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Objective: ω-3 Polyunsaturated α-linolenic acid (ALA) supplementation has not been studied in the setting of adiponectin levels and insulin sensitivity (IS) improvements in patients with type 2 diabetes mellitus (T2DM) by hyperinsulinemic-euglycemic clamp (HEC). The aim of this study was to examine the influence of ω-3 ALA on IS and adiponectin. Methods: We conducted a randomized study in patients with T2DM and assessed IS using HEC. Twenty patients with T2DM were included and randomly assigned to receive 3 g/d of ALA or placebo for 60 d, in a double-blind design. The assessment of IS by HEC was performed at baseline and after 60 d in all patients; blood samples were taken for the measurement of serum lipids, glucose, insulin, adiponectin, and cytokines. The primary outcome variables were an increase of both glucose infusion rate (GIR) in steady state and glucose metabolization (M) by HEC. The secondary outcomes were an increase in adiponectin levels and a decrease in fasting plasma glucose, glycated hemoglobin, homeostasis model assessment-estimated insulin resistance (HOMA-IR) index, lipids and cytokines. The study was conducted at an academic medical center. Results: The ALA group improved IS corrected for fat-free mass (M/FFM; P = 0.04). Both groups showed increased adiponectin after 60 d (P = 0.01), however, the increase for the ALA group was greater (P = 0.04). In the ALAgroup, adiponectin was positively correlated with GIR (r = 0.76; P = 0.01) and M/FFM (r = 0.62; P = 0.06), and negatively correlated with HOMA-IR (r = -0.61; P = 0.03). Conclusion: ω-3 ALA supplementation improved glucose homeostasis and was associated with an increase in adiponectin. Improvement in the overall metabolic profile with ω-3 ALA suggests a potential clinical utility for this agent and requires further investigation. [ABSTRACT FROM AUTHOR]

Objective: Insulin must move from the blood to the interstitium to initiate signaling, yet access to the interstitium may be impaired in cases of insulin resistance, such as obesity. This study investigated whether consuming a short- and long-term high-fat diet (HFD) impairs insulin access to skeletal muscle, the major site of insulin-mediated glucose uptake., Methods: Male mongrel dogs were divided into three groups consisting of control diet (n = 16), short-term (n = 8), and long-term HFD (n = 8). Insulin sensitivity was measured with intravenous glucose tolerance tests. A hyperinsulinemic euglycemic clamp was performed in each animal at the conclusion of the study. During the clamp, lymph fluid was measured as a representation of the interstitial space to assess insulin access to muscle., Results: Short- and long-term HFD induced obesity and reduced insulin sensitivity. Lymph insulin concentrations were approximately 50% of plasma insulin concentrations under control conditions. Long-term HFD caused fasting plasma hyperinsulinemia; however, interstitial insulin concentrations were not increased, suggesting impaired insulin access to muscle., Conclusions: A HFD rapidly induces insulin resistance at the muscle and impairs insulin access under basal insulin concentrations. Hyperinsulinemia induced by a long-term HFD may be a compensatory mechanism necessary to maintain healthy insulin levels in muscle interstitium., (© 2016 The Obesity Society.)

Objectives: To determine whether a selective increase of visceral adipose tissue content will result in insulin resistance., Methods: Sympathetic denervation of the omental fat was performed under general inhalant anesthesia by injecting 6-hydroxydopamine in the omental fat of lean mongrel dogs (n = 11). In the conscious animal, whole-body insulin sensitivity was assessed by the minimal model (SI ) and the euglycemic hyperinsulinemic clamp (SICLAMP ). Changes in abdominal fat were monitored by magnetic resonance. All assessments were determined before (Wk0) and 2 weeks (Wk2) after denervation. Data are medians (upper and lower interquartile)., Results: Denervation of omental fat resulted in increased percentage (and content) of visceral fat [Wk0: 10.2% (8.5-11.4); Wk2: 12.4% (10.4-13.6); P < 0.01]. Abdominal subcutaneous fat remained unchanged. However, no changes were found in SI [Wk0: 4.7 (mU/l)(-1) min(-1) (3.1-8.8); Wk2: 5.3 (mU/l)(-1) min(-1) (4.5-7.2); P = 0.59] or SICLAMP [Wk0: 42.0 × 10(-4) dl kg(-1) min(-1) (mU/l)(-1) (41.0-51.0); Wk2: 40.0 × 10(-4) dl kg(-1) min(-1) (mU/l) (-1) (34.0-52.0); P = 0.67]., Conclusions: Despite a selective increase in visceral adiposity in dogs, insulin sensitivity in vivo did not change, which argues against the concept that accumulation of visceral adipose tissue contributes to insulin resistance., (© 2014 The Obesity Society.)

1. The role of growth hormone (GH) in cardiac remodelling and function in chronic and persistent pressure overload-induced left ventricular hypertrophy has not been defined. The aim of the present study was to assess short-term GH treatment on left ventricular function and remodelling in rats with chronic pressure overload-induced hypertrophy. 2. Twenty-six weeks after induction of ascending aortic stenosis (AAS), rats were treated with daily subcutaneous injections of recombinant human GH (1 mg/kg per day; AAS-GH group) or saline (AAS-P group) for 14 days. Sham-operated animals served as controls. Left ventricular function was assessed by echocardiography before and after GH treatment. Myocardial fibrosis was evaluated by histological analysis. 3. Before GH treatment, AAS rats presented similar left ventricular function and structure. Treatment of rats with GH after the AAS procedure did not change bodyweight or heart weight, both of which were higher in the AAS groups than in the controls. After GH treatment, posterior wall shortening velocity (PWSV) was lower in the AAS-P group than in the control group. However, in the AAS-GH group, PWSV was between that in the control and AAS-P groups and did not differ significantly from either group. Fractional collagen (% of total area) was significantly higher in the AAS-P and AAS-GH groups compared with control (10.34 +/- 1.29, 4.44 +/- 1.37 and 1.88 +/- 0.88%, respectively; P < 0.05) and was higher still in the AAS-P group compared with the AAS-GH group. 4. The present study has shown that short-term administration of GH to rats with chronic pressure overload-induced left ventricular hypertrophy induces cardioprotection by attenuating myocardial fibrosis.

Dopamine (DA) and zinc (Zn++) share common mechanisms in their inhibition of prolactin (PRL) secretion. Both substances are present in the same brain areas, where Zn++ is released together with DA, suggesting a modulatory effect of Zn++ on dopaminergic receptors. The aim of the present study was to evaluate the effect of Zn++ supplementation on basal and PRL secretion stimulated by metoclopramide (MCP), a dopaminergic antagonist. Seven healthy men were evaluated in controlled study, where MCP (5 mg) was given intravenously, before and after 3 months of oral Zn++ (25 mg) administration. Our results indicate that chronic Zn++ administration does not change basal or MCP-stimulated plasma PRL secretion suggesting that, in humans, Zn++ does not interfere on PRL secretion mediated through dopaminergic receptors.