Neuroprotective effects of Pouteria ramiflora (Mart.) Radlk (Sapotaceae) extract on the brains of rats with streptozotocin-induced diabetes.

Diabetes mellitus is a chronic disease involving persistent hyperglycemia, which causes an imbalance between reactive oxygen species and antioxidant enzymes and results in damage to various tissues, including the brain. Many societies have traditionally employed medicinal plants to control the hyperglycemia. Pouteria ramiflora, a species occurring in the savanna biome of the Cerrado (Brazil) has been studied because of its possible ability to inhibit carbohydrate digestion. Rats with streptozotocin-induced diabetes treated with an alcoholic extract of Pouteria ramiflora show an improved glycemic level, increased glutathione peroxidase activity, decreased superoxide dismutase activity, and reduced lipid peroxidation and antioxidant status. The extract also restored myosin-Va expression and the nuclear diameters of pyramidal neurons of the CA3 subregion and that of the polymorphic cells of the hilus. We conclude that Pouteria ramiflora extract exerts a neuroprotective effect against oxidative damage and myosin-Va expression and is able to prevent hippocampal neuronal loss in the CA3 and hilus subfields of diabetic rats. However, future studies are needed to understand the mechanism of action of Pouteria ramiflora extract in acute and chronic diabetes.

Myosins Are Differentially Expressed under Oxidative Stress in Chronic Streptozotocin-Induced Diabetic Rat Brains.

Diabetes mellitus is a disease characterized by persistent hyperglycemia, which may lead to brain tissue damage due to oxidative stress and also contributes to neuronal death and changes in synaptic transmission. This study evaluated the effect of oxidative stress and the use of antioxidants supplementation on myosins expression levels in the brains of chronic diabetic rats induced by streptozotocin. Lipid peroxidation, antioxidant enzymes activities, and myosins-IIB and -Va expressions at transcriptional and translational levels were examined after 90 days induction. The chronic effect of the diabetes led to the upregulation of superoxide dismutase (SOD) and catalase (CAT) activities, and the downregulation of glutathione peroxidase (GPx), but there was no statistically significant increase in the malondialdehyde (MDA) levels. These alterations were accompanied by high myosin-IIB and low myosin-Va expressions. Although the antioxidant supplementation did not interfere on MDA levels, the oxidative stress caused by chronic hyperglycemia was reduced by increasing SOD and restoring CAT and GPx activities. Interestingly, after supplementation, diabetic rats recovered only myosin-Va protein levels, without interfering on myosins mRNA levels expressed in diabetic rat brains. Our results suggest that antioxidant supplementation reduces oxidative stress and also regulates the myosins protein expression, which should be beneficial to individuals with diabetes/chronic hyperglycemia.

The effect of different training programs on antioxidant status, oxidative stress, and metabolic control in type 2 diabetes.

We compared the effects of 12 weeks of 3 different exercise types on type 2 diabetic (T2DM) male and female human subjects, randomly divided into 4 groups: aerobic training (AT; n = 11), strength training (ST; n = 10), combined training (CBT; n = 10), and no training (NT; n = 12). Metabolic control, anthropometric parameters, lipid and hematological profiles, kidney and liver function markers, hormones, antioxidant enzymes, and oxidative stress markers were assessed prior to and after the training programs. At baseline, fasting blood glucose and hemoglobin A(1c) in the ST group were higher than in the NT group; after the training, we no longer observed differences in these groups, suggesting an improvement on these parameters. In the AT group, catalase and superoxide dismutase activity, nitrite concentration, levels of sulfhydryl groups, and peak rate of oxygen consumption were elevated after the training (p < 0.05). No changes were observed in antioxidant enzymes or oxidative stress markers in the ST group. The levels of sulfhydryl groups diminished in the NT group (p < 0.01) and increased in the CBT group (p < 0.05). These data demonstrate that the AT program for the T2DM subjects provided important upregulation in antioxidant enzymes and increased nitric oxide bioavailability, which may help minimize oxidative stress and the development of the chronic complications of diabetes. We propose that the beneficial effects observed in the metabolic parameters of the ST group occurred in response to the poor baseline metabolic health n this group, and not necessarily in response to the training itself.

The effects of aerobic, resistance, and combined exercise on metabolic control, inflammatory markers, adipocytokines, and muscle insulin signaling in patients with type 2 diabetes mellitus.

The purpose of this study was to compare the effects of 3 different modalities of exercise on metabolic control, insulin resistance, inflammatory markers, adipocytokines, and tissue expression of insulin receptor substrate (IRS)-1 after 12 weeks of training among patients with type 2 diabetes mellitus. Forty-eight patients with type 2 diabetes mellitus were randomly assigned to 4 groups of training (3 times a week, 60 minutes per session): aerobic group (n = 12), resistance group (n = 12), combined (aerobic and resistance) group (n = 12), and control group (n = 12). Fasting and postprandial blood glucose, glycated hemoglobin, lipid profile, insulin resistance index (homeostasis model assessment of insulin resistance), adipocytokines (adiponectin, visfatin, and resistin), tumor necrosis factor, interleukin, and high-sensitivity C-reactive protein (hs-CRP) were measured at baseline and at the end of the study. Patients also underwent a muscle microbiopsy before and after training to quantify IRS-1 expression. All 4 groups displayed decreases in blood pressure, fasting plasma glucose, postprandial plasma glucose, lipid profile, and hs-CRP (P < .05); and there was no difference across the groups. After training, the IRS-1 expression increased by 65% in the resistance group (P < .05) and by 90% in the combined group (P < .01). Exercise training favorably affects glycemic parameters, lipid profile, blood pressure, and hs-CRP. In addition, resistance and combined training can increase IRS-1 expression.