Chromium in glucose metabolism: Difference between revisions
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Two modes of action within the insulin signalling cascade under research are: first, the insulin receptors themselves and second, the chromium-peptide complexes that have been shown to improve glucose levels, and have upregulated the associated mRNA levels (insulin receptor, glucose 4 transporter or GLUT4, glycogen synthase and skeletal muscle cells’ uncoupling protein-3). A contentious point that has arisen is on whether there is an effect of Cr on the mRNA levels of the insulin receptor, Akt (protein kinase B), and other protein components within the insulin signalling cascade.<ref name="Chem Biodivers. 2012 Sep;9(9):1923-41."></ref> |
Two modes of action within the insulin signalling cascade under research are: first, the insulin receptors themselves and second, the chromium-peptide complexes that have been shown to improve glucose levels, and have upregulated the associated mRNA levels (insulin receptor, glucose 4 transporter or GLUT4, glycogen synthase and skeletal muscle cells’ uncoupling protein-3). A contentious point that has arisen is on whether there is an effect of Cr on the mRNA levels of the insulin receptor, Akt (protein kinase B), and other protein components within the insulin signalling cascade.<ref name="Chem Biodivers. 2012 Sep;9(9):1923-41."></ref> |
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One study by Wang and Yao using engineered adipocytes, shows that chromium picolinate, [Cr(pic)3], increases glucose uptake, metabolism and increases GLUT4 translocation, but it has no effect on the mRNA levels (insulin receptor β or IR-β, Akt, c-Cbl, extracellular signal-regulated kinase or ERK, c-Jun phosphorylation and c-Cbl-associated protein or CAP). |
One study by Wang and Yao using engineered adipocytes, shows that chromium picolinate, [Cr(pic)3], increases glucose uptake, metabolism and increases GLUT4 translocation, but it has no effect on the mRNA levels (insulin receptor β or IR-β, Akt, c-Cbl, extracellular signal-regulated kinase or ERK, c-Jun phosphorylation and c-Cbl-associated protein or CAP).<ref name="NAME">{{Cite pmid|19195868}}</ref> In another study by Wang and colleagues, engineered Chinese hamster ovary cells, incubated with either [Cr(pic)3], Cr-histidine complex, or CrCl3, activated the insulin receptor tyrosine kinase activity at low insulin doses. Only the Cr-histidine activated receptors were tested for Cr concentration dependence, which was shown to occur. There were also no changes in the phosphorylation of the insulin receptors. It was concluded that cellular Cr somehow enhanced receptor kinase activity.<ref name="NAME">{{Cite pmid|15924436}}</ref> In a study by Hao and colleagues, using engineered skeletal muscle cells partially contradicted the previous study. Using oligosaccharide oligomannuonate, Cr(III) complexes derived from algae, it showed that Cr does enhance the phosphorylation of the insulin receptor and also, that of phosphatidylinositol 3-kinase (PI3K), and Akt.<ref name="NAME">{{Cite pmid|21935427}}</ref> In a study by Wang and colleagues, using engineered rats (insulin-resistant cardiovascular disease models); they were treated with [Cr(pic)3], which increased the phosphorylation of IR, IRS-1 (insulin receptor substrate 1) and Akt, and also increased PI-3 kinase activity after insulin was given. The increased insulin activity was hypothesized to be due to the presence of free intracellular Cr, rather than intact [Cr(pic)3] itself.<ref name="NAME">{{Cite pmid|16424121}}</ref> |
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In a study by Dong and colleagues, treating engineered mouse adipocytes with [Cd(ᴅ-phenylalanine)3], increased insulin-stimulated glucose uptake. Increased insulin-stimulated phosphorylation of the insulin receptor did not occur, but it was seen in Akt phosphorylation. |
In a study by Dong and colleagues, treating engineered mouse adipocytes with [Cd(ᴅ-phenylalanine)3], increased insulin-stimulated glucose uptake. Increased insulin-stimulated phosphorylation of the insulin receptor did not occur, but it was seen in Akt phosphorylation.<ref name="NAME">{{Cite pmid|18806091}}</ref> In another study by Chen and colleagues, CrCl3 and Cr(pic)3 was used on engineered adipocytes, which increased glucose transport and GLUT4 translocation. Phosphorylation levels of the insulin receptor, IRS-1 and Akt did not change. They hypothesized a different route of effect, in that Cr affected change in cholesterol homeostasis by lowering its plasma availability and by increasing membrane permeability instead.<ref name="NAME">{{Cite pmid|16339278}}</ref> |
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==Pharmacology== |
==Pharmacology== |
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Revision as of 04:45, 23 February 2013
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Chromium treatment of diabetes
Recent experimental results
Under the assumption that chromium (Cr) has pharmacological effects, Cr has typically been tested on cultured mammalian cells. The results are generally contradictory to clinical studies in humans and in other mammalian models. Although discrepancies exist, an accepted effect shared by all cultured skeletal muscle, adipocyte or alike cell studies, is that there is insulin-dependent enhancement of glucose uptake and its metabolism in the presence of Cr.[1]
Two modes of action within the insulin signalling cascade under research are: first, the insulin receptors themselves and second, the chromium-peptide complexes that have been shown to improve glucose levels, and have upregulated the associated mRNA levels (insulin receptor, glucose 4 transporter or GLUT4, glycogen synthase and skeletal muscle cells’ uncoupling protein-3). A contentious point that has arisen is on whether there is an effect of Cr on the mRNA levels of the insulin receptor, Akt (protein kinase B), and other protein components within the insulin signalling cascade.[1]
One study by Wang and Yao using engineered adipocytes, shows that chromium picolinate, [Cr(pic)3], increases glucose uptake, metabolism and increases GLUT4 translocation, but it has no effect on the mRNA levels (insulin receptor β or IR-β, Akt, c-Cbl, extracellular signal-regulated kinase or ERK, c-Jun phosphorylation and c-Cbl-associated protein or CAP).[2] In another study by Wang and colleagues, engineered Chinese hamster ovary cells, incubated with either [Cr(pic)3], Cr-histidine complex, or CrCl3, activated the insulin receptor tyrosine kinase activity at low insulin doses. Only the Cr-histidine activated receptors were tested for Cr concentration dependence, which was shown to occur. There were also no changes in the phosphorylation of the insulin receptors. It was concluded that cellular Cr somehow enhanced receptor kinase activity.[2] In a study by Hao and colleagues, using engineered skeletal muscle cells partially contradicted the previous study. Using oligosaccharide oligomannuonate, Cr(III) complexes derived from algae, it showed that Cr does enhance the phosphorylation of the insulin receptor and also, that of phosphatidylinositol 3-kinase (PI3K), and Akt.[2] In a study by Wang and colleagues, using engineered rats (insulin-resistant cardiovascular disease models); they were treated with [Cr(pic)3], which increased the phosphorylation of IR, IRS-1 (insulin receptor substrate 1) and Akt, and also increased PI-3 kinase activity after insulin was given. The increased insulin activity was hypothesized to be due to the presence of free intracellular Cr, rather than intact [Cr(pic)3] itself.[2]
In a study by Dong and colleagues, treating engineered mouse adipocytes with [Cd(ᴅ-phenylalanine)3], increased insulin-stimulated glucose uptake. Increased insulin-stimulated phosphorylation of the insulin receptor did not occur, but it was seen in Akt phosphorylation.[2] In another study by Chen and colleagues, CrCl3 and Cr(pic)3 was used on engineered adipocytes, which increased glucose transport and GLUT4 translocation. Phosphorylation levels of the insulin receptor, IRS-1 and Akt did not change. They hypothesized a different route of effect, in that Cr affected change in cholesterol homeostasis by lowering its plasma availability and by increasing membrane permeability instead.[2]
Pharmacology
Mechanism of action
Chromium toxicity
References
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