Ilkay Aksu

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.

Effects of voluntary and involuntary exercise on cognitive functions, and VEGF and BDNF levels in adolescent rats

Abstract Regular treadmill running during adolescence improves learning and memory in rats. During adolescence, the baseline level of stress is thought to be greater than during other periods of life. We investigated the effects of voluntary and involuntary exercise on the prefrontal cortex and hippocampus, vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF) levels, and spatial learning, memory and anxiety in adolescent male and female rats. The voluntary exercise group was given free access to a running wheel for 6 weeks. The involuntary exercise group was forced to run on a treadmill for 30 min at 8 m/min 5 days/week for 6 weeks. Improved learning was demonstrated in both exercise groups compared to controls. Neuron density in the CA1 region of the hippocampus, dentate gyrus and prefrontal cortex were increased. Hippocampal VEGF and BDNF levels were increased in both exercise groups compared to controls. In females, anxiety and corticosterone levels were decreased; BDNF and VEGF levels were higher in the voluntary exercise group than in the involuntary exercise group. The adolescent hippocampus is affected favorably by regular exercise. Although no difference was found in anxiety levels as a result of involuntary exercise in males, females showed increased anxiety levels, and decreased VEGF and BDNF levels in the prefrontal cortex after involuntary exercise.

Effect of acute and chronic exercise on oxidant–antioxidant equilibrium in rat hippocampus, prefrontal cortex and striatum

Although regular physical exercise is beneficial to the body, it is well known that exhaustive exercise causes oxidative stress in muscle. Recent studies suggest that regular moderate physical exercise has the beneficial effects on brain. There is a little information regarding whether or not exercise could generate oxidative stress in the brain and the findings are conflicting. The aim of this study was to investigate the effects of acute and chronic exercise on thiobarbituric acid reactive substances, as an indicator of lipid peroxidation, in the hippocampus, which has a high concentration of glucocorticoid receptors, and prefrontal cortex and striatum, which have high dopamine content. Additionally we examined antioxidant enzyme activities, superoxide dismutase and glutathione peroxidase and nitrite-nitrate levels to assess the effects of reactive oxygen and nitrogen species. In this study it was shown that acute treadmill exercise at different strengths did not cause oxidative stress in prefrontal cortex, striatum and hypocampus regions of the brain. Regular treadmill exercise performed at different strengths was shown not to cause oxidative stress in prefrontal cortex, striatum and hippocampus regions of brain. As a result, we propose that acute and chronic exercise do not cause oxidant stress in prefrontal cortex, striatum and hippocampus and chronic exercise has a favorable effect on hippocampus, possibly by decreasing superoxide radical formation.

Relationship between circulating IGF-1 levels and traumatic brain injury-induced hippocampal damage and cognitive dysfunction in immature rats.

It is well known that traumatic brain injury (TBI) induces the cognitive dysfunction resulting from hippocampal damage. In the present study, we aimed to assess whether the circulating IGF-I levels are associated with cognition and hippocampal damage in 7-day-old rat pups subjected to contusion injury. Hippocampal damage was examined by cresyl violet staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Spatial memory performance was assessed in the Morris water maze. Serum IGF-1 levels decreased in both early and late period of TBI. Decreased levels of serum IGF-1 were correlated with hippocampal neuron loss and spatial memory deficits. Circulating IGF-1 levels may be predictive of cognitive dysfunction resulted from hippocampal damage following traumatic injury in developing brain. Therapy strategies that increase circulating IGF-1 may be highly promising for preventing the unfavorable outcomes of traumatic damage in young children.

Anxiety correlates to decreased blood and prefrontal cortex IGF-1 levels in streptozotocin induced diabetes

It is well known that diabetes mellitus may cause neuropsychiatric disorders such as anxiety disorders. Diabetes may also cause reduced IGF-1 (insulin like growth factor-1) levels in brain and blood. The purpose of the present study was to investigate the relationship between diabetes induced anxiety and IGF-1 levels in diabetic rats. The anxiety levels of rats were assessed 2 weeks after intraperitoneal injection of streptozotocin. Diabetic rats had higher levels of anxiety, as they spent more time in closed branches in elevated-plus-maze-test and less time in the center cells of open-field-arena. Prefrontal cortex (PFC) IGF-1 levels and neuron numbers were decreased and apoptosis was increased in diabetic rats. Blood IGF-1 levels decreased in a time dependent fashion following streptozotocin injection while blood corticosterone levels increased. They had higher malondialdehyde levels and lower superoxide dismutase enzyme activity. Oxidative stress may negatively affect blood and PFC tissue IGF-1 levels. Reduction in IGF-1 may cause PFC damage, which may eventually trigger anxiety in diabetic rats. Therapeutic strategies that increase blood and brain tissue IGF-1 levels may be promising to prevent psychiatric sequelae of diabetes mellitus.

Maternal treadmill exercise during pregnancy decreases anxiety and increases prefrontal cortex VEGF and BDNF levels of rat pups in early and late periods of life

In a previous study we demonstrated that, regular aerobic exercise during pregnancy decreased maternal deprivation induced anxiety. The purpose of this study is to investigate whether the positive effects of maternal exercise on the male and female offsprings early and late period of life. Half of the test subjects in each group were evaluated when they were 26 days old, and the other half were evaluated when they were 4 months old. The anxiety levels of maternally exercised groups were less than the control groups in both sexes and in both prepubertal and adult periods. The locomotor activity more increased in females. The prefrontal VEGF and BDNF levels were greater for both age groups and sexes in the maternally exercised group compared to control group. Moreover, there was a strong positive correlations between prefrontal cortex BDNF levels and results of open field tests; and VEGF levels and results of elevated plus maze tests. There was no difference in serum corticosterone levels between groups. These results indicate that maternal exercise during pregnancy may protect the pups from anxiety in early and late periods of life, and affects the prefrontal cortex positively.

Maternal exercise decreases maternal deprivation induced anxiety of pups and correlates to increased prefrontal cortex BDNF and VEGF

Maternal deprivation (MD) may cause neuropsychiatric disorders such as anxiety disorder by negatively affecting the cognitive functions and behavior in pups. The aim of this study is to investigate whether maternal exercise during pregnancy has beneficial effects on anxiety that increases with MD, and on the levels of VEGF and BDNF which have anxiolytic effects on the prefrontal cortex, the anxiety-related region of the brain. The anxiety level in the deprivation group was greater than the control group and found more in male than female pups. The prefrontal cortex VEGF and BDNF levels were decreased in the deprivation group compared to control group while serum corticosterone levels were increased in the deprivation group. Anxiety and serum corticosterone levels were decreased in maternally exercised female and male pups, while the prefrontal cortex VEGF and BDNF levels were increased, compared to sedentary mothers pups. These results indicate that maternal exercise may attenuate the negative effect of stresses such as maternal deprivation that can be encountered early in life.

Acute exhaustive exercise does not alter lipid peroxidation levels and antioxidant enzyme activities in rat hippocampus, prefrontal cortex and striatum

Although regular physical exercise is beneficial to the body, it is well known that exhaustive exercise causes oxidative stress in muscle. Recent studies suggest that regular moderate physical exercise has the beneficial effects on brain. However, there is little information regarding whether or not exhaustive exercise could generate oxidative stress in brain and the findings are conflicting. The aim of this study was to investigate the effects of exhaustive exercise on thiobarbituric acid reactive substances, as an indicator of lipid peroxidation, in the hippocampus, prefrontal cortex and striatum. Additionally we examined antioxidant enzymes activities, superoxide dismutase and glutathione peroxidase, to assess the effects of reactive oxygen species. Exhaustive exercise did not change superoxide dismutase and glutathione peroxidase enzyme activities and thiobarbituric acid reactive substances levels neither immediately (0 min) nor at 3, 6, 12, 24 and 48 h after the cessation of exercise in the brain. These results indicate that acute exhaustive exercise may not cause significant lipid peroxidation in the hippocampus, prefrontal cortex and striatum during the post-exercise period.

Acute footshock-stress increases spatial learning–memory and correlates to increased hippocampal BDNF and VEGF and cell numbers in adolescent male and female rats

It is well known that the acute-stress enhances cognitive functions in adults, but is not known in adolescents. The purpose of this study is to investigate the effects of low and high intensities of acute-stress on hippocampus and spatial memory in the adolescent male and female rats. Thirty-eight days aged rats were subjected to 0.2 and 1.6 mA intensity of footshock-stress for 20 min. Spatial memory performance was assessed in the Morris water maze. Learning had been positively affected in stress groups. Neuron density in the CA1 hippocampal region and the gyrus dentatus as well as VEGF and BDNF levels of hippocampus increased in all stress groups. In females, learning process and BDNF levels increased in low-intensity-stress group than high-intensity-stress group. There was no difference in hippocampal apoptosis among groups. We conclude that adolescent hippocampus is affected positively from acute-stress; however, while there is no difference in male response with respect to intensity of stress, females are affected more positively from low-intensity of stress.

Positive effects of aerobic exercise on learning and memory functioning, which correlate with hippocampal IGF-1 increase in adolescent rats.

It is already known that regular aerobic exercise during adolescent period improves learning and memory in rats. In this study, we investigated the effects of regular aerobic exercise on learning, memory functioning and IGF-1 levels. IGF-1 is known to have positive effects on cognitive functions in adolescent rats. Exercise group was separated into two different groups. First half was run on a treadmill for 30 min per session at a speed of 8m/min and 0° slope, five times a week for 6 weeks. The second half was given free access to a running wheel (diameter 11.5 cm) which was connected to a digital counter and run on a treadmill for 6 weeks. Learning and memory functioning were found to be positively correlated with the exercise activity. Findings suggest increased neuron density in CA1 hippocampal region and dentate gyrus. Increased IGF-1 level was detected in hippocampus and blood serum, while IGF-1 level in liver tissue did not change with exercise activity. In conclusion, our findings indicate that learning and memory functioning were positively affected by voluntary and involuntary physical exercise which correlated increased hippocampal activity and elevated IGF-1 levels in adolescent rats.