Cigarette smoke inhibits brain mitochondrial adaptations of exercised mice

Sidestream Smoke Affects Dendritic Complexity and Astrocytes After Model Mild Closed Head Traumatic Brain Injury

Mild traumatic brain injuries can have long-term consequences that interfere with the life of the patient and impose a burden on our health care system. Oxidative stress has been identified as a contributing factor for the progression of neurodegeneration following TBI. A major source of oxidative stress for many veterans is cigarette smoking and second-hand smoke, which has been shown to have an effect on TBI recovery. To examine the potential influences of second-hand smoke during recovery from TBI, we utilized a mouse model of closed head injury, followed by repeated exposure to cigarette smoke and treatment with a neuroprotective antioxidant. We found that neither the mild injuries nor the smoke exposure produced axonal damage detectable with amino cupric silver staining. However, complexity in the dendritic arbors was significantly reduced after mild TBI plus smoke exposure. In the hippocampus, there were astrocytic responses, including Cyp2e1 upregulation, after the injury and tobacco smoke insult. This study provides useful context for the importance of lifestyle changes, such as reducing or eliminating cigarette smoking, during recovery from TBI.

The role of exercise in brain DNA damage

Cells are constantly subjected to cytotoxic and genotoxic insults resulting in the accumulation of unrepaired damaged DNA, which leads to neuronal death. In this way, DNA damage has been implicated in the pathogenesis of neurological disorders, cancer, and aging. Lifestyle factors, such as physical exercise, are neuroprotective and increase brain function by improving cognition, learning, and memory, in addition to regulating the cellular redox milieu. Several mechanisms are associated with the effects of exercise in the brain, such as reduced production of oxidants, up-regulation of antioxidant capacity, and a consequent decrease in nuclear DNA damage. Furthermore, physical exercise is a potential strategy for further DNA damage repair. However, the neuroplasticity molecules that respond to different aspects of physical exercise remain unknown. In this review, we discuss the influence of exercise on DNA damage and adjacent mechanisms in the brain. We discuss the results of several studies that focus on the effects of physical exercise on brain DNA damage.

The role of continuous versus fractionated physical training on muscle oxidative stress parameters and calcium-handling proteins in aged rats

Age-associated decline in skeletal muscle mass and strength is associated with oxidative stress and Ca(2+) homeostasis disturbance. Exercise should be considered a viable modality to combat aging of skeletal muscle. This study aimed to investigate whether continuous and fractionated training could be useful tools to attenuate oxidative damage and retain calcium-handling proteins. We conducted the study using 24-month-old male Wistar rats, divided into control, continuous, and fractionated groups. Animals ran at 13 m min(-1) for five consecutive days (except weekends) for 6 weeks, for a total period of 42 days. Each session comprised 45 min of exercise, either continuous or divided into three daily sessions of 15 min each. Metabolic and oxidative stress markers, protein levels of mitochondrial transcription factors, and calcium-handling proteins were analyzed. Continuous exercise resulted in reduced ROS production as well as showed a decrease in TBARS levels and carbonyl content. On the other hand, fractionated training increased the antioxidant enzyme activities. The ryanodine receptor and phospholamban protein were regulated by continuous training while sodium calcium exchange protein was increased by the fractionated training. These data suggest that intracellular Ca(2+) can be modulated by various training stimuli. In addition, the modulation of oxidative stress by continuous and fractionated training may play an important regulatory role in the muscular contraction mechanism of aged rats, due to changes in calcium metabolism.

Mitochondrial redox system, dynamics, and dysfunction in lung inflammaging and COPD

Myriad forms of endogenous and environmental stress disrupt mitochondrial function by impacting critical processes in mitochondrial homeostasis, such as mitochondrial redox system, oxidative phosphorylation, biogenesis, and mitophagy. External stressors that interfere with the steady state activity of mitochondrial functions are generally associated with an increase in reactive oxygen species, inflammatory response, and induction of cellular senescence (inflammaging) potentially via mitochondrial damage associated molecular patterns (DAMPS). Many of these are the key events in the pathogenesis of chronic obstructive pulmonary disease (COPD) and its exacerbations. In this review, we highlight the primary mitochondrial quality control mechanisms that are influenced by oxidative stress/redox system, including role of mitochondria during inflammation and cellular senescence, and how mitochondrial dysfunction contributes to the pathogenesis of COPD and its exacerbations via pathogenic stimuli.

Mitochondrial dysfunction in inflammatory responses and cellular senescence: pathogenesis and pharmacological targets for chronic lung diseases

Mitochondria are dynamic organelles, which couple the various cellular processes that regulate metabolism, cell proliferation and survival. Environmental stress can cause mitochondrial dysfunction and dynamic changes including reduced mitochondrial biogenesis, oxidative phosphorylation and ATP production, as well as mitophagy impairment, which leads to increased ROS, inflammatory responses and cellular senescence. Oxidative stress, inflammation and cellular senescence all have important roles in the pathogenesis of chronic lung diseases, such as chronic obstructive pulmonary disease, pulmonary fibrosis and bronchopulmonary dysplasia. In this review, we discuss the current state on how mitochondrial dysfunction affects inflammatory responses and cellular senescence, the mechanisms of mitochondrial dysfunction underlying the pathogenesis of chronic lung diseases and the potential of mitochondrial transfer and replacement as treatments for these diseases.

Bacoside A: Role in Cigarette Smoking Induced Changes in Brain

Cigarette smoking (CS) is a major health hazard that exerts diverse physiologic and biochemical effects mediated by the components present and generated during smoking. Recent experimental studies have shown predisposition to several biological consequences from both active and passive cigarette smoke exposure. In particular, passive smoking is linked to a number of adverse health effects which are equally harmful as active smoking. A pragmatic approach should be considered for designing a pharmacological intervention to combat the adverse effects of passive smoking. This review describes the results from a controlled experimental condition, testing the effect of bacoside A (BA) on the causal role of passive/secondhand smoke exposure that caused pathological and neurological changes in rat brain. Chronic exposure to cigarette smoke induced significant changes in rat brain histologically and at the neurotransmitter level, lipid peroxidation states, mitochondrial functions, membrane alterations, and apoptotic damage in rat brain. Bacoside A is a neuroactive agent isolated from Bacopa monnieri. As a neuroactive agent, BA was effective in combating these changes. Future research should examine the effects of BA at molecular level and assess its functional effects on neurobiological and behavioral processes associated with passive smoke.

How cigarette smoking may increase the risk of anxiety symptoms and anxiety disorders: a critical review of biological pathways

Multiple studies have demonstrated an association between cigarette smoking and increased anxiety symptoms or disorders, with early life exposures potentially predisposing to enhanced anxiety responses in later life. Explanatory models support a potential role for neurotransmitter systems, inflammation, oxidative and nitrosative stress, mitochondrial dysfunction, neurotrophins and neurogenesis, and epigenetic effects, in anxiety pathogenesis. All of these pathways are affected by exposure to cigarette smoke components, including nicotine and free radicals. This review critically examines and summarizes the literature exploring the role of these systems in increased anxiety and how exposure to cigarette smoke may contribute to this pathology at a biological level. Further, this review explores the effects of cigarette smoke on normal neurodevelopment and anxiety control, suggesting how exposure in early life (prenatal, infancy, and adolescence) may predispose to higher anxiety in later life. A large heterogenous literature was reviewed that detailed the association between cigarette smoking and anxiety symptoms and disorders with structural brain changes, inflammation, and cell-mediated immune markers, markers of oxidative and nitrosative stress, mitochondrial function, neurotransmitter systems, neurotrophins and neurogenesis. Some preliminary data were found for potential epigenetic effects. The literature provides some support for a potential interaction between cigarette smoking, anxiety symptoms and disorders, and the above pathways; however, limitations exist particularly in delineating causative effects. The literature also provides insight into potential effects of cigarette smoke, in particular nicotine, on neurodevelopment. The potential treatment implications of these findings are discussed in regards to future therapeutic targets for anxiety. The aforementioned pathways may help mediate increased anxiety seen in people who smoke. Further research into the specific actions of nicotine and other cigarette components on these pathways, and how these pathways interact, may provide insights that lead to new treatment for anxiety and a greater understanding of anxiety pathogenesis.