An In Vitro Study on the Combination Effect of Metformin and N-Acetyl Cysteine against Hyperglycaemia-Induced Cardiac Damage.

Chronic hyperglycaemia is a major risk factor for diabetes-induced cardiovascular dysfunction. In a hyperglycaemic state, excess production of reactive oxygen species (ROS), coupled with decreased levels of glutathione, contribute to increased lipid peroxidation and subsequent myocardial apoptosis. N-acetylcysteine (NAC) is a thiol-containing antioxidant known to protect against hyperglycaemic-induced oxidative stress by promoting the production of glutathione. While the role of NAC against oxidative stress-related cardiac dysfunction has been documented, to date data is lacking on its beneficial effect when used with glucose lowering therapies, such as metformin (MET). Thus, the aim of the study was to better understand the cardioprotective effect of NAC plus MET against hyperglycaemia-induced cardiac damage in an H9c2 cardiomyoblast model. H9c2 cardiomyoblasts were exposed to chronic high glucose concentrations for 24 h. Thereafter, cells were treated with MET, NAC or a combination of MET and NAC for an additional 24 h. The combination treatment mitigated high glucose-induced oxidative stress by improving metabolic activity i.e. ATP activity, glucose uptake (GU) and reducing lipid accumulation. The combination treatment was as effective as MET in diminishing oxidative stress, lipid peroxidation and apoptosis. We observed that the combination treatment prevented hyperglycaemic-induced cardiac damage by increasing GLUT4 expression and mitigating lipid accumulation via phosphorylation of both AMPK and AKT, while decreasing nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB), as well as protein kinase C (PKC), a known activator of insulin receptor substrate-1 (IRS-1), via phosphorylation at Ser307. On this basis, the current results support the notion that the combination of NAC and MET can shield the diabetic heart against impaired glucose utilization and therefore its long-term protective effect warrants further investigation.

High-fat programming of hyperglycemia, hyperinsulinemia, insulin resistance, hyperleptinemia, and altered islet architecture in 3-month-old wistar rats.

High-fat programming, by exposure to a high-saturated-fat diet in utero and/or during lactation, compromises beta-cell development and function in neonatal and weanling offspring. Therefore, high-fat programming effects were investigated on metabolism and islet architecture in young adult rats. Three-month-old male and female Wistar rat offspring were studied: HFG (maintained on a high-fat diet throughout fetal life), HFP (high-fat diet maintenance from birth to 3 months), and HFGP (high-fat diet maintenance throughout fetal and postnatal life). Control rats were maintained on a standard laboratory diet. Pancreata were double immunolabeled for insulin and glucagon to assess islet morphology and with Ki-67 to determine islet and acinar cell proliferation. HFP and HFGP males were heavier, hyperleptinemic, and hyperinsulinemic. Hyperglycemia presented in HFP males, HFP females, and HFGP males. HFGP males and HFP females were insulin resistant. HFP males displayed beta- and alpha-cell hyperplasia with alpha-cell hypertrophy evident in HFP females. Acinar cell proliferation rates were increased in HFP males. Postnatal high-fat programming induced the most diabetogenic phenotype with high-fat maintenance throughout fetal and postnatal life resulting in a severely obese phenotype. Fetal and postnatal nutrition shapes offspring health outcomes.

Gestational high-fat programming impairs insulin release and reduces Pdx-1 and glucokinase immunoreactivity in neonatal Wistar rats.

Hyperglycemia and compromised beta-cell development were demonstrated in neonatal rats programmed with a gestational high-fat diet. The aim of this study was to determine whether these changes were attributed to impaired insulin release and altered immunoreactivity of Pdx-1, glucokinase (GK), and glucose transporter (GLUT)-2 in high-fat-programmed neonates. Fetuses were maintained, via maternal nutrition, on either a standard laboratory diet (control) or a high-fat diet throughout gestation (HFG). Pancreata from 1-day-old neonates were excised for islet isolation and the subsequent measurement of insulin release at 2.8, 6.5, 13, and 22 mmol/L glucose. Other pancreata were either snap frozen for quantitative polymerase chain reaction or formalin fixed for immunohistochemistry followed by image analysis. The HFG neonates had reduced insulin release at 13- and 22-mmol/L glucose concentrations. No significant differences were found in Pdx-1, GK, or GLUT-2 messenger RNA expression. In HFG neonates, immunoreactivity of both Pdx-1 and GK was significantly reduced, with a nonsignificant reduction in GLUT-2. Gestational high-fat programming impairs insulin release and reduces Pdx-1 and GK immunoreactivity.

Compromised beta-cell development and beta-cell dysfunction in weanling offspring from dams maintained on a high-fat diet during gestation.

OBJECTIVES: Reported here are the effects of a high-fat diet (HFD) fed to dams during pregnancy on the weight, beta- and alpha-cell development, and beta-cell function of their weanling offspring. METHODS: Offspring were obtained from dams maintained on an HFD for the first, second, or third week of gestation or throughout gestation and then on a standard laboratory diet for the duration of lactation. Weanling weights and circulating glucose and insulin concentrations were measured on postnatal day 21, after which pancreata were excised and snap-frozen for quantitative polymerase chain reaction of glucokinase (GK) or processed for immunohistochemical examination and image analysis (beta- and alpha-cell volume, number, and size, and GK immunoreactivity). RESULTS: All of the weanlings had low body weights and were hypoinsulinemic. In weanlings maintained on an HFD for either the first, second, or third week of gestation, hyperglycemia and a reduction in beta-cell volume and number, in beta- and alpha-cell size, and in both GK messenger RNA expression and immunoreactivity were observed. The development of beta and alpha cells was normal in weanlings maintained on an HFD throughout gestation. CONCLUSIONS: Maintenance of dams on an HFD for any single week of gestation results in weanling offspring with an impairment in beta-cell development and function.