Pyruvate modulates antioxidant status of cultured human lens epithelial cells under hypergalactosemic conditions.
ABSTRACT Lens epithelial cells are the metabolic unit of the lens and antioxidant enzymes are mainly concentrated here. The purpose of this study was to maintain human lens epithelial cells (HLEC) in culture and examine the status of antioxidant enzymes (glutathione peroxidase (GSHPx), catalase (CAT), glutathione-S-transferase (GST)), lipid peroxidation product malondialdehyde (MDA) and glutathione (GSH) levels in these cells under normal as well as hypergalactosemic (30 mM galactose) conditions. Further, effect of pyruvate, a physiological antioxidant has also been evaluated on these parameters. For conducting experiments, anterior capsule specimens obtained from fresh cadaver eyes from eye bank were cultured in Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 20% fetal calf serum. Upon confluency, the cells were subcultured in three separate flasks containing DMEM alone (normal group), DMEM + 30 mM D-galactose (control group), DMEM + 30 mM D-galactose + 5 mM pyruvate (test group) and incubated for 24 or 72 h. These cells were observed under the phase contrast microscope for any morphological changes and harvested for the estimation of various antioxidant parameters. Our results show significant weakened antioxidant defense in HLEC when incubated in the presence of galactose as compared to normal. Addition of pyruvate significantly modulated levels of GSH, MDA, GSHPx, CAT and GST.
- SourceAvailable from: Kerstin Tiedemann[Show abstract] [Hide abstract]
ABSTRACT: Cell differentiation leads to adaptive changes in energy metabolism. Conversely, hyperglycemia induces malfunction of many body systems, including bone, suggesting that energy metabolism reciprocally affects cell differentiation. We investigated how the differentiation of bone-resorbing osteoclasts, large polykaryons formed through fusion and growth of cells of monocytic origin, is affected by excess of energy substrate pyruvate and how energy metabolism changes during osteoclast differentiation. Surprisingly, small increases in pyruvate (1-2 mM above basal levels) augmented osteoclastogenesis in vitro and in vivo, while larger increases were not effective in vitro. Osteoclast differentiation increased cell mitochondrial activity and ATP levels, which were further augmented in energy-rich conditions. Conversely, the inhibition of respiration significantly reduced osteoclast number and size. AMP-activated protein kinase (AMPK) acts as a metabolic sensor, which is inhibited in energy-rich conditions. We found that osteoclast differentiation was associated with an increase in AMPK levels and a change in AMPK isoform composition. Increased osteoclast size induced by pyruvate (1 mM above basal levels) was prevented in the presence of AMPK activator 5-amino-4-imidazole carboxamide ribonucleotide (AICAR). In keeping, inhibition of AMPK using dorsomorphin or siRNA to AMPKγ increased osteoclast size in control cultures to the level observed in the presence of pyruvate. Thus, we have found that a moderate excess of pyruvate enhances osteoclastogenesis, and that AMPK acts to tailor osteoclastogenesis to a cell's bioenergetics capacity.04/2013; 2(4):387-95. DOI:10.1242/bio.20133269
- [Show abstract] [Hide abstract]
ABSTRACT: The present study was designed to evaluate the cardioprotective potential of pyruvate and to characterize the mechanism underlying the protection. Wistar albino rats were randomly divided into three groups. Two groups were administered saline orally (sham, ischemia-reperfusion (I-R) control group) and animals of third group received pyruvate (500 mg/kg) for 4 weeks. On the 29th day, animals of the I-R control and pyruvate treated groups underwent 45 min of occlusion of the left anterior descending (LAD) coronary artery and were thereafter reperfused for 60 min. In the I-R control group, a significant cardiac necrosis, depressed mean arterial pressure (MAP) and heart rate (HR), decline in myocardial antioxidant status and elevation in lipid peroxidation were observed as compared to sham control. Pyruvate treatment restored the myocardial antioxidant status and favorably modulated the altered MAP as compared to I-R control. Furthermore, I/R-induced lipid peroxidation was significantly inhibited by pyruvate treatment. These beneficial cardioprotective effects translated into significant improvement in MAP. Histopathological examination and restored specific myocardial injury marker CK-MB isoenzyme activity further confirmed protective effects of pyruvate. In conclusion, our study has demonstrated that the beneficial effect of pyruvate likely results from improved MAP and suppression of oxidative stress.Life Sciences 06/2006; 79(1):38-44. DOI:10.1016/j.lfs.2005.12.039 · 2.30 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Glucose is a principal metabolic fuel in the central nervous system, but, when glucose is unavailable, the brain can utilize alternative metabolic substrates such as monocarboxylates to sustain brain functions. This study examined whether the replacement of glucose with monocarboxylates (particularly pyruvate and lactate) had an equivalent effect of glucose on neuronal survival in rat hippocampal organotypic slice cultures, or ameliorate the neurotoxicity induced by amyloid beta-peptide (Abeta). The possible mechanism was also explored. We found that pyruvate and lactate alone increased cell death in the hippocampal slice cultures at 24 and 48 h. Supplementation of glucose-containing culture media and Abeta-treated culture media with pyruvate, but not lactate, attenuated cell death as strong as with trolox, known as a reactive oxygen species scavenger, and niacinamide, an NAD(+) precursor, and this protective effect was reversed by alpha-cyano-4-hydroxycinnamic acid. Pyruvate significantly increased the aconitase activity and the NAD(+) levels in the hippocampal slices in the presence of Abeta, but did not maintain the ATP levels. Our results indicate that pyruvate and lactate alone cannot replace glucose as an alternative energy source to preserve the neuronal viability in the hippocampal slice cultures. Pyruvate, in the presence of glucose, improves neuronal survival in the hippocampal slice cultures and also protects neurons against Abeta-induced cell death in which mitochondrial NAD(P) redox status may play a central role.European Journal of Neuroscience 11/2007; 26(8):2142-50. DOI:10.1111/j.1460-9568.2007.05853.x · 3.67 Impact Factor