Alexandre dos Santos Martins

Memory deficits and oxidative stress in cerebral ischemia–reperfusion: Neuroprotective role of physical exercise and green tea supplementation

Ischemic stroke is a major cause of morbidity and mortality all over the world. Among impairments observed in survivors there is a significant cognitive learning and memory deficit. Neuroprotective strategies are being investigated to minimize such deficits after an ischemia event. Here we investigated the neuroprotective potential of physical exercise and green tea in an animal model of ischemia-reperfusion. Eighty male rats were divided in 8 groups and submitted to either transient brain ischemia-reperfusion or a sham surgery after 8 weeks of physical exercise and/or green tea supplementation. Ischemia-reperfusion was performed by bilateral occlusion of the common carotid arteries during 30 min. Later, their memory was evaluated in an aversive and in a non-aversive task, and hippocampus and prefrontal cortex were removed for biochemical analyses of possible oxidative stress effects. Ischemia-reperfusion impaired learning and memory. Reactive oxygen species were increased in the hippocampus and prefrontal cortex. Eight weeks of physical exercise and/or green tea supplementation before the ischemia-reperfusion event showed a neuroprotective effect; both treatments in separate or together reduced the cognitive deficits and were able to maintain the functional levels of antioxidant enzymes and glutathione.

Effects of green tea and physical exercise on memory impairments associated with aging.

We investigated the effects of physical exercise and green tea supplementation (associated or not) on biochemical and behavioral parameters in the time course of normal aging. Male Wistar rats aged 9 months were divided into groups: control, physical exercise (treadmill running), and supplemented with green tea while either performing physical exercise or not. A young control group was also studied. Physical exercise and green tea supplementation lasted 3 months. Afterwards, behavioral and biochemical tests were performed. Biochemical measurements revealed differences in antioxidant and oxidant responses in hippocampus, prefrontal cortex and striatum. Behavioral testing showed age-related memory impairments reversed by physical exercise. The association of green tea supplementation and physical exercise did not provide aged rats with additional improvements in memory or brain oxidative markers. Green tea per se significantly decreased reactive oxygen species levels and improved antioxidant defenses although it did not reverse memory deficits associated with normal aging.

Supplementation with different teas from Camellia sinensis prevents memory deficits and hippocampus oxidative stress in ischemia-reperfusion

&NA; Memory and cognition impairments resultant of ischemic stroke could be minimized or avoided by antioxidant supplementation. In this regard, the neuroprotective potential of Green tea from Camellia sinensis has been investigated. However, there is a lack of information regarding the neuroprotective potential of others teas processed from the Camellia sinensis. Here we investigate the neuroprotective role of green, red, white and black tea on memory deficits and brain oxidative stress in a model of ischemic stroke in rats. Our findings show that green and red teas prevent deficits in object and social recognition memories, but only green tea protects against deficits in spatial memory and avoids hippocampal oxidative status and intense necrosis and others alterations in the brain tissue. In summary, green tea shows better neuroprotection in ischemic stroke than the others teas from Camellia sinensis. HighlightsWhite, green and red teas protect recognition memory deficit after ischemic stroke.Only green tea protects against ischemic stroke induced spatial memory deficit.Only green tea protects against hippocampal oxidative stress after ischemic stroke.Neuroprotection is higher after green tea supplementation.

Influence of mental practice and movement observation on motor memory, cognitive function and motor performance in the elderly

Background With aging, it is important to maintain cognitive and motor functions to ensure autonomy and quality of life. During the acquisition of motor skills, it is necessary for the elderly to understand the purpose of the proposed activities. Physical and mental practice, as well as demonstrations, are strategies used to learn movements. Objectives To investigate the influence of mental practice and the observation of movement on motor memory and to understand the relationship between cognitive function and motor performance in the execution of a sequence of digital movements in the elderly. Method This was a cross-sectional study conducted with 45 young and 45 aged subjects. The instruments used were Mini-Mental State Examination (MMSE), Manual Preference Inventory and a Digital Motor Task (composed of a training of a sequence of movements, an interval and a test phase). The subjects were divided into three subgroups: control, mental practice and observation of movement. Results The elderly depend more strongly on mental practice for the acquisition of a motor memory. In comparing the performances of people in different age groups, we found that in the elderly, there was a negative correlation between the MMSE score and the execution time as well as the number of errors in the motor task. Conclusions For the elderly, mental practice can advantage motor performance. Also, there is a significant relationship between cognitive function, learning and the execution of new motor skills.

Short-term green tea supplementation prevents recognition memory deficits and ameliorates hippocampal oxidative stress induced by different stroke models in rats

This study investigated the effect of green tea (GT) on short and long term declarative memory and oxidative damage induced by transient ischemia-reperfusion (IR) and intracerebral hemorrhage (ICH) in rats. Male Wistar rats were divided into 8 groups of 10 according the stroke type induced: Sham IR, Sham IR+GT, IR, IR+GT, Sham ICH, Sham ICH+GT, ICH, ICH+GT. Supplementation with GT was initiated 10days before stroke surgery and continuous for 6days after (GT dose 400mg/kg). Short (STM) and long term memory (LTM) we evaluated with object recognition task (OR) and hippocampus were used to evaluate parameters related to oxidative stress (ROS, lipid peroxidation and total antioxidant capacity). The rats subjected to IR and ICH showed STM and LTM deficits and GT intervention prevented it in both stroke models. IR and ICH induced increase on ROS levels in hippocampus. ICH increased the lipid peroxidation in hippocampus and the GT supplementation avoided it. IR induced decrease on total antioxidant capacity and GT prevented it. These results reveal that GT supplementation presents a neuroprotective role, attenuates redox imbalance and might have a beneficial impact on cognitive function after stroke.