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International Journal of Molecular... May 2024The N-terminal portion of the octapeptide angiotensin II (DRVYIHPF; AngII), a vasopressor peptide that favorably binds to, and activates, AngII type 1 receptor (ATR),... (Review)
Review
Structural Features Influencing the Bioactive Conformation of Angiotensin II and Angiotensin A: Relationship between Receptor Desensitization, Addiction, and the Blood-Brain Barrier.
The N-terminal portion of the octapeptide angiotensin II (DRVYIHPF; AngII), a vasopressor peptide that favorably binds to, and activates, AngII type 1 receptor (ATR), has an important role in maintaining bioactive conformation. It involves all three charged groups, namely (i) the N-terminal amino group cation, (ii) the Asp sidechain anion and (iii) the Arg guanidino cation. Neutralization of any one of these three charged groups results in a substantial reduction (<5%) in bioactivity, implicating a specialized function for this cluster. In contrast, angiotensin A (ARVYIHPF; AngA) has reduced bioactivity at ATR; however, replacement of Asp in AngII with sarcosine (N-methyl-glycine) not only restores bioactivity but increases the activity of agonist, antagonist, and inverse agonist analogues. A bend produced at the N-terminus by the introduction of the secondary amino acid sarcosine is thought to realign the functional groups that chaperone the C-terminal portion of AngII, allowing transfer of the negative charge originating at the C-terminus to be transferred to the Tyr hydroxyl-forming tyrosinate anion, which is required to activate the receptor and desensitizes the receptor (tachyphylaxis). Peptide (sarilesin) and nonpeptide (sartans) moieties, which are long-acting inverse agonists, appear to desensitize the receptor by a mechanism analogous to tachyphylaxis. Sartans/bisartans were found to bind to alpha adrenergic receptors resulting in structure-dependent desensitization or resensitization. These considerations have provided information on the mechanisms of receptor desensitization/tolerance and insights into possible avenues for treating addiction. In this regard sartans, which appear to cross the blood-brain barrier more readily than bisartans, are the preferred drug candidates.
Topics: Blood-Brain Barrier; Angiotensin II; Humans; Animals; Receptor, Angiotensin, Type 1; Protein Conformation
PubMed: 38891966
DOI: 10.3390/ijms25115779 -
Scientific Reports Jun 2024Binge drinking (BD) contributes strongly to the harms of alcohol use disorder. Most rodent models do not result in binge-level blood alcohol concentrations (BACs), and...
Binge drinking (BD) contributes strongly to the harms of alcohol use disorder. Most rodent models do not result in binge-level blood alcohol concentrations (BACs), and to better understand individual and sex differences in neurobiological mechanisms related to BD, the use of outbred rat strains would be valuable. Here, we developed a novel BD model where after 3+ months of intermittent access to 20% alcohol Wistar rats drank, twice a week, with two 5-min intake (what we called Two-shot) separated by a 10-min break. Our findings showed during Two-Shot that most animals reached ≥ 80 mg% BAC levels (when briefly food-restricted). However, when increasing alcohol concentrations from 20 to 30%, 40%, or 50%, rats titrated to similar intake levels, suggesting rapid sensing of alcohol effects even when front-loading. Two-Shot drinking was reduced in both sexes by naltrexone (1 mg/kg), validating intake suppression by a clinical therapeutic agent for human problem drinking. Further, both propranolol (β-adrenergic receptor antagonist) and prazosin (α1-adrenergic receptor antagonist) reduced female but not male BD at the lower dose. Thus, our results provide a novel model for BD in outbred rats and suggest that female binging is more sensitive to adrenergic modulation than males, perhaps providing a novel sex-related therapy.
Topics: Animals; Female; Binge Drinking; Male; Rats; Disease Models, Animal; Rats, Wistar; Ethanol; Adrenergic Antagonists; Naltrexone; Propranolol; Sex Factors; Alcohol Drinking
PubMed: 38890353
DOI: 10.1038/s41598-024-64565-9 -
The American Journal of the Medical... Jun 2024Incomplete decongestion is the main cause of readmission in the early post-discharge period of a hospitalization for acute heart failure. Recent heart failure guidelines... (Review)
Review
Incomplete decongestion is the main cause of readmission in the early post-discharge period of a hospitalization for acute heart failure. Recent heart failure guidelines have highlighted initiation and rapid up-titration of quadruple therapy with angiotensin receptor neprilysin inhibitor, beta adrenergic receptor blocker, mineralocorticoid receptor antagonist, and sodium glucose cotransporter 2 inhibitor to prevent hospitalizations for heart failure with reduced ejection fraction. However, full decongestion remains the foremost therapeutic goal of hospitalization for heart failure. While early addition of sodium glucose cotransporter 2 inhibitors and mineralocorticoid receptor antagonists may be helpful, the value of the other therapeutics comes after decongestion is complete.
PubMed: 38880301
DOI: 10.1016/j.amjms.2024.06.002 -
Therapeutic Advances in Respiratory... 2024Some systematic reviews (SRs) on triple therapy (consisting of long-acting β-agonist, long-acting muscarinic antagonist, and inhaled corticosteroid, LABA/LAMA/ICS) for...
BACKGROUND
Some systematic reviews (SRs) on triple therapy (consisting of long-acting β-agonist, long-acting muscarinic antagonist, and inhaled corticosteroid, LABA/LAMA/ICS) for chronic obstructive pulmonary disease (COPD) have reported conflicting results. As the number of syntheses increases, the task of identifying and interpreting evidence becomes increasingly complex and demanding.
OBJECTIVES
To provide a comprehensive overview of the efficacy and safety of triple therapy for COPD.
DESIGN
Overview of SRs.
METHODS
Two independent reviewers conducted comprehensive searches in PubMed, Embase, Web of Science, and the Cochrane Library to identify relevant SRs that compared triple therapy with any non-triple therapy for COPD, from the inception of these databases until 1 June 2023. The AMSTAR 2 and GRADE tools were utilized to assess the quality of the included studies and the evidence for each outcome.
RESULTS
Eighteen SRs encompassing 30 original studies and involving 47,340 participants were analyzed. The overall AMSTAR 2 rating revealed that 3 SRs were of low quality, 13 SRs were of critically low quality, and 2 SRs were of high quality. No high-certainty evidence revealed a significant advantage of triple therapy in improving lung function or reducing acute exacerbations. However, all evidence, including one high certainty, supported the benefits of improving quality of life. Regarding all-cause mortality, no significant difference was found when compared to LAMA or ICS/LABA; however, high-certainty evidence confirmed its effectiveness when compared with LABA/LAMA. Notably, high-certainty evidence indicated that triple therapy was associated with a significant increase in the risk of pneumonia compared to LABA/LAMA.
CONCLUSION
Triple therapy demonstrated notable benefits in improving lung function, reducing exacerbations, improving quality of life, and reducing all-cause mortality. However, it is important to note that it may also significantly increase the risk of pneumonia.
TRIAL REGISTRATION
This overview protocol was prospectively registered with PROSPERO (No. CRD42023431548).
Topics: Humans; Pulmonary Disease, Chronic Obstructive; Systematic Reviews as Topic; Drug Therapy, Combination; Muscarinic Antagonists; Treatment Outcome; Administration, Inhalation; Adrenergic beta-2 Receptor Agonists; Adrenal Cortex Hormones; Bronchodilator Agents; Lung; Quality of Life
PubMed: 38877687
DOI: 10.1177/17534666241259634 -
Annales D'endocrinologie Jun 2024Brown adipose tissue (BAT) and beige adipose tissues are important contributors to cold-induced whole body thermogenesis in rodents. The documentation in humans of cold-... (Review)
Review
Brown adipose tissue (BAT) and beige adipose tissues are important contributors to cold-induced whole body thermogenesis in rodents. The documentation in humans of cold- and ß-adrenergic receptor agonist-stimulated BAT glucose uptake using positron emission tomography (PET) and of a decrease of this response in individuals with cardiometabolic disorders led to the suggestion that BAT/beige adipose tissues could be relevant targets for prevention and treatment of these conditions. In this brief review, we will critically assess this question by first describing the basic rationale for this affirmation, second by examining the evidence in human studies, and third by discussing the possible means to activate the thermogenic response of these tissues in humans.
Topics: Humans; Adipose Tissue, Brown; Thermogenesis; Adipose Tissue, Beige; Animals; Positron-Emission Tomography; Adrenergic beta-Agonists; Obesity; Cold Temperature
PubMed: 38871497
DOI: 10.1016/j.ando.2024.05.006 -
Journal of Investigative Medicine High... 2024Patients infected with COVID-19 can develop coinfections or acute respiratory disorder that result in ventilation. Dexmedetomidine is a common medication used to sedate...
Patients infected with COVID-19 can develop coinfections or acute respiratory disorder that result in ventilation. Dexmedetomidine is a common medication used to sedate ventilated patients in the intensive care unit and for nonintubated patients prior to a surgical procedure. As a highly selective alpha-2 agonist, dexmedetomidine provides sedation while reducing the need for anxiolytics or opioids. However, previous case reports suggest dexmedetomidine can induce fever in a variety of conditions. The purpose of this case report is to describe a patient who acquired a fever of 42.6°C in the setting of COVID-19 after administration of dexmedetomidine.
Topics: Humans; Dexmedetomidine; COVID-19; Fever; SARS-CoV-2; Hypnotics and Sedatives; Male; Pandemics; Pneumonia, Viral; Coronavirus Infections; Betacoronavirus; Middle Aged; Adrenergic alpha-2 Receptor Agonists; Drug Fever
PubMed: 38869108
DOI: 10.1177/23247096241260959 -
Proceedings of the National Academy of... Jun 2024The heart beats approximately 100,000 times per day in humans, imposing substantial energetic demands on cardiac muscle. Adenosine triphosphate (ATP) is an essential...
The heart beats approximately 100,000 times per day in humans, imposing substantial energetic demands on cardiac muscle. Adenosine triphosphate (ATP) is an essential energy source for normal function of cardiac muscle during each beat, as it powers ion transport, intracellular Ca handling, and actin-myosin cross-bridge cycling. Despite this, the impact of excitation-contraction coupling on the intracellular ATP concentration ([ATP]) in myocytes is poorly understood. Here, we conducted real-time measurements of [ATP] in ventricular myocytes using a genetically encoded ATP fluorescent reporter. Our data reveal rapid beat-to-beat variations in [ATP]. Notably, diastolic [ATP] was <1 mM, which is eightfold to 10-fold lower than previously estimated. Accordingly, ATP-sensitive K (K) channels were active at physiological [ATP]. Cells exhibited two distinct types of ATP fluctuations during an action potential: net increases (Mode 1) or decreases (Mode 2) in [ATP]. Mode 1 [ATP] increases necessitated Ca entry and release from the sarcoplasmic reticulum (SR) and were associated with increases in mitochondrial Ca. By contrast, decreases in mitochondrial Ca accompanied Mode 2 [ATP] decreases. Down-regulation of the protein mitofusin 2 reduced the magnitude of [ATP] fluctuations, indicating that SR-mitochondrial coupling plays a crucial role in the dynamic control of ATP levels. Activation of β-adrenergic receptors decreased [ATP], underscoring the energetic impact of this signaling pathway. Finally, our work suggests that cross-bridge cycling is the largest consumer of ATP in a ventricular myocyte during an action potential. These findings provide insights into the energetic demands of EC coupling and highlight the dynamic nature of ATP concentrations in cardiac muscle.
Topics: Myocytes, Cardiac; Adenosine Triphosphate; Excitation Contraction Coupling; Animals; Calcium; Heart Ventricles; Action Potentials; Sarcoplasmic Reticulum; Heart Rate; Humans; KATP Channels; Myocardial Contraction; Mice
PubMed: 38865270
DOI: 10.1073/pnas.2318535121 -
Bioscience Reports Jun 2024High blood pressure in the portal vein, portal hypertension (PH), is the final common pathway in liver cirrhosis regardless of aetiology. Complications from PH are the...
High blood pressure in the portal vein, portal hypertension (PH), is the final common pathway in liver cirrhosis regardless of aetiology. Complications from PH are the major cause of morbidity and mortality in these patients. Current drug therapy to reduce portal pressure is mainly limited to β-adrenergic receptor blockade but about forty percent of patients do not respond. Our aim was to use microarray to measure the expression of ~20,800 genes in portal vein from patients with PH undergoing transplantation for liver cirrhosis (PH, n = 12) versus healthy vessels (control, n = 9) to identify potential drug targets to improve therapy. Expression of 9,964 genes above background was detected in portal vein samples. Comparing PH veins versus control (adjusted p value < 0.05, fold change > 1.5) identified 548 upregulated genes and 1,996 downregulated genes. The 2,544 differentially expressed genes were subjected to pathway analysis. We identified 49 significantly enriched pathways. The endothelin pathway was ranked the tenth most significant, the only vasoconstrictive pathway to be identified. ET-1 gene (EDN1) was significantly upregulated, consistent with elevated levels of ET-1 peptide previously measured in PH and cirrhosis. ETA receptor gene (EDNRA) was significantly downregulated, consistent with an adaptive response to increased peptide levels in the portal vein but there was no change in the ETB gene (EDNRB). The results provide further support for evaluating the efficacy of ETA receptor antagonists as a potential therapy in addition to β-blockers in patients with PH and cirrhosis.
PubMed: 38860875
DOI: 10.1042/BSR20240528 -
Journal of the American Heart... Jun 2024Chronic sympathetic stimulation drives desensitization and downregulation of β1 adrenergic receptor (βAR) in heart failure. We aim to explore the differential...
BACKGROUND
Chronic sympathetic stimulation drives desensitization and downregulation of β1 adrenergic receptor (βAR) in heart failure. We aim to explore the differential downregulation subcellular pools of βAR signaling in the heart.
METHODS AND RESULTS
We applied chronic infusion of isoproterenol to induced cardiomyopathy in male C57BL/6J mice. We applied confocal and proximity ligation assay to examine βAR association with L-type calcium channel, ryanodine receptor 2, and SERCA2a ((Sarco)endoplasmic reticulum calcium ATPase 2a) and Förster resonance energy transfer-based biosensors to probe subcellular βAR-PKA (protein kinase A) signaling in ventricular myocytes. Chronic infusion of isoproterenol led to reduced βAR protein levels, receptor association with L-type calcium channel and ryanodine receptor 2 measured by proximity ligation (puncta/cell, 29.65 saline versus 14.17 isoproterenol, <0.05), and receptor-induced PKA signaling at the plasma membrane (Förster resonance energy transfer, 28.9% saline versus 1.9% isoproterenol, <0.05) and ryanodine receptor 2 complex (Förster resonance energy transfer, 30.2% saline versus 10.6% isoproterenol, <0.05). However, the βAR association with SERCA2a was enhanced (puncta/cell, 51.4 saline versus 87.5 isoproterenol, <0.05), and the receptor signal was minimally affected. The isoproterenol-infused hearts displayed decreased PDE4D (phosphodiesterase 4D) and PDE3A and increased PDE2A, PDE4A, and PDE4B protein levels. We observed a reduced role of PDE4 and enhanced roles of PDE2 and PDE3 on the βAR-PKA activity at the ryanodine receptor 2 complexes and myocyte shortening. Despite the enhanced βAR association with SERCA2a, the endogenous norepinephrine-induced signaling was reduced at the SERCA2a complexes. Inhibiting monoamine oxidase A rescued the norepinephrine-induced PKA signaling at the SERCA2a and myocyte shortening.
CONCLUSIONS
This study reveals distinct mechanisms for the downregulation of subcellular βAR signaling in the heart under chronic adrenergic stimulation.
Topics: Animals; Receptors, Adrenergic, beta-1; Male; Down-Regulation; Signal Transduction; Ryanodine Receptor Calcium Release Channel; Mice, Inbred C57BL; Isoproterenol; Cyclic AMP-Dependent Protein Kinases; Myocytes, Cardiac; Sarcoplasmic Reticulum Calcium-Transporting ATPases; Calcium Channels, L-Type; Disease Models, Animal; Mice; Heart Failure; Cardiomyopathies; Fluorescence Resonance Energy Transfer
PubMed: 38860414
DOI: 10.1161/JAHA.123.033733 -
RSC Advances Jun 2024Halo-cycloetherification of lactam-tethered alkenols enables the construction of oxygen-heterocycles that are fused to nitrogen heterocycles intramolecular...
Harnessing the 1,3-azadiene-anhydride reaction for the regioselective and stereocontrolled synthesis of lactam-fused bromotetrahydropyrans by bromoetherification of lactam-tethered trisubstituted tertiary alkenols.
Halo-cycloetherification of lactam-tethered alkenols enables the construction of oxygen-heterocycles that are fused to nitrogen heterocycles intramolecular halonium-induced nucleophilic addition. Specifically, tetrahydropyrans (THPs) that are fused to a nitrogen heterocycle constitute the core of several bioactive molecules, including tachykinin receptor antagonists and alpha-1 adrenergic antagonists. Although the literature is replete with successful examples of the halo-cycloetherification of simple mono- or disubstituted primary alkenols, methods for the modular, efficient, regioselective, and stereocontrolled intramolecular haloetherification of sterically encumbered trisubstituted tertiary alkenols are rare. Here, we describe a simple intramolecular bromoetherification strategy that meets these benchmarks and proceeds with exclusive 6- regioselectivity. The transformation employs mild and water-tolerant conditions, which bodes well for late-stage diversification. The hindered ethers contain four contiguous stereocenters as well as one halogen-bearing tetrasubstituted stereocenter.
PubMed: 38860240
DOI: 10.1039/d4ra02523g