The Role of Metformin in Controlling Oxidative Stress in Muscle of Diabetic Rats

Metformin can act in muscle, inhibiting the complex I of the electron transport chain and decreasing mitochondrial reactive oxygen species. Our hypothesis is that the inhibition of complex I can minimize damage oxidative in muscles of hypoinsulinemic rats. The present study investigated the effects of insulin and/or metformin treatment on oxidative stress levels in the gastrocnemius muscle of diabetic rats. Rats were rendered diabetic (D) with an injection of streptozotocin and were submitted to treatment with insulin (D+I), metformin (D+M), or insulin plus metformin (D+I+M) for 7 days. The body weight, glycemic control, and insulin resistance were evaluated. Then, oxidative stress levels, glutathione antioxidant defense system, and antioxidant status were analyzed in the gastrocnemius muscle of hypoinsulinemic rats. The body weight decreased in D+M compared to ND rats. D+I and D+I+M rats decreased the glycemia and D+I+M rats increased the insulin sensitivity compared to D rats. D+I+M reduced the oxidative stress levels and the activity of catalase and superoxide dismutase in skeletal muscle when compared to D+I rats. In conclusion, our results reveal that dual therapy with metformin and insulin promotes more benefits to oxidative stress control in muscle of hypoinsulinemic rats than insulinotherapy alone

The influence of a hot environment on physiological stress responses in exercise until exhaustion

Exhaustive exercise in a hot environment can impair performance. Higher epinephrine plasma levels occur during exercise in heat, indicating greater sympathetic activity. This study examined the influence of exercise in the heat on stress levels. Nine young healthy men performed a maximal progressive test on a cycle ergometer at two different environmental conditions: hot (40 degrees C) and normal (22 degrees C), both between 40% and 50% relative humidity. Venous blood and saliva samples were collected pre-test and post-test. Before exercise there were no significant changes in salivary biomarkers (salivary IgA: p = 0.12; alpha-amylase: p = 0.66; cortisol: p = 0.95; nitric oxide: p = 0.13; total proteins: p = 0.07) or blood lactate (p = 0.14) between the two thermal environments. Following exercise, there were significant increases in all variables (salivary IgA 22 degrees C: p = 0.04, 40 degrees C: p = 0.0002; alpha-amylase 22 degrees C: p = 0.0002, 40 degrees C: p = 0.0002; cortisol 22 degrees C: p = 0.02, 40 degrees C: p = 0.0002; nitric oxide 22 degrees C: p = 0.0005, 40 degrees C: p = 0.0003, total proteins 22 degrees C: p<0.0001, 40 degrees C: p<0.0001 and; blood lactate 22 degrees C: p<0.0001, 40 degrees C: p<0.0001) both at 22 degrees C and 40 degrees C. There was no significant adjustment regarding IgA levels between the two thermal environments (p = 0.74), however the levels of alpha-amylase (p = 0.02), cortisol (p<0.0001), nitric oxide (p = 0.02) and total proteins (p = 0.01) in saliva were higher in the hotter conditions. Blood lactate was lower under the hot environment (p = 0.01). In conclusion, enduring hot temperature intensified stressful responses elicited by exercise. This study advocates that hot temperature deteriorates exercise performance under exhaustive stress and effort conditions

Correlation Between Blood Lactate and Salivary Biomarkers During Exercise in Women with Hypothyroidism Treated With L-Thyroxine

Background: Hypothyroidism reduces circulating levels of thyroid hormones metabolic enzymatic activities, and the skeletal muscle's work capacity and lactatemia increase during exertion. Objectives: To analyze salivary biomarkers and blood lactate obtained in exercise stages through exhaustion and investigate their correlation. Methods: Eight females attended the University Clinical Hospital who showed a condition of subclinical hypothyroidism. Before they began replacing with L-thyroxine, they were submitted to an ergometric test to check their tolerance to effort. Eight weeks after treatment, all volunteers were again submitted to lab and ergometric tests. Saliva and blood were collected to determine total protein, nitric oxide, IgA, lactate, and lipid profile. Results: The present study identified a correlation (0.8), so the behavior of the blood lactate could explain the behavior of the salivary of total proteins by 74.22% (R2 = 0.7422). Lactate production was minimized when women underwent L-thyroxine treatment in the first six stages of exercise. Still, total salivary proteins increased for pharmacotherapy between stages 1 and 8. While salivary nitric oxide had a percentage variation between pre- and post-exercise times of 96% before the start of treatment when the same exercise was performed after eight weeks of treatment with L-Thyroxine, this variation was 150%. Conclusion: The measurement of STP is an essential marker of stress, and it is highly correlated with the most used blood marker, lactate. Regarding treatment with L-Thyroxine in women with subclinical hypothyroidism, after eight weeks of this therapy, it was possible to observe a reduction in blood lactate production after the incremental load test on a cycle ergometer, accompanied by a reduction in the concentration of SA. SNO and SIgA tended to increase in women undergoing treatment, and this treatment should be considered in subsequent studies as causing a different effect on these markers

Salivary surrogates of plasma nitrite and catecholamines during a 21-week training season in swimmers

The collection of samples of saliva is noninvasive and straightforward, which turns saliva into an ideal fluid for monitoring the adaptive response to training. Here, we investigated the response of the salivary proteins alpha-amylase (sAA), chromogranin A (sCgA), and the concentration of total protein (sTP) as well as salivary nitrite (sNO2) in relation to plasma catecholamines and plasma nitrite (pNO2), respectively. The variation in these markers was compared to the intensity and load of training during a 21-week training season in 12 elite swimmers. Overall, the salivary proteins tracked the concentration of plasma adrenaline and were inversely correlated with the training outcomes. No correlations were observed between sNO2 and pNO2. However, sNO2 correlated positively with the intensity and load of training. We argue that the decrease in sympathetic activity is responsible for the decrease in the concentration of proteins throughout the training season. Furthermore, the increase in nitrite is likely to reflect changes in hemodynamics and regulation of vascular tone. The association of the salivary markers with the training outcomes underlines their potential as noninvasive markers of training status in professional athletes

Response of salivary markers of autonomic activity to elite competition

We investigated the response of salivary total protein (TP), alpha-amylase (sAA) and chromogranin A (CgA) to sporting competition and their relation with positive and negative affect. 11 professional swimmers were examined during the first day of a national contest and on a recreated event that matched time-of-the-day and day-of-the-week assessments 2 weeks later. Total protein was determined by the Bradford method and sAA and CgA by Western blotting upon awakening, 30 and 60 min post awakening, immediately before warming up for competition and 5, 20 and 60 min after competition. Psychometric instruments included the Positive Affect and Negative Affect Schedule-X. The concentrations of TP, sAA and CgA differed from controls only prior to and 5 min after the event. We observed positive correlations between higher negative affect scores with higher levels of TP, sAA and CgA prior to the event on the competition day. All 3 markers showed a similar reactivity to sporting competition, which may be attributed to the mechanisms responsible for protein secretion into saliva when collection is performed with no exogenous stimulation. TP is an attractive marker in sports psychology since its determination is faster and cheaper than traditional kinetic or immune assays

Salivary nitric oxide and alpha-amylase as indexes of training intensity and load

This study examined the variation in salivary nitric oxide (NO), alpha-amylase (sAA) and serum markers of muscle injury during 21 weeks of training in elite swimmers. Samples of saliva and blood were collected once a month during 5 months from 11 male professional athletes during their regular training season. The variation in each marker throughout the 21 weeks was compared with the dynamics of trainingvolume, intensity and load. Unstimulated whole saliva was assessed for NO and sAA whereas venous blood was assessed for lactate dehydrogenase, creatine kinase, and γ-glutamyltransferase. Nitric oxide and sAA showed a proportional response to the intensity of training. However, whereas the concentration of NO increased across the 21 weeks, the activity of sAA decreased. Similar variations in the concentration of NO and the markers of muscle injury were also observed. The higher concentration of NO might be attributed to changes in haemodynamics and muscle regenerative processes. On the other hand, autonomic regulation towards parasympathetic predominance might have been responsible for the decrease in sAA activity. These findings provide appealing evidence for the utilization of salivary constituents in sports medicine to monitor training programmes

Characterization and localization of dynein and myosins V and VI in the ovaries of queen bees

The presence of myosin and dynein in the ovaries of both Apis mellifera and Scaptotrigona postica was investigated in extracts and in histological sections. In the ovary extracts, motor proteins, myosins V, VI and dynein were detected by Western blot. In histological sections, they were detected by immunocytochemistry, using a mouse monoclonal antibody against the intermediary chain of dynein and a rabbit polyclonal antibody against the myosin V head domain. The myosin VI tail domain was recognized by a pig polyclonal antibody. The results show that these molecular motors are expressed in the ovaries of both bee species with few differences in location and intensity, in regions where movement of substances is expected during oogenesis. The fact that antibodies against vertebrate proteins recognize proteins of bee species indicates that the specific epitopes are evolutionarily well preserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Vochysia rufa stem bark extract protects endothelial cells against high glucose damage

This article belongs to the Special Issue Herbal Medicines and Functional Foods.[Background]: Increased oxidative stress by persistent hyperglycemia is a widely accepted factor in vascular damage responsible for type 2 diabetes complications. The plant Vochysia rufa (Vr) has been used in folk medicine in Brazil for the treatment of diabetes. Thus; the protective effect of a Vr stem bark extract against a challenge by a high glucose concentration on EA.hy926 (EA) endothelial cells is evaluated.[Methods]: Vegetal material is extracted with distilled water by maceration and evaporated until dryness under vacuum. Then; it is isolated by capillary electrophoresis–tandem mass spectrometry. Cell viability is evaluated on EA cells treated with 0.5–100 µg/mL of the Vr extract for 24 h. The extract is diluted at concentrations of 5, 10 and 25 µg/mL and maintained for 24 h along with 30 mM of glucose to evaluate its protective effect on reduced glutathione (GSH); glutathione peroxidase (GPx) and reductase (GR) and protein carbonyl groups.[Results]: V. rufa stem bark is composed mainly of sugars; such as inositol; galactose; glucose; mannose; sacarose; arabinose and ribose. Treatment with Vr up to 100 µg/mL for 24 h did not affect cell viability. Treatment of EA cells with 30 mM of glucose for 24 h significantly increased the cell damage. EA cells treated with 30 mM of glucose showed a decrease of GSH concentration and increased Radical Oxygen Species (ROS) and activity of antioxidant enzymes and protein carbonyl levels; compared to control. Co-treatment of EA with 30 mM glucose plus 1–10 μg/mL Vr significantly reduced cell damage while 5–25 μg/mL Vr evoked a significant protection against the glucose insult; recovering ROS; GSH; antioxidant enzymes and carbonyls to baseline levels.[Conclusion]: V. rufa extract protects endothelial cells against oxidative damage by modulating ROS; GSH concentration; antioxidant enzyme activity and protein carbonyl levels.CAPES—Coordenação de Aperfeiçoamento de Pessoal de Nível Superior. This work was supported by grant AGL2010-17579 from the Spanish Ministry of Science and Innovation (MICINN).Peer reviewe

Representative blots of sAA and sCgA in response to training.

<p>Representative blots of sAA and sCgA in response to training.</p