Β-adrenergic Agonist Research Articles

The Effect of Inhaled Albuterol on PaO2 in Anesthetized Horses Receiving a FiO2 of 0.5 or >0.95

Impairment of oxygen uptake can occur during general anesthesia in horses resulting in hypoxemia. Multiple treatments have been investigated for correction of hypoxemia with varying levels of success. In clinical trials, albuterol, a short-acting β2 adrenergic agonist, improved arterial oxygen partial pressure (PaO2) in anesthetized horses unresponsive to adjustments in mechanical ventilation and administration of positive inotropic drugs. However, controlled studies comparing the magnitude of change and duration of effect of albuterol on PaO2 in healthy, nonhypoxemic anesthetized horses are lacking. In a prospective study, 14 horses were anesthetized and received a FiO2 of 0.5 (n = 7) or > 0.95 (n = 7). Horses were maintained on isoflurane and mechanically ventilated. After 15 minutes, baseline PaO2 was determined. Within each FiO2 group, five horses were administered inhaled albuterol (2 µg/kg) and two horses received no treatment. At 10, 20, 30, and 40 minutes after baseline, PaO2 was measured. Data for horses that received albuterol were analyzed with repeated measures analysis of variance with significance at P < .05. Horses that received albuterol had an increase in PaO2 for at least 40 minutes after baseline. Albuterol administered via inhalation, was associated with an increased PaO2 of at least 40 minutes compared to baseline in healthy, nonhypoxemic horses undergoing anesthesia at similar depth, using a FiO2 of 0.5 and > 0.95. Side effects were mild and consisted of increased heart rate and sweating. Albuterol administered at 2 μg/kg via inhalation may be useful for increasing PaO2 in anesthetized horses.

Title: β3 Adrenergic Receptor Signaling in the Human Myometrium

Preterm labor leading to preterm birth is the leading cause of infant morbidity and mortality. Although β2 adrenergic agonists fail to provide adequate tocolysis, the expression of the β3 adrenergic receptor in myometrium and its unique signaling suggest a role for β3 agonist in the management of preterm labor. Western blot analysis showed that the β3 adrenergic receptor expression increased in human pregnancy myometrium compared to nonpregnant tissues (p < 0.0001). There was no difference in β3 adrenergic receptor expression throughout pregnancy (p > 0.05). The addition of the β3 agonist mirabegron in the tissue bath relaxed oxytocin contracted myometrium with an EC50 of 41.5 µM. Relaxation was partially blocked by the addition of the eNOS blocker Nω-nitro-L-arginine, or the large conductance potassium channel blocker paxilline. Combination of Nω-nitro-L-arginine and paxilline prevented mirabegron-mediated relaxation. Imaging revealed that the β3 adrenergic receptors are expressed by both myocyte and microvascular endothelial cells isolated from human myometrium. Nitric oxide production measured by 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate revealed that mirabegron stimulated nitric oxide production in myometrial endothelial cells. These data suggest that both endothelial and smooth muscle cells contribute to relaxation through disparate signaling pathways. Repurposing of approved medications tested in human myometrium as uterine tocolytics can advance prevention of preterm birth. These data argue that further examination of β3 adrenergic receptor signaling in myometrium may reveal mirabegron as a useful tocolytic in combination tocolysis regimens.

Nobiletin and 3'-Demethyl Nobiletin Activate Brown Adipocytes upon β-Adrenergic Stimulation.

Brown adipose tissue (BAT) specifically regulates energy expenditure via heat production. Nobiletin (NOB), a natural polymethoxylated flavone present in citrus fruits, can activate thermogenesis in the BAT of high-fat diet-induced obese mice. The activity of BAT is directly regulated by β-adrenergic stimulation. In this study, we report the effects of NOB on BAT activation using β-adrenergic agonists. We observed that when HB2 brown adipocyte cell lines are stimulated with β-adrenergic agonists, NOB enhances the expression of uncoupling protein 1 (UCP1), which is associated with the mitochondrial energy metabolism in these cells. Moreover, NOB increases the mRNA expression of the brown adipokines neuregulin-4 (Nrg4) and fibroblast growth factor-21 (FGF-21) and the secretion of FGF-21. These results suggest that NOB can enhance the thermogenic functions of brown adipocytes and promote brown adipokine secretion due to enhanced β-adrenergic stimulation. In addition, 3'-demethyl nobiletin (3'-DMN), an NOB CYP-enzyme metabolite, can increase UCP1 mRNA expression. Both NOB and 3'-DMN significantly promoted mitochondrial membrane potential in HB2 adipocytes following β-adrenergic stimulation. Therefore, we believe that NOB could be a promising candidate for activating BAT under β-adrenergic stimulation and preventing the onset of obesity.

Variation in CFTR-dependent 'β-sweating' among healthy adults.

The genetic disease cystic fibrosis (CF) results when mutations in the gene for the anion channel CFTR reduce CFTR’s activity below a critical level. CFTR activity = N·PO·γ (number of channels x open probability x channel conductance). Small molecules are now available that partially restore CFTR function with dramatic improvements in health of CF subjects. Continued evaluation of these and other compounds in development will be aided by accurate assessments of CFTR function. However, measuring CFTR activity in vivo is challenging and estimates vary widely. The most accurate known measure of CFTR activity in vivo is the ‘β/M’ ratio of sweat rates, which is produced by stimulation with a β-adrenergic agonist cocktail referenced to the same individual’s methacholine-stimulated sweat rate. The most meaningful metric of CFTR activity is to express it as a percent of normal function, so it is critical to establish β/M carefully in a population of healthy control subjects. Here, we analyze β/M from a sample of 50 healthy adults in which sweat rates to cholinergic and β-adrenergic agonists were measured repeatedly (3 times) in multiple, (~50) identified sweat glands from each individual (giving ~20,000 measurements). The results show an approximately 7-fold range, 26–187% of the WT average set to 100%. These provide a benchmark against which other measures of CFTR activity can be compared. Factors contributing to β/M variation in healthy controls are discussed.

Mechanisms Involved in the Stimulatory and Inhibitory Effects of 5-Hydroxytryptamine on Vagal Mechanosensitive Afferents in Rat Lung.

Mechanosensitive vagal afferents in the lung, rapidly and slowly adapting receptors (RARs and SARs, respectively), play an important role in eliciting the reflexes that regulate the normal airway function. A profound bronchoconstrictive effect of 5-hydroxytryptamine (5-HT) has been extensively reported in various animal species, but its influence on the SAR and RAR activity is not known. This study investigated the effect of 5-HT on these receptors, and the possible mechanisms involved. Single-fiber activities of these afferents were measured in anesthetized, open-chest, and mechanically ventilated rats. Our results showed that intravenous injection of 5-HT evoked a consistent and pronounced stimulation of phasic RARs. In contrast, 5-HT generated an inconsistent and paradoxical action on SARs: no effect in 29% (5 of 17) of the SARs; stimulation in 35% (6 of 17); and inhibition in the remainder. These responses of both RARs and SARs to 5-HT were reproducible and dose-dependent. After the injection of a high dose of 5-HT (16 μg/kg), the receptor responses slowly reached a peak (after ∼8 s) and returned toward the baseline in ∼20 s, accompanied by a consistent increase in total pulmonary resistance and a decrease in dynamic lung compliance in a temporal pattern very similar to the increased receptor activity. When these changes in lung mechanics induced by 5-HT were prevented by pretreatment with salbutamol, a β2 adrenergic receptor agonist, the delayed responses of both RARs and SARs to 5-HT were also abolished, except that the immediate stimulatory effect on a subset of RARs, the silent RARs, was not affected. In conclusion, 5-HT generated a delayed stimulatory effect on RARs and a paradoxical effect on SARs, which resulted primarily from the 5-HT-induced changes in mechanical properties of the lung.

The involvement of the adrenergic nervous system in activating human brown adipose tissue and browning.

Obesity is a chronic condition of multifactorial etiology characterized by excessive body fat due to a calorie intake higher than energy expenditure. Given the intrinsic limitations of surgical interventions and the difficulties associated with lifestyle changes, pharmacological manipulation is currently one of the main therapies for metabolic diseases. Approaches aiming to promote energy expenditure through induction of thermogenesis have been explored and, in this context, brown adipose tissue (BAT) activation and browning have been shown to be promising strategies. Although such processes are physiologically stimulated by the sympathetic nervous system, not all situations that are known to increase adrenergic signaling promote a concomitant increase in BAT activation or browning in humans. Thus, a better understanding of factors involved in the thermogenesis attributed to these tissues is needed to enable the development of future therapies against obesity. Herein we carry out a critical review of original articles in humans under conditions previously known to trigger adrenergic responses-namely, cold, catecholamine-secreting tumor (pheochromocytoma and paraganglioma), burn injury, and adrenergic agonists-and discuss which of them are associated with increased BAT activation and browning. BAT is clearly stimulated in individuals exposed to cold or treated with high doses of the β3-adrenergic agonist mirabegron, whereas browning is certainly induced in patients after burn injury or with pheochromocytoma, as well as in individuals treated with β3-adrenergic agonist mirabegron for at least 10weeks. Given the potential effect of increasing energy expenditure, adrenergic stimuli are promising strategies in the treatment of metabolic diseases.

Surgical stress quickly affects the numbers of circulating B-cells and neutrophils in murine septic and aseptic models through a β2 adrenergic receptor

Sepsis is a pathology accompanied by increases in myeloid cells and decreases in lymphoid cells in circulation. In a murine sepsis model induced by cecum ligation and puncture (CLP), increasing numbers of neutrophils and decreasing levels of B-cells in circulation are among the earliest changes in the immune system. However, to date, the mechanisms for these changes remain to be elucidated. The study here sought to elucidate mechanisms underlying the changes in the leukocyte levels after CLP and also to determine what, if any, role for an involvement of the sympathetic nervous system (SNS). Here, male C57/BL6 mice were subjected to CLP or sham-CLP (abdominal wall incised, but cecum was not punctured). The changes in the number of circulating leukocytes over time were then investigated using flow cytometry. The results showed that a sham-CLP led to increased polymorphonuclear cells (PMN; most of which are neutrophils) and decreased B-cells in the circulation to an extent similar to that induced by CLP. Effects of adrenergic agonists and antagonists, as well as of adrenalectomy, were also examined in mice that underwent CLP or sham-CLP. Administering adrenaline or a β2 adrenergic receptor agonist (clenbuterol) to mice 3 h before sacrifice produced almost identical changes to as what was seen 2 h after performing a sham-CLP. In contrast, giving a β2 adrenergic receptor antagonist ICI118,551 1 h before a CLP or sham-CLP suppressed the expected changes 2 h after the operations. Noradrenaline and an α1 adrenergic receptor agonist phenylephrine did not exert significant effects. Adrenalectomy 24 h before a sham-CLP significantly abolished the expected sham-CLP-induced changes seen earlier. Clenbuterol increased splenocyte expression of Cxcr4 (a chemokine receptor gene); adrenalectomy abolished sham-CLP-induced Cxcr4 expression. A CXCR4 antagonist AMD3100 repressed the sham-CLP-induced changes. From these results, it may be concluded that sepsis-induced activation of the SNS may be one cause for immune dysfunction in sepsis – regardless of the pathogenetic processes.

Microvascular β-Adrenergic Receptor-Mediated Vasodilation Is Attenuated in Adults With Major Depressive Disorder.

Major depressive disorder (MDD) is associated with sympathetic overactivity and alterations in peripheral adrenergic receptor function; however, no studies have directly assessed vasoconstrictor responsiveness in adults with MDD. We tested the hypotheses that β-adrenergic receptor-mediated vasodilation would be blunted in adults with MDD compared with healthy nondepressed adults (HA) and would functionally contribute to exaggerated norepinephrine-induced vasoconstriction. In 13 HA (8 female; 24±4 years) and in 12 adults with MDD (8 female; 22±3 yrs), red blood cell flux was measured during graded intradermal microdialysis perfusion of the β-adrenergic receptor agonist isoproterenol (10-10 to 10-4 mol/L) and, separately, during the perfusion of norepinephrine (10-12 to 10-2 mol/L), alone and in combination with the β-adrenergic receptor antagonist propranolol (2 mmol/L). Nonadrenergic vasoconstriction was assessed via perfusion of angiotensin II (10-12 to 10-4 mol/L). Isoproterenol-induced vasodilation was blunted in adults with MDD (188.9±70.1 HA versus 128.3±39.4 au MDD, P=0.025). Net norepinephrine-induced vasoconstriction was exaggerated in adults with MDD (-0.16±0.54 HA versus -0.75±0.56 au MDD, P=0.014); however, there were no group differences in angiotensin II-induced vasoconstriction. Propranolol potentiated norepinephrine-induced vasoconstriction in HA (-0.16±0.54 norepinephrine versus -1.60±1.40 au propranolol, P<0.01) but had no effect in adults with MDD (-0.75±0.56 norepinephrine versus -1.58±1.56 au propranolol, P=0.08). β-adrenergic receptor-mediated microvascular vasodilation was blunted in adults with MDD and contributed to exaggerated adrenergic vasoconstriction. The relative loss of the vasoprotective effect of β-adrenergic receptor-mediated vasodilation may contribute to increased peripheral resistance, thereby driving the development of hypertension in adults with MDD.

Effects of long-term treatment with dietary theobromine on rat skeletal muscles.

Plastic changes of skeletal muscles, such as hypertrophy and atrophy, are dependent on physiological activities and regulated by a variety of signaling pathways, including cyclic adenosine monophosphate (cAMP) pathway. The cAMP inducing agents, such as the β2-adrenergic agonist clenbuterol, are known to induce muscle hypertrophy, and has been reported to induce slow-to-fast transitions in rat soleus muscle. Theobromine, one of the active components of cacao, functions as an inhibitor of phosphodiesterase and increases cAMP. This study hypothesized that theobromine, like clenbuterol, can induce muscle hypertrophy and influence contractile properties. Male Wistar rats were fed a normal diet or a diet containing 0.05% theobromine for 20weeks. Using biochemical, anatomical, and physiological techniques, effects of dietary theobromine on skeletal muscles (soleus, extensor digitorum longus, plantaris, and gastrocnemius) were examined. There were no significant differences in body weight, serum levels of proteins and lipids, muscle weights, dry/wet ratio of muscle weights, mitochondrial oxidation enzyme activity of muscles, isometric contractile properties of muscles, and muscle fatigue between control and theobromine-fed rats. Quantitative analysis of mRNA, however, revealed upregulation of myosin heavy chain 2x and myogenic differentiation 1, as previously reported in clenbuterol-treated muscles. The long-term theobromine (0.05%) diet in rats had no effect in inducing muscle hypertrophy and in changing contractile properties, although it had some similar effects of clenbuterol on muscle gene expression.

Chemical Interrogation of Nuclear Size Identifies Compounds with Cancer Cell Line-Specific Effects on Migration and Invasion.

Background: Lower survival rates for many cancer types correlate with changes in nuclear size/scaling in a tumor-type/tissue-specific manner. Hypothesizing that such changes might confer an advantage to tumor cells, we aimed at the identification of commercially available compounds to guide further mechanistic studies. We therefore screened for Food and Drug Administration (FDA)/European Medicines Agency (EMA)-approved compounds that reverse the direction of characteristic tumor nuclear size changes in PC3, HCT116, and H1299 cell lines reflecting, respectively, prostate adenocarcinoma, colonic adenocarcinoma, and small-cell squamous lung cancer. Results: We found distinct, largely nonoverlapping sets of compounds that rectify nuclear size changes for each tumor cell line. Several classes of compounds including, e.g., serotonin uptake inhibitors, cyclo-oxygenase inhibitors, β-adrenergic receptor agonists, and Na+/K+ ATPase inhibitors, displayed coherent nuclear size phenotypes focused on a particular cell line or across cell lines and treatment conditions. Several compounds from classes far afield from current chemotherapy regimens were also identified. Seven nuclear size-rectifying compounds selected for further investigation all inhibited cell migration and/or invasion. Conclusions: Our study provides (a) proof of concept that nuclear size might be a valuable target to reduce cell migration/invasion in cancer treatment and (b) the most thorough collection of tool compounds to date reversing nuclear size changes specific to individual cancer-type cell lines. Although these compounds still need to be tested in primary cancer cells, the cell line-specific nuclear size and migration/invasion responses to particular drug classes suggest that cancer type-specific nuclear size rectifiers may help reduce metastatic spread.

RNA-binding protein YBX1 promotes brown adipogenesis and thermogenesis via PINK1/PRKN-mediated mitophagy.

Promoting the thermogenic function of brown adipose tissue (BAT) is a promising strategy to combat obesity and metabolic disorders. While much is known about the transcriptional regulation of BAT activation, however, the underlying mechanism of post-transcriptional control by RNA binding proteins remains largely unknown. Here, we found that RNA binding protein Y-box binding protein 1 (YBX1) expression was abundant in BAT and induced by cold exposure and a β-adrenergic agonist in mice. Loss-of-function experiments showed that YBX1 deficiency inhibited mouse primary brown adipocyte differentiation and thermogenic function. Further study showed that YBX1 positively regulates thermogenesis through enhancing mitophagy. Mechanistically, RNA immunoprecipitation identified that YBX1 directly targeted the transcripts of PTEN-induced kinase 1 (Pink1) and parkin RBR E3 ubiquitin-protein ligase (Prkn), two key regulators of mitophagy. RNA decay assay proved that loss of YBX1 decreased mRNA stability of Pink1 and Prkn, leading to reduced protein expression, thereby alleviating mitophagy and inhibiting thermogenic program. Importantly, in vivo experiments demonstrated that YBX1 overexpression in BAT promoted thermogenesis and mitophagy in mice. Collectively, our results reveal novel insight into the molecular mechanism of YBX1 in post-transcriptional regulation of PINK1/PRKN-mediated mitophagy and highlight the critical role of YBX1 in brown adipogenesis and thermogenesis.

Clinical pharmacology of salbutamol in infants and children

Inhaled β2 agonists are the bronchodilator treatment of choice in asthma because they are the most effective bronchodilators. β2 agonists may cause bronchodilation by inhibiting the release of bronchoconstrictor neurotransmitters from airway nerves. Inhaled short-acting β2 agonists are the most widely used and effective bronchodilators for the treatment of asthma due to their functional antagonisms of bronchoconstriction. Salbutamol is a short-acting β-adrenergic agonist widely used by asthmatics for its bronchodilator activity. Salbutamol is a racemic mixture of active R-salbutamoland inactive S-salbutamol. In infants, salbutamol is administered by nebulizer solution at a dose of 2.5 mg trice-daily to treat chronic lung disease. In children, salbutamol may be administered intravenously, by inhalational, nebulisation, or orally and salbutamol dose varies with the child's age. The efficacy and safety of salbutamol have been extensively studied in infants and children and salbutamol is sulphatedin-vivo in patients and in-vitro in human lung, liver, and duodenum and the sulfation-rate remarkably varies among patients and among lung, liver, and duodenum specimens. The pharmacokinetics of salbutamol have been studied in infants and children and the elimination half-life of salbutamol is 2.2 hours in infants and about 6 years in children. The treatment of infants and children with salbutamol has been extensively studied and salbutamol poorly crosses the human placenta. The aim of this study is to review the salbutamol dosing, efficacy and safety, pharmacokinetics, and treatment in infants and children and salbutamol metabolism and transfer across the human placenta.

Elevated MCU Expression by CaMKIIδB Limits Pathological Cardiac Remodeling.

Calcium (Ca2+) is a key regulator of energy metabolism. Impaired Ca2+ homeostasis damages mitochondria, causing cardiomyocyte death, pathological hypertrophy, and heart failure. This study investigates the regulation and the role of the mitochondrial Ca2+ uniporter (MCU) in chronic stress-induced pathological cardiac remodeling. MCU knockout or transgenic mice were infused with isoproterenol (ISO; 10 mg/kg per day, 4 weeks). Cardiac hypertrophy and remodeling were evaluated by echocardiography and histology. Primary cultured rodent adult cardiomyocytes were treated with ISO (1 nmol/L, 48 hours). Intracellular Ca2+ handling and cell death pathways were monitored. Adenovirus-mediated gene manipulations were used in vitro. Chronic administration of the β-adrenergic receptor agonist ISO increased the levels of the MCU and the MCU complex in cardiac mitochondria, raising mitochondrial Ca2+ concentrations, in vivo and in vitro. ISO also upregulated MCU without affecting its regulatory proteins in adult cardiomyocytes. It is interesting that ISO-induced cardiac hypertrophy, fibrosis, contractile dysfunction, and cardiomyocyte death were exacerbated in global MCU knockout mice. Cardiomyocytes from knockout mice or overexpressing a dominant negative MCU exhibited defective intracellular Ca2+ handling and activation of multiple cell death pathways. Conversely, cardiac-specific overexpression of MCU maintained intracellular Ca2+ homeostasis and contractility, suppressed cell death, and prevented ISO-induced heart hypertrophy. ISO upregulated MCU expression through activation of Ca2+/calmodulin kinase II δB (CaMKIIδB) and promotion of its nuclear translocation via calcineurin-mediated dephosphorylation at serine 332. Nuclear CaMKIIδB phosphorylated CREB (cAMP-response element binding protein), which bound the Mcu promoter to enhance Mcu gene transcription. The β-adrenergic receptor/CaMKIIδB/CREB pathway upregulates Mcu gene expression in the heart. MCU upregulation is a compensatory mechanism that counteracts stress-induced pathological cardiac remodeling by preserving Ca2+ homeostasis and cardiomyocyte viability.

Cross-talk of cholinergic and β-adrenergic receptor signalling in chronic myeloid leukemia K562 cells.

In many studies on breast, skin and intestinal cancers, β-adrenergic receptor antagonists have been shown to inhibit cell proliferation and angiogenesis and increase apoptosis in cancers. Carbachol inhibits chronic myeloid leukaemia K562 cell proliferation. Beta-blockers are known to inhibit cell progression. The aim of this study is to explain the mechanism of action of β-adrenergic receptors agonists and antagonists on apoptosis in chronic myeloid leukaemia cells. We tried to determine the effect of combined treatment of β-adrenergic and cholinergic drugs on adrenergic β1 and β2 gene expression, cell proliferation and apoptosis in chronic myeloid leukaemia K562 cells. Cell proliferation was evaluated by the 5-bromo-2-deoxy-uridine (BrdU) incorporation kit. Caspase 3, 8, 9 activities were measured by the caspase assay kit. Protein expression level was detected by western blotting. We found that exposure to propranolol either by combination with carbachol facilitates additive effects on inhibition of caspase 3 and 8 expression in chronic myeloid leukaemia K562 cells. However, caspase 9 expression level was increased by propranolol alone or with propranolol and carbachol combination. The combined therapy of cholinergic and adrenergic receptor drugs will decrease cell proliferation in K562 cells. This decrease in cell proliferation may be mediated by the mitochondrial-dependent intrinsic apoptosis pathway.

Downregulation of PTEN Promotes Autophagy via Concurrent Reduction in Apoptosis in Cardiac Hypertrophy in PPAR α-/- Mice.

Cardiac hypertrophy is characterized by an increase in the size of the cardiomyocytes which is initially triggered as an adaptive response but ultimately becomes maladaptive with chronic exposure to different hypertrophic stimuli. Prolonged cardiac hypertrophy is often associated with mitochondrial dysfunctions and cardiomyocyte cell death. Peroxisome proliferator activated receptor alpha (PPAR α), which is critical for mitochondrial biogenesis and fatty acid oxidation, is down regulated in hypertrophied cardiomyocytes. Yet, the role of PPAR α in cardiomyocyte death is largely unknown. To assess the role of PPAR α in chronic hypertrophy, isoproterenol, a β-adrenergic receptor agonist was administered in PPAR α knock out (PPAR α−/−) mice for 2 weeks and hypertrophy associated changes in cardiac tissues were observed. Echocardiographic analysis ensured the development of cardiac hypertrophy and compromised hemodynamics in PPAR α−/− mice. Proteomic analysis using high resolution mass spectrometer identified about 1,200 proteins enriched in heart tissue. Proteins were classified according to biological pathway and molecular functions. We observed an unexpected down regulation of apoptotic markers, Annexin V and p53 in hypertrophied heart tissue. Further validation revealed a significant down regulation of apoptosis regulator, PTEN, along with other apoptosis markers like p53, Caspase 9 and c-PARP. The autophagy markers Atg3, Atg5, Atg7, p62, Beclin1 and LC3 A/B were up regulated in PPAR α−/− mice indicating an increase in autophagy. Similar observations were made in a high cholesterol diet fed PPAR α−/−mice. The results were further validated in vitro using NRVMs and H9C2 cell line by blocking PPAR α that resulted in enhanced autophagosome formation upon hypertrophic stimulation. The results demonstrate that in the absence of PPAR α apoptotic pathway is inhibited while autophagy is enhanced. The data suggest that PPAR α signaling might act as a molecular switch between apoptosis and autophagy thereby playing a critical role in adaptive process in cardiac hypertrophy.

Role of Autonomous Neuropathy in Diabetic Bone Regeneration.

Diabetes mellitus has multiple negative effects on regenerative processes, especially on wound and fracture healing. Despite the well-known negative effects of diabetes on the autonomous nervous system, only little is known about the role in bone regeneration within this context. Subsequently, we investigated diabetic bone regeneration in db−/db− mice with a special emphasis on the sympathetic nervous system of the bone in a monocortical tibia defect model. Moreover, the effect of pharmacological sympathectomy via administration of 6-OHDA was evaluated in C57Bl6 wildtype mice. Diabetic animals as well as wildtype mice received a treatment of BRL37344, a β3-adrenergic agonist. Bones of animals were examined via µCT, aniline-blue and Masson–Goldner staining for new bone formation, TRAP staining for bone turnover and immunoflourescence staining against tyrosinhydroxylase and stromal cell-derived factor 1 (SDF-1). Sympathectomized wildtype mice showed a significantly decreased bone regeneration, just comparable to db−/db− mice. New bone formation of BRL37344 treated db−/db− and sympathectomized wildtype mice was markedly improved in histology and µCT. Immunoflourescence stainings revealed significantly increased SDF-1 due to BRL37344 treatment in diabetic animals and sympathectomized wildtypes. This study depicts the important role of the sympathetic nervous system for bone regenerative processes using the clinical example of diabetes mellitus type 2. In order to improve and gain further insights into diabetic fracture healing, β3-agonist BRL37344 proved to be a potent treatment option, restoring impaired diabetic bone regeneration.

Association of Generalized Anxiety Disorder With Autonomic Hypersensitivity and Blunted Ventromedial Prefrontal Cortex Activity During Peripheral Adrenergic Stimulation

β-Adrenergic stimulation elicits heart palpitations and dyspnea, key features of acute anxiety and sympathetic arousal, yet no neuroimaging studies have examined how the pharmacologic modulation of interoceptive signals is associated with fear-related neurocircuitry in individuals with generalized anxiety disorder (GAD). To examine the neural circuitry underlying autonomic arousal induced via isoproterenol, a rapidly acting, peripheral β-adrenergic agonist akin to adrenaline. This crossover randomized clinical trial of 58 women with artifact-free data was conducted from January 1, 2017, to November 31, 2019, at the Laureate Institute for Brain Research in Tulsa, Oklahoma. Functional magnetic resonance imaging was used to assess neural responses during randomized intravenous bolus infusions of isoproterenol (0.5 and 2.0 μg) and saline, each administered twice in a double-blind fashion. Blood oxygen level-dependent responses across the whole brain during isoproterenol administration in patients with GAD vs healthy comparators. Cardiac and respiratory responses, as well as interoceptive awareness and anxiety, were also measured during the infusion protocol. Of the 58 female study participants, 29 had GAD (mean [SD] age, 26.9 [6.8] years) and 29 were matched healthy comparators (mean [SD] age, 24.4 [5.0] years). During the 0.5-μg dose of isoproterenol, the GAD group exhibited higher heart rate responses (b = 5.34; 95% CI, 2.06-8.61; P = .002), higher intensity ratings of cardiorespiratory sensations (b = 8.38; 95% CI, 2.05-14.71; P = .01), higher levels of self-reported anxiety (b = 1.04; 95% CI, 0.33-1.76; P = .005), and significant hypoactivation in the ventromedial prefrontal cortex (vmPFC) that was evident throughout peak response (Cohen d = 1.55; P < .001) and early recovery (Cohen d = 1.52; P < .001) periods. Correlational analysis of physiological and subjective indexes and percentage of signal change extracted during the 0.5-μg dose revealed that vmPFC hypoactivation was inversely correlated with heart rate (r56 = -0.51, adjusted P = .001) and retrospective intensity of both heartbeat (r56 = -0.50, adjusted P = .002) and breathing (r56 = -0.44, adjusted P = .01) sensations. Ventromedial prefrontal cortex hypoactivation correlated inversely with continuous dial ratings at a trend level (r56 = -0.38, adjusted P = .051), whereas anxiety (r56 = -0.28, adjusted P = .27) and chronotropic dose 25 (r56 = -0.14, adjusted P = .72) showed no such association. In this crossover randomized clinical trial, women with GAD exhibited autonomic hypersensitivity during low levels of adrenergic stimulation characterized by elevated heart rate, heightened interoceptive awareness, increased anxiety, and a blunted neural response localized to the vmPFC. These findings support the notion that autonomic hyperarousal may be associated with regulatory dysfunctions in the vmPFC, which could serve as a treatment target to help patients with GAD more appropriately appraise and regulate signals of sympathetic arousal. ClinicalTrials.gov Identifier: NCT02615119.

Transcriptome analyses indicate that heat stress-induced inflammation in white adipose tissue and oxidative stress in skeletal muscle is partially moderated by zilpaterol supplementation in beef cattle.

Heat stress (HS) triggers oxidative stress, systemic inflammation, and disrupts growth efficiency of livestock. β-adrenergic agonists supplemented to ruminant livestock improve growth performance, increase skeletal muscle mass, and decrease carcass fat. The objective of this study was to understand the independent and interacting effects of HS and zilpaterol hydrochloride (ZH) supplementation on the transcriptome of subcutaneous white adipose tissue and the longissimus dorsi muscle in steers. Twenty-four Red Angus-based steers were assigned to thermoneutral (TN; Temperature Humidity Index [THI] = 68) or HS (THI = 73-85) conditions and were not supplemented or supplemented with ZH (8.33mg/kg/d) for 21 d in a 2×2 factorial. Steers in the TN condition were pair-fed to the average daily feed intake of HS steers. RNA was isolated from adipose tissue and skeletal muscle samples collected via biopsy on 3, 10, and 21 d and sequenced using 3' Tag-Seq to an achieved average depth of 3.6 million reads/sample. Transcripts, mapped to ARS-UCD1.2, were quantified. Differential expression (DE) analyses were performed in DESeq2 with a significance threshold for false discovery rate of 0.05. In adipose, 4 loci (MISP3, APOL6, SLC25A4, and S100A12) were DE due to ZH on day 3, and 2 (RRAD, ALB) were DE due to the interaction of HS and ZH on day 10 (Padj < 0.05). In muscle, 40 loci (including TENM4 and OAZ1) were DE due to ZH on day 10, and 6 loci (HIF1A, LOC101903734, PDZD9, HNRNPU, MTUS1, and TMCO6) were DE due to environment on day 21 (Padj < 0.05). To explore biological pathways altered by environment, supplement, and their interaction, loci with DE (Praw < 0.05) were evaluated in Ingenuity Pathway Analysis. In adipose, 509 pathways were predicted to be altered (P < 0.01): 202 due to HS, 126 due to ZH, and 181 due to the interaction; these included inflammatory pathways predicted to be upregulated due to HS but downregulated due to the interaction of HS and ZH. In muscle, 113 pathways were predicted to be altered (P < 0.01): 23 due to HS, 66 due to ZH, and 24 due to the interaction of HS and ZH. Loci and pathway data in muscle suggest HS induced oxidative stress and that the stress response was moderated by ZH. Metabolic pathways were predicted to be altered due to HS, ZH, and their interaction in both tissues. These data provide evidence that HS and ZH interact to alter expression of genes in metabolic and immune function pathways and that ZH moderates some adverse effects of HS.

ADRB2 gene polymorphism and preterm labor

This article discusses issues related to the role of polymorphism of the ADRB2 gene encoding β2-adrenergic receptor in preterm labor and tocolysis. Information is provided on scientific studies related to the search for associations of the carriage of alleles and genotypes of ADRB2 with the preterm labor, as well as with the pharmacological response to tocolytic therapy using β2-adrenergic agonists. The history of the discovery of the relationship of ADRB2 gene polymorphisms with preterm labor is presented in chronological order. As scientific facts emerge, researchers are faced with the question: how can ADRB2 gene polymorphisms affect physiological processes? That is, whether they affect by changing the primary structure of the receptor or by changing the level of expression. Depending on the answer to this question, pharmacogenetics are faced with a further task: what to study - individual polymorphisms or haplotypes?

Liraglutide Activates Type 2 Deiodinase and Enhances β3-Adrenergic-Induced Thermogenesis in Mouse Adipose Tissue.

AimsLiraglutide is a long-acting glucagon-like peptide 1 (GLP-1) receptor agonist used as an anti-hyperglycemic agent in type 2 diabetes treatment and recently approved for obesity management. Weight loss is attributed to appetite suppression, but therapy may also increase energy expenditure. To further investigate the effect of GLP-1 signaling in thermogenic fat, we assessed adipose tissue oxygen consumption and type 2 deiodinase (D2) activity in mice treated with liraglutide, both basally and after β3-adrenergic treatment.MethodsMale C57BL/6J mice were randomly assigned to receive liraglutide (400 μg/kg, n=12) or vehicle (n=12). After 16 days, mice in each group were co-treated with the selective β3-adrenergic agonist CL316,243 (1 mg/kg, n=6) or vehicle (n=6) for 5 days. Adipose tissue depots were assessed for gene and protein expression, oxygen consumption, and D2 activity.ResultsLiraglutide increased interscapular brown adipose tissue (iBAT) oxygen consumption and enhanced β3-adrenergic-induced oxygen consumption in iBAT and inguinal white adipose tissue (ingWAT). These effects were accompanied by upregulation of UCP-1 protein levels in iBAT and ingWAT. Notably, liraglutide increased D2 activity without significantly upregulating its mRNA levels in iBAT and exhibited additive effects to β3-adrenergic stimulation in inducing D2 activity in ingWAT.ConclusionsLiraglutide exhibits additive effects to those of β3-adrenergic stimulation in thermogenic fat and increases D2 activity in BAT, implying that it may activate this adipose tissue depot by increasing intracellular thyroid activation, adding to the currently known mechanisms of GLP-1A-induced weight loss.