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Effects of hyperglycemia on sperm and testicular cells of Goto-Kakizaki and str...
Amaral, Sandra; Moreno, António J.; Santos, Maria Sancha; Seiça, Raquel; Ramalho-Santos, JoãoDiabetes mellitus is a degenerative disease that has deleterious effects on male reproductive function, possibly through an increase in oxidative stress. This study was conducted in order to clarify the mechanisms by which oxidative stress influences animal models for both type 1 (streptozotocin-treated rats, STZ) and type 2 (Goto-Kakizaki (GK) rats) diabetes. We determined the extent of lipid peroxidation, pro...
Insulin affects synaptosomal GABA and glutamate transport under oxidative stres...
Duarte, Ana Isabel; Santos, Maria Sancha; Seiça, Raquel; Oliveira, Catarina Resende deIn this study, we investigated the in vitro effect of exogenously administered insulin on the susceptibility to oxidative stress and on the accumulation of the amino acid neurotransmitters [gamma]-aminobutyric acid (GABA) and glutamate in a synaptosomal fraction isolated from male Wistar rat brain cortex. Insulin (1 [mu]M) did not affect synaptosomal lipid peroxidation induced by the oxidant pair ascorbate/Fe2+...
Diabetes and mitochondrial oxidative stress: A study using heart mitochondria f...
Santos, Dario Loureiro; Palmeira, Carlos Marques; Seiça, Raquel; Dias, José; Mesquita, José; Moreno, Antonio Joaquim; Santos, Maria SanchaIncreasing evidence shows that the overproduction of reactive oxygen species, induced by diabetic hyperglycemia, contributes to the development of several cardiopathologies. The susceptibility of diabetic hearts to oxidative stress, induced in vitro by ADP-Fe2+ in mitochondria, was studied in 12-month-old Goto-Kakizaki rats, a model of non-insulin dependent diabetes mellitus, and normal (non-diabetic) Wistar ra...
Glutamate regulates the viability of retinal cells in culture
Rego, A. Cristina; Santos, Maria Sancha; Areias, Filipe; Proença, Teresa; Oliveira, Catarina R.In this study, we show that glutamate regulates the viability of cultured retinal cells upon transient glucose deprivation. At low concentrations (10-100 [mu]M) glutamate decreased MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] reduction to about 50% of control and decreased intracellular ATP levels (about 4-fold) after transient glucose removal. Under these conditions, the decrease in MTT r...
Influence of the antioxidants vitamin E and idebenone on retinal cell injury me...
Rego, Ana Cristina; Santos, Maria Sancha; Oliveira, Catarina R.A role for the antioxidants vitamin E and idebenone in decreasing retinal cell injury, after metabolic inhibition induced by chemical ischemia and hypoglycemia, was investigated and compared with oxidative stress conditions. Preincubation of the antioxidants, vitamin E (20 [mu]M) and idebenone (10 [mu]M), effectively protected from retinal cell injury after oxidative stress or hypoglycemia, whereas the protecti...
Distinct Glycolysis Inhibitors Determine Retinal Cell Sensitivity to Glutamate-...
Rego, Ana Cristina; Areias, Filipe; Santos, Maria Sancha; Oliveira, CatarinaIn this study, we analyzed how distinct glycolysis inhibitors influenced the redox status of retinal cells, used as a neuronal model. Three different approaches were used to inhibit glycolysis: the cells were submitted to iodoacetic acid (IAA), an inhibitor of glyceraldehyde 3-phosphate dehydrogenase, to 2-deoxy-glucose (DG) in glucose-free medium, which was used as a substitute of glucose, or in the absence of...
Effect of Glucose Deprivation and Acute Glutamate Exposure in Cultured Retinal ...
Rego, Ana Cristina; Areias, Filipe Miguel; Santos, Maria Sancha; Oliveira, Catarina R.The relationship between bioenergetics and the glutamate system was analyzed in a neuronal model of retinal cells in culture, submitted to glucose deprivation and exposed to glutamate for 2 h, and compared with exposure to glutamate in the presence of glucose. Under glucose deprivation, a reduction (about 1.1-fold) in the energy charge of the cells occurred, probably as a result of a decrement (by about 75%) in...
Influence of vitamin E succinate on retinal cell survival
Rego, Ana Cristina; Santos, Maria Sancha; Proença, Maria Teresa; Oliveira, Catarina R.In this study, we analyzed the influence of vitamin E succinate (5-80 [mu]M), supplemented in the culture medium, on the survival of cultured retinal cells. The release of lactate dehydrogenase (LDH) was decreased in the presence of low concentrations (10-20 [mu]M) of vitamin E succinate, whereas high concentrations (80 [mu]M) induced a significant increase (about 2-fold) in the release of LDH, indicating a red...
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