Adiponectin expression and the cardioprotective role of the vitamin D receptor activator paricalcitol and the angiotensin converting enzyme inhibitor enalapril in ApoE-deficient mice.

The aim of this study was to explore the association between the expression of adenosine monophosphate-activated protein kinase (AMPK) pathway and adiponectin (APN), leptin, and vascular endothelial function in rats with coronary heart disease (CHD). Experimental rats were divided into three groups, including: control (Col) group, CHD model (CHD) group, and CHD+AMPK activator (CHD+AICAR) group. Except those in Col group, all rats were fed with high-fat diet and intraperitoneally injected with pituitrin to establish the CHD model. The levels of serum APN, leptin, and endothelin-1 (ET-1) were determined via enzyme-linked immunosorbent assay (ELISA). The content of serum nitric oxide (NO) was detected using the nitrate reductase method. Meanwhile, the expression of AMPK pathway-related protein AMPKα in vascular endothelial tissues was detected via Western blotting (WB). Aortic vascular endothelial cells (VECs) were cultured with AICAR or ET-1 in vitro. Subsequently, the expressions of AMPK pathway and protein kinase B (AKT) pathway-related proteins were determined through co-immunoprecipitation and WB. Moreover, the expression level of NO in VECs was determined using the DAF-FM DA fluorescence probe. Compared with Col group, CHD group showed significantly decreased levels of serum APN and NO (p<0.05), significantly increased the levels of leptin and ET-1 (p<0.05), as well as remarkably decreased protein expression of p-AMPKα in vascular endothelial tissues (p<0.05). After injection of AMPK activator AICAR (200 mg/kg), the protein expression of p-AMPKα in CHD rats was significantly activated (p<0.05). The levels of serum APN and NO were remarkably upregulated (p<0.05), while the levels of leptin and ET-1 were significantly reduced (p<0.05). Besides, AICAR could evidently activate the activity of AMPK pathway in VECs in vitro, upregulate the protein levels of p-eNOS (Ser1177) and p-AMPKα, and promote the secretion of NO (p<0.05). In addition, AICAR remarkably inhibited ET-1-induced expression of AKT pathway (p<0.05). Activating the AMPK pathway may play a positive role in the normal function of VECs and exert a certain curative effect on CHD in rats.

Effect of dietary carbohydrate challenge on activation of 5’-adenosine monophosphate activated protein kinase (AMPK) in liver, skeletal muscle, and digital laminae of lean and obese ponies

Adipokine, chemokine, and cytokine expression profiles in adipose tissue depots of lean and overweight ponies

Berberine (BBR) has been shown to improve several metabolic disorders, such as obesity, type 2 diabetes, and dyslipidemia, by stimulating AMP-activated protein kinase (AMPK). However, the effects of BBR on proinflammatory responses in macrophages are poorly understood. Here we show that BBR represses proinflammatory responses through AMPK activation in macrophages. In adipose tissue of obese db/db mice, BBR treatment significantly downregulated the expression of proinflammatory genes such as TNF-alpha, IL-1beta, IL-6, monocyte chemoattractant protein-1 (MCP-1), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2). Consistently, BBR inhibited LPS-induced expression of proinflammatory genes including IL-1beta, IL-6, iNOS, MCP-1, COX-2, and matrix metalloprotease-9 in peritoneal macrophages and RAW 264.7 cells. Upon various proinflammatory signals including LPS, free fatty acids, and hydrogen peroxide, BBR suppressed the phosphorylation of MAPKs, such as p38, ERK, and JNK, and the level of reactive oxygen species in macrophages. Moreover, these inhibitory effects of BBR on proinflammatory responses were abolished by AMPK inhibition via either compound C, an AMPK inhibitor, or dominant-negative AMPK, implying that BBR would downregulate proinflammatory responses in macrophages via AMPK stimulation.

Cardiac expression of adiponectin and its receptors in streptozotocin-induced diabetic rats

Objective To explore the effect of insulin on the expression of adiponectin, adiponectin receptors, and adiponectin receptor-mediated signaling pathways in the testes of type 1 diabetic rats. Methods Thirty male 6- week Sprague - Dawley(SD) rats(body weight: 180- 200 g) were randomly divided into normal control group (group A,n=8) and streptozotocin injection group(n=22) by using random number table. Type 1 diabetic model was established by intraperitoneal injection of streptozotocin. Sixteen successfully- induced diabetic rats were randomly divided into diabetic group(group B,n=8) and diabetic treated with insulin(group C,n=8). Rats in group B were given subcutaneous protamine-zinc insulin in does of 3-5 U daily to control blood glucose at 10 mmol/L. The other two groups were given equal volume of normal saline daily. At the end of the eight-week of experiment, rats were sacrificed after blood samples were collected, and then the bilateral testes were collected quickly. Blood samples were used to detect the levels of biochemical index, insulin, adiponectin and sex hormone. Sperm number and motility were counted. The expression of testicular adiponectin, adiponectin receptors, adenosine 5'- monophosphate (AMP)- activated protein kinase(AMPK), protein kinase B(AKT), endothelial nitric oxide synthase(e- NOS), nitric oxide(NO), interleukin-6(IL-6), and tumor necrosis factor alpha(TNF-α) were assayed. Statistical analysis was performed by using LSD-t test and one way ANOVA. Results There were significant pathological changes in the testes of group B than those in group A. Compared with group A, the level of testes weight, sperm number and motility were decreased in group B(t=3.899, 21.139, 26.770, allP<0.05), the testicular adiponectin and its receptor 1, the ratio of p-AMPK to AMPK were significantly decreased in group B ((0.66±0.09) vs (1.00± 0.00), (0.68±0.05) vs (1.00±0.00), (0.34±0.11) vs (1.00±0.00),t=8.658, 14.297, 5.551, respectively, allP< 0.05); however, the level of the ratio of p-AKT to AKT, e-NOS in the testes were significantly increased in group B (1.54±0.27 vs 1.00±0.00, 1.56±0.26 vs 1.00±0.00,t=5.083, 4.997, respectively, bothP<0.05). These changes could be significantly reversed by insulin treatment. Compared with group B, the level of testes weight, sperm number and motility were increased in group C (t=3.444, 18.453, 23.103, allP<0.05); the level of adiponectin and its receptor 1, the ratio of p- AMPK to AMPK were significantly increased in group C (0.85±0.11 vs 0.66±0.09, 0.82±0.06 vs 0.68±0.05, 0.87±0.40 vs 0.34±0.11,t=4.969, 6.151, 4.454, respectively, allP<0.05); surely, the level of the ratio of p-AKT to AKT, e-NOS were significantly decreased in group B than those in group A (1.31±0.25 vs 1.54±0.27, 1.24±0.29 vs 1.56±0.26,t=2.169, 2.830, respectively, bothP<0.05). Conclusions Adiponectin and its receptors and adiponectin receptor-mediated signaling pathway may play an important role in testicular tissue injury in diabetic rats. Insulin may reduce the the degree of testicular tissue damage and produce the protective effect on testicular tissues in diabetic rats by regulating the expression of adiponectin, adiponectin receptors and adiponectin receptor- mediated signaling pathways. Key words: Diabetes mellitus, type 1; Adiponectin; Testes; Rats; Insulin

Background The renoprotective mechanisms of adenosine monophosphate (AMP)-activated protein kinase (AMPK) agonist - metformin have not been stated clearly. We hypothesized that metformin may ameliorate inflammation via AMPK interaction with critical inflammatory cytokines. The aim of this study was to observe the effects of metformin on expression of nuclear factor-κB (NF-κB), monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1) and transforming growth factor-beta 1 (TGF-β1) induced by high glucose (HG) in cultured rat glomerular mesangial cells (MCs). Methods MCs were cultured in the medium with normal concentration glucose (group NG, 5.6 mmol/L), high concentration glucose (group HG, 25 mmol/L) and different concentrations of metformin (group M1, M2, M3). After 48-hour exposure, the supernatants and MCs were collected. The expression of NF-κB, MCP-1, ICAM-1, and TGF-β1 mRNA was analyzed by real time polymerase chain reaction. Western blotting was used to detect the expression of AMPK, phospho-Thr-172 AMPK (p-AMPK), NF-κB p65, MCP-1, ICAM-1, and TGF-β1 protein. Results After stimulated by HG, the expression of NF-κB, MCP-1, ICAM-1, TGF-β1 mRNA and protein of MCs in group HG increased significantly compared with group NG (P &lt;0.05). Both genes and protein expression of NF-κB, MCP-1, ICAM-1, TGF-β1 of MCs induced by high glucose were markedly reduced after metformin treatment in a dose-dependent manner (P &lt;0.05). The expression of p-AMPK increased with the rising of metformin concentration, presenting the opposite trend, while the level of total-AMPK protein was unchanged with exposure to HG or metformin. Conlusion Metformin can suppress the expression of NF-κB, MCP-1, ICAM-1 and TGF-β1 of glomerular MCs induced by high glucose via AMPK activation, which may partly contribute to its reno-protection.

Metformin inhibits inflammatory response via AMPK–PTEN pathway in vascular smooth muscle cells

Objective To investigate the role of AMP activated protein kinase (AMPK)signal in the modulation of Clq/TNF related protein 3 (CTRP3) on the expression of adiponectin in adipocytes.Methods The 3T3-L1 adipocytes were divided into control group,CTRP3 (250 μg/L) intervention group and CTRP3 (250 μg/L)+ Compound C (10 μmol/L pretreated for 1 h) intervention group.The content of adiponectin in supernatant was detected by enzyme linked immunosorbent assay.The relative expression of adiponectin mRNA was detected by real-time polymerase chain reaction.The relative expression of AMPK (thr172) was detected by Western blot.Results Compared with control group,expression of adiponectin mRNA and protein increased 53.0％ (q =15.09,P＜0.01) and 63.3％ (q =8.11,P＜0.01) respectively,the expression of AMPK(thr172) increased 43.0％ (q =14.64,P＜0.01) in CTRP3 intervention group.Compared with CTRP3 intervention group,the expression of AMPK(thr172) in CTRP3+ Compound C intervention group decreased 57.3％ (q =27.92,P＜0.01),expression of adiponectin mRNA and protein decreased 26.1％ (q =11.39,P＜0.01) and 54.1％ (q =11.31,P＜0.01) respectively.Conclusion AMPK signal participates in the modulation of CTRP3 on the expression of adiponectin in 3T3-L1 adipocytes. Key words: CTRP3 ; 3T3-L1 adipocytes; Adiponectin; AMPK

Analysis of Recent Papers in Hypertension. Jan Basile, MD, Section Editor

ACE inhibitors to block MMP-9 activity: New functions for old inhibitors

Differences in AMPK expression between subcutaneous and visceral adipose tissue in morbid obesity

Section 7: Heart Failure in Patients With Left Ventricular Systolic Dysfunction

Aim: The increase in monocyte chemoattractant protein-1 (MCP-1) and the decrease in adiponectin production from hypertrophic adipocytes are associated with adipose tissue inflammation and its metabolic complications. The aim of this study was to determine whether 5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR), an adenosine monophosphate-activated protein kinase (AMPK) activator, modulates these adipocytokine productions in tumor necrosis factor-α (TNFα)-treated adipocytes.Methods: AICAR and/or other reagents were added to the culture medium, and then, TNFα was added to fully differentiated 3T3-L1 adipocytes. The MCP-1 and adiponectin production in the culture supernatant was measured by ELISA. AMPK, phosphatidylinositol 3-kinase (PI3K), and nuclear factor-κB (NF-κB) activities were also assayed.Results: Treatment with TNFα increased MCP-1 and decreased adiponectin secretion dose-dependently in the 3T3-L1 adipocytes, and AICAR significantly inhibited these TNFα-mediated changes. Interestingly, metformin, another AMPK activator, did not have such effects on these adipocytokines. Both the AMPK and PI3K systems in the cells were significantly activated by the AICAR treatment, but the effects of AICAR on adipocytokines were not weakened by the addition of dorsomorphin, an AMPK inhibitor, or LY294002, a PI3K inhibitor. Pyrrolidine dithiocarbamate (PDTC), an NF-κB inhibitor, showed protective effects similar to those as AICAR. AICAR, but not metformin, significantly inhibited the TNFα-stimulated activation of NF-κB, and dorsomorphin did not change AICAR's effect.Conclusion: AICAR attenuates the TNFα-induced secretion of MCP-1 and adiponectin in 3T3-L1 adipocytes. The observed effects of AICAR seem to be mainly due to the inhibition of NF-κB activation rather than the activation of the AMPK pathway, at least in TNFα-treated adipocytes.

The increased expression of heme oxygenase-1 content, a stress-response protein, directly correlates with the incidence of coronary heart disease. Down-regulation of hypoxia inducible factor-1alpha activity, a major downstream effector of the signaling pathways activated by hypoxia, increases cell survival after hypoxia. The ubiquitin system, a non-lysosomal pathway of protein degradation, is involved in processes of coronary heart disease. The aim of this study was to investigate the expression of heme oxygenase-1, hypoxia inducible factor-1alpha, and ubiquitin in both monocytes and lymphocytes isolated from patients at the mRNA and protein levels in different stages of coronary heart disease and their possible correlation. A total of 90 patients with coronary heart disease (30 acute myocardial infarction, 30 unstable angina pectoris, and 30 stable angina pectoris) were selected, and 30 cases with normal coronary artery served as controls. The mRNA and protein expression of heme oxygenase-1, hypoxia inducible factor-1alpha, and ubiquitin in monocytes and lymphocytes were examined by semi-quantitative reverse transcriptase polymerase chain reaction and Western blotting, respectively. The mRNA expression of heme oxygenase-1 and ubiquitin was associated with the severity of coronary heart disease (p<0.05). There was no significant difference in hypoxia inducible factor-1alpha mRNA expression between the coronary heart disease patients and controls. The protein expression of heme oxygenase-1, hypoxia inducible factor-1alpha, and ubiquitin was significantly stronger in patients with coronary heart disease than in controls, and the expression levels increased with the severity of the disease. There was a positive association between heme oxygenase-1 and hypoxia inducible factor-1alpha and ubiquitin, antioxidative therapy with adrenergic receptor blocker, angiotensin-converting enzyme inhibitor or statins up-regulated the expression of heme oxygenase-1 and hypoxia inducible factor-1alpha. These data suggest that heme oxygenase-1, hypoxia inducible factor-1alpha, and ubiquitin are involved in the development and progression of coronary heart disease and thus may be useful biomarkers for coronary heart disease.