Effects of Growth Hormone and Pioglitazone in Viscerally Obese Adults with Impaired Glucose Tolerance: A Factorial Clinical Trial

OBJECTIVE: Recombinant human growth hormone (GH) and pioglitazone (PIO) in abdominally obese adults with impaired glucose tolerance were evaluated under the hypothesis that the combination attenuates GH-induced increases in glucose concentrations, reduces visceral adipose tissue (VAT), and improves insulin sensitivity over time. DESIGN: Randomized, double-blind, placebo-controlled, 2 × 2 factorial design. SETTING: Veterans Affairs Palo Alto Health Care System, Palo Alto, California, United States. PARTICIPANTS: 62 abdominally obese adults aged 40–75 with impaired glucose tolerance. INTERVENTIONS: GH (8 μg/kg/d, or placebo) and pioglitazone (30 mg/d, or placebo) for 40 wk. OUTCOME MEASURES: Baseline and after 40 wk of treatment, VAT content was quantified by CT scan, glucose tolerance was assessed using a 75-g oral glucose tolerance test, and insulin sensitivity was measured using steady-state plasma glucose levels obtained during insulin suppression test. RESULTS: Baseline: body mass index (BMI), plasma glucose, and visceral fat content were similar. 40 wk: visceral fat area declined 23.9 ± 7.4 cm(2) in GH group, mean difference from placebo: −28.1 cm(2) (95% CI −49.9 to −6.3 cm(2); p = 0.02). Insulin resistance declined 52 ± 11.8 mg/dl with PIO, mean difference from placebo of −58.8 mg/dl (95% CI −99.7 to −18.0 mg/dl; p = 0.01). VAT and SSPG declined with GH and PIO combined, mean differences from placebo of −31.4 cm(2) (95% CI −56.5 cm(2) to −6.3 cm(2); p = 0.02) and −55.3 mg/dl (95% CI −103.9 to −6.7 mg/dl; p = 0.02), respectively. Fasting plasma glucose increased transiently in GH group. No significant changes in BMI were observed. CONCLUSIONS: Addition of PIO to GH attenuated the short-term diabetogenic effect of GH; the drug combination reduced VAT and insulin resistance over time. GH plus PIO may have added benefit on body composition and insulin sensitivity in the metabolic syndrome

Different Rho GTPase–dependent signaling pathways initiate sequential steps in the consolidation of long-term potentiation

The releasable factor adenosine blocks the formation of long-term potentiation (LTP). These experiments used this observation to uncover the synaptic processes that stabilize the potentiation effect. Brief adenosine infusion blocked stimulation-induced actin polymerization within dendritic spines along with LTP itself in control rat hippocampal slices but not in those pretreated with the actin filament stabilizer jasplakinolide. Adenosine also blocked activity-driven phosphorylation of synaptic cofilin but not of synaptic p21-activated kinase (PAK). A search for the upstream origins of these effects showed that adenosine suppressed RhoA activity but only modestly affected Rac and Cdc42. A RhoA kinase (ROCK) inhibitor reproduced adenosine's effects on cofilin phosphorylation, spine actin polymerization, and LTP, whereas a Rac inhibitor did not. However, inhibitors of Rac or PAK did prolong LTP's vulnerability to reversal by latrunculin, a toxin which blocks actin filament assembly. Thus, LTP induction initiates two synaptic signaling cascades: one (RhoA-ROCK-cofilin) leads to actin polymerization, whereas the other (Rac-PAK) stabilizes the newly formed filaments

The Tyrphostin Agent AG490 Prevents and Reverses Type 1 Diabetes in NOD Mice

<div><h3>Background</h3><p>Recent studies in the NOD (non-obese diabetic) mouse model of type 1 diabetes (T1D) support the notion that tyrosine kinase inhibitors have the potential for modulating disease development. However, the therapeutic effects of AG490 on the development of T1D are unknown.</p> <h3>Materials and Methods</h3><p>Female NOD mice were treated with AG490 (i.p, 1 mg/mouse) or DMSO starting at either 4 or 8 week of age, for five consecutive week, then once per week for 5 additional week. Analyses for the development and/or reversal of diabetes, insulitis, adoptive transfer, and other mechanistic studies were performed.</p> <h3>Results</h3><p>AG490 significantly inhibited the development of T1D (p = 0.02, p = 0.005; at two different time points). Monotherapy of newly diagnosed diabetic NOD mice with AG490 markedly resulted in disease remission in treated animals (n = 23) in comparision to the absolute inability (0%; 0/10, p = 0.003, Log-rank test) of DMSO and sustained eugluycemia was maintained for several months following drug withdrawal. Interestingly, adoptive transfer of splenocytes from AG490 treated NOD mice failed to transfer diabetes to recipient NOD.<em>Scid</em> mice. CD4 T-cells as well as bone marrow derived dendritic cells (BMDCs) from AG490 treated mice, showed higher expression of Foxp3 (p<0.004) and lower expression of co-stimulatory molecules, respectively. Screening of the mouse immune response gene arrary indicates that expression of costimulaotry molecule Ctla4 was upregulated in CD4+ T-cell in NOD mice treated with AG490, suggesting that AG490 is not a negative regulator of the immune system.</p> <h3>Conclusion</h3><p>The use of such agents, given their extensive safety profiles, provides a strong foundation for their translation to humans with or at increased risk for the disease.</p> </div

Topical Insulin Accelerates Wound Healing in Diabetes by Enhancing the AKT and ERK Pathways: A Double-Blind Placebo-Controlled Clinical Trial

Background: Wound healing is impaired in diabetes mellitus, but the mechanisms involved in this process are virtually unknown. Proteins belonging to the insulin signaling pathway respond to insulin in the skin of rats. Objective: The purpose of this study was to investigate the regulation of the insulin signaling pathway in wound healing and skin repair of normal and diabetic rats, and, in parallel, the effect of a topical insulin cream on wound healing and on the activation of this pathway. Research Design and Methods: We investigated insulin signaling by immunoblotting during wound healing of control and diabetic animals with or without topical insulin. Diabetic patients with ulcers were randomized to receive topical insulin or placebo in a prospective, double-blind and placebo-controlled, randomized clinical trial (NCT 01295177) of wound healing. Results and Conclusions: Expression of IR, IRS-1, IRS-2, SHC, ERK, and AKT are increased in the tissue of healing wounds compared to intact skin, suggesting that the insulin signaling pathway may have an important role in this process. These pathways were attenuated in the wounded skin of diabetic rats, in parallel with an increase in the time of complete wound healing. Upon topical application of insulin cream, the wound healing time of diabetic animals was normalized, followed by a reversal of defective insulin signal transduction. In addition, the treatment also increased expression of other proteins, such as eNOS (also in bone marrow), VEGF, and SDF-1 alpha in wounded skin. In diabetic patients, topical insulin cream markedly improved wound healing, representing an attractive and cost-free method for treating this devastating complication of diabetes.Sao Paulo Research Foundation (FAPESP)Sao Paulo Research Foundation (FAPESP)National Institute of Science and Technology (INCT)National Institute of Science and Technology (INCT)National Council for Scientific and Technological Development (CNPq)National Council for Scientific and Technological Development (CNPq

Atorvastatin Improves Survival in Septic Rats: Effect on Tissue Inflammatory Pathway and on Insulin Signaling

The aim of the present study was to investigate whether the survival-improving effect of atorvastatin in sepsis is accompanied by a reduction in tissue activation of inflammatory pathways and, in parallel, an improvement in tissue insulin signaling in rats. Diffuse sepsis was induced by cecal ligation and puncture surgery (CLP) in male Wistar rats. Serum glucose and inflammatory cytokines levels were assessed 24 h after CLP. The effect of atorvastatin on survival of septic animals was investigated in parallel with insulin signaling and its modulators in liver, muscle and adipose tissue. Atorvastatin improves survival in septic rats and this improvement is accompanied by a marked improvement in insulin sensitivity, characterized by an increase in glucose disappearance rate during the insulin tolerance test. Sepsis induced an increase in the expression/activation of TLR4 and its downstream signaling JNK and IKK/NF-κB activation, and blunted insulin-induced insulin signaling in liver, muscle and adipose tissue; atorvastatin reversed all these alterations in parallel with a decrease in circulating levels of TNF-α and IL-6. In summary, this study demonstrates that atorvastatin treatment increased survival, with a significant effect upon insulin sensitivity, improving insulin signaling in peripheral tissues of rats during peritoneal-induced sepsis. The effect of atorvastatin on the suppression of the TLR-dependent inflammatory pathway may play a central role in regulation of insulin signaling and survival in sepsis insult

The Double-stranded RNA–dependent Protein Kinase Differentially Regulates Insulin Receptor Substrates 1 and 2 in HepG2 Cells

The RNA-dependent protein kinase (PKR), initially known as a virus infection response protein, is found to differentially regulate two major players in the insulin signaling pathway, IRS1 and IRS2. PKR up-regulates the inhibitory phosphorylation of IRS1 and the expression of IRS2 at the transcriptional level

Mecanismo molecular de ação do hormonio do crescimento (GH) no animal intacto : efeitos do envelhecimento, no crescimento renal e do antagonista do GH, G120K-PEG

Orientador : Mario Jose Abdalla SaadTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias MedicasResumo: o hormônio do crescimento (GH) exerce ações somatotróficas e também interfere em muitos aspectos do metabolismo. As ações somatotróficas são desempenhadas pelo próprio GH e pela geração de um outro fator de crescimento, a IGF-l (insulin-like growth factor-l). Estudos mostram que o GH exerce uma ação inicial no metabolismo de carboidratos semelhante à insulina ("insulina-like"). A fim de exercer seus efeitos biológicos, o GH deve ser reconhecido e especificamente ligado ao seu receptor de membrana (GHR) das células-alvo. O GHR não contém um sítio tirosina quinase intrínseco, entretanto a ligação do GH a seu receptor determina estimulação da atividade tirosina quinase do JAK-2, resultando em fosforilação do receptor de GH e do próprio JAK-2. Demonstramos in vivo que, as proteínas IRSs e SHC servem como moléculas sinalizadoras para o GH em tecidos de ratos em jejum e que ocorre ativação da atividade tirosina quinase do JAK2 em direção ao IRS-l após estímulo com GH, sugerindo que o IRS-l possa interagir primariamente com JAK2, o qual seria mediador da fosforilação em tirosina deste substrato....Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digitalAbstract: Growth hormone (OR) stimulates the tyrosine phosphorylation of various cel1ularpolypeptides, including the OH receptor itself, in an early part of the intracel1ular response. This study demonstrated that OH increased the tyrosine phosphorylation of IRS- 1, IRS-2, JAK2 and Shc proteins in the liver, heart, kidney, muscle and adipose tissue of rats and that OH stimulated the association of IRS-1I2 with PI 3-kinase, Grb2 and SHP2 and of Shc with Grb2. The correlation between JAK2 tyrosyl phosphorylation and IRS-1 tyrosyl phosphorylation in response to OH, together with the results of the in vitro tyrosine kinase assay, is consistent with that JAK2 might mediate the phosphorylation of IRS-1 induced by ...Note: The complete abstract is available with the full electronic digital thesis or dissertationsDoutoradoClinica MedicaDoutor em Clínica Médic