Melatonin is a product of the amino acid tryptophan in the pineal gland. Once synthesized, the specific mechanisms governing the release of melatonin from the pineal gland and its functions are largely unknown. Besides its regulatory role in circadian rhythms in mammals, because of its widespread subcellular distribution, melatonin contributes to the reduction of oxidative damage in both the lipid and the aqueous environments of the cell. This postulate is widely supported by the experimental observations showing that melatonin protects lipids in membranes, proteins in the cytosol, and DNA in the nucleus and mitochondria from free radical damage. Melatonin thus reduces the severity of disease conditions where free radicals are implicated. The direct free radical scavenging effects of melatonin are receptor independent. It has recently been shown that it has an ability to scavenge free radicals, including hydroxyl radicals, hydrogen peroxide, peroxyl radicals, singlet oxygen and nitric oxide (NO) and peroxynitrite anion. An excessive amount of NO, a free radical which is generated by the inducible form of NO synthase, is known to cause cytotoxic changes in cells. Hence, NO synthase is considered a pro-oxidative enzyme, and any factor that reduces its activity would be considered an antioxidant. Recent studies have shown that melatonin inhibits the activity of NO synthase, beside its NO and peroxynitrite scavenging activity. Thus, inhibition of NO production may be another means whereby melatonin reduces oxidative damage under conditions, such as ischemia-reperfusion, sepsis, etc, where NO seems to be important in terms of the resulting damage.
Impaired red blood cell deformability is a hemorheological perturbation induced by many kinds of diseases. An increase in free radicals causes a reduction in erythrocyte flexibility and deformability. Carnosine is a dipeptide abundant in skeletal muscle and brain of humans. One of the main function of carnosine is its antioxidant and free-radical scavenger effect. In this study our aim is to investigate the protective effect of L-carnosine on RBCs in H 2 O 2 -induced oxidative stress in vitro conditions.Twenty male wistar albino rats, 10 were 3 months old, 10 were 12 months old used. The blood from each rat were divided into ten tubes and these blood samples divided into two groups. The first tube of the first group was the control and the rest 4 tubes were treated with different concentrations of L-carnosine. All tubes in the second group were incubated with H 2 O 2 additively. The deformability indexes of the erythrocytes were measured by a laser diffractometer (Myrenne Rheodyne SSD).L-carnosine has improved the RBC deformability significantly which is impaired by H 2 O 2 treatment (p < 0.05). Increase in deformability is more significant in young rat group when compared to old rat group.L-carnosine, as an antioxidant molecules, has a dose dependent positive effect on RBC deformability and has improved or protect the deformability of erythrocytes, especially in young rat group which impaired by H 2 O 2 -induced oxidative stress in vitro conditions. The results of this study first suggest that L-carnosine supplemention can be used to improve the RBC quality or to protect them from oxidative damage in survival of RBC in the circulation.
SummaryStudy aim: The purpose of this study was to examine the effects of a repeated sprint training program in addition to volleyball training on the aerobic capacity of college volleyball players. Materials and methods: Eighteen male volleyball players were randomly assigned to either an experimental group (n = 9, age: 21.2 ± 1.3 years) or a control (n = 9, age: 21.2 ± 1.6 years) group. Both groups followed a traditional volleyball training program three times per week for 6 weeks. The experimental group additionally performed a repeated sprint training protocol immediately before each volleyball training session. The repeated sprint training consisted of 1-3 sets of 5 × 20 m maximal sprints with 20 seconds of active recovery between sprints and 4 min of passive recovery between sets. Before and after the 6-week training period, all participants performed an incremental treadmill test to determine maximal oxygen uptake (VO 2max ) and time to exhaustion, and the repeated sprint test (10 × 20 m with a 20-second recovery between each sprint). Results: The experimental group showed significant improvements in VO 2max (+7.1 ± 4.8%; p = 0.001) and running time to exhaustion (+15.8 ± 6.8%; p = 0.004) after training. The best 20-m sprint time (−2.3 ± 2.5%; p = 0.029), mean sprint time (−5.3 ± 3.1%; p = 0.001) and fatigue index (−34.1 ± 28.2%; p = 0.012) also improved significantly in the experimental group. None of these variables changed significantly in the control group (p > 0.05). Conclusions:The current findings indicate that the addition of a repeated sprint training program can improve both the aerobic capacity and anaerobic performance of college volleyball players.
Further more detailed studies are needed to find out the effects of drugs on these parameters or to disclose the exact mechanism underlying the alteration of these parameters.
It is known that oxidative stress plays an important role in the chronic complications of diabetes. Lipid peroxidation is one of the consequences of oxidative stress. Erythrocyte deformability abilities are reduced as a result of lipid peroxidation. Conversely, a decrease nitric oxide (NO) production seems to be responsible in endothelial dysfunction which occurs in diabetic vascular complications. Carnosine is a molecule with anti-oxidant properties. The aim of this study was to investigate erythrocyte deformability indices and the effects of carnosine on erythrocyte deformability in diabetes and to determine a possible relationship between carnosine and nitric oxide. Male Wistar albino rats were used in the study. Injections were administered to seven groups consisting of eight rats each. The groups were: Control, Carnosine, L-NAME (NG-nitro-L-arginine methyl ester), Diabetic, STZ (Streptozotocin) +Carnosine, STZ+L-NAME and STZ+Carnosine+L-NAME. In addition, glucose, insulin, MDA (Malondialdehyde) and NO levels were measured and erythrocyte deformability indices were calculated in all groups. Erythrocyte deformability indices and NO levels were decreased and MDA levels were found to be increased in diabetic group. It was also found that carnosine can significantly reverse erythrocyte deformability, reduce lipid peroxidation and increase NO levels in diabetes. It can be concluded that carnosine can recover from microvascular circulation problems by increasing erythrocyte deformability, can protect cells and tissues against lipid peroxidation and can be used as a multi-functional anti-oxidant in the treatment of diabetes mellitus to prevent the complications of diabetes.
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