Resolvin E3 ameliorates high-fat diet-induced insulin resistance via the phosphatidylinositol-3-kinase/Akt signaling pathway in adipocytes.

Obesity-associated type 2 diabetes mellitus is associated with the development of insulin resistance. Among several metabolites, resolvins that are metabolites of eicosapentaenoic acid have been shown to exert insulin-sensitizing effects; however, the role of resolvin E3 (RvE3) in glucose metabolism has not been studied. In this study, the effect of RvE3 on glucose metabolism in mice with high-fat diet-induced obesity and 3T3L1 adipocytes was studied. C57BL/6 mice fed a high-fat diet were administered RvE3, for which insulin tolerance, oral glucose tolerance tests, and the homeostasis model assessment of insulin resistance, were performed. RvE3 treatment significantly improved insulin sensitivity and glucose tolerance and regulated protein kinase B (Akt) phosphorylation in the adipose tissue. Moreover, RvE3 treatment enhanced the insulin-stimulated glucose transporter 4 (Glut4) translocation, glucose uptake, phosphatidylinositol-3-kinase (PI3K) activity, and Akt phosphorylation in 3T3L1 adipocytes, whereas a PI3K inhibitor inhibited the enhanced insulin-stimulated glucose uptake induced by RvE3. These findings indicate that RvE3 likely improves insulin sensitivity, resulting in the upregulation of glucose uptake in adipocytes by activating the PI3K/Akt signaling pathways. Collectively, the findings of this study show that RvE3 may play a role in glucose homeostasis and could be used as a potential therapeutic target for developing treatments for obesity-associated diabetes.

Transducin ß-like 1, X-linked and nuclear receptor co-repressor cooperatively augment the ligand-independent stimulation of TRH and TSHß gene promoters by thyroid hormone receptors.

Mutations in TBL1X, a component of the nuclear receptor co-repressor (N-CoR) and silencing mediator of retinoic acid and thyroid hormone receptor co-repressor complexes, have recently been implicated in isolated central hypothyroidism (CeH). However, the mechanisms by which TBL1X mutations affect negative feedback regulation in the hypothalamus-pituitary-thyroid axis remain unclear. N-CoR was previously reported to paradoxically enhance the ligand-independent stimulation of TRH and TSHß gene promoters by thyroid hormone receptors (TR) in cell culture systems. We herein investigated whether TBL1X affects the unliganded TR-mediated stimulation of the promoter activities of genes negatively regulated by T3 in cooperation with N-CoR. In a hypothalamic neuronal cell line, the unliganded TR-mediated stimulation of the TRH gene promoter was significantly enhanced by co-transfected TBL1X, and the co-transfection of TBL1X with N-CoR further enhanced promoter activity. In contrast, the knockdown of endogenous Tbl1x using short interfering RNA significantly attenuated the N-CoR-mediated enhancement of promoter activity in the presence of unliganded TR. The co-transfection of N365Y or Y458C, TBL1X mutants identified in CeH patients, showed impaired co-activation with N-CoR for the ligand-independent stimulation of the TRH promoter by TR. In the absence of T3, similar or impaired enhancement of the TSHß gene promoter by the wild type or TBL1X mutants, respectively, was observed in the presence of co-transfected TR and N-CoR in CV-1 cells. These results suggest that TBL1X is needed for the full activation of TRH and TSHß gene promoters by unliganded TR. Mutations in TBL1X may cause CeH due to the impaired up-regulation of TRH and/or TSHß gene transcription despite low T3 levels.

Glycosuria medicated with ipragliflozin and nifedipine or ipragliflozin and candesartan: a case report.

INTRODUCTION: Animal studies have reported that treatment with angiotensin II receptor blockers reduced kidney sodium-dependent glucose cotransporter expression. We therefore hypothesized that patients with hypertension treated with an angiotensin II receptor blocker (candesartan) would probably have an increased response to sodium-dependent glucose cotransporter inhibitor therapy (ipragliflozin) compared with patients treated with alternative hypertensive medications such as calcium channel blockers (nifedipine). Although sodium-dependent glucose cotransporter inhibitor (ipragliflozin) is a new anti-diabetic medicine, the clinical efficacy in the Japanese population has not been fully evaluated. We compared the combined effect of angiotensin II receptor blocker candesartan plus ipragliflozin with nifedipine plus ipragliflozin therapy and found that the combination of candesartan plus ipragliflozin was more effective in increasing glycosuria and lowering plasma glucose. CASE PRESENTATION: A 57-year-old Japanese man with essential hypertension was treated with candesartan. Candesartan was switched to nifedipine for the initial 10 days of an observation period and 5 days later he was started on ipragliflozin (day 6 of nifedipine treatment) with nifedipine for the next 5 days. Thereafter (from day 11 to day 20), candesartan was started instead of nifedipine and ipragliflozin was continued. In the last 5 days ipragliflozin was stopped and he was treated with candesartan alone. Neither nifedipine alone (0.038+/-0.004) nor candesartan alone (0.048+/-0.006) produce any trace amount of glycosuria. However, the extent of glycosuria under ipragliflozin with candesartan treatment (37.5+/-8.45) was significantly greater than that of ipragliflozin with nifedipine (23.75+/-0.35; P<0.05). CONCLUSION: Candesartan demonstrated additive actions with ipragliflozin to increase glycosuria compared to ipragliflozin with nifedipine treatment.

NR4A1 (Nur77) mediates thyrotropin-releasing hormone-induced stimulation of transcription of the thyrotropin ß gene: analysis of TRH knockout mice.

Thyrotropin-releasing hormone (TRH) is a major stimulator of thyrotropin-stimulating hormone (TSH) synthesis in the anterior pituitary, though precisely how TRH stimulates the TSHß gene remains unclear. Analysis of TRH-deficient mice differing in thyroid hormone status demonstrated that TRH was critical for the basal activity and responsiveness to thyroid hormone of the TSHß gene. cDNA microarray and K-means cluster analyses with pituitaries from wild-type mice, TRH-deficient mice and TRH-deficient mice with thyroid hormone replacement revealed that the largest and most consistent decrease in expression in the absence of TRH and on supplementation with thyroid hormone was shown by the TSHß gene, and the NR4A1 gene belonged to the same cluster as and showed a similar expression profile to the TSHß gene. Immunohistochemical analysis demonstrated that NR4A1 was expressed not only in ACTH- and FSH- producing cells but also in thyrotrophs and the expression was remarkably reduced in TRH-deficient pituitary. Furthermore, experiments in vitro demonstrated that incubation with TRH in GH4C1 cells increased the endogenous NR4A1 mRNA level by approximately 50-fold within one hour, and this stimulation was inhibited by inhibitors for PKC and ERK1/2. Western blot analysis confirmed that TRH increased NR4A1 expression within 2 h. A series of deletions of the promoter demonstrated that the region between bp -138 and +37 of the TSHß gene was responsible for the TRH-induced stimulation, and Chip analysis revealed that NR4A1 was recruited to this region. Conversely, knockdown of NR4A1 by siRNA led to a significant reduction in TRH-induced TSHß promoter activity. Furthermore, TRH stimulated NR4A1 promoter activity through the TRH receptor. These findings demonstrated that 1) TRH is a highly specific regulator of the TSHß gene, and 2) TRH mediated induction of the TSHß gene, at least in part by sequential stimulation of the NR4A1-TSHß genes through a PKC and ERK1/2 pathway.

Expression of 11beta-hydroxysteroid dehydrogenase 2 contributes to glucocorticoid resistance in lymphoblastic leukemia cells.

Synthetic glucocorticoids (GCs) form a crucial first-line treatment for childhood acute lymphoblastic leukemia (ALL). However prolonged GC therapy frequently leads to GC-resistance with an unclear molecular mechanism. 11ß-hydroxysteroid dehydrogenase (11ß-HSD) 2 inactivates GCs within cells. Here, we show the association between GC sensitivity and 11ß-HSD2 expression in human T-cell leukemic cell lines. 11ß-HSD2 mRNA and protein levels were considerably higher in GC-resistant MOLT4F cells than in GC-sensitive CCRF-CEM cells. The 11ß-HSD inhibitor, carbenoxolone pre-treatment resulted in greater cell death with prednisolone assessed by methyl-thiazol-tetrazolium assay and caspase-3/7 assay, suggesting that 11ß-HSD2 is a cause of GC-resistance in ALL.

Identification of nesfatin-1 as a satiety molecule in the hypothalamus.

The brain hypothalamus contains certain secreted molecules that are important in regulating feeding behaviour. Here we show that nesfatin, corresponding to NEFA/nucleobindin2 (NUCB2), a secreted protein of unknown function, is expressed in the appetite-control hypothalamic nuclei in rats. Intracerebroventricular (i.c.v.) injection of NUCB2 reduces feeding. Rat cerebrospinal fluid contains nesfatin-1, an amino-terminal fragment derived from NUCB2, and its expression is decreased in the hypothalamic paraventricular nucleus under starved conditions. I.c.v. injection of nesfatin-1 decreases food intake in a dose-dependent manner, whereas injection of an antibody neutralizing nesfatin-1 stimulates appetite. In contrast, i.c.v. injection of other possible fragments processed from NUCB2 does not promote satiety, and conversion of NUCB2 to nesfatin-1 is necessary to induce feeding suppression. Chronic i.c.v. injection of nesfatin-1 reduces body weight, whereas rats gain body weight after chronic i.c.v. injection of antisense morpholino oligonucleotide against the gene encoding NUCB2. Nesfatin-1-induced anorexia occurs in Zucker rats with a leptin receptor mutation, and an anti-nesfatin-1 antibody does not block leptin-induced anorexia. In contrast, central injection of alpha-melanocyte-stimulating hormone elevates NUCB2 gene expression in the paraventricular nucleus, and satiety by nesfatin-1 is abolished by an antagonist of the melanocortin-3/4 receptor. We identify nesfatin-1 as a satiety molecule that is associated with melanocortin signalling in the hypothalamus.

Molecular mechanisms associated with leptin resistance: n-3 polyunsaturated fatty acids induce alterations in the tight junction of the brain.

High-fat diets cause peripheral leptin resistance, and dietary lipid composition affects sensitivity to leptin. We examined the role of n-3 polyunsaturated fatty acid (PUFA) in peripheral leptin resistance. Dietary PUFAs (0.4% wt/wt) caused insensitivity to peripherally but not intracerebroventricularly administered leptin. n-3 PUFA increased body weight, associated with a significant reduction of leptin concentration in the cerebrospinal fluid. Dietary n-3 PUFA reduced transport of endogenous or exogenously administered leptin into the brain, associated with increased expression of hypothalamic occludin, but caused no change in expression of leptin receptors, proteins associated with leptin signaling or other tight junction proteins. Continuous intracerebroventricular infusion of an antisense morpholino oligonucleotide targeted to occludin mRNA reversed n-3 PUFA-induced insensitivity to peripherally administered leptin. We conclude that n-3 PUFA induces peripheral leptin resistance via an increase in the expression of hypothalamic occludin, reducing paracellular transport of leptin into the brain.

Small-field radiotherapy in combination with concomitant chemotherapy for locally advanced pancreatic carcinoma.

PURPOSE: To evaluate the effectiveness of small-field radiotherapy in combination with concomitant 5-fluorouracil (5FU) or cisplatin for locally advanced pancreatic carcinoma. MATERIALS AND METHODS: From November 1993 to January 1999, 53 patients underwent continuous 5FU infusion at 200mg/m2 (27 patients) or a 30-min cisplatin infusion at 5mg/m2/day (26 patients) just prior to each irradiation. The radiation field was limited to cover the primary and the paraaortic regions at celiac and supramesenteric axis levels. A total dose of 50.4Gy in 28 sessions was given in 5.6 weeks. RESULTS: Median and 1-year survival rates were 10.2 months and 35.2%, respectively. Local failure occurred in 19 patients (36%) and liver metastases in 16 patients (30%). All local recurrences occurred only within the radiation field. CONCLUSIONS: Median survival rates were comparable to other studies. Because local failure occurred only within the radiation field, the use of relatively small-field radiotherapy may be justified in the treatment of locally advanced pancreatic carcinoma in addition to concurrent administration of either 5FU or cisplatin.