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The effects of long-term oral administration of magnesium sulfate and insulin on hyperglycemia were investigated using Akt2 and IRS1 gene expression methods in streptozotocin-induced diabetic rats. Fifty rats were randomly divided into five experimental groups: 1, non-diabetic control (NDC); 2, Mg2+-treated non-diabetic control (Mg-NDC); 3, chronic diabetic (CD); 4, Mg2+-treated chronic diabetic (Mg-CD); and 5, insulin-treated chronic diabetic (Ins-CD). Streptozotocin was used to induce diabetes. The Mg-CD and Mg-NDC groups received 10 g/l of MgSO4 added to drinking water. The Ins-CD group received 2.5 U/kg of insulin twice a day. Blood glucose level and body weight were measured every week. The intraperitoneal glucose tolerance test (IPGTT) was performed after 16 weeks. MgSO4 administration improved the blood glucose level and IPGTT. It also increased Akt2 and IRS1 genes as well as protein expression. Insulin lowered the blood glucose level and increased IRS1 gene and protein expression, but did not affect Akt2 gene and protein expression. Glucose reduction after Mg therapy may be mediated, at least partially, via IRS1 and Akt2 genes and protein stimulation. In insulin-treated rats, insulin resistance was not significant due to the absence of Akt2 gene expression.

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The present study was designed to investigate the possible role of Mg2+ in suppression of phosphoenolpyruvate carboxy kinase (PEPCK) enzyme via inhibition of FOXO1gene expression in liver and we also examined whether Mg contributes to decrease blood glucose in muscle via inhibiting FOXO1 gene and protein expression. Fifty rats in five groups of experiment were considered as; non-diabetic control (NDC), Mg2+-treated non-diabetic control (Mg2+-NDC), chronic diabetic (CD), Mg2+-treated chronic diabetic (Mg2+-CD), and insulin-treated chronic diabetic (Ins-CD). Streptozotocin (STZ) was used for diabetes induction. The Mg2+-CD and Mg2+-NDC groups received 10 g/l of magnesium sulfate (MgSO4) added to drinking water, and Ins-CD group received 2.5 U/kg of insulin. The blood glucose level and body weight were measured weekly. After 16 weeks, intraperitoneal glucose tolerance test (IPGTT) was done and blood samples were taken to determine the plasma levels of Mg and gastrocnemius muscle legs, and liver were isolated for both Forkhead transcription factor (FOXO1) and PEPCK enzyme genes and proteins expression. Administration of MgSO4 improved IPGTT, lowered blood glucose levels and decreased FOXO1 and PEPCK genes and proteins expression in muscle and liver, while insulin just could decrease FOXO1 gene and protein expression in the muscle. These findings illustrated that MgSO4 improved hyperglycemia via inhibition of FOXO1 gene and protein level in the muscle and liver, and it also decreased blood glucose level by prohibition of gluconeogenesis pathway in the liver. However, long time administration of insulin did not have any effect on liver.

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AIMS/INTRODUCTION: The purpose of the present study was to investigate the possible effect of oral magnesium sulfate (MgSO4 ) in the reduction of atherosclerosis plaques through inhibition of lectin-like low-density lipoprotein receptor-1 (LOX-1) gene expression in diabetic vessels. MATERIALS AND METHODS: A total of 50 rats were divided into five groups, including non-diabetic control, Mg-treated non-diabetic control, chronic diabetic, Mg-treated chronic diabetic and insulin-treated chronic diabetic. The induction of diabetes was carried out by streptozotocin. The Mg-treated chronic diabetic and Mg-treated non-diabetic control groups were treated with 10 g/L of MgSO4 added to their drinking water. The insulin-treated chronic diabetic group received 2.5 U/kg of insulin twice per day. The fasting blood glucose level and bodyweight were determined weekly. Blood pressure measurement and the intraperitoneal glucose tolerance test were carried out after 16 weeks, and the plasma levels of Mg, lipid profile and oxidized low-density lipoprotein cholesterol (oxLDL) were determined. The mesenteric bed was isolated and perfused according to the McGregor method. The aorta was isolated for LOX-1 genes and proteins expression, and pathological investigation. RESULTS: MgSO4 administration improved blood pressure, sensitivity to phenylephrine, intraperitoneal glucose tolerance test, lipid profile and plasma ox-LDL level, and also lowered the blood glucose level to the normal range, and decreased LOX-1 gene and protein expressions. Insulin decreased blood pressure, sensitivity to phenylephrine, blood glucose, lipid profiles and plasma oxLDL level, but it did not decrease LOX-1 gene and protein expressions. CONCLUSIONS: The present findings suggested that MgSO4 improves blood pressure and vessel structure through decreasing oxLDL, and LOX-1 gene and protein expressions; however, insulin did not repair vessel structure, and LOX-1 gene and protein expressions.

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The present study was designed to investigate the possible role of magnesium (Mg2+) on activation of the peroxisome proliferator-activated receptor gamma (PPAR-γ) and inhibition of nuclear factor-KB (NFKB p65) in muscle to increase glucose transporter 4 (GLUT4) gene expression. Fifty rats were divided into five groups, namely non-diabetic control (NDC), Mg2+-treated non-diabetic control (Mg2+-NDC), chronic diabetic (CD), Mg2+-treated chronic diabetic (Mg2+-CD), and insulin-treated chronic diabetic (Ins-CD). Diabetes was induced with streptozotocin (STZ) injection. The Mg2+-CD and Mg2+-NDC groups received 10 g/l of magnesium sulfate (MgSO4) added to drinking water and Ins-CD group received 2.5 U/kg of insulin. The blood glucose level and body weight were measured every week. After 16 weeks, intraperitoneal glucose tolerance test (IPGTT) was done and then animals were decapitated, blood samples were taken to determine the plasma levels of Mg2+ and gastrocnemius muscle legs were isolated for both PPAR-γ and NFKB (p65) genes and proteins expression. Administration of MgSO4 improved IPGTT, lowered blood glucose levels and increased PPAR-γ gene and protein expression. Diabetes increased NFKB gene and protein expression. Although Mg2+ therapy could not decrease NFKB (p65) gene expression, the protein decreased by Mg2+ therapy. Insulin decreased NFKB (p65) gene and protein expression, without any effect on PPAR-γ gene and protein expression. According to our findings it seems that suppressing NFKB (p65) protein synthesis and increases in PPAR-γ gene and protein expression could help Mg2+ administration to decreases blood glucose levels. But decreasing in NFKB (p65) gene and protein expression help insulin to decrease blood glucose level.