A large number of β-adrenergic receptor (β-AR) agonists and antagonists are widely used in the treatment of cardiovascular diseases and other diseases. Nonetheless, it remains unclear whether these commonly used β-AR drugs can activate downstream β- arrestin-biased signaling pathways. The objective of this study was to investigate β-arrestin2 recruitment effects of β-AR agonists and antagonists that were commonly used in clinical practice. We used TANGO (transcriptional activation following arrestin translocation) assay to detect the β-arrestin2 recruitment by β-AR ligands in HEK293 cell line (HTLA cells) stably transfected with tetracycline transactivator protein (tTA) dependent luciferase reporter and β-arrestin2-TEV fusion gene. Upon activation of β-AR by a β-AR ligand, β-arrestin2 was recruited to the C terminus of the receptor, followed by cleavage of the G protein-coupled receptors (GPCRs) fusion protein at the TEV protease-cleavage site. The cleavage resulted in the release of tTA, which, after being transported to the nucleus, activated transcription of the luciferase reporter gene. The results showed that β-AR non-selective agonists epinephrine, noradrenaline and isoprenaline all promoted β-arrestin2 recruitment at β1-AR and β2-AR. β1-AR selective agonists dobutamine and denopamine both promoted β-arrestin2 recruitment at β1-AR. β2-AR selective agonists procaterol and salbutamol promoted β-arrestin2 recruitment at β2-AR. β-AR non-selective antagonists alprenolol and pindolol promoted β-arrestin2 recruitment at β1-AR. β1-AR selective antagonists celiprolol and bevantolol showed β-arrestin2 recruitment at β1-AR. β2-AR selective antagonists butoxamine showed β-arrestin2 recruitment at β1-AR. These results provide some clues for the potential action of β-AR drugs, and lay a foundation for the screening of β-arrestin-biased β-AR ligands.
Humans ; beta-Arrestin 2/metabolism* ; HEK293 Cells ; Adrenergic beta-Agonists/pharmacology* ; Isoproterenol/pharmacology* ; Receptors, Adrenergic, beta-2/metabolism* ; Norepinephrine/pharmacology*

The purpose of this study was to investigate the effects of α₂ adrenergic receptor agonist dexmedetomidine on withdrawal symptoms in alcohol-dependent rats and the underlying mechanism, so as to provide a scientific basis for the treatment of alcohol withdrawal syndrome (AWS). Adult Sprague-Dawley (SD) male rats were orally administered with 6% aqueous alcohol continuously for 28 d to establish alcohol drinking model, and then stopped drinking to induce AWS. Enzyme-linked immunosorbent assay (ELISA) was used to determine the content of norepinephrine (NE) in the locus coeruleus and hippocampus of rats. Dexmedetomidine (5, 10, and 20 μg/kg) was intraperitoneally injected respectively when the rats showed significant AWS. In some rats, α₂ adrenergic receptor antagonist yohimbine was injected into hippocampus in advance. The results showed that, compared with the control group, the 6 h withdrawal group exhibited significantly increased AWS score and amount of repeat drinking. The NE contents in hippocampus and locus coeruleus of the last drinking and the 6 h withdrawal groups were significantly increased compared with those of the control group. Dexmedetomidine intervention significantly decreased AWS score and hippocampus NE content in the 6 h withdrawal group, while yohimbine could reverse these effects of dexmedetomidine. These results suggest that dexmedetomidine might improve the withdrawal symptoms in alcohol-dependent rats via activating α₂ adrenergic receptor.
Adrenergic alpha-2 Receptor Agonists/therapeutic use* ; Alcoholism/drug therapy* ; Animals ; Dexmedetomidine/therapeutic use* ; Hippocampus/metabolism* ; Male ; Norepinephrine ; Rats ; Rats, Sprague-Dawley ; Receptors, Adrenergic, alpha-2/metabolism* ; Substance Withdrawal Syndrome/drug therapy* ; Yohimbine/pharmacology*

OBJECTIVE: Dexmedetomidine (DEX), the most specific α ₂-adrenergic receptor agonist widely used for its sedative and analgesic properties, has been reported to upregulate HIF-1α expression to protect hypoxic and ischemic tissues. However, it is largely unclear whether DEX can also upregulate Hypoxia-inducible factor-1 alpha (HIF-1α) expression and its downstream vascular endothelial growth factor-A (VEGFA) in cancer tissues with oxygen-deficient tumor microenvironment. METHODS: We used SMMC-7721 cells, MHCC97-H cells, and a mouse model of orthotopic hepatic carcinoma to explore the effect of DEX on angiogenesis and vasculogenic mimicry (VM) and its mechanism. Under normoxic (20% O ₂) and hypoxic (1% O ₂) conditions, DEX was used to intervene cells, and yohimbine was used to rescue them. RESULTS: The results showed that DEX promoted angiogenesis and VM in human liver cancer cells within a certain dose range, and the addition of yohimbine inhibited this effect. DEX could activate HIF-1α/VEGFA pathway, which was further verified by silencing HIF-1α. Consistently, in vivo results also showed that DEX can up-regulate HIF-1α/VEGFA expression, and enhance the number of VM channels and microvessel density (MVD). CONCLUSION We believe that HIF-1α/VEGFA might be an important signaling pathway by which DEX promotes angiogenesis and VM formation in human hepatocellular carcinoma, whereas α ₂-adrenergic receptor mediation might be the critical mechanisms.
Animals ; Humans ; Mice ; Adrenergic alpha-2 Receptor Agonists/pharmacology* ; Carcinoma, Hepatocellular ; Cardiovascular Physiological Phenomena ; Dexmedetomidine/pharmacology* ; Hypoxia ; Liver Neoplasms/drug therapy* ; Oxygen ; Tumor Microenvironment ; Vascular Endothelial Growth Factor A/genetics* ; Receptors, Adrenergic, alpha-2/metabolism*

Objective: To explore the protective effects of dexmedetomidine (Dex) against high glucose-induced epithelial-mesenchymal transition in HK-2 cells and relevant mechanisms. Methods: HK-2 cells were exposed to either glucose or glucose+Dex for 6 h. The production of ROS, morphology of HK-2 cells, and cell cycle were detected. Moreover, the expression of AKT, p-AKT, ERK, p-ERK, PI3K, E-Cadherin, Claudin-1, and α-SMA were determined and compared between HK-2 cells exposed to glucose and those exposed to both glucose and Dex with or without PI3K/AKT pathway inhibitor LY294002 and ERK pathway inhibitor U0126. Results: Compared with HK-2 cells exposed to high level of glucose, the HK-2 cells exposed to both high level of glucose and Dex showed: (1) lower level of ROS production; (2) cell morphology was complete; (3) more cells in G1 phase; (4) lower expression of p-AKT, p-ERK and α-SMA, higher expression of E-Cadherin and Claudin-1. PI3K/AKT inhibitor LY294002 and ERK inhibitor U0126 decreased the expression of p-AKT, p-ERK and α-SMA, and increased the expression of E-Cadherin and Claudin-1. Conclusion Dex can attenuate high glucose-induced HK-2 epithelial-mesenchymal transition by inhibiting AKT and ERK.
Adrenergic alpha-2 Receptor Agonists ; pharmacology ; Cell Line ; Dexmedetomidine ; pharmacology ; Epithelial-Mesenchymal Transition ; drug effects ; Glucose ; metabolism ; Humans ; MAP Kinase Signaling System ; drug effects ; Proto-Oncogene Proteins c-akt ; antagonists & inhibitors ; Signal Transduction ; drug effects

To characterize the timeliness of β3 adrenergic receptor agonist CL316,243-induced browning of white adipose tissues in mice.
 Methods: Male C57BL/6J mice at 10 weeks of age were housed in conventional cages and given sterile saline for the control group or CL316,243 (1 μg/g) for the experimental group via intraperitoneal injection for 1, 3, and 5 days. Food intake and body weight were measured daily. Interscapular brown adipose tissue (iBAT), inguinal subcutaneous white adipose (sWAT) and epididymal white adipose tissue (eWAT) were harvested for histological and gene expression analysis.
 Results: Compared with the control group, intraperitoneal injection of CL316,243 reduced the weight of eWAT on the first day. Meanwhile, CL316,243 continuously promoted the mRNA and protein expression of uncoupling protein-1 (UCP-1) in sWAT and eWAT. Furthermore, CL316,243 injection significantly decreased the food intake and weight gain of the mice, and reduced the diameter of adipocyte and accumulation of small lipid droplets in adipose tissues.
 Conclusion: CL316,243 can induce the brown-like remodeling in adipose tissues of mice in vivo, which show different time-dependent manners in different adipose tissues.
Adipose Tissue, Brown ; Adipose Tissue, White ; Adrenergic beta-Agonists ; Animals ; Male ; Mice ; Mice, Inbred C57BL ; Uncoupling Protein 1

OBJECTIVE: To explore the intervention measures to maintain clinical control in children with asthma in the remission stage when concomitant with acute upper respiratory infection (AURI). METHODS: A total of 100 asthmatic children who had achieved clinical control were randomly divided into observation group and control group. The two groups were both treated with a combination of inhaled corticosteroids and long-acting β2 receptor agonist (ICS/LABA) at the lowest dose every night. Conventional therapies were used for the two groups when suffering from AURI. In addition to conventional therapies, the observation group was given early short-term upgrade therapy, i.e., on the basis of maintenance therapy, the same amount of ICS/LABA complex preparation was inhaled every morning, which lasted for 7-10 days. Both groups were treated following asthma guidelines according to the severity of the disease at the time of acute attacks. The control rate of asthma, severity of acute attacks, changes in pulmonary function indices, and occurrence of adverse events were evaluated after 3, 6, 9, and 12 months of treatment. RESULTS: At each time point of follow-up, the rate of asthma control in the observation group was significantly higher than that in the control group (90% vs 80%; P<0.05). The severity of acute attacks in the observation group was significantly lower than that in the control group at all follow-up time points (P<0.05). Compared with the control group, the observation group had significantly improved pulmonary function indices of large and small airways (P<0.05) and significantly reduced mean amount of inhaled glucocorticoids and impact on family life (P<0.01). CONCLUSIONS Early short-term upgrade therapy for children with asthma in the remission stage when concomitant with AURI can prevent acute attacks of asthma, raise the rate of asthma control and improve pulmonary function.
Administration, Inhalation ; Adrenal Cortex Hormones ; Adrenergic beta-Agonists ; Anti-Asthmatic Agents ; Asthma ; Child ; Drug Therapy, Combination ; Humans

Dexmedetomidine is a potent, highly selective α-2 adrenoceptor agonist, with sedative, analgesic, anxiolytic, sympatholytic, and opioid-sparing properties. Dexmedetomidine induces a unique sedative response, which shows an easy transition from sleep to wakefulness, thus allowing a patient to be cooperative and communicative when stimulated. Dexmedetomidine may produce less delirium than other sedatives or even prevent delirium. The analgesic effect of dexmedetomidine is not strong; however, it can be administered as a useful analgesic adjuvant. As an anesthetic adjuvant, dexmedetomidine decreases the need for opioids, inhalational anesthetics, and intravenous anesthetics. The sympatholytic effect of dexmedetomidine may provide stable hemodynamics during the perioperative period. Dexmedetomidine-induced cooperative sedation with minimal respiratory depression provides safe and acceptable conditions during neurosurgical procedures in awake patients and awake fiberoptic intubation. Despite the lack of pediatric labelling, dexmedetomidine has been widely studied for pediatric use in various applications. Most adverse events associated with dexmedetomidine occur during or shortly after a loading infusion. There are some case reports of dexmedetomidine-related cardiac arrest following severe bradycardia. Some extended applications of dexmedetomidine discussed in this review are promising, but still limited, and further research is required. The pharmacological properties and possible adverse effects of dexmedetomidine should be well understood by the anesthesiologist prior to use. Moreover, it is necessary to select patients carefully and to determine the appropriate dosage of dexmedetomidine to ensure patient safety.
Adrenergic alpha-Agonists ; Analgesics ; Analgesics, Opioid ; Anesthetics ; Anesthetics, Intravenous ; Bradycardia ; Conscious Sedation ; Delirium ; Dexmedetomidine ; Heart Arrest ; Hemodynamics ; Humans ; Hypnotics and Sedatives ; Intubation ; Neurosurgical Procedures ; Patient Safety ; Perioperative Period ; Respiratory Insufficiency ; Sympatholytics ; Wakefulness

BACKGROUND AND OBJECTIVES: Knowing the ototoxic potential of the agents used in medical treatments is important for the protection of hearing. Although we have knowledge regarding some effects of dexmedetomidine, which is an anesthetic-sparing drug, its influence over the hearing system has never been studied and is obscure yet. The aim of this study is to determine the effects of intravenous dexmedetomidine application during sevoflurane anesthesia on otoacoustic emissions (OAEs). SUBJECTS AND METHODS: This prospective randomized study was performed on 60 patients (34 male, 26 female, mean age: 30.6±9.2 years) who were scheduled for an elective surgery under general anesthesia and the patients were enrolled and randomly divided into 2 groups. They received dexmedetomidine (Group D) or Saline (Group S) infusion during a standardized Sevoflurane anesthesia. Transient and distortion product OAEs were measured preoperatively and postoperatively (24th hour). OAE results were compared within and between groups. RESULTS: In group D postoperative OAEs were lower than preoperative OAEs and postoperative levels of group S, especially at low frequencies (p<0.05). CONCLUSIONS: Dexmedetomidine infusion affects the micromechanical function of cochlea especially in the low-frequency region. Dexmedetomidine should be carefully used during general anesthesia to avoid its probable harmful effects on cochlear micromechanics.
Adrenergic alpha-2 Receptor Agonists ; Anesthesia ; Anesthesia, General ; Cochlea ; Dexmedetomidine ; Female ; Hearing ; Humans ; Male ; Prospective Studies

BACKGROUND: This study evaluated the effect of decrease in loading dose administration rate of dexmedetomidine (DMT) on sedation and DMT requirement in elderly patients. METHODS: Fifty-eight patients over 65 years old with ASA I–II who were planned to receive DMT sedation during spinal anesthesia were randomly assigned to two groups. Group S (n = 29) received a 0.5 µg/kg DMT loading dose over 20 minutes, while group C (n = 29) received the DMT loading dose over 10 minutes. Then, both groups received a continuous infusion of 0.4 µg/kg/h. The sedative status was recorded before and at 5, 10, 15, 20, 25, and 30 minutes after administration of DMT and at the end of the anesthesia according to the Ramsay sedation scale (RSS). Also, the time to reach RSS-3 (patients asleep, responsive to commands) and the dose of DMT until reaching RSS-3 were recorded. RESULTS: The time to reach RSS-3 was similar between the two groups (group S = 16.0 ± 4.3 minutes vs. group C = 15.5 ± 4.2 minutes, P = 0.673). However, the DMT required to reach RSS-3 in group S was significantly lower than that in group C (23.3 ± 7.1 vs. 32.5 ± 6.0 µg, P < 0.001). There was no difference in RSS between the two groups from the administration of DMT to the end of the anesthesia (P = 0.927). CONCLUSIONS: Decreasing the administration rate of the DMT loading dose did not delay the onset of RSS-3 sedation and reduced the DMT requirement in elderly patients.
Adrenergic alpha-2 Receptor Agonists ; Aged* ; Anesthesia ; Anesthesia, Spinal* ; Dexmedetomidine* ; Humans ; Hypnotics and Sedatives

Adrenal Cortex Hormones ; metabolism ; Adrenergic beta-2 Receptor Agonists ; metabolism ; Humans ; Multiple Pulmonary Nodules ; diagnosis ; metabolism ; pathology ; Pulmonary Disease, Chronic Obstructive ; diagnosis ; metabolism ; pathology ; World Health Organization