Toxicology update: the cardiotoxicity of the oxidative stress metabolites of catecholamines (aminochromes)

Pheochromocytoma Multisystem Crisis Requiring Temporary Mechanical Circulatory Support: A Narrative Review

Background: Pheochromocytoma and paraganglioma are catecholamine-secreting tumors, rarely presenting with pheochromocytoma multisystem crisis (PMC), a life-threatening endocrine emergency. The severity of the condition includes a refractory cardiogenic shock and may therefore require the use of temporary mechanical circulatory support. The aim of this review is to describe the incidence of pheochromocytoma and paraganglioma crises associated with refractory cardiogenic shock, the physiopathological impact of this condition on the myocardial function, the role of temporary mechanical circulatory support (tMCS) in its management, and the outcomes of this specific population. Methods: For the purpose of this narrative review, a literature search of PubMed was conducted as of 16 November 2024. Medical Subject Headings (MeSH) terms used included extracorporeal circulation", "Impella", "pheochromocytoma", "paraganglioma", and "cardiogenic shock", combined with Boolean "OR" and "AND". Data from case series, retrospective studies, and systematic reviews were considered. Seven studies reporting on 45 patients who developed PMC with cardiogenic shock requiring tMCS were included. Patients were young, with a median age of 43 years (range 25-65) at presentation. Most cases presented with severe hemodynamic instability, blood pressure lability, and rapid progression to severe left ventricular dysfunction. Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) was the most common tMCS used to stabilize patients, initiate specific pheochromocytoma treatments, and, in some cases, provide circulatory support during emergent surgery. The median duration of VA-ECMO support was 4 days (range 1-7) and the reported mean in-hospital survival rate was 93.5%. Following VA-ECMO weaning, survivors showed full recovery of the left ventricular ejection fraction (LVEF). Conclusions: The cardiac dysfunction observed in PMC-associated cardiogenic shock may be severe and life-threatening but appears reversible. tMCS should therefore be considered in eligible cases, as a bridge to recovery, treatment, or surgery. The reported survival rates are impressively high, suggesting possibly a substantial risk of publication bias.

Reducing the Formation of Toxic Byproducts During the Photochemical Release of Epinephrine

Engineered light-sensitive molecules offer a sophisticated toolkit for the manipulation of biological systems with both spatial and temporal precision. Notably, artificial "caged" compounds can activate specific receptors solely in response to light exposure. However, the uncaging process can lead to the formation of potentially harmful byproducts. For example, the photochemical release of adrenaline (epinephrine) is accompanied by the formation of adrenochrome, which has neuro- and cardiotoxic effects. To investigate this effect in detail, we synthesized and compared two "caged" epinephrine analogs. The first was a classical compound featuring an ortho-nitrobenzyl protecting group attached to the amino group of epinephrine. The second analog retained the ortho-nitrobenzyl group but included an additional carbamate linker. The photolysis of both compounds was conducted under identical conditions, and the resulting products were analyzed using UV-Vis spectroscopy, chromatography, and NMR techniques. Surprisingly, while the classical compound led to the formation of adrenochrome, the carbamate-type caged epinephrine did not produce this byproduct, resulting in the clean release of the active substance. Subsequently, we assessed the novel compound in an in vitro platelet activation assay. The results demonstrated that the uncaging of epinephrine significantly enhances platelet activation, making it a valuable tool for advanced signaling studies.

Drug-Induced Myocardial Infarction: A Review of Pharmacological Triggers and Pathophysiological Mechanisms

Myocardial infarction (MI) is a significant cardiovascular event caused by the decrease in or complete cessation of blood flow to a portion of the myocardium. It can arise from a variety of etiological factors, including pharmacological triggers. This review aims to explore the diverse drugs and substances that might lead to drug-induced myocardial infarction, focusing on their mechanisms of action and the pathophysiological processes involved. Various established and emerging pharmacological agents that could elevate the risk of myocardial infarction, such as nonsteroidal anti-inflammatory drugs, hormonal therapies, anticoagulants, and antipsychotic medications, are discussed. The role of drug-induced endothelial dysfunction, coronary artery spasm, and thrombosis are presented in order to highlight the underlying mechanisms. This review emphasizes the need for increased awareness among healthcare professionals to mitigate the risks associated with different pharmacological therapies to improve patient outcomes.

Adrenochrome formation during photochemical decomposition of "caged" epinephrine derivatives

Control of biological activity with light is a fascinating idea. "Caged" compounds, molecules modified with photolabile protecting group, are one of the instruments for this purpose. Adrenergic receptors are essential regulators of neuronal, endocrine, cardiovascular, vegetative, and metabolic functions. These receptors are largely used as pharmacologic targets. Photolabile "caged" analogs of adrenergic receptor agonists has been reported more than 30 years ago. We report that the photolysis of epinephrine analogs, apart from liberation of the epinephrine, is accompanied by a formation of significant amount of adrenochrome, a compound with neuro- and cardiotoxic effect.

An integrated strategy to explore the potential role of melatonin against copper-induced adrenaline toxicity in rat cardiomyocytes: Insights into oxidative stress, inflammation, and apoptosis

AIMS

Circumstantial anxiety as well as chronic stress may stimulate the release of stress hormones including catecholamines. Adrenaline toxicity has been implicated in many cardiovascular conditions. Considering previous literature that suggests the oxidative potential of the adrenaline-copper entity, we have investigated its potential nocuous role in isolated adult rat cardiomyocytes, the underlying molecular mechanism, and its possible protection by melatonin.

MAIN METHODS

Given the mechanistic congruity of adrenaline-copper (AC) with the well-established H₂O₂-copper-ascorbate (HCA) system of free radical generation, we have used the latter as a representative model to study the cytotoxic nature of AC. We further investigated the cardioprotective efficacy of melatonin in both the stress models through scanning electron microscopy, immunofluorescence, flow cytometry, and western blot analysis.

KEY FINDINGS

Results show that melatonin significantly protects AC-treated cardiomyocytes from ROS-mediated membrane damage, disruption of mitochondrial membrane potential, antioxidant imbalance, and distortion of cellular morphology. Melatonin protects cardiomyocytes from inflammation by downregulating pro-inflammatory mediators viz., COX-2, NF-κB, TNF-α, and upregulating anti-inflammatory IL-10. Melatonin significantly ameliorated cardiomyocyte apoptosis in AC and HCA-treated cells as evidenced by decreased BAX/BCL-2 ratio and subsequent suppression of caspase-9 and caspase-3 levels. The isothermal calorimetric study revealed that melatonin inhibits the binding of adrenaline bitartrate with copper in solution, which fairly explains the rescue potential of melatonin against AC-mediated toxicity in cardiomyocytes.

SIGNIFICANCE

Findings suggest that the multipronged strategy of melatonin that includes its antioxidant, anti-inflammatory, anti-apoptotic, and overall cardioprotective ability may substantiate its potential therapeutic efficacy against adrenaline-copper-induced damage and death of adult rat cardiomyocytes.

Hormone-linked redox status and its modulation by antioxidants

Hormones have been considered as key factors involved in the maintenance of the redox status of the body. We are making considerable progress in understanding interactions between the endocrine system, redox status, and oxidative stress with the dynamics of life, which encompasses fertilization, development, growth, aging, and various pathophysiological states. One of the reasons for changes in redox states of vertebrates leading to oxidative stress scenario is the disruption of the endocrine system. Comprehending the dynamics of hormonal status to redox state and oxidative stress in living systems is challenging. It is more difficult to come to a unifying conclusion when some hormones exhibit oxidant properties while others have antioxidant features. There is a very limited approach to correlate alteration in titers of hormones with redox status and oxidative stress with growth, development, aging, and pathophysiological stress. The situation is further complicated when considering various tissues and sexes in vertebrates. This chapter discusses the beneficial impacts of hormones with antioxidative properties, such as melatonin, glucagon, insulin, estrogens, and progesterone, which protect cells from oxidative damage and reduce pathophysiological effects. Additionally, we discuss the protective effects of antioxidants like vitamins A, E, and C, curcumin, tempol, N-acetyl cysteine, α-lipoic acid, date palm pollen extract, resveratrol, and flavonoids on oxidative stress triggered by hormones such as aldosterone, glucocorticoids, thyroid hormones, and catecholamines. Inflammation, pathophysiology, and the aging process can all be controlled by understanding how antioxidants and hormones operate together to maintain cellular redox status. Identifying the hormonal changes and the action of antioxidants may help in developing new therapeutic strategies for hormonal imbalance-related disorders.

Cerebral amyloid angiopathy-related cardiac injury: Focus on cardiac cell death

Cerebral amyloid angiopathy (CAA) is a kind of disease in which amyloid β (Aβ) and other amyloid protein deposits in the cerebral cortex and the small blood vessels of the brain, causing cerebrovascular and brain parenchymal damage. CAA patients are often accompanied by cardiac injury, involving Aβ, tau and transthyroxine amyloid (ATTR). Aβ is the main injury factor of CAA, which can accelerate the formation of coronary artery atherosclerosis, aortic valve osteogenesis calcification and cardiomyocytes basophilic degeneration. In the early stage of CAA (pre-stroke), the accompanying locus coeruleus (LC) amyloidosis, vasculitis and circulating Aβ will induce first hit to the heart. When the CAA progresses to an advanced stage and causes a cerebral hemorrhage, the hemorrhage leads to autonomic nervous function disturbance, catecholamine surges, and systemic inflammation reaction, which can deal the second hit to the heart. Based on the brain-heart axis, CAA and its associated cardiac injury can create a vicious cycle that accelerates the progression of each other.

Myocardial infarction and oxidative damage in animal models: objective and expectations from the application of cysteine derivatives

Reactive oxygen species (ROS) and associated oxidative stress are the main contributors to pathophysiological changes following myocardial infarction (MI), which is the principal cause of death from cardiovascular disease. The glutathione (GSH)/glutathione peroxidase (GPx) system appears to be the main and most active cardiac antioxidant mechanism. Hence, enhancement of the myocardial GSH system might have protective effects in the setting of MI. It follows that by increasing antioxidant capacity, the heart will be able to reduce the damage associated with MI and even prevent/weaken the occurrence of oxidative stress, which is highly ranked among the factors responsible for the occurrence of acute MI. For these reasons, the primary goal of future investigations should be to address the effects of different antioxidative compounds and especially cysteine derivatives like N-acetyl cysteine (NAC) and L-2-oxothiazolidine-4-carboxylic acid (OTC) as precursors responsible for the enhancement of the GSH-related antioxidant system's capacity. It is assumed that this will lay down the basis for elucidation of the mechanisms throughout which applicable doses of OTC will manifest a potentially positive impact in the reduction of adverse effects of acute MI. The inclusion of OTC in the models for prediction of the distribution of oxygen in infarcted animal hearts can help to upgrade existing computational models. Such a model would be based on computational geometries of the heart, but the inclusion of biochemical redox features in addition to angiogenic therapy, despite improvement of the post-infarcted oxygenated outcome could enhance the accuracy of the predictive values of oxygenation.

Culture medium-dependent isoproterenol stability and its impact on DNA strand breaks formation and repair

In vitro mechanistic research is mostly performed without taking into consideration the potential influence of cell culture media and/or their supplements and therefore, interactions between compounds of interest and medium ingredients may be overlooked. Isoproterenol (isoprenaline) is a synthetic catecholamine used as sympathomimetic drug that stimulates β-adrenergic receptors and is widely used in biomedical research. Clinical studies have shown that isoproterenol is rapidly metabolized in the human body with a plasma half-life of about 2-5 min. However, despite its use in many in vitro and ex vivo studies, the stability of isoproterenol in cell culture media has not been characterized. Our results show a decrease of isoproterenol concentration in RPMI medium but high stability of the compound in TexMACS medium. The isoproterenol oxidation product isoprenochrome forms during treatment in both media. However, isoprenochrome formation is significantly lower in TexMACS medium. The effective level of isoproterenol and the formation of oxidation products might explain the discrepancies observed in isoproterenol-induced genotoxicity and cytotoxicity.

Catecholamine-induced cardiotoxicity: A critical element in the pathophysiology of stroke-induced heart injury

Cerebrovascular diseases such as ischemic stroke, brain hemorrhage, and subarachnoid hemorrhage provoke cardiac complications such as heart failure, neurogenic stress-related cardiomyopathy and Takotsubo cardiomyopathy. With regards to the pathophysiology of stroke-induced heart injury, several mechanisms have been postulated to contribute to this complex interaction between brain and heart, including damage from gut dysbiosis, immune and systematic inflammatory responses, microvesicle- and microRNA-mediated vascular injury and damage from a surge of catecholamines. All these cerebrovascular diseases may trigger pronounced catecholamine surges through diverse ways, including stimulation of hypothalamic-pituitary adrenal axis, dysregulation of autonomic system, and secretion of adrenocorticotropic hormone. Primary catecholamines involved in this pathophysiological response include norepinephrine (NE) and epinephrine. Both are important neurotransmitters that connect the nervous system with the heart, leading to cardiac damage via myocardial ischemia, calcium (Ca²⁺) overload, oxidative stress, and mitochondrial dysfunction. In this review, we will aim to summarize the molecular mechanisms behind catecholamine-induced cardiotoxicity including Ca²⁺ overload, oxidative stress, apoptosis, cardiac hypertrophy, interstitial fibrosis, and inflammation. In addition, we will focus on how synchronization among these pathways evokes cardiotoxicity.

Oxidative Stress in Takotsubo Syndrome-Is It Essential for an Acute Attack? Indirect Evidences Support Multisite Impact Including the Calcium Overload-Energy Failure Hypothesis

Indirect evidences in reviews and case reports on Takotsubo syndrome (TTS) support the fact that the existence of oxidative stress (OS) might be its common feature in the pre-acute stage. The sources of OS are exogenous (environmental factors including pharmacological and toxic influences) and endogenous, the combination of both may be present, and they are being discussed in detail. OS is associated with several pathological conditions representing TTS comorbidities and triggers. The dominant source of OS electrones are mitochondria. Our analysis of drug therapy related to acute TTS shows many interactions, e.g., cytostatics and glucocorticoids with mitochondrial cytochrome P450 and other enzymes important for OS. One of the most frequently discussed mechanisms in TTS is the effect of catecholamines on myocardium. Yet, their metabolic influence is neglected. OS is associated with the oxidation of catecholamines leading to the synthesis of their oxidized forms - aminochromes. Under pathological conditions, this pathway may dominate. There are evidences of interference between OS, catecholamine/aminochrome effects, their metabolism and antioxidant protection. The OS offensive may cause fast depletion of antioxidant protection including the homocystein-methionine system, whose activity decreases with age. The alteration of effector subcellular structures (mitochondria, sarco/endoplasmic reticulum) and subsequent changes in cellular energetics and calcium turnover may also occur and lead to the disruption of cellular function, including neurons and cardiomyocytes. On the organ level (nervous system and heart), neurocardiogenic stunning may occur. The effects of OS correspond to the effect of high doses of catecholamines in the experiment. Intensive OS might represent "conditio sine qua non" for this acute clinical condition. TTS might be significantly more complex pathology than currently perceived so far.

Cerebral-Cardiac Syndrome and Diabetes: Cardiac Damage After Ischemic Stroke in Diabetic State

Cerebral-cardiac syndrome (CCS) refers to cardiac dysfunction following varying brain injuries. Ischemic stroke is strongly evidenced to induce CCS characterizing as arrhythmia, myocardial damage, and heart failure. CCS is attributed to be the second leading cause of death in the post-stroke stage; however, the responsible mechanisms are obscure. Studies indicated the possible mechanisms including insular cortex injury, autonomic imbalance, catecholamine surge, immune response, and systemic inflammation. Of note, the characteristics of the stroke population reveal a common comorbidity with diabetes. The close and causative correlation of diabetes and stroke directs the involvement of diabetes in CCS. Nevertheless, the role of diabetes and its corresponding molecular mechanisms in CCS have not been clarified. Here we conclude the features of CCS and the potential role of diabetes in CCS. Diabetes drives establish a “primed” inflammatory microenvironment and further induces severe systemic inflammation after stroke. The boosted inflammation is suspected to provoke cardiac pathological changes and hence exacerbate CCS. Importantly, as the key element of inflammation, NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome is indicated to play an important role in diabetes, stroke, and the sequential CCS. Overall, we characterize the corresponding role of diabetes in CCS and speculate a link of NLRP3 inflammasome between them.

Synthesis of porous 2D layered nickel oxide-reduced graphene oxide (NiO-rGO) hybrid composite for the efficient electrochemical detection of epinephrine in biological fluid

In the present research work, 2D-Porous NiO decorated graphene nanocomposite was synthesized by hydrothermal method to monitored the concentration of epinephrine (EPI). The morphology (SEM and TEM) results confirmed 2D-Porous NiO nanoparticles firmly attached over graphene nanosheets. FTIR and XPS analysis confirmed the formation of nickel oxide formation and complete reduction of GO to rGO. The electrochemical activity of the proposed NiO-rGO/GCE modified electrode on epinephrine was analyzed by simple cyclic voltammetry technique. The proposed low cost NiO-rGO/GCE modified electrode showed excellent catalytic activity over GCE and rGO/GCE electrodes. Due to its high conductivity and charge transfer ability of the NiO-rGO/GCE modified electrode exhibited high sensitivity of EPI at optimized conditions. The anodic peak current of the EPI linearly increases with increasing the concertation of EPI. A wide linear range (50 μM-1000 μM) was achieved with high correlation coefficient (R² = 0.9986) and the limit of detection (LOD) of NiO-rGO/GCE modified electrode was calculated to be 10 μM. NiO-rGO/GCE electrode showed good stability and repeatability towards the EPI oxidation. Mainly, the proposed NiO-rGO/GCE modified electrode showed good sensitivity of EPI in the human biological fluid with high recovery percentage. The low cost, NiO-rGO/GCE electrode could be the promising sensor electrode for the detection of Epinephrine in the real samples.

Resistance training improves cardiac function and cardiovascular autonomic control in doxorubicin-induced cardiotoxicity

Doxorubicin (DOX) is an anticancer chemotherapy drug that is widely used in clinical practice. It is well documented that DOX impairs baroreflex responsiveness and left ventricular function and enhances sympathetic activity, cardiac sympathetic afferent reflexes and oxidative stress, which contribute to hemodynamic deterioration. Because resistance training (RT)-induced cardioprotection has been observed in other animal models, the objective of this study was to assess the effects of RT during DOX treatment on hemodynamics, arterial baroreflex, cardiac autonomic tone, left ventricular function and oxidative stress in rats with DOX-induced cardiotoxicity. Male Wistar rats were submitted to a RT protocol (3 sets of 10 repetitions, 40% of one-repetition maximum (1RM) of intensity, 3 times per week, for 8 weeks). The rats were separated into 3 groups: sedentary control, DOX sedentary (2.5 mg/kg of DOX intraperitoneal injection, once a week, for 6 weeks) and DOX + RT. After training or time control, the animals were anesthetized and 2 catheters were implanted for hemodynamic, arterial baroreflex and cardiac autonomic tone. Another group of animals was used to evaluate left ventricular function. We found that RT in DOX-treated rats decreased diastolic arterial pressure, heart rate, sympathetic tone and oxidative stress. In addition, RT increased arterial baroreflex sensitivity, vagal tone and left ventricular developed pressure in rats with DOX-induced cardiotoxicity. In summary, RT is a useful non-pharmacological strategy to attenuate DOX-induced cardiotoxicity.

Nonhypertensive male with multiple paragangliomas of the heart and neck: A case report

BACKGROUND

Paraganglioma is a rare disease that can be lethal if undiagnosed. Thus, quick recognition is very important. Cardiac paragangliomas are found in patients who have hypertension. The classic symptoms are the triad of headaches, palpitations, and profuse sweating. We describe a very rare case of multiple paragangliomas of the heart and bilateral carotid artery without hypertension and outline the management strategies for this disease.

CASE SUMMARY

A 46-year-old man presented with the chief complaint of recently recurrent chest pain with a history of hemangioma of the bilateral carotid artery that had been surgically removed. He was found to have an intracardiac mass in the right atrioventricular groove and underwent successful excision. The final pathology demonstrated that the intracardiac mass was a cardiac paraganglioma, and the patient had an increased level of normetanephrine in the blood. The pathology and immunohistochemistry results showed that the bilateral carotid masses were also paragangliomas. During the 3 mo follow-up period, the patient did not experience recurrence of chest pain.

CONCLUSION

To our knowledge, this is the first case of multiple paragangliomas of the heart and neck without hypertension. This rare disease can be lethal if left undiagnosed. Thus, quick recognition is very important. The key to the diagnosis of cardiac paraganglioma is the presence of typical symptoms, including headaches, palpitations, profuse sweating, hypertension, and chest pain. Radiology can demonstrate the intracardiac mass. It is important to determine the levels of normetanephrine in the blood. The detection of genetic mutations is also recommended. Surgical resection is necessary to treat the disease and obtain pathological evidence.

Melatonin attenuates chemical-induced cardiotoxicity

Environmental chemicals and drugs can induce cardiotoxicity, mainly by generating free radicals. Reactive oxygen species play a critical role in the pathogenesis of cardiac tissue injury. This highlights a need for prevention of cardiotoxicity by scavenging free radicals. Melatonin has been shown to act as a protector against various conditions in which free radicals cause molecular and tissue injury. Some of the mechanisms by which melatonin operates as a free radical scavenger and antioxidant have been identified. The importance of endogenous melatonin in cardiovascular health and the benefits of melatonin supplementation in different cardiac pathophysiological disorders have been shown in a variety of model systems. Melatonin continues to attract attention for its potential therapeutic value for cardiovascular toxicity. The therapeutic potential of melatonin in treatment of cardiotoxicities caused by various chemicals along with suggested molecular mechanisms of action for melatonin is reviewed.

Chemical Reactivities of ortho-Quinones Produced in Living Organisms: Fate of Quinonoid Products Formed by Tyrosinase and Phenoloxidase Action on Phenols and Catechols

Tyrosinase catalyzes the oxidation of phenols and catechols (o-diphenols) to o-quinones. The reactivities of o-quinones thus generated are responsible for oxidative browning of plant products, sclerotization of insect cuticle, defense reaction in arthropods, tunichrome biochemistry in tunicates, production of mussel glue, and most importantly melanin biosynthesis in all organisms. These reactions also form a set of major reactions that are of nonenzymatic origin in nature. In this review, we summarized the chemical fates of o-quinones. Many of the reactions of o-quinones proceed extremely fast with a half-life of less than a second. As a result, the corresponding quinone production can only be detected through rapid scanning spectrophotometry. Michael-1,6-addition with thiols, intramolecular cyclization reaction with side chain amino groups, and the redox regeneration to original catechol represent some of the fast reactions exhibited by o-quinones, while, nucleophilic addition of carboxyl group, alcoholic group, and water are mostly slow reactions. A variety of catecholamines also exhibit side chain desaturation through tautomeric quinone methide formation. Therefore, quinone methide tautomers also play a pivotal role in the fate of numerous o-quinones. Armed with such wide and dangerous reactivity, o-quinones are capable of modifying the structure of important cellular components especially proteins and DNA and causing severe cytotoxicity and carcinogenic effects. The reactivities of different o-quinones involved in these processes along with special emphasis on mechanism of melanogenesis are discussed.

Sudden death in a dog with aortic coarctation

A previously healthy, one-year-old, intact female Vizsla dog collapsed and experienced cardiopulmonary arrest after a stressful event. Postmortem examination identified juxtaductal aortic coarctation (AoCo) with complex morphology. Located in the isthmus aorta adjacent to the ligamentum arteriosum, the AoCo comprised a shelf-like structure caused by invagination of the aortic wall into the lumen. Just distally, a second region of aortic occlusion resulted from an obstructing aortic membrane that restricted blood flow into the descending aorta through a small, eccentric ostium. Plausibly, the AoCo contributed to high afterload which led to reduction of coronary blood flow, myocardial hypoxia, and sudden death during physical stress. Although AoCo is a well-recognized congenital defect in humans, it has been reported only rarely in animals. The present case details the gross and histologic features of a complex, juxtaductal AoCo in a dog who died suddenly after stress. These morphologic findings may be informative when contemplating diagnosis of this anomaly.

Red Blood Cell Dysfunction in Critical Illness

Oxygen (O2) delivery, which is fundamental to supporting patients with critical illness, is a function of blood O2 content and flow. This article reviews red blood cell (RBC) physiology and dysfunction relevant to disordered O2 delivery in the critically ill. Flow is the focus of O2 delivery regulation: O2 content is relatively fixed, whereas flow fluctuates greatly. Thus, blood flow volume and distribution vary to maintain coupling between O2 delivery and demand. This article reviews conventional RBC physiology influencing O2 delivery and introduces a paradigm for O2 delivery homeostasis based on coordinated gas transport and vascular signaling by RBCs.

Hormones and oxidative stress: an overview

In aerobes, oxygen is essential for maintenance of life. However, incomplete reduction of oxygen leads to generation of reactive oxygen species. These oxidants oxidise biological macromolecules present in their vicinity and thereby impair cellular functions causing oxidative stress (OS). Aerobes have evolved both enzymatic and nonenzymatic antioxidant defences to protect themselves from OS. Although hormones as means of biological coordination involve in regulation of physiological activities of tissues by regulating metabolism, any change in their normal titre leads to pathophysiological states. While, hormones such as melatonin, insulin, oestrogen, progesterone display antioxidant features, thyroid hormone, corticosteroids and catecholamines elicit free radical generation and OS, and the role of testosterone in inducing OS is debateable. This review is an attempt to understand the impact of free radical generation and cross talk between the hormones modulating antioxidant defence system under various pathophysiological conditions.

Adrenergic Downregulation in Critical Care: Molecular Mechanisms and Therapeutic Evidence

Catecholamines remain the mainstay of therapy for acute cardiovascular dysfunction. However, adrenergic receptors quickly undergo desensitization and downregulation after prolonged stimulation. Moreover, prolonged exposure to high circulating catecholamines levels is associated with several adverse effects on different organ systems. Unfortunately, in critically ill patients, adrenergic downregulation translates into progressive reduction of cardiovascular response to exogenous catecholamine administration, leading to refractory shock. Accordingly, there has been a growing interest in recent years toward use of noncatecholaminergic inotropes and vasopressors. Several studies investigating a wide variety of catecholamine-sparing strategies (eg, levosimendan, vasopressin, β-blockers, steroids, and use of mechanical circulatory support) have been published recently. Use of these agents was associated with improvement in hemodynamics and decreased catecholamine use but without a clear beneficial effect on major clinical outcomes. Accordingly, additional research is needed to define the optimal management of catecholamine-resistant shock.

Assessment of adrenaline-induced DNA damage in whole blood cells with the comet assay

Harmful effects of elevated levels of catecholamines are mediated by various mechanisms, including gene transcription and formation of oxidation products. The aim of this study was to see whether the molecular mechanisms underlying the damaging action of adrenaline on DNA are mediated by reactive oxygen species (ROS). To do that, we exposed human whole blood cells to 10 μmol L-1adrenaline or 50 μmol L-1H2O2(used as positive control) that were separately pre-treated or post-treated with 500 μmol L-1of quercetin, a scavenger of free radicals. Quercetin significantly reduced DNA damage in both pre- and post-treatment protocols, which suggests that adrenaline mainly acts via the production of ROS. This mechanism is also supported by gradual lowering of adrenaline and H2O2-induced DNA damage 15, 30, 45, and 60 min after treatment. Our results clearly show that DNA repair mechanisms are rather effective against ROS-mediated DNA damage induced by adrenaline.

Catecholamine-Induced Cardiomyopathy in Pheochromocytoma: How to Manage a Rare Complication in a Rare Disease?

Pheochromocytomas and paragangliomas (PHEOs) are rare neuroendocrine tumors. Clinical manifestations include different cardiovascular signs and symptoms, which are related to excessive secretion of catecholamines. Catecholamine-induced cardiomyopathy in PHEO (CICMPP) is a rare but dreaded complication of PHEO. Once patient is diagnosed with this condition, the prognosis is worse and a surgical risk is much higher than expected. This article focuses on how catecholamines affect the heart and the pathophysiologic mechanism of CICMPP. The cardiovascular responses to catecholamine depend mostly on which catecholamine is released as well as the amount of catecholamine that is released. The acute release of norepinephrine and epinephrine from PHEO increases heart rate, systemic vascular resistance, myocardial contractility, and reduces venous compliance. The excessive adrenergic stimulation by catecholamine results in severe vasoconstriction and coronary vasospasm, myocardial ischemia, and subsequently damage, and necrosis. Chronically elevated catecholamine levels lead to significant desensitization of cardiac β-adrenoceptors. The increased levels of the enzyme β-adrenoceptors kinase (βARK) in the heart seems to mediate these biochemical and physiological changes that are consistently correlated with attenuated responsiveness to catecholamine stimulation. Through these mechanisms different types of cardiomyopathy (CMP) can be formed. This review discusses extensively the 3 types of cardiomyopathies that can be present in a PHEO patient. It also provides the clinical presentation and diagnostic and therapeutic algorithm in managing patients with CICMPP.

Mechanism and impact of catecholamine conversion by Vibrio cholerae

Bacterial pathogens are influenced by signaling molecules including the catecholamines adrenaline and noradrenaline which are host-derived hormones and neurotransmitters. Adrenaline and noradrenaline modulate growth, motility and virulence of bacteria. We show that adrenaline is converted by the pathogen Vibrio cholerae to adrenochrome in the course of respiration, and demonstrate that superoxide produced by the respiratory, Na⁺ - translocating NADH:quinone oxidoreductase (NQR) acts as electron acceptor in the oxidative conversion of adrenaline to adrenochrome. Adrenochrome stimulates growth of V. cholerae, and triggers specific responses in V. cholerae and in immune cells. We performed a quantitative proteome analysis of V. cholerae grown in minimal medium with glucose as carbon source without catecholamines, or with adrenaline, noradrenaline or adrenochrome. Significant regulation of proteins participating in iron transport and iron homeostasis, in energy metabolism, and in signaling was observed upon exposure to adrenaline, noradrenaline or adrenochrome. On the host side, adrenochrome inhibited lipopolysaccharide-triggered formation of TNF-α by THP-1 monocytes, though to a lesser extent than adrenaline. It is proposed that adrenochrome produced from adrenaline by respiring V. cholerae functions as effector molecule in pathogen-host interaction.

Role of catecholamines in the pathogenesis of diabetic cardiomyopathy 1

Although the sympathetic nervous system plays an important role in the regulation of cardiac function, the overactivation of the sympathetic nervous system under stressful conditions including diabetes has been shown to result in the excessive production of circulating catecholamines as well as an increase in the myocardial concentration of catecholamines. In this brief review, we provide some evidence to suggest that the oxidation products of catecholamines such as aminochrome and oxyradicals, lead to metabolic derangements, Ca²⁺-handling abnormalities, increase in the availability of intracellular free Ca²⁺, as well as activation of proteases and changes in myocardial gene expression. These alterations due to elevated levels of circulatory catecholamines are associated with oxidative stress, subcellular remodeling, and the development of cardiac dysfunction in chronic diabetes.

Nanoyttria attenuates isoproterenol-induced cardiac injury

Aim: The present study was designed to probe the cardioprotective effects of nanoyttria (NY). Materials & methods: NY was characterized using various techniques. Isoproterenol (ISO)-induced cardiotoxicity challenged mice were treated with NY for 28 days at two doses (0.4 and 4 mg/kg, intraperitoneally). Results: NY demonstrated free radical scavenging activity as shown by a 2,2-diphenyl-1-picrylhydrazyl assay. NY treatment showed alleviation of ISO-induced cardiotoxicity as evident from the reduction in biochemical parameters. The expression of proinflammatory cytokines (IL-1β, IL-6 and TNF-α) showed significant decrease upon NY treatment. Histopathology and ECG showed protection in histoarchitecture and rhythm of heart, respectively. Reduction in hydroxyproline and TGF-β1 expression indicated antifibrotic activity. Conclusion: We report for the first time that NY ameliorates ISO-induced cardiac remodeling.

Nitroso-Oxidative Stress, Acute Phase Response, and Cytogenetic Damage in Wistar Rats Treated with Adrenaline

This study is aimed at analysing biochemical and genetic endpoints of toxic effects after administration of adrenaline. For this purpose, the study was carried out on Wistar rats and three doses of adrenaline were used: 0.75 mg/kg, 1.5 mg/kg, and 3 mg/kg body weight. To achieve these aims, we investigated the effects of adrenaline on catalase (CAT), Cu, Zn-superoxide dismutase (SOD), malondialdehyde (MDA), nitrite (NO₂−), carbonyl groups (PCC), and nitrotyrosine (3-NT). Total activity of lactate dehydrogenase (LDH), its relative distribution (LDH₁–LDH₅) activity, level of acute phase proteins (APPs), and genotoxic effect were also evaluated. The obtained results revealed that all doses of adrenaline induced a significant rise in CAT activity, MDA level, PCC, NO₂⁻, and 3-NT and a significant decrease in SOD activity compared to control. Adrenaline exerted an increase in total activity of LDH, LDH₁, and LDH₂ isoenzymes. Further study showed that adrenaline significantly decreased serum albumin level and albumin-globulin ratio, while the level of APPs (α₁-acid glycoprotein and haptoglobulin) is increased. The micronucleus test revealed a genotoxic effect of adrenaline at higher concentrations (1.5 mg/kg and 3 mg/kg body weight) compared to untreated rats. It can be concluded that adrenaline exerts oxidative and nitrative stress in rats, increased damage to lipids and proteins, and damage of cardiomyocytes and cytogenetic damage. Obtained results may contribute to better understanding of the toxicity of adrenaline with aims to preventing its harmful effects.

Pathophysiology of Takotsubo Syndrome

Originally described by Japanese authors in the 1990s, Takotsubo syndrome (TTS) generally presents as an acute myocardial infarction characterized by severe left ventricular dysfunction. TTS, however, differs from an acute coronary syndrome because patients have generally a normal coronary angiogram and left ventricular dysfunction, which extends beyond the territory subtended by a single coronary artery and recovers within days or weeks. The prognosis was initially thought to be benign, but subsequent studies have demonstrated that both short-term mortality and long-term mortality are higher than previously recognized. Indeed, mortality reported during the acute phase in hospitalized patients is ≈4% to 5%, a figure comparable to that of ST-segment-elevation myocardial infarction in the era of primary percutaneous coronary interventions. Despite extensive research, the cause and pathogenesis of TTS remain incompletely understood. The aim of the present review is to discuss the pathophysiology of TTS with particular emphasis on the role of the central and autonomic nervous systems. Different emotional or psychological stressors have been identified to precede the onset of TTS. The anatomic structures that mediate the stress response are found in both the central and autonomic nervous systems. Acute stressors induce brain activation, increasing bioavailability of cortisol and catecholamine. Both circulating epinephrine and norepinephrine released from adrenal medullary chromaffin cells and norepinephrine released locally from sympathetic nerve terminals are significantly increased in the acute phase of TTS. This catecholamine surge leads, through multiple mechanisms, that is, direct catecholamine toxicity, adrenoceptor-mediated damage, epicardial and microvascular coronary vasoconstriction and/or spasm, and increased cardiac workload, to myocardial damage, which has a functional counterpart of transient apical left ventricular ballooning. The relative preponderance among postmenopausal women suggests that estrogen deprivation may play a facilitating role, probably mediated by endothelial dysfunction. Despite the substantial improvement in our understanding of the pathophysiology of TTS, a number of knowledge gaps remain.

Cardiovascular Mitochondrial Dysfunction Induced by Cocaine: Biomarkers and Possible Beneficial Effects of Modulators of Oxidative Stress

Cocaine abuse has long been known to cause morbidity and mortality due to its cardiovascular toxic effects. The pathogenesis of the cardiovascular toxicity of cocaine use has been largely reviewed, and the most recent data indicate a fundamental role of oxidative stress in cocaine-induced cardiovascular toxicity, indicating that mitochondrial dysfunction is involved in the mechanisms of oxidative stress. The comprehension of the mechanisms involving mitochondrial dysfunction could help in selecting the most appropriate mitochondria injury biological marker, such as superoxide dismutase-2 activity and glutathionylated hemoglobin. The potential use of modulators of oxidative stress (mitoubiquinone, the short-chain quinone idebenone, and allopurinol) in the treatment of cocaine cardiotoxic effects is also suggested to promote further investigations on these potential mitochondria-targeted antioxidant strategies.

Genetics of Takotsubo Syndrome

Takotsubo syndrome (TTS) is an enigmatic disease with a multifactorial and still unresolved pathogenesis. A genetic predisposition has been suggested based on the few familial TTS cases. Conflicting results have been published regarding the role of functional polymorphisms in relevant candidate genes, such as α1-, β1-, and β2-adrenergic receptors; G protein-coupled receptor kinase 5; and estrogen receptors. Further research is required to help clarify the role of genetic susceptibility in TTS.

Bucindolol improves right ventricle function in rats with pulmonary arterial hypertension through the reversal of autonomic imbalance

Pulmonary arterial hypertension (PAH) is characterised by an elevation in afterload imposed on the right ventricle (RV), leading to hypertrophy and failure. The autonomic nervous system (ANS) plays a key role in the progression to heart failure, and the use of beta-blockers attenuates this process. The aim of this study was to verify the role of bucindolol, aβ1-, β2- and α1-blocker, on the ANS, and its association with RV function in rats with PAH. Male Wistar rats were divided into four groups: control, monocrotaline, control+bucindolol, and monocrotaline+bucindolol. PAH was induced by a single intraperitoneal injection of monocrotaline (60mg/kg). After two weeks, animals were treated for seven days with bucindolol (2mg/kg/day i.p.) or vehicle. At the end of the treatment, animals underwent echocardiographic assessment, catheterisation of the femoral artery and RV, and tissue collection for morphometric and histological evaluation. In the monocrotaline+bucindolol group, there was a decrease in mean pulmonary artery pressure (33%) and pulmonary congestion (21%), when compared to the monocrotaline. Bucindolol treatment also reduced RV pleomorphism, necrosis, fibrosis and infiltration of inflammatory cells. An improvement in RV systolic function was also observed in the monocrotaline+bucindolol group compared to the monocrotaline. In addition, bucindolol promoted a decrease in the cardiac sympathovagal balance (93%) by reducing sympathetic drive (70%) and increasing parasympathetic drive (142%). Bucindolol also reduced blood pressure variability (75%). Our results show that the beneficial effects from bucindolol treatment appeared to be a consequence of the reversal of monocrotaline-induced autonomic imbalance.

Hypochlorite converts cysteinyl-dopamine into a cytotoxic product: A possible factor in Parkinson's Disease

The dopamine oxidation product cysteinyl-dopamine has attracted attention as a contributor to the death of dopaminergic neurons in Parkinson's disease. Treatment of cysteinyl-dopamine with hypochlorite yields an even more cytotoxic product. This product has potent redox-cycling activity and initiates production of superoxide in PC12 cells. Taurine, which scavenges hypochlorite, protects PC12 cells from cysteinyl-dopamine but not from the hypochlorite product, suggesting that the product, not cysteinyl-dopamine itself, is toxic. Furthermore, rotenone, which enhances expression of the hypochlorite-producing enzyme myeloperoxidase, increases the cytotoxicity of cysteinyl-dopamine but not of the hypochlorite product. This suggests that dopamine oxidation to cysteinyl-dopamine followed by hypochlorite-dependent conversion to a cytotoxic redox-cycling product leads to the generation of reactive oxygen species and oxidative stress and may contribute to the death of dopaminergic neurons.

Cardioprotective effects of iron chelator HAPI and ROS-activated boronate prochelator BHAPI against catecholamine-induced oxidative cellular injury

Catecholamines may undergo iron-promoted oxidation resulting in formation of reactive intermediates (aminochromes) capable of redox cycling and reactive oxygen species (ROS) formation. Both of them induce oxidative stress resulting in cellular damage and death. Iron chelation has been recently shown as a suitable tool of cardioprotection with considerable potential to protect cardiac cells against catecholamine-induced cardiotoxicity. However, prolonged exposure of cells to classical chelators may interfere with physiological iron homeostasis. Prochelators represent a more advanced approach to decrease oxidative injury by forming a chelating agent only under the disease-specific conditions associated with oxidative stress. Novel prochelator (lacking any iron chelating properties) BHAPI [(E)-Ń-(1-(2-((4-(4,4,5,5-tetramethyl-1,2,3-dioxoborolan-2-yl)benzyl)oxy)phenyl)ethylidene) isonicotinohydrazide] is converted by ROS to active chelator HAPI with strong iron binding capacity that efficiently inhibits iron-catalyzed hydroxyl radical generation. Our results confirmed redox activity of oxidation products of catecholamines isoprenaline and epinephrine, that were able to activate BHAPI to HAPI that chelates iron ions inside H9c2 cardiomyoblasts. Both HAPI and BHAPI were able to efficiently protect the cells against intracellular ROS formation, depletion of reduced glutathione and toxicity induced by catecholamines and their oxidation products. Hence, both HAPI and BHAPI have shown considerable potential to protect cardiac cells by both inhibition of deleterious catecholamine oxidation to reactive intermediates and prevention of ROS-mediated cardiotoxicity.

Pathophysiology and prevention of sudden cardiac death

Sudden cardiac death (SCD) is known to occur in individuals with diverse diseases. Each disease state has a specific etiology and pathophysiology, and is diagnosed and treated differently. Etiologies for SCD include cardiac arrhythmias, coronary artery disease, congenital coronary artery anomalies, hypertrophic cardiomyopathy, arrhythmogenic right ventricular dysplasia, dilated cardiomyopathy, and aortic valve stenosis. A potential unifying mechanism of SCD in these diseases involves a massive stimulation of the sympathetic nervous system’s stress response and the subsequent elevation of circulating catecholamines. The diagnosis of cardiac diseases that contribute to an increased risk for SCD is accomplished by a combination of different techniques including electrocardiography, echocardiography, magnetic resonance imaging, and invasive cardiac catheterization. Several therapies including anti-arrhythmic drugs, β-blockers, and antiplatelet agents may be used as medical treatment in patients for the prevention of SCD. Invasive therapies including percutaneous angioplasty, coronary artery bypass surgery, and implantable cardioverter-defibrillators are also used in the clinical management of SCD.

Cardiovascular and Hepatic Toxicity of Cocaine: Potential Beneficial Effects of Modulators of Oxidative Stress

Oxidative stress (OS) is thought to play an important role in the pharmacological and toxic effects of various drugs of abuse. Herein we review the literature on the mechanisms responsible for the cardiovascular and hepatic toxicity of cocaine with special focus on OS-related mechanisms. We also review the preclinical and clinical literature concerning the putative therapeutic effects of OS modulators (such as N-acetylcysteine, superoxide dismutase mimetics, nitroxides and nitrones, NADPH oxidase inhibitors, xanthine oxidase inhibitors, and mitochondriotropic antioxidants) for the treatment of cocaine toxicity. We conclude that available OS modulators do not appear to have clinical efficacy.

Extracellular Ubiquitin: Role in Myocyte Apoptosis and Myocardial Remodeling

Ubiquitin (UB) is a highly conserved low molecular weight (8.5 kDa) protein. It consists of 76 amino acid residues and is found in all eukaryotic cells. The covalent linkage of UB to a variety of cellular proteins (ubiquitination) is one of the most common posttranslational modifications in eukaryotic cells. This modification generally regulates protein turnover and protects the cells from damaged or misfolded proteins. The polyubiquitination of proteins serves as a signal for degradation via the 26S proteasome pathway. UB is present in trace amounts in body fluids. Elevated levels of UB are described in the serum or plasma of patients under a variety of conditions. Extracellular UB is proposed to have pleiotropic roles including regulation of immune response, anti-inflammatory, and neuroprotective activities. CXCR4 is identified as receptor for extracellular UB in hematopoietic cells. Heart failure represents a major cause of morbidity and mortality in western society. Cardiac remodeling is a determinant of the clinical course of heart failure. The components involved in myocardial remodeling include-myocytes, fibroblasts, interstitium, and coronary vasculature. Increased sympathetic nerve activity in the form of norepinephrine is a common feature during heart failure. Acting via β-adrenergic receptor (β-AR), norepinephrine is shown to induce myocyte apoptosis and myocardial fibrosis. β-AR stimulation increases extracellular levels of UB in myocytes, and UB inhibits β-AR-stimulated increases in myocyte apoptosis and myocardial fibrosis. This review summarizes intracellular and extracellular functions of UB with particular emphasis on the role of extracellular UB in cardiac myocyte apoptosis and myocardial remodeling.

Pathophysiological mechanisms of catecholamine and cocaine-mediated cardiotoxicity

Overactivation of the sympatho-adrenergic system is an essential mechanism providing short-term adaptation to the stressful conditions of critical illnesses. In the same way, the administration of exogenous catecholamines is mandatory to support the failing circulation in acutely ill patients. In contrast to these short-term benefits, prolonged adrenergic stress is detrimental to the cardiovascular system by initiating a series of adverse effects triggering significant cardiotoxicity, whose pathophysiological mechanisms are complex and only partially elucidated. In addition to the development of myocardial oxygen supply/demand imbalance induced by the sustained activation of adrenergic receptors, catecholamines can damage cardiomyocytes by fostering mitochondrial dysfunction, via two main mechanisms. The first one is calcium overload, consecutive to β-adrenergic receptor-mediated activation of protein kinase A and subsequent phosphorylation of multiple Ca(2+)-cycling proteins. The second one is oxidative stress, primarily related to the transformation of catecholamines into "aminochromes," which undergo redox cycling in mitochondria to generate copious amounts of oxygen-derived free radicals. In turn, calcium overload and oxidative stress promote mitochondrial permeability transition and cardiomyocyte cell death, both via the apoptotic and necrotic pathways. Comparable mechanisms of myocardial toxicity, including marked oxidative stress and mitochondrial dysfunction, have been reported with the use of cocaine, a common recreational drug with potent sympathomimetic activity. The aim of the current review is to present in detail the pathophysiological processes underlying the development of catecholamine and cocaine-induced cardiomyopathy, as such conditions may be frequently encountered in the clinical practice of cardiologists and ICU specialists.

Photocatalytic actions of the pesticide metabolite 2-hydroxyquinoxaline: destruction of antioxidant vitamins and biogenic amines – implications of organic redox cycling

Toxicity of the pesticide quinalphos may comprise secondary, delayed effects by its main metabolite 2-hydroxyquinoxaline (HQO). We demonstrate that HQO can destroy photocatalytically vitamins C and E, catecholamines, serotonin, melatonin, the melatonin metabolite AMK (N(1)-acetyl-5-methoxykynuramine), and unsubstituted and substituted anthranilic acids when exposed to visible light. In order to avoid HQO-independent ascorbate oxidation by light and to exclude actions by hydroxyl radicals, experiments on this vitamin were carried out in ethanolic solutions. Other substances tested (vitamin E, melatonin, anthranilic acids) were also photocatalytically destroyed by HQO in ethanol. After product analyses had indicated that HQO was not, or only poorly, degraded in the light, despite its catalytic action on other compounds, we followed directly the time course of HQO and ascorbate concentrations in ethanol. While ascorbate was largely destroyed, no change in HQO was demonstrable within 2 h of incubation. Destruction was not prevented by the singlet oxygen quencher DABCO. Obviously, HQO is capable of undergoing a process of organic redox cycling, perhaps via an intermediate quinoxaline-2-oxyl radical. Health problems from HQO intoxication may not only arise from the loss of valuable biomolecules, such as antioxidant vitamins and biogenic amines, but also from the formation of potentially toxic products. Dimerization and oligomerization are involved in several oxidation processes catalyzed by HQO, especially in the indoleamines, in dopamine, and presumably also in vitamin E. Melatonin oxidation by HQO did not only lead to the well-known - and usually protective - metabolite AFMK (N(1)-acetyl-N(2)-formyl-5-methoxykynuramine), but also to a high number of additional products, among them dimers and trimers. DABCO did not prevent melatonin destruction, but changed the spectrum of products. Serotonin was preferentially converted to a dimer, which can further oligomerize. Several indole dimers are known to be highly neurotoxic, as well as oxidation products formed from catecholamines via the adrenochrome/noradrenochrome pathway. Destruction of melatonin may cause deficiencies in circadian physiology, in immune functions and in antioxidative protection.

Pheochromocytoma mimicking both acute coronary syndrome and sepsis: a case report

OBJECTIVE

To present an atypical manifestation in a patient with pheochromocytoma.

CLINICAL PRESENTATION AND INTERVENTION

A 48-year-old man presented with chest pain, fever and leukocytosis. Elevated cardiac biomarkers and diffuse ST-T abnormalities on electrocardiography suggested myocardial infarction. However, coronary angiography showed normal coronary arteries. Abdominal computed tomography revealed a left adrenal tumor of 6.7 × 6.8 cm. Paroxysmal fluctuation of blood pressure raised the suspicion of pheochromocytoma, which was further supported by elevated urine catecholamine levels. He underwent left adrenalectomy and pathological findings confirmed the diagnosis.

CONCLUSION

Pheochromocytoma should be considered as part of the differential diagnosis in a patient with symptoms suggestive of both acute coronary syndrome and sepsis.

Exogenous ubiquitin modulates chronic β-adrenergic receptor-stimulated myocardial remodeling: role in Akt activity and matrix metalloproteinase expression

β-Adrenergic receptor (β-AR) stimulation increases extracellular ubiquitin (UB) levels, and extracellular UB inhibits β-AR-stimulated apoptosis in adult cardiac myocytes. This study investigates the role of exogenous UB in chronic β-AR-stimulated myocardial remodeling. l-Isoproterenol (ISO; 400 μg·kg(-1)·h(-1)) was infused in mice in the presence or absence of UB (1 μg·g(-1)·h(-1)). Left ventricular (LV) structural and functional remodeling was studied 7 days after infusion. UB infusion enhanced serum UB levels. In most parts, UB alone had no effect on morphometric or functional parameters. Heart weight-to-body weight ratios were increased to a similar extent in the ISO and UB + ISO groups. Echocardiographic analyses showed increased percent fractional shortening, ejection fraction, and LV circumferential stress and fiber-shortening velocity in the ISO group. These parameters were significantly lower in UB + ISO vs. ISO. Isovolumic contraction and relaxation times and ejection time were significantly lower in ISO vs. UB + ISO. The increase in the number of TUNEL-positive myocytes and fibrosis was significantly higher in ISO vs. UB + ISO. Activation of Akt was higher, whereas activation of GSK-3β and JNKs was lower in UB + ISO vs ISO. Expression of MMP-2, MMP-9, and TIMP-2 was higher in UB + ISO vs ISO. In isolated cardiac fibroblasts, UB enhanced expression of MMP-2 and TIMP-2 in the presence of ISO. Neutralizing UB antibodies negated the effects of UB on MMP-2 expression, whereas recombinant UB enhanced MMP-2 expression. UB activated Akt, and inhibition of Akt inhibited UB + ISO-mediated increases in MMP-2 expression. Thus, exogenous UB plays an important role in β-AR-stimulated myocardial remodeling with effects on LV function, fibrosis, and myocyte apoptosis.

Dietary methyl-consuming compounds and metabolic syndrome

The metabolic syndrome, a major risk factor for type 2 diabetes and cardiovascular disease, is a cluster of metabolic abnormalities including obesity, insulin resistance, hypertension and dyslipidemia. Although systemic oxidative stress and aberrant methylation status are known to have important roles in the development of metabolic syndrome, how they occur remains unclear. The metabolism of methyl-consuming compounds generates reactive oxygen species and consumes labile methyl groups; therefore, a chronic increase in the levels of methyl-consuming compounds in the body can induce not only oxidative stress and subsequent tissue injury, but also methyl-group pool depletion and subsequent aberrant methylation status. In the past few decades, the intake amount of methyl-consuming compounds has substantially increased primarily due to pollution, food additives, niacin fortification and high meat consumption. Thus, increased methyl consumers might have a causal role in the development and prevalence of metabolic syndrome and its related diseases. Moreover, factors that decrease the elimination/metabolism of methyl-consuming compounds and other xenobiotics (for example, sweat gland inactivity and decreased liver function) or increase the generation of endogenous methyl-consuming compounds (for example, mental stress-induced increase in catecholamine release) may accelerate the progression of metabolic syndrome. Based on current nutrition knowledge and the available evidence from epidemiological, ecological, clinical and laboratory studies on metabolic syndrome and its related diseases, this review outlines the relationship between methyl supply-consumption imbalance and metabolic syndrome, and proposes a novel mechanism for the pathogenesis and prevalence of metabolic syndrome and its related diseases.