Relationship of GRK5 and oxidative stress in sustained βAR-stimulated cardiac hypertrophy / 国际生物医学工程杂志

Objective To explore the role of GRK5 in sustained β adrenergic receptor (βAR)-stimulated increased levels of oxidative stress.Methods Male SD rats (180-200 g) were separated into 4 groups according to the random principal: control group (CTRL), control with NAC supplement group (CTRL+NAC), ISO treated group (ISO), and ISO treated with NAC supplement group (ISO+NAC), with 6 rats in each group.ISO group was treated by method of intraperitoneal injection for 3 mg/(kg· d).CTRL rats received same volume of physiological saline by same method, while NAC was treated by supplement in drinking water for 15 g/L per day.After 2 weeks of treatment, BP, heart mass index (HMI), histology changes, expression of NOX4 and GRK5 of myocardium was examined.Results HMI of ISO rats was significantly higher than that of the CTRL group [(3.99±0.10 vs 3.31±0.13) mg/g, P＜0.05], and the cardio-myocyte cross-sectional area of ISO group was also significantly increased compared with CTRL group [(11 117.00±387.57 vs 4572.23±176.39) μm, P＜O.05].ISO+NAC significantly reduced the ISO-induced increases of heart weight index (3.56±0.12 mg/g, vs ISO, P＜0.05) and myocyte cross-sectional area (6160.33±141.44 μm2, vs ISO,P＜0.05).The immunohistochemistry results showed that the expression of myocardial NOX4 of ISO group was significantly higher than that of CTRL group [(10.59±1.61 vs 4.35±1.65), P＜0.05], and NAC reduced the ISO induced NOX4 expression increase [(4.67±1.25 vs 10.59±1.61), P＜0.05].Western Blot and immunohistochemistry were used to detect the protein expression of myocardial GRK5.Both results showed that there were no significant differences between ISO and CTRL, ISO+NAC and ISO group (P＞0.05).RT-qPCR detected no significant differences of myocardial GRK5 mRNA expression between ISO and CTRL, ISO+NAC and ISO groups (P＞0.05).Arterial blood pressure showed no significant difference among the 4 groups of rats (P＞0.05).No significant differences were found between rats from CTRL+NAC and CTRL group.Conclusions In the mechanism of sustained βAR-stimulated cardiac hypertrophy, GRK5 may not participate the regulation of hypertrophy-induced factor, and this process needs to be proved in further study.

Distribution of 5-HT3, 5-HT4, and 5-HT7 Receptors Along the Human Colon

BACKGROUND/AIMS: Several disorders of the gastrointestinal tract are associated with abnormal serotonin (5-HT) signaling or metabolism where the 5-HT3 and 5-HT4 receptors are clinically relevant. The aim was to examine the distribution of 5-HT3, 5-HT4, and 5-HT7 receptors in the normal human colon and how this is associated with receptor interacting chaperone 3, G protein coupled receptor kinases, and protein LIN-7 homologs to extend previous observations limited to the sigmoid colon or the upper intestine. METHODS: Samples from ascending, transverse, descending, and sigmoid human colon were dissected into 3 separate layers (mucosa, longitudinal, and circular muscles) and ileum samples were dissected into mucosa and muscle layers (n = 20). Complementary DNA was synthesized by reverse transcription from extracted RNA and expression was determined by quantitative or end point polymerase chain reaction. RESULTS: The 5-HT3 receptor subunits were found in all tissues throughout the colon and ileum. The A subunit was detected in all samples and the C subunit was expressed at similar levels while the B subunit was expressed at lower levels and less frequently. The 5-HT3 receptor E subunit was mainly found in the mucosa layers. All splice variants of the 5-HT4 and 5-HT7 receptors were expressed throughout the colon although the 5-HT4 receptor d, g, and i variants were expressed less often. CONCLUSIONS: The major differences in 5-HT receptor distribution within the human colon are in relation to the mucosa and muscular tissue layers where the 5-HT3 receptor E subunit is predominantly found in the mucosal layer which may be of therapeutic relevance.

Alterations of epinephrine-induced gluconeogenesis in aging

The effects of glucagon and epinephrine on gluconeogenesis in young (4 month) and old (24 month) Fisher 344 rat hepatocytes were compared. In contrast to glucagon, which had a similar effect on gluconeogenesis in both young and old cells, epinephrine caused a smaller increase in gluconeogenesis in old rat hepatocytes than in young hepatocytes. beta2 adrenergic receptor (beta2-AR) expression slightly decreased in aged rat liver, and there were differences between young and old hepatocytes in their patterns of G protein coupled receptor kinases, which are involved in the activation of beta2-AR receptor signal desensitization. The major isoform of the kinase changed from GRK2 to GRK3 and the expression of beta-arrestin, which is recruited by the phosphorylated beta2-AR for internalization and degradation, increased in aged rat liver. GRK3 overexpression also decreased the glucose output from young rat hepatocytes. We conclude that an age-associated reduction in epinephrine-induced gluconeogenesis occurs through the epinephrine receptor desensitizing system.

Alterations of epinephrine-induced gluconeogenesis in aging

The effects of glucagon and epinephrine on gluconeogenesis in young (4 month) and old (24 month) Fisher 344 rat hepatocytes were compared. In contrast to glucagon, which had a similar effect on gluconeogenesis in both young and old cells, epinephrine caused a smaller increase in gluconeogenesis in old rat hepatocytes than in young hepatocytes. beta2 adrenergic receptor (beta2-AR) expression slightly decreased in aged rat liver, and there were differences between young and old hepatocytes in their patterns of G protein coupled receptor kinases, which are involved in the activation of beta2-AR receptor signal desensitization. The major isoform of the kinase changed from GRK2 to GRK3 and the expression of beta-arrestin, which is recruited by the phosphorylated beta2-AR for internalization and degradation, increased in aged rat liver. GRK3 overexpression also decreased the glucose output from young rat hepatocytes. We conclude that an age-associated reduction in epinephrine-induced gluconeogenesis occurs through the epinephrine receptor desensitizing system.

Relationships of ?-AR and GRK2 in lung,lung injury in rats with severe acute pancreatitis and therapeutic effect by methlyprednisolone / 中国病理生理杂志

AIM: To investigate the variation of ?-AR in pulmonary microvascular endothelial cells and variation of GRK2 in lung and to explore the therapeutic effect of methlyprednisolone in severe acute pancreatitis-associated lung injury model in rats.METHODS: 36 rats were divided into three groups randomly: the control group,the experimental group,and the intervention group.In the experimental group,severe acute pancreatitis-associated lung injury model was induced in SD rats by retrograde injection of 5% sodium taurocholate into biliopancreatic duct.In the control group,laparotomy was performed,duodenum and pancreas were flipped only.In the intervention group,methlyprednisolone(30 mg/kg) was injected into rump muscle of rats after model developed.At 6 and 12 h after model was developed,the maximum binding capacity(Bmax) and the Kd value of ?-AR were detected in lung by means of radioactive ligand binding assay.GRK2 expression was detected in lung by means of immunofluorescence.RESULTS: The scores of the severity of pancreatitis and the severity of lung injury in the experimental group were obviously higher than those in control group.In the experimental group,Bmax was obviously lower,Kd and GRK2 were obviously higher than those in control group and the intervention group.CONCLUSION: The ?-AR in lung is lower down and GRK2 expression in lung is up-regulated in severe acute pancreatitis-associated lung injury model in rats.The therapeutic effect of methlyprednisolone to severe acute pancreatitis-associated lung injury is positive.

Correlation between of G protein-coupled receptor kinases 4 polymorphism and essential hypertension:a Meta-analysis / 第三军医大学学报

Objective To access the relationship between the polymorphism of G protein-coupled receptor kinases 4(GRK4,including R65L,A486V and A142V) and essential hypertension.Methods All the literature on the subjects was searched by keywords such as essential hypertension,hypertension,G protein-coupled receptor kinases 4 gene,and polymorphism in the electronic databases,Medline of Year 1997 to 2006.RevMan 4.2 software was used for Meta analysis.Results A total of 857 cases and 913 controls from 4 studies were included.The ORs of genotypes of R65L,A142V and A486V were 0.97(0.75 to 1.25,P=0.81),0.81(0.30 to 2.08,P=0.65) and 1.48(1.16 to 1.8,P=0.001) respectively.Conclusion GRK4 gene polymorphism A486V is significantly associated with susceptibility of essential hypertension.People who carries A486V have a higher risk to be subject to essential hypertension.