Background β2-adrenoceptor （β2AR） desensitization is a common problem in clinical practice, β2AR desensitization proceeds by at least such three mechanisms as heterologous desensitization, homologous desensitizat...Background β2-adrenoceptor （β2AR） desensitization is a common problem in clinical practice, β2AR desensitization proceeds by at least such three mechanisms as heterologous desensitization, homologous desensitization and a kind of agonist-induced rapid phosphorylation by a variety of serine/threonine kinases. It is not clear whether there are other mechanisms, This study aimed to investigate potential mechanisms of β2AR desensitization.Methods Twenty-four BALB/c （6-8 weeks old） mice were divided into three groups, which is, group A, phosphate buffered saline （PBS）-treated; group B, ovalbumin （OVA）-induced; and group C, salbutamol-treated. Inflammatory cell counts, cytokine concentrations of bronchoalveolar lavage fluid （BALF）, pathological sections, total serum IgE, airway responsiveness, membrane receptor numbers and total amount of β2AR were observed. Asthmatic mouse model and β2AR desensitization asthmatic mouse model were established. Groups B and C were selected for two-dimensional gel electrophoresis （2DE） analysis so as to find key protein spots related to β2AR desensitization.Results Asthmatic mouse model and β2AR desensitization asthmatic mouse model were verified by inflammatory cell count, cytokine concentration of BALF, serum IgE level, airway hyperreactivity measurement, radioligand receptor binding assay, Western blot analysis, and pathologic examination. Then the two groups （groups B and C） were subjected to 2DE. Two key protein spots associated with β2AR desensitization, Rho GDP-dissociation inhibitor 2 （RhoGDl2） and peroxiredoxin 5, were found by comparative proteomics （2DE and mass spectrum analysis）.Conclusion Oxidative stress and small G protein regulators may play an important role in the process of β2AR desensitization.v展开更多
Objective:To establish and verify aβ_(2)-AR desensitization asthma mice model.Methods:A total of 30 SPF male BALB/c mice were randomly divided into blank group,the common asthma group,andβ_(2)-AR desensitization ast...Objective:To establish and verify aβ_(2)-AR desensitization asthma mice model.Methods:A total of 30 SPF male BALB/c mice were randomly divided into blank group,the common asthma group,andβ_(2)-AR desensitization asthma model group.Asthma model was established,and on this basis,the method of atom-izing inhalation and intraperitoneal injections of salbutamol was used to prepareβ_(2)-AR desensitization asthma model.After the last stimulation on the 21st day of modeling,the airway resistance of mice was measured.ELISA was used to detect the content of serum IgE;HE staining was used to observe the lung organization degree of infla-mmatory cell infiltration;Western blot method was used to detect theβ_(2)-AR content in lung tissue,RT-PCR was used to detect theβ_(2)-ARmRNA expressionin lung tissue.Results:Compared with the blank group,as acetyl choline(Mch)levels increased,groups of OVA induced airway resistance increases;but theβ_(2)-AR desensitization asthma model group increased airway resistance was more significant(P<0.05);compared with the blank group,IgE levels of common asthma group andβ_(2)-AR desensitization asthma model group elevated(P<0.01).The pathological histology observation found theβ_(2)-AR desensitization asthma airway inflammation infiltration in mice,the excessive mucus secretion and collagen deposition,and the pathological performance obviously increase compared with the common asthma group;β_(2)-AR content in the lung tissue ofβ_(2)-AR desensitization asthma model in mice,β_(2)-AR mRNA expression level in the blank group and common asthma model group were significantly decreased(P<0.05).Conclusion:Theβ_(2)-AR desensitization asthma mouse model was successfully established,and the buildingcycle was short.展开更多
Obstructive airway disease is a complex disease entity including several maladies characterized by bronchoconstriction and abnormal airway inflammation. Reversing bronchoconstriction leads to symptomatic relief and im...Obstructive airway disease is a complex disease entity including several maladies characterized by bronchoconstriction and abnormal airway inflammation. Reversing bronchoconstriction leads to symptomatic relief and improvement in quality of life, both in reversible(bronchial asthma) and partially reversible(chronic obstructive airway disease) obstructive airway diseases. β2-adrenoceptor expressed in human airway is the main β-receptor subtype, and its activation in airway smooth muscle cells leads to bronchodilatation. Drugs targeting β-adrenoceptors have been around for many years, for which agonists of the receptors are used in bronchodilation while antagonists are used in cardiovascular diseases. This review article summarizes the effect and usage of β2-agonist in obstructive airway disease, addressing the benefits and potential risks of β2-agonist. The article also looks at the safety of β-blocker usage for cardiovascular disease in patients with obstructive airway disease. There is also emerging evidence that non-selective β-blockers with inverse agonism ironically can have longterm beneficial effects in obstructive airway disease that is beyond cardiovascular protection. Further trials are urgently needed in this area as it might lead to a dramatic turnaround in clinical practice for obstructive airway diseases as has already been seen in the usage of β-blockers for heart failure.展开更多
BACKGROUND: The increased β-arrestin-2 and its combination with G-protein-coupled receptors (GPCRs) lead to GPCRs desensitization. The latter may be responsible for decreased contractile reactivity in the mesenteric ...BACKGROUND: The increased β-arrestin-2 and its combination with G-protein-coupled receptors (GPCRs) lead to GPCRs desensitization. The latter may be responsible for decreased contractile reactivity in the mesenteric arteries of cirrhotic patients and rats. The present study is to investigate the machinery changes of α-adrenergic receptors and G proteins and their roles in the contractility of mesenteric arteries of cirrhotic patients and animal models. METHODS: Patients with cirrhosis due to hepatitis B and cirrhotic rats induced by CCl 4 were studied. Mesenteric artery contractility in response to norepinephrine was determined by a vessel perfusion system. The contractile effect of G protein-coupled receptor kinase-2 (GRK-2) inhibitor on the mesenteric artery was evaluated. The protein expression of the α 1 adrenergic receptor, G proteins, β-arrestin-2, GRK-2 as well as the activity of Rho associated coiled-coil forming protein kinase-1 (ROCK-1) were measured by Western blot. In addition, the interaction of α 1 adrenergic receptor with β-arrestin-2 was assessed by co-immunoprecipitation. RESULTS: The portal vein pressure of cirrhotic patients and rats was significantly higher than that of controls. The doseresponse curve to norepinephrine in mesenteric arteriole was shifted to the right, and EC 50 was significantly increased in cirrhotic patients and rats. There were no significant differences in the expressions of the α 1 adrenergic receptor and G proteins in the cirrhotic group compared with the controls. However, the protein expressions of GRK-2 and β-arrestin-2 were significantly elevated in cirrhotic patients and rats compared with those of the controls. The interaction of the α 1 adrenergic receptor and β-arrestin-2 was significantly aggravated. This interaction was significantly reversed by GRK-2 inhibitor. Both the protein expression and activity of ROCK-1 were significantly decreased in the mesenteric artery in patients with cirrhosis compared with those of the controls, and this phenomenon was not shown in the cirrhotic rats. Norepinephrine significantly increased the activity of ROCK-1 in normal rats but not in cirrhotic ones. Norepinephrine significantly increased ROCK-1 activity in cirrhotic rats when GRK-2 inhibitor was used. CONCLUSIONS: β-arrestin-2 expression and its interaction with GPCRs are significantly upregulated in the mesenteric arteries in patients and rats with cirrhosis. These upregulations result in GPCR desensitization, G-protein dysfunction and ROCK inhibition. These may explain the decreased contractility of the mesenteric artery in response to vasoconstrictors.展开更多
Norepinephrine plays an important role in motor functional recovery after a brain injury caused by ferrous chloride.Inhibition of norepinephrine release by clonidine is correlated with motor deficits after motor corte...Norepinephrine plays an important role in motor functional recovery after a brain injury caused by ferrous chloride.Inhibition of norepinephrine release by clonidine is correlated with motor deficits after motor cortex injury.The aim of this study was to analyze the role ofα-adrenergic receptors in the restoration of motor deficits in recovering rats after brain damage.The rats were randomly assigned to the sham and injury groups and then treated with the following pharmacological agents at 3 hours before and 8 hours,3 days,and 20 days after ferrous chloride-induced cortical injury:saline,clonidine,efaroxan(a selective antagonist ofα-adrenergic receptors)and clonidine+efaroxan.The sensorimotor score,the immunohistochemical staining forα-adrenergic receptors,and norepinephrine levels were evaluated.Eight hours post-injury,the sensorimotor score and norepinephrine levels in the locus coeruleus of the injured rats decreased,and these effects were maintained 3 days post-injury.However,20 days later,clonidine administration diminished norepinephrine levels in the pons compared with the sham group.This effect was accompanied by sensorimotor deficits.These effects were blocked by efaroxan.In conclusion,an increase inα-adrenergic receptor levels was observed after injury.Clonidine restores motor deficits in rats recovering from cortical injury,an effect that was prevented by efaroxan.The underlying mechanisms involve the stimulation of hypersensitiveα-adrenergic receptors and inhibition of norepinephrine activity in the locus coeruleus.The results of this study suggest thatαreceptor agonists might restore deficits or impede rehabilitation in patients with brain injury,and therefore pharmacological therapies need to be prescribed cautiously to these patients.展开更多
Treatment of hepatitis C, even when absolutely necessary, is almost impossible when interferon cannot be administered for any reason. We report a 65-year-old patient with chronic hepatitis C virus (HCV) infection and ...Treatment of hepatitis C, even when absolutely necessary, is almost impossible when interferon cannot be administered for any reason. We report a 65-year-old patient with chronic hepatitis C virus (HCV) infection and fibrosis, who was unable to receive interferon because of systemic hypersensitivity. The patient was desensitized successfully through gradual incremental exposure to interferon, and HCV infection was eradicated after a complete course of treatment, with no further allergic reactions. This case report that describes successful eradication of hepatitis C in a patient with advanced liver disease after desensitization to interferon revealed that desensitization may not necessarily damage the therapeutic efficacy of the drug.展开更多
The aim of this study was to compare the binding profile of a range of β2-adrenoceptor (β2-AR) agonists and antagonists in human lung tissue. Radioligand saturation and competition binding experiments were performed...The aim of this study was to compare the binding profile of a range of β2-adrenoceptor (β2-AR) agonists and antagonists in human lung tissue. Radioligand saturation and competition binding experiments were performed by filtration with a β2-AR antagonist ([3H]propranolol) or agonist ([3H]vilanterol) radioligand and membrane fragments generated from lung parenchyma in the presence of 100 μM guanosine 5’-[β,γ-imido]triphosphate (Gpp(NH)p). In membranes prepared from human lung parenchyma, carmoterol, formoterol, ICI118551, propranolol and salbutamol resulted in inhibition of [3H]vilanterol binding to levels that were significantly different from indacaterol, salmeterol and vilanterol (ANOVA, Bonferroni post-test, P < 0.001 except formoterol vs indacaterol where P < 0.01). Indacaterol and salmeterol resulted in inhibition of [3H]vilanterol binding to levels that were not significantly different from vilanterol (ANOVA, Bonferroni post-test, P > 0.05). Indacaterol, salmeterol and vilanterol resulted in full inhibition of [3H]propranolol binding to levels not significantly different from ICI118551 (ANOVA, Bonferroni post-test, P > 0.05). Indacaterol, salmeterol and vilanterol bind to an additional site in human lung parenchyma membranes that is distinct from the β2-AR.展开更多
Clonidine is a classically categorized α2-adrenoceptor (α2-AR) agonist that produces vascular contractions by stimulating arterial smooth muscle α2-ARs. However, clonidine inhibits α1-AR-mediated arterial contract...Clonidine is a classically categorized α2-adrenoceptor (α2-AR) agonist that produces vascular contractions by stimulating arterial smooth muscle α2-ARs. However, clonidine inhibits α1-AR-mediated arterial contractions. Recently, it was suggested that repeated stimulation with clonidine induces desensitization of α2-ARs, thus inhibiting noradrenaline-induced smooth muscle contractions. In the present study, we examined whether clonidine-mediated inhibition of α1-AR contractions involves interactions with α2-ARs in rat thoracic aortae. 1) Clonidine and guanfacine inhibited electrical field stimulation-induced contractions in a concentration-dependent, yohimbine-sensitive manner in isolated rat vas deferens preparations. 2) Clonidine almost completely suppressed phenylephrine-induced sustained contractions of rat thoracic aortae. 3) Clonidine competitively inhibited phenylephrine-induced contractions with a pA2 value of 6.77 at concentrations between 10-7 and 10-6 M. At 10-5 M, clonidine inhibited phenylephrine-induced contractions and dramatically reduced maximum contractions. 4) In contrast, clonidine did not inhibit contractions produced by high KCl or prostaglandin F2α. 5) Inhibition of phenylephrine-induced sustained contractions by clonidine was also produced in the presence of yohimbine. However, guanfacine did not inhibit phenylephrine-induced sustained contractions. These findings suggest that clonidine inhibits phenylephrine-induced contraction of rat thoracic aortae by competitive antagonism of α1-ARs, which is mediated through a mechanism independent of α2-AR stimulation.展开更多
Antibodies against &-adrenoceptor can be detected in serum of patients with dilated cardiomyopathy (DCM), which have 5-agonist-like activity, and induce a positive chronotropic effect on cardiac myocytes by its pe...Antibodies against &-adrenoceptor can be detected in serum of patients with dilated cardiomyopathy (DCM), which have 5-agonist-like activity, and induce a positive chronotropic effect on cardiac myocytes by its persistence at full strength. Effects of the antibodies against Padrenoceptor from sera of patients with DCM on myocardial cytotoxicity and cytoplasmic free Ca2+-concentration (LCa2+ji) were observed in the cultured single layer SD rat ventricular cells by using the cytotoxicity assay and fluorescent Ca2+- indicat0r fura-2/AM. The positive sera of the anti-&adrenoceptor antibodies from patients with DCM markedly enhanced myocardial [Ca2+]i. Betaloc, a 5, -receptor blocker, might inhibit the increase of the antibody-mediated myocardial [Ca2+]i, and the sera from healthy donors had no effect on myocardial [Ca2+]i,. Our results suggest that the anti-β-adrenoceptor antibody might increase myocardial [Ca2+]i, and result in myocardial damage. The antibodies might activate receptor-gating Ca2+-channel, thereby causing myocardial [Ca2+]i, rise and calcium overload. Early use of betaloc is recommended in the treatment of dilated cardiomyopathy.展开更多
Impaired hippocampal neurogenesis is one of the early pathological features of Alzheimer＇s disease. Enhancing adult hippocampal neuro- genesis has been pursued as a potential therapeutic strategy for Alzheimer＇s dis...Impaired hippocampal neurogenesis is one of the early pathological features of Alzheimer＇s disease. Enhancing adult hippocampal neuro- genesis has been pursued as a potential therapeutic strategy for Alzheimer＇s disease. Recent studies have demonstrated that environmental novelty activates β2-adrenergic signaling and prevents the memory impairment induced by amyloid-β oligomers. Here, we hypothesized that β2-adrenoceptor activation would enhance neurogenesis and ameliorate memory deficits in Alzheimer＇s disease. To test this hypothe- sis, we investigated the effects and mechanisms of action of β2-adrenoceptor activation on neurogenesis and memory in amyloid precursor protein/presenilin 1 （APP/PS1） mice using the agonist clenbuterol （intraperitoneal injection, 2 mg/kg）. We found that β2-adrenoceptor ac- tivation enhanced hippocampal neurogenesis, ameliorated memory deficits, and increased dendritic branching and the density of dendritic spines, lhese effects were associated with the upregulation of postsynaptic density 95, synapsin 1 and synaptophysin in APP/PS1 mice. Furthermore, β2-adrenoceptor activation decreased cerebral amyloid plaques by decreasing APP phosphorylation at Thr668. These findings suggest that β2-adrenoceptor activation enhances neurogenesis and ameliorates memory deficits in APP/PS 1 mice.展开更多
Metabolic syndrome is a pre-diabetic state characterized by several biochemical and physiological alterations,including insulin resistance,visceral fat accumulation,and dyslipidemias,which increase the risk for develo...Metabolic syndrome is a pre-diabetic state characterized by several biochemical and physiological alterations,including insulin resistance,visceral fat accumulation,and dyslipidemias,which increase the risk for developing cardiovascular disease.Metabolic syndrome is associated with augmented sympathetic tone,which could account for the etiology of pre-diabetic cardiomyopathy.This review summarizes the current knowledge of the pathophysiological consequences of enhanced and sustainedβ-adrenergic response in pre-diabetes,focusing on cardiac dysfunction reported in diet-induced experimental models of pre-diabetic cardiomyopathy.The research reviewed indicates that both protein kinase A and Ca^(2+)/calmodulin-dependent protein kinase Ⅱ play important roles in functional responses mediated byβ1-adrenoceptors;therefore,alterations in the expression or function of these kinases can be deleterious.This review also outlines recent information on the role of protein kinase A and Ca^(2+)/calmodulin-dependent protein kinase Ⅱ in abnormal Ca^(2+)handling by cardiomyocytes from diet-induced models of pre-diabetic cardiomyopathy.展开更多
基金This study was supported by grants from the National Youth Natural Science Foundation of China （No. 30400191）, the National Natural Science Foundation China （No. 30570797）, and the Key Subject of＂135＂ Project of Jiangsu Province （No. 20013102）.
文摘Background β2-adrenoceptor （β2AR） desensitization is a common problem in clinical practice, β2AR desensitization proceeds by at least such three mechanisms as heterologous desensitization, homologous desensitization and a kind of agonist-induced rapid phosphorylation by a variety of serine/threonine kinases. It is not clear whether there are other mechanisms, This study aimed to investigate potential mechanisms of β2AR desensitization.Methods Twenty-four BALB/c （6-8 weeks old） mice were divided into three groups, which is, group A, phosphate buffered saline （PBS）-treated; group B, ovalbumin （OVA）-induced; and group C, salbutamol-treated. Inflammatory cell counts, cytokine concentrations of bronchoalveolar lavage fluid （BALF）, pathological sections, total serum IgE, airway responsiveness, membrane receptor numbers and total amount of β2AR were observed. Asthmatic mouse model and β2AR desensitization asthmatic mouse model were established. Groups B and C were selected for two-dimensional gel electrophoresis （2DE） analysis so as to find key protein spots related to β2AR desensitization.Results Asthmatic mouse model and β2AR desensitization asthmatic mouse model were verified by inflammatory cell count, cytokine concentration of BALF, serum IgE level, airway hyperreactivity measurement, radioligand receptor binding assay, Western blot analysis, and pathologic examination. Then the two groups （groups B and C） were subjected to 2DE. Two key protein spots associated with β2AR desensitization, Rho GDP-dissociation inhibitor 2 （RhoGDl2） and peroxiredoxin 5, were found by comparative proteomics （2DE and mass spectrum analysis）.Conclusion Oxidative stress and small G protein regulators may play an important role in the process of β2AR desensitization.v
基金General Projects of National Natural Science Fund(81873338)Key Scientific and Technological Projects in Henan Province(202102310491)Training Subjects of Leading Talents in the Department of Traditional Chinese Medicine in Henan Province(Yuweizhongyihan[2021]No.8)。
文摘Objective:To establish and verify aβ_(2)-AR desensitization asthma mice model.Methods:A total of 30 SPF male BALB/c mice were randomly divided into blank group,the common asthma group,andβ_(2)-AR desensitization asthma model group.Asthma model was established,and on this basis,the method of atom-izing inhalation and intraperitoneal injections of salbutamol was used to prepareβ_(2)-AR desensitization asthma model.After the last stimulation on the 21st day of modeling,the airway resistance of mice was measured.ELISA was used to detect the content of serum IgE;HE staining was used to observe the lung organization degree of infla-mmatory cell infiltration;Western blot method was used to detect theβ_(2)-AR content in lung tissue,RT-PCR was used to detect theβ_(2)-ARmRNA expressionin lung tissue.Results:Compared with the blank group,as acetyl choline(Mch)levels increased,groups of OVA induced airway resistance increases;but theβ_(2)-AR desensitization asthma model group increased airway resistance was more significant(P<0.05);compared with the blank group,IgE levels of common asthma group andβ_(2)-AR desensitization asthma model group elevated(P<0.01).The pathological histology observation found theβ_(2)-AR desensitization asthma airway inflammation infiltration in mice,the excessive mucus secretion and collagen deposition,and the pathological performance obviously increase compared with the common asthma group;β_(2)-AR content in the lung tissue ofβ_(2)-AR desensitization asthma model in mice,β_(2)-AR mRNA expression level in the blank group and common asthma model group were significantly decreased(P<0.05).Conclusion:Theβ_(2)-AR desensitization asthma mouse model was successfully established,and the buildingcycle was short.
基金Supported by NMRC/CBRG/0027/2012 from the National Medical Research Council of Singapore(in part)by NUHS Seed Fund R-184-000-238-112
文摘Obstructive airway disease is a complex disease entity including several maladies characterized by bronchoconstriction and abnormal airway inflammation. Reversing bronchoconstriction leads to symptomatic relief and improvement in quality of life, both in reversible(bronchial asthma) and partially reversible(chronic obstructive airway disease) obstructive airway diseases. β2-adrenoceptor expressed in human airway is the main β-receptor subtype, and its activation in airway smooth muscle cells leads to bronchodilatation. Drugs targeting β-adrenoceptors have been around for many years, for which agonists of the receptors are used in bronchodilation while antagonists are used in cardiovascular diseases. This review article summarizes the effect and usage of β2-agonist in obstructive airway disease, addressing the benefits and potential risks of β2-agonist. The article also looks at the safety of β-blocker usage for cardiovascular disease in patients with obstructive airway disease. There is also emerging evidence that non-selective β-blockers with inverse agonism ironically can have longterm beneficial effects in obstructive airway disease that is beyond cardiovascular protection. Further trials are urgently needed in this area as it might lead to a dramatic turnaround in clinical practice for obstructive airway diseases as has already been seen in the usage of β-blockers for heart failure.
基金supported by a grant from the National Natural Science Foundation of China (30972920)
文摘BACKGROUND: The increased β-arrestin-2 and its combination with G-protein-coupled receptors (GPCRs) lead to GPCRs desensitization. The latter may be responsible for decreased contractile reactivity in the mesenteric arteries of cirrhotic patients and rats. The present study is to investigate the machinery changes of α-adrenergic receptors and G proteins and their roles in the contractility of mesenteric arteries of cirrhotic patients and animal models. METHODS: Patients with cirrhosis due to hepatitis B and cirrhotic rats induced by CCl 4 were studied. Mesenteric artery contractility in response to norepinephrine was determined by a vessel perfusion system. The contractile effect of G protein-coupled receptor kinase-2 (GRK-2) inhibitor on the mesenteric artery was evaluated. The protein expression of the α 1 adrenergic receptor, G proteins, β-arrestin-2, GRK-2 as well as the activity of Rho associated coiled-coil forming protein kinase-1 (ROCK-1) were measured by Western blot. In addition, the interaction of α 1 adrenergic receptor with β-arrestin-2 was assessed by co-immunoprecipitation. RESULTS: The portal vein pressure of cirrhotic patients and rats was significantly higher than that of controls. The doseresponse curve to norepinephrine in mesenteric arteriole was shifted to the right, and EC 50 was significantly increased in cirrhotic patients and rats. There were no significant differences in the expressions of the α 1 adrenergic receptor and G proteins in the cirrhotic group compared with the controls. However, the protein expressions of GRK-2 and β-arrestin-2 were significantly elevated in cirrhotic patients and rats compared with those of the controls. The interaction of the α 1 adrenergic receptor and β-arrestin-2 was significantly aggravated. This interaction was significantly reversed by GRK-2 inhibitor. Both the protein expression and activity of ROCK-1 were significantly decreased in the mesenteric artery in patients with cirrhosis compared with those of the controls, and this phenomenon was not shown in the cirrhotic rats. Norepinephrine significantly increased the activity of ROCK-1 in normal rats but not in cirrhotic ones. Norepinephrine significantly increased ROCK-1 activity in cirrhotic rats when GRK-2 inhibitor was used. CONCLUSIONS: β-arrestin-2 expression and its interaction with GPCRs are significantly upregulated in the mesenteric arteries in patients and rats with cirrhosis. These upregulations result in GPCR desensitization, G-protein dysfunction and ROCK inhibition. These may explain the decreased contractility of the mesenteric artery in response to vasoconstrictors.
基金supported by Consejo Nacional de Ciencia y Tecnología(CONACy T)project CB 2016-287614(to RGP and ABN)by Scholarship Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica de la Universidad Nacional Autónoma de México(PAPIIT-UNAM)IA203319 and PAPIIT-UNAM IN216221 to(LERL)。
文摘Norepinephrine plays an important role in motor functional recovery after a brain injury caused by ferrous chloride.Inhibition of norepinephrine release by clonidine is correlated with motor deficits after motor cortex injury.The aim of this study was to analyze the role ofα-adrenergic receptors in the restoration of motor deficits in recovering rats after brain damage.The rats were randomly assigned to the sham and injury groups and then treated with the following pharmacological agents at 3 hours before and 8 hours,3 days,and 20 days after ferrous chloride-induced cortical injury:saline,clonidine,efaroxan(a selective antagonist ofα-adrenergic receptors)and clonidine+efaroxan.The sensorimotor score,the immunohistochemical staining forα-adrenergic receptors,and norepinephrine levels were evaluated.Eight hours post-injury,the sensorimotor score and norepinephrine levels in the locus coeruleus of the injured rats decreased,and these effects were maintained 3 days post-injury.However,20 days later,clonidine administration diminished norepinephrine levels in the pons compared with the sham group.This effect was accompanied by sensorimotor deficits.These effects were blocked by efaroxan.In conclusion,an increase inα-adrenergic receptor levels was observed after injury.Clonidine restores motor deficits in rats recovering from cortical injury,an effect that was prevented by efaroxan.The underlying mechanisms involve the stimulation of hypersensitiveα-adrenergic receptors and inhibition of norepinephrine activity in the locus coeruleus.The results of this study suggest thatαreceptor agonists might restore deficits or impede rehabilitation in patients with brain injury,and therefore pharmacological therapies need to be prescribed cautiously to these patients.
文摘Treatment of hepatitis C, even when absolutely necessary, is almost impossible when interferon cannot be administered for any reason. We report a 65-year-old patient with chronic hepatitis C virus (HCV) infection and fibrosis, who was unable to receive interferon because of systemic hypersensitivity. The patient was desensitized successfully through gradual incremental exposure to interferon, and HCV infection was eradicated after a complete course of treatment, with no further allergic reactions. This case report that describes successful eradication of hepatitis C in a patient with advanced liver disease after desensitization to interferon revealed that desensitization may not necessarily damage the therapeutic efficacy of the drug.
文摘The aim of this study was to compare the binding profile of a range of β2-adrenoceptor (β2-AR) agonists and antagonists in human lung tissue. Radioligand saturation and competition binding experiments were performed by filtration with a β2-AR antagonist ([3H]propranolol) or agonist ([3H]vilanterol) radioligand and membrane fragments generated from lung parenchyma in the presence of 100 μM guanosine 5’-[β,γ-imido]triphosphate (Gpp(NH)p). In membranes prepared from human lung parenchyma, carmoterol, formoterol, ICI118551, propranolol and salbutamol resulted in inhibition of [3H]vilanterol binding to levels that were significantly different from indacaterol, salmeterol and vilanterol (ANOVA, Bonferroni post-test, P < 0.001 except formoterol vs indacaterol where P < 0.01). Indacaterol and salmeterol resulted in inhibition of [3H]vilanterol binding to levels that were not significantly different from vilanterol (ANOVA, Bonferroni post-test, P > 0.05). Indacaterol, salmeterol and vilanterol resulted in full inhibition of [3H]propranolol binding to levels not significantly different from ICI118551 (ANOVA, Bonferroni post-test, P > 0.05). Indacaterol, salmeterol and vilanterol bind to an additional site in human lung parenchyma membranes that is distinct from the β2-AR.
文摘Clonidine is a classically categorized α2-adrenoceptor (α2-AR) agonist that produces vascular contractions by stimulating arterial smooth muscle α2-ARs. However, clonidine inhibits α1-AR-mediated arterial contractions. Recently, it was suggested that repeated stimulation with clonidine induces desensitization of α2-ARs, thus inhibiting noradrenaline-induced smooth muscle contractions. In the present study, we examined whether clonidine-mediated inhibition of α1-AR contractions involves interactions with α2-ARs in rat thoracic aortae. 1) Clonidine and guanfacine inhibited electrical field stimulation-induced contractions in a concentration-dependent, yohimbine-sensitive manner in isolated rat vas deferens preparations. 2) Clonidine almost completely suppressed phenylephrine-induced sustained contractions of rat thoracic aortae. 3) Clonidine competitively inhibited phenylephrine-induced contractions with a pA2 value of 6.77 at concentrations between 10-7 and 10-6 M. At 10-5 M, clonidine inhibited phenylephrine-induced contractions and dramatically reduced maximum contractions. 4) In contrast, clonidine did not inhibit contractions produced by high KCl or prostaglandin F2α. 5) Inhibition of phenylephrine-induced sustained contractions by clonidine was also produced in the presence of yohimbine. However, guanfacine did not inhibit phenylephrine-induced sustained contractions. These findings suggest that clonidine inhibits phenylephrine-induced contraction of rat thoracic aortae by competitive antagonism of α1-ARs, which is mediated through a mechanism independent of α2-AR stimulation.
文摘Antibodies against &-adrenoceptor can be detected in serum of patients with dilated cardiomyopathy (DCM), which have 5-agonist-like activity, and induce a positive chronotropic effect on cardiac myocytes by its persistence at full strength. Effects of the antibodies against Padrenoceptor from sera of patients with DCM on myocardial cytotoxicity and cytoplasmic free Ca2+-concentration (LCa2+ji) were observed in the cultured single layer SD rat ventricular cells by using the cytotoxicity assay and fluorescent Ca2+- indicat0r fura-2/AM. The positive sera of the anti-&adrenoceptor antibodies from patients with DCM markedly enhanced myocardial [Ca2+]i. Betaloc, a 5, -receptor blocker, might inhibit the increase of the antibody-mediated myocardial [Ca2+]i, and the sera from healthy donors had no effect on myocardial [Ca2+]i,. Our results suggest that the anti-β-adrenoceptor antibody might increase myocardial [Ca2+]i, and result in myocardial damage. The antibodies might activate receptor-gating Ca2+-channel, thereby causing myocardial [Ca2+]i, rise and calcium overload. Early use of betaloc is recommended in the treatment of dilated cardiomyopathy.
基金supported by the National Natural Science Foundation of China,No.81601121,31500968the Natural Science Foundation of Jiangsu Province of China,No.BK20150163the Fundamental Research Fund for the Central Universities of China,No.JUSRP11567
文摘Impaired hippocampal neurogenesis is one of the early pathological features of Alzheimer＇s disease. Enhancing adult hippocampal neuro- genesis has been pursued as a potential therapeutic strategy for Alzheimer＇s disease. Recent studies have demonstrated that environmental novelty activates β2-adrenergic signaling and prevents the memory impairment induced by amyloid-β oligomers. Here, we hypothesized that β2-adrenoceptor activation would enhance neurogenesis and ameliorate memory deficits in Alzheimer＇s disease. To test this hypothe- sis, we investigated the effects and mechanisms of action of β2-adrenoceptor activation on neurogenesis and memory in amyloid precursor protein/presenilin 1 （APP/PS1） mice using the agonist clenbuterol （intraperitoneal injection, 2 mg/kg）. We found that β2-adrenoceptor ac- tivation enhanced hippocampal neurogenesis, ameliorated memory deficits, and increased dendritic branching and the density of dendritic spines, lhese effects were associated with the upregulation of postsynaptic density 95, synapsin 1 and synaptophysin in APP/PS1 mice. Furthermore, β2-adrenoceptor activation decreased cerebral amyloid plaques by decreasing APP phosphorylation at Thr668. These findings suggest that β2-adrenoceptor activation enhances neurogenesis and ameliorates memory deficits in APP/PS 1 mice.
文摘Metabolic syndrome is a pre-diabetic state characterized by several biochemical and physiological alterations,including insulin resistance,visceral fat accumulation,and dyslipidemias,which increase the risk for developing cardiovascular disease.Metabolic syndrome is associated with augmented sympathetic tone,which could account for the etiology of pre-diabetic cardiomyopathy.This review summarizes the current knowledge of the pathophysiological consequences of enhanced and sustainedβ-adrenergic response in pre-diabetes,focusing on cardiac dysfunction reported in diet-induced experimental models of pre-diabetic cardiomyopathy.The research reviewed indicates that both protein kinase A and Ca^(2+)/calmodulin-dependent protein kinase Ⅱ play important roles in functional responses mediated byβ1-adrenoceptors;therefore,alterations in the expression or function of these kinases can be deleterious.This review also outlines recent information on the role of protein kinase A and Ca^(2+)/calmodulin-dependent protein kinase Ⅱ in abnormal Ca^(2+)handling by cardiomyocytes from diet-induced models of pre-diabetic cardiomyopathy.
