Cerebral klotho protein as a humoral factor for maintenance of baroreflex.

The klotho protein produced by the choroid plexus is known as a humoral factor in central nervous system. Many hormones affecting the baroreflex sensitivity have been introduced in the brain. However, role of klotho in the baroreflex sensitivity is still unknown. Recently, mutations in the klotho gene have been linked to cardiovascular diseases in both animals and human subjects. Also, silencing of brain klotho has been reported to enhance cold-induced elevation of blood pressure. Thus, we investigated the role of klotho in maintenance of central cardiovascular reflex sensitivity. Male Wistar Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs) were used. Either klotho shRNA or scramble shRNA was also ICV-infused into the brains of WKY rats to investigate the role of klotho in brain. Recombinant klotho or rat IgG was infused into the cerebral paraventricle (ICV) of SHRs for further understanding the role of klotho in hypertension. The baroreflex sensitivity was detected using the challenge with a depressor dose of sodium nitroprusside (SNP, 50 µg/kg) or with a pressor dose of phenylephrine (PE, 8 µg/kg). We found that silencing of klotho expression in the brain decreased the baroreflex sensitivity in WKY rats. Also, modulation of the blood pressure for one week altered the cardiovascular homeostasis and resulted in an increased expression of klotho in medulla oblongata. Moreover, the baroreflex sensitivity was restored in SHRs that received recombinant klotho through ICV brain. Thus, klotho is involved in the maintenance of baroreflex sensitivity in the brain.

Insulin resistance induced by zymosan as a new animal model in mice.

Insulin resistance (IR) is known as a main problem in diabetic disorders. Some animal models for research in IR have been mentioned. Each model shows merit with some disadvantages. Thus, a new animal model for IR is required. The present study used zymosan, a mixture of cell-wall particles from the yeast named Saccharomyces cerevisiae, to establish a new model of IR in mice. Also, we compared the difference of this model with fructose-rich chow-induced model and found some merits of this model. Moreover, we identified that this model induced by zymosan is reversible and IR can be reversed gradually after termination of treatment. Taken together, we suggest zymosan as a useful agent to induce IR through inflammatory pathway in mice.

Activation of receptors δ (PPARδ) by agonist (GW0742) may enhance lipid metabolism in heart both in vivo and in vitro.

It has been documented that cardiac agents may regulate the lipid metabolism through increased expression of PPARδ in cardiac cells. However, the effect on lipid metabolism by direct activation of PPARδ is still unknown. The present study applied specific PPARδ agonist (GW0742) to investigate this point in the heart of Wistar rats and in the primary cultured cardiomyocytes from neonatal rat. Expressions of PPARδ in the heart and cardiomyocytes after treatment with GW0742 were detected using Western blots. The fatty acid (FA) oxidation and the citric acid (TCA) cycle related genes in cardiomyocytes were also examined. In addition, PPARδ antagonist (GSK0660) and siRNA-PPARδ were employed to characterize the potential mechanisms. After a 7-day treatment with GW0742, expressions of PPARδ in the heart were markedly increased. Increased expressions of FA oxidation and TCA cycle related genes were also observed both in vivo and in vitro. This action of GW0742 was blocked by GSK0660 or by siRNA-PPARδ. The obtained results show that activation of PPARδ by GW0742 is responsible for the increase of FA oxidation and TCA cycle related genes in hearts. Role of PPARδ in the regulation of lipid metabolism in heart is then established.

Characterization of the specificity of imidazoline I-1 receptor antibody for subtype of imidazoline receptors in vitro.

Specific antibodies are essential in the study of receptor protein. Gene matching shows that Nischarin (NISCH) is a mouse homologue of human imidazoline receptor antisera-selective (IRAS) protein, a viable candidate for imidazoline I-1 receptor. However, selectivity of this antibody against imidazoline I-2 or imidazoline I-3 receptors remained obscure. At first, an intracerebroventricular (ICV) injection of anti-NISCH antibody blocked the blood pressure lowering action of rilmenidine (I-1 receptor agonist) in spontaneous hypertensive rat (SHR). However, the same injection of anti-NISCH antibody showed no effect in SHR treated with clonidine (α2 agonist). In order to clarify the selectivity of anti-NISCH antibody for each subtype of imidazoline receptors, this anti-NISCH antibody was subjected to the lysate of organs isolated from Wistar rats including cortex, hippocampus, cerebellum, and brain stem as central nervous tissues, and heart, liver, pancreas, skeletal muscle, kidney, prostate, and bladder as peripheral tissues. The results show that anti-NISCH antibody positively reacted with all tissues including heart, pancreas, skeletal muscle, kidney and bladder by Western blot analysis. Also, the blotting spots for anti-NISCH antibody show a concentration-dependent manner. Moreover, anti-NISCH antibody blocked the action of glucose uptake induced by 2-BFI (I-2 receptor agonist) in L6 cells. Taken together, the obtained data suggest that anti-NISCH antibody can be used not only for imidazoline I-1 receptor but also for I-2 and I-3 subtypes in immunoassays.

Mediation of AMP kinase in the increase of glucose uptake in L6 cells induced by activation of imidazoline I-2 receptors.

Recent work using radioactive tracer indicates that activation of imidazoline I2 receptor (I2R) by guanidinium derivatives may increase the glucose uptake in the skeletal muscle. However, the effect of I2R activation on nonradioactive glucose uptake is still unknown. The ability of glucose uptake in cultured L6 cells is then determined using 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxyglucose (2-NBDG) as a fluorescence indicator. The changes in 5'-AMP-activated protein kinase (AMPK) expression were also identified by Western blot analysis. In the present study, 2-(2-benzofuranyl)-2-imidazoline (2-BFI) is used to stimulate I2R while 5-aminoimidazole-4-carboxamide-1-ß-D-ribofuranoside (AICAR) is applied to activate AMPK directly. Both compounds can increase 2-NBDG in L6 cells in a concentration-dependent manner. Meanwhile, compound C at concentrations sufficient to inhibit AMPK blocked this increase of glucose uptake by 2-BFI or AICAR. However, only 2-BFI-induced glucose uptake action was dose-dependently blocked by BU224, a specific I2R antagonist, in L6 cells. Moreover, AMPK phosphorylation was markedly increased by 2-BFI or AICAR in L6 cells. Similarly, only the effect of 2-BFI was attenuated by BU224 in L6 cells. Thus, we suggest that AMPK is mediated in I2R activation for increase of glucose uptake in the skeletal muscle cell and I2R will be a new target for diabetic therapy.

Endoscopic management of tumors of the major duodenal papilla: Refined techniques to improve outcome and avoid complications.

BACKGROUND: Adenomas of the major duodenal papilla have malignant potential and are traditionally treated by pancreaticoduodenectomy. This is a report of our experience with endoscopic management and a description of techniques for decreasing complications and enhancing efficacy. METHODS: Forty-one patients were referred for endoscopic management of papillary tumors. If there was no duct invasion and the appearance suggested a benign lesion, biductal sphincterotomy with pancreatic duct stent placement was performed. If the lesion could be elevated by injection of an epinephrine solution, piecemeal resection was performed. The base of the lesion was thermally ablated as needed. Resection/ablation together with stent removal was performed 1 month later. RESULTS: Nine patients (22%) had lesions other than papillary adenoma or cancer. Malignant appearance, ductal stricturing, or extension into the ducts was found in 16 of 41 patients (39%) in whom biopsy specimens alone were obtained. Three patients with adenomas (7%) did not undergo endoscopic resection (because of extremely large lesions and/or comorbid illnesses). Thirteen patients with adenomas (32%) had endoscopic resection; 12 (92%) were lesion-free after 32 ERCPs (mean 2.7). Endoscopic management was unsuccessful in 1 patient (8%). Pancreatitis developed in 1 patient. CONCLUSIONS: Endoscopically treatable papillary neoplasms can be identified on the basis of endoscopic, radiographic, and biopsy features. Preresection sphincterotomy, stent placement, elevation by epinephrine injection, and piecemeal resection may reduce complications and permit more aggressive treatment.