPP2 in cardiomyocytes. In cardiomyocytes, nicotine significantly increased NADPH oxidase 4 (NOX4), which coincided with increased reactive oxygen species (ROS) and increased cardiomyocyte apoptosis which were dependent on PHLPP1 expression. PHLPP1 expression was both necessary and sufficient for nicotine induced mitochondrial dysfunction. Mechanistically, nicotine activated extracellular signal-regulated protein kinases (ERK1/2) and subsequent eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) to increase PHLPP1 protein expression. Inhibition of protein synthesis with cycloheximide (CHX) and 4EGI-1 abolished nicotine induced PHLPP1 protein expression. Moreover, inhibition of ERK1/2 activity by U0126 significantly blocked nicotine induced PHLPP1 expression. Overall, this study reveals a novel mechanism by which nicotine regulates PHLPP1 expression through ERK-4E-BP1 signaling axis to drive cardiomyocyte injury.

Interrelated involvement of the endocannabinoid/endovanilloid (TRPV1) systems and epigenetic processes in anxiety- and working memory impairment-related behavioural effects of nicotine as a stressor

The addictive use of nicotine contained in tobacco is associated with stressor-like emotional and cognitive effects such as anxiety and working memory impairment, and the involvement of epigenetic mechanisms such as histone acetylation has recently been reported. Although the precise nature of behavioural plasticity remains unclear, both anxiogenic- and working memory impairment-like effects were observed in the present experimental model of mice treated with repeated subcutaneous nicotine and/or immobilization stress, and these effects were commonly attenuated by the histone deacetylase (HDAC) inhibitors that induce histone acetylation. Such HDAC inhibitor-induced resilience was mimicked by ligands for the endocannabinoid (ECB) system, a neurotransmitter system that is closely associated with nicotine-induced addiction-related behaviours: the anxiogenic-like effects were mitigated by the cannabinoid type 1 (CB1) agonist arachidonylcyclopropylamide (ACPA), whereas the working memory impairment-like effects were mitigated by the CB1 antagonist SR 141716A. Moreover, the effects of the HDAC inhibitors were also mimicked by ligands for the endovanilloid (transient receptor potential vanilloid 1 [TRPV1]) system, a system that shares common characteristics with the ECB system: the anxiogenic-like effects were mitigated by the TRPV1 antagonist capsazepine, whereas the working memory impairment-like effects were mitigated by the TRPV1 agonist olvanil. Notably, the HDAC inhibitor-induced anxiolytic-like effects were attenuated by SR 141716A, which were further counteracted by capsazepine, whereas the working memory improvement-like effects were attenuated by capsazepine, which were further counteracted by SR 141716A. These results suggest the contribution of interrelated control of the ECB/TRPV1 systems and epigenetic processes such as histone acetylation to novel therapeutic approaches.

Nicotinic Acetylcholine Receptors in Glial Cells as Molecular Target for Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by resting tremor, bradykinesia, rigidity, and postural instability that also includes non-motor symptoms such as mood dysregulation. Dopamine (DA) is the primary neurotransmitter involved in this disease, but cholinergic imbalance has also been implicated. Current intervention in PD is focused on replenishing central DA, which provides remarkable temporary symptomatic relief but does not address neuronal loss and the progression of the disease. It has been well established that neuronal nicotinic cholinergic receptors (nAChRs) can regulate DA release and that nicotine itself may have neuroprotective effects. Recent studies identified nAChRs in nonneuronal cell types, including glial cells, where they may regulate inflammatory responses. Given the crucial role of neuroinflammation in dopaminergic degeneration and the involvement of microglia and astrocytes in this response, glial nAChRs may provide a novel therapeutic target in the prevention and/or treatment of PD. In this review, following a brief discussion of PD, we focus on the role of glial cells and, specifically, their nAChRs in PD pathology and/or treatment.

Neurobiology of Stress-Induced Nicotine Relapse

Tobacco smoking is the leading cause of preventable death and disease. Although there are some FAD-approved medicines for controlling smoking, the relapse rate remains very high. Among the factors that could induce nicotine relapse, stress might be the most important one. In the last decades, preclinical studies have generated many new findings that lead to a better understanding of stress-induced relapse of nicotine-seeking. Several molecules such as α3β4 nicotinic acetylcholine receptor, α2-adrenergic receptors, cannabinoid receptor 1, trace amine-associated receptor 1, and neuropeptide systems (corticotropin-releasing factor and its receptors, dynorphine and kappa opioid receptor) have been linked to stress-induced nicotine relapse. In this review, we discuss recent advances in the neurobiology, treatment targets, and potential therapeutics of stress-induced nicotine relapse. We also discuss some factors that may influence stress-induced nicotine relapse and that should be considered in future studies. In the final section, a perspective on some research directions is provided. Further investigation on the neurobiology of stress-induced nicotine relapse will shed light on the development of new medicines for controlling smoking and will help us understand the interactions between the stress and reward systems in the brain.