Role of Vasoactive Hormone-Induced Signal Transduction in Cardiac Hypertrophy and Heart Failure

Heart failure is the common concluding pathway for a majority of cardiovascular diseases and is associated with cardiac dysfunction. Since heart failure is invariably preceded by adaptive or maladaptive cardiac hypertrophy, several biochemical mechanisms have been proposed to explain the development of cardiac hypertrophy and progression to heart failure. One of these includes the activation of different neuroendocrine systems for elevating the circulating levels of different vasoactive hormones such as catecholamines, angiotensin II, vasopressin, serotonin and endothelins. All these hormones are released in the circulation and stimulate different signal transduction systems by acting on their respective receptors on the cell membrane to promote protein synthesis in cardiomyocytes and induce cardiac hypertrophy. The elevated levels of these vasoactive hormones induce hemodynamic overload, increase ventricular wall tension, increase protein synthesis and the occurrence of cardiac remodeling. In addition, there occurs an increase in proinflammatory cytokines and collagen synthesis for the induction of myocardial fibrosis and the transition of adaptive to maladaptive hypertrophy. The prolonged exposure of the hypertrophied heart to these vasoactive hormones has been reported to result in the oxidation of catecholamines and serotonin via monoamine oxidase as well as the activation of NADPH oxidase via angiotensin II and endothelins to promote oxidative stress. The development of oxidative stress produces subcellular defects, Ca2+-handling abnormalities, mitochondrial Ca2+-overload and cardiac dysfunction by activating different proteases and depressing cardiac gene expression, in addition to destabilizing the extracellular matrix upon activating some metalloproteinases. These observations support the view that elevated levels of various vasoactive hormones, by producing hemodynamic overload and activating their respective receptor-mediated signal transduction mechanisms, induce cardiac hypertrophy. Furthermore, the occurrence of oxidative stress due to the prolonged exposure of the hypertrophied heart to these hormones plays a critical role in the progression of heart failure.

New Trends in Fluorescent Nanomaterials-Based Bio/Chemical Sensors for Neurohormones Detection-A Review

The study of neurotransmitters and stress hormones allows the determination of indicators of the current stress load in the body. These species also create a proper strategy of stress protection. Nowadays, stress is a general factor that affects the population, and it may cause a wide range of serious disorders. Abnormalities in the level of neurohormones, caused by chronic psychological stress, can occur in, for instance, corporate employees, health care workers, shift workers, policemen, or firefighters. Here we present a new nanomaterials-based sensors technology development for the determination of neurohormones. We focus on fluorescent sensors/biosensors that utilize nanomaterials, such as quantum dots or carbon nanomaterials. Nanomaterials, owing to their diversity in size and shape, have been attracting increasing attention in sensing or bioimaging. They possess unique properties, such as fluorescent, electronic, or photoluminescent features. In this Review, we summarize new trends in adopting nanomaterials for applications in fluorescent sensors for neurohormone monitoring.

Serotonin and Pulmonary Hypertension; Sex and Drugs and ROCK and Rho

Serotonin is often referred to as a "happy hormone" as it maintains good mood, well-being, and happiness. It is involved in communication between nerve cells and plays a role in sleeping and digestion. However, too much serotonin can have pathogenic effects and serotonin synthesis is elevated in pulmonary artery endothelial cells from patients with pulmonary arterial hypertension (PAH). PAH is characterized by elevated pulmonary pressures, right ventricular failure, inflammation, and pulmonary vascular remodeling; serotonin has been shown to be associated with these pathologies. The rate-limiting enzyme in the synthesis of serotonin in the periphery of the body is tryptophan hydroxylase 1 (TPH1). TPH1 expression and serotonin synthesis are elevated in pulmonary artery endothelial cells in patients with PAH. The serotonin synthesized in the pulmonary arterial endothelium can act on the adjacent pulmonary arterial smooth muscle cells (PASMCs), adventitial macrophages, and fibroblasts, in a paracrine fashion. In humans, serotonin enters PASMCs cells via the serotonin transporter (SERT) and it can cooperate with the 5-HT1B receptor on the plasma membrane; this activates both contractile and proliferative signaling pathways. The "serotonin hypothesis of pulmonary hypertension" arose when serotonin was associated with PAH induced by diet pills such as fenfluramine, aminorex, and chlorphentermine; these act as indirect serotonergic agonists causing the release of serotonin from platelets and cells through the SERT. Here the role of serotonin in PAH is reviewed. Targeting serotonin synthesis or signaling is a promising novel alternative approach which may lead to novel therapies for PAH. © 2022 American Physiological Society. Compr Physiol 12: 1-16, 2022.

Interactive relationship between Trp metabolites and gut microbiota: The impact on human pathology of disease

Tryptophan (Trp), an α-amino acid, is the precursor of serotonin (5-hydroxytryptamine, 5-HT), which is involved in a variety of features of metabolic function and human nutrition. Evidence highlights the role of Trp metabolites (exclusively 5-HT) in the gastrointestinal (GI) tract; however, the mechanisms of action involved in the release of 5-HT in the GI tract are still unknown. Considering the fact that variations of 5-HT may facilitate the growth of certain GI disorders, gaining a better understanding of the function and release of 5-HT in the GI tract would be beneficial. Additionally, investigating Trp metabolism may clarify the relationship between Trp and gut microbiota. It is believed that other metabolites of Trp (mostly that of the kynurenine pathway) may play a significant role in controlling gut microbiota function. In this review, we have attempted to summarize the current research investigating the relationship of gut microbiota, Trp, and 5-HT metabolism (with particular attention paid to their metabolite type, as well as a discussion of the research methods used in each study). Taking together, regarding the role that Trp/5-HT plays in a range of physical and mental diseases, the gut bacterial types, as well as the related disorders, have been exclusively considered.

Plasma Serotonin is Elevated in Adult Patients with Sudden Sensorineural Hearing Loss

Background The roles of thrombophilia and cardiovascular risk factors in sudden sensorineural hearing loss (SSNHL) remain controversial. Cochlear microthrombosis and vasospasm have been hypothesized as possible pathogenic mechanisms of SSNHL. This article investigates the circulating serotonin and homocysteine levels besides thrombophilia screening in patients with idiopathic SSNHL.

Methods A total of 133 SSNHL patients and age- and sex-matched controls were investigated (discovery cohort). Measurement included common inherited natural coagulation inhibitors, factor VIII, von Willebrand factor (VWF), antiphospholipid antibodies, homocysteine, and serotonin (whole blood, platelet, and plasma) levels, along with frequent relevant genetic variants. A validation cohort (128 SSNHL patients) was studied for homocysteine and serotonin levels.

Results and Conclusion In the discovery cohort, 58.6% of patients exhibited thrombophilia, of which most had a low to moderate titers of antiphospholipid antibodies and high levels of factor VIII/VWF. Twenty-seven patients (20%) had mild-to-moderate hyperhomocysteinemia or were homozygous for the methylenetetrahydrofolate reductase (MTHFR) C677T mutation. Regarding serotonin, SSNHL patients had elevated whole blood levels that remained within the normal range and normal platelet content. However, approximately 90% patients of both cohorts had elevated plasma serotonin. Elevated plasma serotoninemia was accompanied by serotonylation of platelet rhoA protein. This study shows that increased plasma serotonin appears as a biomarker of SSNHL (specificity: ∼96%, sensitivity: ∼90%) and could participate in the pathophysiology of SSNHL.

Nanomaterial based electrochemical sensing of the biomarker serotonin: a comprehensive review

This review (with 131 references) summarizes the progress made in the past years in the field of nanomaterial based sensing of serotonin (5-HT). An introduction summarizes the significant role of 5-HT as a biomarker for several major diseases, methods for its determination and the various kinds of nanomaterials for use in electrochemical sensing process relies principally on a precise choice of electrodes. The next main section covers nanomaterial based methods for sensing 5-HT, with subsections on electrodes modified with carbon nanotubes, graphene related materials, gold nanomaterials, and by other nanomaterials. A concluding section discusses future perspectives and current challenges of 5-HT determination. Graphical abstract Conceptual design of electrochemical sensing process of the biomarker serotonin by using nanomaterials and the role of 5-HTas biomarker in the body from preclinical to clincal.

Oxidative Stress is Closely Associated with Increased Arterial Stiffness, Especially in Aged Male Smokers without Previous Cardiovascular Events: A Cross-Sectional Study

Aim: Cigarette smoking is one of the major risk factors for cardiovascular diseases and induces deleterious vascular damage. Oxidative stress is involved in vascular inflammation, the process of atherosclerosis. The purpose of the present study was to investigate whether the effects of oxidative stress on the arterial wall differ between smokers and non-smokers.

Methods: Male smokers and non-smokers without physical deconditioning who visited Enshu hospital for an annual physical check-up were enrolled in the study. To assess oxidative stress, serum levels of derivative reactive oxygen metabolites (d-ROM) were measured. The radial augmentation index (RAI) was measured using an automated device and was used as an index for arterial stiffness.

Results: Univariate and multivariate linear regression analysis showed that RAI was independently associated with d-ROM levels only in smokers. Moreover, RAI was significantly higher in smokers than in non-smokers. Logistic regression analysis with the endpoint of a higher RAI than the mean revealed that older age (> 65 years), hypertension, and smoking were independently associated with higher RAI. Similarly, logistic regression analysis with the endpoint of higher d-ROM levels than the mean showed that older age and smoking were independently associated with higher d-ROM levels.

Conclusions: Increased RAI is significantly associated with smoking and, in smokers, with increased d-ROM levels. These results suggest that the effects of oxidative stress on arterial properties differ between smokers and non-smokers and that oxidative stress is closely associated with arterial stiffness, especially in smokers.

Optimization of spirocyclic proline tryptophan hydroxylase-1 inhibitors

As a follow-up to the discovery of our spirocyclic proline-based TPH1 inhibitor lead, we describe the optimization of this scaffold. Through a combination of X-ray co-crystal structure guided design and an in vivo screen, new substitutions in the lipophilic region of the inhibitors were identified. This effort led to new TPH1 inhibitors with in vivo efficacy when dosed as their corresponding ethyl ester prodrugs. In particular, 15b (KAR5585), the prodrug of the potent TPH1 inhibitor 15a (KAR5417), showed robust reduction of intestinal serotonin (5-HT) levels in mice. Furthermore, oral administration of 15b generated high and sustained systemic exposure of the active parent 15a in rats and dogs. KAR5585 was selected for further pharmacological evaluation in disease models associated with a dysfunctional peripheral 5-HT system.

Reduced Blood Serotonin Levels in Chronic Central Serous Chorioretinopathy

PURPOSE

To evaluate blood serotonin (5-hydroxytryptamine [5-HT]) levels in patients with chronic central serous chorioretinopathy (CSC).

DESIGN

A case-controlled retrospective study.

PARTICIPANTS

Forty-nine patients with CSC and 30 age-matched control subjects.

METHODS

Blood 5-HT levels were measured using high-performance liquid chromatography.

MAIN OUTCOME MEASURES

Blood 5-HT levels in patients with acute or chronic CSC were measured at the initial visit and compared with those in controls.

RESULTS

The blood 5-HT level (98.2±27.5 ng/ml) in patients with chronic CSC was significantly lower than those in patients with acute CSC (122.5±23.9 ng/ml, P = 0.0081) and controls (128.5±35.8 ng/ml, P = 0.0013). After adjusting for covariates, patients with decreased blood 5-HT levels were found to be more likely to develop chronic CSC (odds ratio, 0.97; 95% confidence interval, 0.95-0.99; P = 0.009).

CONCLUSIONS

These results suggest that serotonin may have a role in chronic CSC pathogenesis and is associated with disease progression.

Blood levels of serotonin are specifically correlated with plasma lysophosphatidylserine among the glycero-lysophospholipids

Backgrounds

Glycero-lysophospholipids (glycero-LPLs), which are known to exert potent biological activities, have been demonstrated to be secreted from activated platelets in vitro; however, their association with platelet activation in vivo has not been yet elucidated. In this study, we investigated the correlations between the blood levels of each glycero-LPL and serotonin, a biomarker of platelet activation, in human subjects to elucidate the involvement of platelet activation in glycero-LPLs in vivo.

Methods and Results

We measured the plasma serotonin levels in 141 consecutive patients undergoing coronary angiography (acute coronary syndrome, n = 38; stable angina pectoris, n = 71; angiographically normal coronary arteries, n = 32) and investigated the correlations between the plasma levels of serotonin and glycero-LPLs. The results revealed the existence of a specific and significant association between the plasma serotonin and plasma lysophosphatidylserine (LysoPS) levels. On the contrary, regular aspirin intake failed to affect the plasma LysoPS levels despite the fact that the plasma lysophosphatidic acid, lysophosphatidylethanolamine, lysophosphatidylglycerol, and lysophosphatidylinositol levels were lower in those who had taken aspirin regularly.

Conclusion

We found a specific positive correlation between the blood levels of serotonin and LysoPS, a new lipid mediator. Thus, LysoPS might be specifically involved in strong platelet activation, which is associated with the release of serotonin.

General Significance

Our present results suggest the possible involvement of LysoPS in the pathogenesis of atherosclerotic diseases.

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A significant positive correlation between the plasma serotonin and lysophosphatidylserine was observed.

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Regular intake of aspirin had no influence on plasma lysophosphatidylserine.

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PS-PLA1 was correlated with lysophosphatidylserine only in acute coronary syndrome.

Quality markers addressing preanalytical variations of blood and plasma processing identified by broad and targeted metabolite profiling

BACKGROUND

Metabolomics is a valuable tool with applications in almost all life science areas. There is an increasing awareness of the essential need for high-quality biospecimens in studies applying omics technologies and biomarker research. Tools to detect effects of both blood and plasma processing are a key for assuring reproducible and credible results. We report on the response of the human plasma metabolome to common preanalytical variations in a comprehensive metabolomics analysis to reveal such high-quality markers.

METHODS

Human EDTA blood was subjected to preanalytical variations while being processed to plasma: microclotting, prolonged processing times at different temperatures, hemolysis, and contamination with buffy layer. In a second experiment, EDTA plasma was incubated at different temperatures for up to 16 h. Samples were subjected to GC-MS and liquid chromatography-tandem mass spectrometry-based metabolite profiling (MxP™ Broad Profiling) complemented by targeted methods, i.e., sphingoids (as part of MxP™ Lipids), MxP™ Catecholamines, and MxP™ Eicosanoids.

RESULTS

Short-term storage of blood, hemolysis, and short-term storage of noncooled plasma resulted in statistically significant increases of 4% to 19% and decreases of 8% to 12% of the metabolites. Microclotting, contamination of plasma with buffy layer, and short-term storage of cooled plasma were of less impact on the metabolome (0% to 11% of metabolites increased, 0% to 8% decreased).

CONCLUSIONS

The response of the human plasma metabolome to preanalytical variation demands implementation of thorough quality assurance and QC measures to obtain reproducible and credible results from metabolomics studies. Metabolites identified as sensitive to preanalytics can be used to control for sample quality.