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Whole-body Level (whole-body + level)

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Life Sciences75%

Selected Abstracts

AMPK-dependent hormonal regulation of whole-body energy metabolism

ACTA PHYSIOLOGICA, Issue 1 2009
N. L. Dzamko
Abstract AMP-dependent protein kinase (AMPK) is an evolutionarily conserved serine/threonine protein kinase central to the regulation of energy balance at both the cellular and whole-body levels. In its classical role as an intracellular metabolic stress-sensing kinase, AMPK switches on fatty acid oxidation and glucose uptake in muscle, while switching off hepatic gluconeogenesis. AMPK also has a broader role in metabolism through the control of appetite. Regulation of AMPK activity at the whole-body level is coordinated by a growing number of hormones and cytokines secreted from adipose tissue, skeletal muscle, pancreas and the gut including leptin, adiponectin, insulin, interluekin-6, resistin, TNF-, and ghrelin. Understanding how these secreted signalling proteins regulate AMPK activity to control fatty acid oxidation, glucose uptake, gluconeogenesis and appetite may yield therapeutic treatments for metabolic disorders such as diabetes, insulin resistance and obesity. [source]

Ethanol Feeding Impairs Insulin-Stimulated Glucose Uptake in Isolated Rat Skeletal Muscle: Role of Gs , and cAMP

ALCOHOLISM, Issue 8 2005
Qiang Wan
Background: The mechanism by which chronic alcohol consumption impairs insulin sensitivity is unclear. We investigated the role of the Gs ,,mediated pathway in decreasing insulin sensitivity in skeletal muscle after ethanol consumption. Methods: Sixty male Wistar rats, divided into four groups, received either distilled water (controls; group I) or ethanol, which was administered by a gastric tube as a single daily dose of 5 g/kg (group II), 2.5 g/kg (group III), or 0.5 g/kg (group IV). After 20 weeks, fasting plasma glucose and serum insulin levels were measured. The hyperinsulinemic-euglycemic clamp study was performed under anesthesia to estimate whole-body insulin sensitivity. Insulin-stimulated glucose uptake was measured in vitro in dissected gastrocnemius muscle. Expression of glut4, Gs ,, and Gi , was quantified using real-time PCR analysis and western blotting. cAMP levels were measured by ELISA. Results: Compared with controls, the following observations were made: (1) the hyperinsulinemic-euglycemic clamp study revealed impaired insulin action at the whole-body level after ethanol treatment; (2) chronic ethanol feeding at 5 g/kg and 2.5 g/kg significantly decreased both basal and insulin-stimulated glucose uptakes in isolated skeletal muscle (p < 0.05), which was accompanied by decreased expression of glut4 (p < 0.05); (3) Gs , (mRNA and protein) expression in skeletal muscle was significantly increased in all three ethanol groups (p < 0.05), and cAMP levels were also increased by ethanol treatment (p < 0.05); and (4) there was no significant change in Gi , expression in all three ethanol groups. Conclusions: Chronic ethanol exposure decreased insulin-induced glucose uptake in rat skeletal muscle, which was associated with increased expression of Gs ,. Because Gs , is a negative regulator of insulin sensitivity, the alteration in Gs , expression may contribute to the ethanol-induced impairment of insulin signal transduction. [source]

AMPK-dependent hormonal regulation of whole-body energy metabolism

ACTA PHYSIOLOGICA, Issue 1 2009
N. L. Dzamko
Abstract AMP-dependent protein kinase (AMPK) is an evolutionarily conserved serine/threonine protein kinase central to the regulation of energy balance at both the cellular and whole-body levels. In its classical role as an intracellular metabolic stress-sensing kinase, AMPK switches on fatty acid oxidation and glucose uptake in muscle, while switching off hepatic gluconeogenesis. AMPK also has a broader role in metabolism through the control of appetite. Regulation of AMPK activity at the whole-body level is coordinated by a growing number of hormones and cytokines secreted from adipose tissue, skeletal muscle, pancreas and the gut including leptin, adiponectin, insulin, interluekin-6, resistin, TNF-, and ghrelin. Understanding how these secreted signalling proteins regulate AMPK activity to control fatty acid oxidation, glucose uptake, gluconeogenesis and appetite may yield therapeutic treatments for metabolic disorders such as diabetes, insulin resistance and obesity. [source]

High temperature causes masculinization of genetically female medaka by elevation of cortisol

MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 8 2010
Yuki Hayashi
In poikilothermic vertebrates, sex determination is sometimes influenced by environmental factors such as temperature. However, little is known about the molecular mechanisms underlying environmental sex determination. The medaka (Oryzias latipes) is a teleost fish with an XX/XY sex determination system. Recently, it was reported that XX medaka can be sex-reversed into phenotypic males by high water temperature (HT; 32,34°C) treatment during the sex differentiation period. Here we report that cortisol caused female-to-male sex reversal and that metyrapone (an inhibitor of cortisol synthesis) inhibited HT-induced masculinization of XX medaka. HT treatment caused elevation of whole-body levels of cortisol, while metyrapone suppressed the elevation by HT treatment during sexual differentiation. Moreover, cortisol and 33°C treatments inhibited female-type proliferation of germ cells as well as expression of follicle-stimulating hormone receptor (fshr) mRNA in XX medaka during sexual differentiation. These results strongly suggest that HT induces masculinization of XX medaka by elevation of cortisol level, which, in turn, causes suppression of germ cell proliferation and of fshr mRNA expression. Mol. Reprod. Dev. 77: 679,686, 2010. © 2010 Wiley-Liss, Inc. [source]