Semin I

The effects of regular aerobic exercise in adolescent period on hippocampal neuron density, apoptosis and spatial memory

It is known that positive effects of regular aerobic exercise on cognitive functions in humans and also animals; but how to the effects of aerobic exercise in adolescent period is unknown. The present study examined the effects of regular aerobic exercise on spatial memory using the Morris water maze, cell density and apoptosis of hippocampus in adolescent rats. Twenty-two days of age male rats were run on a treadmill for 30 min/session at a speed of 8m/min and 0 degrees slope, five times a week for 8 weeks. The present study showed that exercise induced significant cognitive improvement throughout brain maturation in rats. The number of hippocampal CA1 and CA3 neurons, and gyrus dentatus neurons were significantly increased in the exercised rats. There was no significant difference of CA2 neuron density between exercise and control groups. There was no significantly differences in any groups according to the results of apoptosis that account of TUNEL positive cells. The present results suggest that regular moderate aerobic treadmill exercise benefit in cognitive functions. This result may derive from treadmill exercise-induced increase cell density without altering of apoptosis in the hippocampus and dentate gyrus of adolescent rats.

Lipid Peroxidation and Antioxidant Activity in Chronic Haemodialysis Patients Treated with Recombinant Human Erythropoietin

In anaemia of chronic renal failure, the most important factor in the shortened erythrocyte survival may be lipid peroxidation of the cell membrane. Defective antioxidant activity may increase this damage. Although recombinant human erythropoietin (r-HuEPO) can effectively correct anaemia in chronic haemodialysis patients, its actions on lipid peroxidation and antioxidant activity are not clear. These actions were investigated in 13 patients undergoing chronic haemodialysis. Antioxidant activity, including red blood cell superoxide dismutase and total glutathione peroxidase levels and the lipid peroxidation product malondialdehyde, were measured before and 3 months after initiation of r-HuEPO treatment, using heparinized venous whole blood for cell and plasma determinations. Age-matched healthy volunteers were controls. Significantly higher levels of superoxide dismutase and total glutathione peroxidase were found in the patients than in the controls (p < 0.01). Plasma malondialdehyde levels were not affected by r-HuEPO. The results are explained by erythropoiesis and cellular haemoglobin synthesis due to r-HuEPO, followed by increase of circulating young red cells. The membranes of these young cells contain more antioxidant enzymes than the others. Despite r-HuEPO treatment, plasma malondialdehyde levels in haemodialysis patients may be higher than normal because of the uraemic milieu and the chronic haemodialysis.

Age-dependent effects of maternal deprivation on oxidative stress in infant rat brain

Developing brain is much more sensitive to all kind of stressors than the developed brain. Early maternal deprivation causes some behavioural and physiological effects on rats. After the birth, there is no endocrinological response to stressors between post-natal 4 and 14th days, which is called stress-hyporesponsive period (SHRP) in rats. This hypo-responsiveness is time- and stressor-specific, as some more severe stressors have been shown to induce a stress response. The present study examined the effects of maternal deprivation on oxidative stress in the hippocampus, prefrontal cortex (PFC) and striatum regions of the brain both during and after SHRP of the infant rats. The results showed that maternal deprivation in SHRP increased antioxidant enzyme activities and reduced lipid peroxidation in infant rat brain. However, by the termination of SHRP, maternal deprivation reduced enzyme activities and increased lipid peroxidation. The results indicated that infant brain might be protected in SHRP from maternal deprivation-induced oxidative stress.

Methamphetamine causes depletion of glutathione and an increase in oxidized glutathione in the rat striatum and prefrontal cortex

The administration of methamphetamine to experimental animals results in damage to dopaminergic neurons. The hypothesis that methampheta-mine-induced neurotoxicity is mediated by reactive oxygen species was evaluated. It was found that acute administration of methamphetamine (5 and 15 mg kg-1) resulted in production of oxidative stress as demonstrated by decreased glutathione and increased oxidized glutathione levels in the rat striatum and prefrontal cortex. These changes in glutathione and oxidized glutathione levels were dose-dependent in striatum, but not in prefrontal cortex. In conclusion, the results of present study provide further evidence in support of the notion that oxidative stress may play an important role in the metham-phetamine-induced neurotoxicity.

Effects of conventional heparin and low-molecular-weight heparin treatment on lipid metabolism during a single hemodialysis session

Accessible online at: http://BioMedNet.com/karger Dear Sir, The importance of safe and efficient anticoagulation has been crucial in the development of hemodialysis (HD) treatment. Although standard heparin (H) is a reliable anticoagulant, there are some problems associated with its use during dialysis. Bleeding, thrombocytopenia, allergic reactions, hair loss, osteoporosis and interactions of lipid metabolism are the main problems [1, 2]. The anticoagulant activity of low-molecular-weight heparin (LMWH) is safe, as well as H, and the risks of bleeding and thrombocytopenia are lower than for H [3]. For these reasons, in recent years LMWH has been used for its antithrombotic activity in HD patients. Widespread use of these drugs has revealed adverse effects such as release of lipoprotein lipase and hepatic lipase from the endothelial surface. Increment of intravascular lipolytic activity results in elevation of plasma free fatty acids which cause oxidative damage to endothelium and other cells [4]. Additionally, interactions of plasma lipid levels during HD session are detected [5, 6]. In this study, the effects of LMWH and H on lipid metabolism during a single HD session were investigated. During the study the particular dialysis procedure used for each patient was not altered. The same type of dialyzer was used in the study group. The HD session lasted 4 h at blood flow rates ranging from 250 to 350 ml/min. Sixteen HD patients (8 men and 8 women; mean age 48 years) were studied on two different conditions; the characteristics of the patients from both groups were similar: