[Show abstract][Hide abstract] ABSTRACT: Given that the inter-limb asymmetry and additional balance control are required for turning, stroke subjects spend more time to turn than healthy subjects. Few studies have investigated specific turning-related neuromuscular and biomechanical strategies post-stroke to clarify factors favoring or hindering turning speed toward different directions. The purpose of this study was to compare the speed and lower-limb muscular and kinematic strategies of turning between individuals with stroke and matched controls. Fifteen ambulatory individuals with chronic stroke and 15 matched healthy controls participated in this study. Turning speed during turning along a 0.8-meter radius curved path toward both sides for 5 meters was recorded. Simultaneously, kinematics and muscle activation patterns of lower extremity were measured by the joint angle and electromyography during turning. The slower speed was noted for the turning task in stroke patients when compared to controls. Individuals with stroke have insufficient muscle activation in tibialis anterior and biceps femoris of the affected inner leg, accompanied by reduced standing knee flexion, which disturb turning toward the affected side. The augmented standing knee flexion of unaffected side in stroke patients hindered the function of the outer leg while turning toward the affected side, but assisted the role of the inner leg while turning toward the unaffected side. However, the absence of difference in turning speeds toward the affected and unaffected sides may attribute to the diminished swing phase knee flexion of the affected outer leg. Our findings suggest that there are direction-related strategies in turning for stroke subjects since the inner and outer legs, respectively, have specific roles for standing support and leg swing during turning. Therefore, in addition to turning speed, kinematics and muscular components during turning toward either direction should be considered to improve turning performance as well as to prevent falls in stroke rehabilitation.
The Chinese journal of physiology 06/2014; 57(3). · 0.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Reactive oxygen species are markedly increased after ischemia and play important roles in the mechanism of ischemia-reperfusion injury. Regulating the oxidative stress response after brain ischemia provides a potential therapeutic strategy. Quercetin is a natural flavonoid that exhibits antioxidant properties, the mechanisms by which it protects cells are, however, not fully understood. Exercise training also reduces oxidative stress and enhances brain recovery. The purpose of this study was to determine whether combined exercise training with quercetin treatment could result in better neuroprotection and functional recovery in rats subjected to brain ischemia.
Rats were randomly assigned to the following groups: middle cerebral artery occlusion (MCAO) with rest control, MCAO with quercetin, MCAO with exercise, or MCAO with exercise and quercetin. To determine the effect of PI3K/Akt pathway in quercetin and exercise mediated neuroprotection, two additional groups, a group of MCAO with quercetin and PI3K/Akt inhibitor (LY294002) and a group of MCAO with exercise, quercetin, and PI3K/Akt inhibitor, were added in this study. Motor function was examined at 24th hour and 14th day post-MCAO. Brain samples were used to measure the expression of antioxidative and anti-apoptotic proteins, as well as to measure the infarct volume.
Treatment with either exercise or quercetin significantly decreased oxidative stress and infarct volume, increased antioxidative and anti-apoptotic signaling, and improved motor function. Exercise training combined with quercetin treatment resulted in better outcomes than either treatment alone. PI3K/Akt inhibition eliminated the protective effects of exercise training and quercetin treatment.
Quercetin enhances exercise-mediated functional recovery after brain ischemia via up-regulation of PI3K/Akt activity to promote antioxidative and anti-apoptotic signaling.
Medicine and science in sports and exercise 02/2014; · 4.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Tripping over obstacles is the major cause of falls in community-dwelling patients with Parkinson's disease (PD). Understanding the factors associated with the obstacle crossing behavior may help to develop possible training programs for crossing performance. This study aimed to identify the relationships and important factors determining obstacle crossing performance in patients with PD.
Forty-two idiopathic patients with PD (Hoehn and Yahr stages I to III) participated in this study. Obstacle crossing performance was recorded by the Liberty system, a three-dimensional motion capture device. Maximal isometric strength of the lower extremity was measured by a handheld dynamometer. Dynamic balance and sensory integration ability were assessed using the Balance Master system. Movement velocity (MV), maximal excursion (ME), and directional control (DC) were obtained during the limits of stability test to quantify dynamic balance. The sum of sensory organization test (SOT) scores was used to quantify sensory organization ability.
Both crossing stride length and stride velocity correlated significantly with lower extremity muscle strength, dynamic balance control (forward and sideward), and sum of SOT scores. From the regression model, forward DC and ankle dorsiflexor strength were identified as two major determinants for crossing performance (R(2) = .37 to.41 for the crossing stride length, R(2) = .43 to.44 for the crossing stride velocity).
Lower extremity muscle strength, dynamic balance control and sensory integration ability significantly influence obstacle crossing performance. We suggest an emphasis on muscle strengthening exercises (especially ankle dorsiflexors), balance training (especially forward DC), and sensory integration training to improve obstacle crossing performance in patients with PD.
PLoS ONE 01/2014; 9(1):e84245. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Falls are a major problem for people with Parkinson's disease (PD). Many studies indicate that more than 50% of people with PD have difficulty in turning that may lead to falls during daily activities. The aims of this study were to identify the relationship between turning performance and falls, and to determine the factors that influence turning performance.
This study examined 45 patients with idiopathic PD (Hoehn and Yahr stage 1-3) using a battery of tests, including 180° turn time, balance, and muscle strength. The levels of disease severity and freezing of gait were also measured. The number of falls in the past 6 months was recorded.
Sixteen out of forty-five participants experienced falls in the past 6 months. A receiver operating characteristic curve showed that turn time was highly related to falls [more affected side: sensitivity = 0.81, specificity = 0.79, area under the curve (AUC) = 0.83; less affected side: sensitivity = 0.88, specificity = 0.76, AUC = 0.83]. The most important factor influencing turn time was balance ability (both sides: p = 0.000) according to the regression model. Correlations between turn time and dynamic balance were further established with reaction time, movement velocity, endpoint excursion, and maximal excursion of the LOS (limits of stability) test.
The time needed to complete a 180° turn during the SQT (step/quick turn) test is a good index to differentiate fallers from non-fallers in persons with PD. Turn time is most influenced by balance. Furthermore, balance control, especially in an anterior or sideways direction, is important for turning performance.
PLoS ONE 01/2014; 9(4):e93572. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background
Predicting functional improvement at an early stage after stroke is critical to setting treatment goals and strategies. The aim of this study was to identify factors that can predict motor function improvement at 3 months and 6 months poststroke.
Forty-four patients with stroke were included in the study. We recorded age, interval between stroke onset and initiation of physical therapy, stroke type, history of diabetes or cardiovascular disease, functional status prior to stroke, cognition, motivation, walking ability, eating ability, hemineglect, sensory function, and brain lesion site as predictive factors. The Stroke Rehabilitation Assessment of Movement, Berg Balance Scale, Timed Up & Go Test, and the 6-Minute Walk Test were conducted upon intake and at 3 months and 6 months poststroke. Patients were assigned to a progressive group or a nonprogressive group based on their improvement in four functional measures. Variables for which there were significant group differences were used for stepwise discriminant analysis as determining factors and for setting the prediction model.
Patient age, history of diabetes, functional status prior to stroke, and motivation were predictive factors of functional progress at 3 months poststroke. Motivation and functional status prior to stroke predicted functional progress at 6 months poststroke. By comparing the discriminant function values of the progressive and nonprogressive groups, functional improvement can be predicted.
Functional status prior to stroke and motivation are predictive of functional outcome at 3 months and 6 months poststroke. We have provided a formula that can be used to predict a patient’s progress and then set treatment goals and programs accordingly.
Journal of the Chinese Medical Association 01/2014; · 0.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Coactivation of primary motor cortex ipsilateral to a unilateral movement (M1ipsilateral) has been observed, and the magnitude of activation is influenced by the contracting muscles. It has been suggested that the microstructural integrity of the callosal motor fibers (CMFs) connecting M1 regions may reflect the observed response. However, the association between the structural connectivity of CMFs and functional changes in M1ipsilateral remains unclear. The purpose of this study was to investigate the relationship between functional changes within M1ipsilateral during unilateral arm or leg movements and the microstructure of the CMFs connecting both homotopic representations (arm or leg).
PLoS ONE 01/2014; 9(8):e104218. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background
Direction change while walking is a complex task of locomotor activity and is necessary during daily activities, but little is known about whether aging alters turn-related characteristics compared with straight walking. The objective of this study was to investigate the effects of aging on the biomechanical characteristics and walking velocity during circular turning.
The participants included 17 healthy older adults (65–80 years old) and 16 young adults. Walking velocity, the first and second peak knee flexion, ankle plantarflexion, ankle dorsiflexion, and electromyographic amplitudes of the rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius medialis were measured during walking along a 5 m straight path and a 5 m circumference curved path with a radius of 0.8 m.
The two groups made comparable decreases in turning velocity as compared with straight walking, but older adults decreased the second peak knee flexion instead of the second peak ankle plantarflexion, and the knee remained flexed during the loading response. Older people also needed higher amplitudes of the tibialis anterior in the outer leg, and biceps femoris in the inner leg, to facilitate turning, which were not seen in young adults. Moreover, older adults did not decrease amplitudes of the rectus femoris and biceps femoris in the outer leg, and tibialis anterior in the inner leg, as noted in young adults.
Aging does not exert further effects on turning velocity, but older adults use different biomechanical strategies to turn.
International Journal of Gerontology 09/2013; 7(3):162–166. · 0.24 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: . Turning is a challenging task for stroke patients. Programs that effectively target turning, however, have not been established.
. This study examined the effects of a novel turning-based treadmill training on turning performance, gait symmetry, balance, and muscle strength in patients with chronic stroke.
. Thirty participants were randomly assigned to the experimental group that received 30 minutes of turning-based treadmill training or to the control group that received 30 minutes of regular treadmill training, followed by a 10-minute general exercise program for 12 sessions over 4 weeks. Primary outcomes (overground turning speed and temporal-spatial characteristics of straight walking) and secondary outcomes (balance and muscle strength) were assessed at baseline, after training, and at 1-month follow-up.
. Fifteen participants per group were 54.2 ± 9.6 years old, poststroke 2.6 ± 1.9 years, and walked overground at 0.59 ± 0.28 m/s. Sixteen had an ischemic and 14 a hemorrhagic stroke. There were significant interaction effects between groups and time on turning speed regardless of turning direction, straight-walking performance (speed and temporal symmetry), strength of hip muscles and ankle dorsiflexors, and balance control (Berg Balance Scale, weight shifting in the forward direction and vestibular function). Compared with the control group, the experimental group showed greater improvements in these measures following training. These improvements persisted at the 1-month follow-up evaluation.
. Turning-based treadmill training may be a feasible and effective strategy to improve turning ability, gait symmetry, muscle strength, and balance control for individuals with chronic stroke.
Neurorehabilitation and neural repair 07/2013; · 4.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE: This study aims to investigate the role of the primary motor cortex ipsilateral to the movement (ipsilateral M1) in unilateral motor execution. METHODS: Fifteen right-handed healthy subjects underwent functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) experiments. Motor tasks were performed with the right-side limb. Subjects followed visual cues to execute movements in the scanner and independent component analysis (ICA) was applied to analyse the data. Interhemispheric inhibition (IHI), short-interval intracortical inhibition (SICI) and recruitment curves (RCs) of motor-evoked potentials (MEPs) in right M1 were measured by TMS and responses were recorded from the left flexor carpi radialis (FCR) and left anterior deltoid (AD). RESULTS: Group ICA showed activations of bilateral M1s highly related to motor tasks. Additionally, TMS results showed significant increases of MEP RCs on the left FCR and left AD during right wrist flexion and right shoulder flexion. Prominent decreases of IHI and SICI were also observed under the same conditions. CONCLUSIONS: During unilateral muscle contraction, co-activation of the ipsilateral M1 involves additional processes modulated by intra- and interhemispheric interactions and its size of activations is specifically enhanced on the homotopic representation. SIGNIFICANCE: The ipsilateral M1 plays a central role in unilateral motor executions.
Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 03/2013; · 3.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Adult hippocampal neurogenesis is important for learning and memory, especially after a brain injury such as ischemia. Newborn hippocampal neurons contribute to memory performance by establishing functional synapses with target cells. This study demonstrated that the maturation of hippocampal neurons is enhanced by postischemia intermittent hypoxia (IH) intervention. The effects of IH intervention in cultured neurons were mediated by increased synaptogenesis, which was primarily regulated by brain-derived neurotrophic factor (BDNF)/PI3K/AKT. Hippocampal neo-neurons expressed BDNF and exhibited enhanced presynaptic function as indicated by increases in the pSynapsin expression, synaptophysin intensity, and postsynapse density following IH intervention after ischemia. Postischemia IH-induced hippocampal neo-neurons were affected by presynaptic activity, which reflected the dynamic plasticity of the glutamatergic receptors. These alterations were also associated with the alleviation of ischemia-induced long-term memory impairment. Our results suggest that postischemia IH intervention rescued ischemia-induced spatial learning and memory impairment by inducing hippocampal neurogenesis and functional synaptogenesis via BDNF expression.Journal of Cerebral Blood Flow & Metabolism advance online publication, 27 February 2013; doi:10.1038/jcbfm.2013.15.
Journal of cerebral blood flow and metabolism: official journal of the International Society of Cerebral Blood Flow and Metabolism 02/2013; · 5.46 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Brain ischemia leads to muscle inactivity-induced atrophy and may exacerbate motor function deficits. Intramuscular insulin-like growth factor I (IGF-I) injection has been shown to alleviate the brain ischemia-induced muscle atrophy and thus improve the motor function. Motor function is normally gauged by the integrity and coordination of the central nervous system and peripheral muscles. Whether brain ischemic regions are adaptively changed by the intramuscular IGF-I injection is not well understood. In this study, the effect of intramuscular IGF-I injection was examined on the central nervous system of brain ischemic rats. Rats were divided into 4 groups: sham control, brain ischemia control, brain ischemia with IGF-I treatment, and brain ischemia with IGF-I plus IGF-I receptor inhibitor treatment. Brain ischemia was induced by right middle cerebral artery occlusion. IGF-I and an IGF-1 receptor inhibitor were injected into the affected calf and anterior tibialis muscles of the treated rats for 4 times. There was an interval of 2 days between each injection. Motor function was examined and measured at the 24 hours and 7 days following a brain ischemia. The affected hind-limb muscles, sciatic nerve, lumbar spinal cord, and motor cortex were collected for examination after euthanizing the rats. IGF-I expression in the central nervous system and affected muscles were significantly decreased after brain ischemia. Intramuscular IGF-I injection increased the IGF-I expression in the affected muscles, sciatic nerve, lumbar spinal cord, and motor cortex. It also increased the p-Akt expression in the affected motor cortex. Furthermore, intramuscular IGF-I injection decreased the neuronal apoptosis and improved the motor function. However, co-administration of the IGF-I receptor inhibitor eliminated these effects. Intramuscular IGF-I injection after brain ischemia attenuated or reversed the decrease of IGF-I in both central and peripheral tissues, and these effects could contribute to neuroprotection and improve motor function.
PLoS ONE 01/2013; 8(5):e64015. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Co-activation of homo- and heterotopic representations in the primary motor cortex (M1) ipsilateral to a unilateral motor task has been observed in neuroimaging studies. Further analysis showed that the ipsilateral M1 is involved in motor execution along with the contralateral M1 in humans. Additionally, transcranial magnetic stimulation (TMS) studies have revealed that the size of the co-activation in the ipsilateral M1 has a muscle-dominant effect in the upper limbs, with a prominent decline of inhibition within the ipsilateral M1 occurring when a homologous muscle contracts. However, the homologous muscle-dominant effect in the ipsilateral M1 is less clear in the lower limbs. The present study investigates the response of corticospinal output and intracortical inhibition in the leg representation of the ipsilateral M1 during a unilateral motor task, with homo- or heterogeneous muscles. We assessed functional changes within the ipsilateral M1 and in corticospinal outputs associated with different contracting muscles in 15 right-handed healthy subjects. Motor tasks were performed with the right-side limb, including movements of the upper and lower limbs. TMS paradigms were measured, consisting of short-interval intracortical inhibition (SICI) and recruitment curves (RCs) of motor evoked potentials (MEPs) in the right M1, and responses were recorded from the left rectus femoris (RF) and left tibialis anterior (TA) muscles. TMS results showed that significant declines in SICI and prominent increases in MEPs of the left TA and left RF during unilateral movements. Cortical activations were associated with the muscles contracting during the movements. The present data demonstrate that activation of the ipsilateral M1 on leg representation could be increased during unilateral movement. However, no homologous muscle-dominant effect was evident in the leg muscles. The results may reflect that functional coupling of bilateral leg muscles is a reciprocal movement.
PLoS ONE 01/2013; 8(8):e72231. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Memory impairment is commonly noted in stroke survivors, and can lead to delay of functional recovery. Exercise has been proved to improve memory in adult healthy subjects. Such beneficial effects are often suggested to relate to hippocampal synaptic plasticity, which is important for memory processing. Previous evidence showed that in normal rats, low intensity exercise can improve synaptic plasticity better than high intensity exercise. However, the effects of exercise intensities on hippocampal synaptic plasticity and spatial memory after brain ischemia remain unclear. In this study, we investigated such effects in brain ischemic rats. The middle cerebral artery occlusion (MCAO) procedure was used to induce brain ischemia. After the MCAO procedure, rats were randomly assigned to sedentary (Sed), low-intensity exercise (Low-Ex), or high-intensity exercise (High-Ex) group. Treadmill training began from the second day post MCAO procedure, 30 min/day for 14 consecutive days for the exercise groups. The Low-Ex group was trained at the speed of 8 m/min, while the High-Ex group at the speed of 20 m/min. The spatial memory, hippocampal brain-derived neurotrophic factor (BDNF), synapsin-I, postsynaptic density protein 95 (PSD-95), and dendritic structures were examined to document the effects. Serum corticosterone level was also quantified as stress marker. Our results showed the Low-Ex group, but not the High-Ex group, demonstrated better spatial memory performance than the Sed group. Dendritic complexity and the levels of BDNF and PSD-95 increased significantly only in the Low-Ex group as compared with the Sed group in bilateral hippocampus. Notably, increased level of corticosterone was found in the High-Ex group, implicating higher stress response. In conclusion, after brain ischemia, low intensity exercise may result in better synaptic plasticity and spatial memory performance than high intensity exercise; therefore, the intensity is suggested to be considered during exercise training.
PLoS ONE 01/2013; 8(10):e78163. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The current study aims to investigate the effects of primary caregiver participation in vestibular rehabilitation (VR) on improving the measures of neglect, activities of daily living (ADL), balance, and falls of unilateral neglect (UN) patients.
This study is a single-blind randomized controlled trial. Both experimental (n = 24) and control groups (n = 24) received conventional rehabilitation. The experimental group undertook VR for a month. During the first and second weeks, a registered nurse trained the experimental group in VR. The primary caregivers in the experimental group supervised and guided their patients in VR during the third and fourth weeks. The outcome measures were neglect, ADL, balance, and falls.
The two groups of UN patients showed a significant improvement in neglect, ADL, and balance over time. Based on the generalized estimating equations model, an interaction was observed between groups and times. Significant interactions were observed between the VR group at days 14 and 28 in the areas of neglect, ADL, and balance. No significant difference was observed between the two groups in the number of falls.
Neglect, ADL, and balance among UN patients with right hemispheric stroke can be improved through the participation of primary caregivers in VR. Trained informal caregivers were recommended to provide VR guidance and supervision to patients who suffer from UN.
Neuropsychiatric Disease and Treatment 01/2013; 9:477-84. · 2.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) of the brain has been shown to modulate cortical excitability. Combinations of rehabilitation therapies with rTMS might enhance the therapeutic effects. OBJECTIVE: The purpose of this study was to investigate the effects of high-frequency rTMS followed by treadmill training on cortical inhibition and walking function in individuals with Parkinson disease (PD). METHODS: A total of 20 patients with PD were randomized into an experimental group and a control group. Participants received rTMS (experimental group) or sham rTMS (control group) followed by treadmill training (30 minutes) for 12 sessions over 4 weeks. Repetitive TMS was applied at a 5-Hz frequency over the leg area of the motor cortex contralaterally to the more affected side for 6 minutes. Outcomes, including corticomotor inhibition and walking performance, were measured before and after training. RESULTS: The results showed significant time effects on almost all corticomotor and functional variables. There are significant interaction effects between group and time of evaluation on the motor threshold, duration of the cortical silent period, and short interval intracortical inhibition of the contralateral hemisphere relatively to the more affected side as well as on the fast walking speed and timed up and go. CONCLUSIONS: The findings suggested that combination of rTMS and treadmill training enhances the effect of treadmill training on modulation of corticomotor inhibition and improvement of walking performance in those with PD.
Neurorehabilitation and neural repair 07/2012; · 4.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The model of interhemispheric competition after stroke has been established for the upper but not for the lower extremity. Repetitive transcranial magnetic stimulation (rTMS) of the brain has been shown to modulate cortical excitability.
The purpose of this study was to investigate the effects of rTMS followed by task-oriented training on cortical excitability and walking performance in individuals with chronic stroke.
A total of 24 patients with average Fugl-Meyer lower limb scores of 17.88 ± 5.27 and average walking speeds of 63.81 ± 18.25 cm/s were randomized into an experimental group and a control group. Participants received rTMS (experimental group) or sham rTMS (control group) followed by task-oriented training (30 minutes) for 10 sessions over 2 weeks. Repetitive TMS was applied at a 1-Hz frequency over the leg area of the motor cortex of the unaffected hemisphere for 10 minutes. Outcomes, including motor-evoked potential (MEP), lower-extremity Fugl-Meyer score, and gait performance, were measured before and after training.
Decreased interhemispheric asymmetry of the amplitude of the MEP was noted after rTMS and task-oriented training. Improvement in spatial asymmetry of gait was comparable with increased symmetry in interhemispheric excitability. Motor control and walking ability were also significantly improved after rTMS and task-oriented training.
rTMS enhances the effect of task-oriented training in those with chronic stroke, especially by increasing gait spatial symmetry and corticomotor excitability symmetry.
Neurorehabilitation and neural repair 03/2012; 26(3):222-30. · 4.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Physical exercise may induce neuroprotective effects against brain damage after stroke. The authors aimed to investigate the effects of various exercises on motor function, striatal angiogenesis, and infarct volume in cerebral ischemic rats. Adult male Sprague Dawley rats were subjected to middle cerebral artery occlusion and randomly assigned to 1 of the 4 groups: Rota-rod training, lower speed treadmill training, higher speed treadmill training, or no exercise control. Motor function, striatal angiogenesis, and infarct volume were evaluated before or after motor training. After training, motor function and striatal angiogenesis changed significantly in Rota-rod and higher speed treadmill training groups as compared with the control group. Improvement in motor function significantly correlated with striatal angiogenesis after motor training. Infarct volumes were significantly decreased in lower and higher speed treadmill training groups. The results indicated that both motor training procedures can be used as effective training programs in stroke rehabilitation.
Journal of Motor Behavior 02/2012; 44(2):97-103. · 1.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Exercise increases neuron survival and plasticity in the adult brain by enhancing the uptake of insulin-like growth factor I (IGF-I). Exercise also reduces the infarct volume in the ischemic brain and improves motor function after such a brain insult. However, the underlying mechanisms are not fully known. The purpose of this study was to investigate the involvement of IGF-I signaling in neuroprotection after exercise.
Rats were assigned to one of four groups: middle cerebral artery occlusion (MCAO) without exercise training (MC), MCAO with exercise training (ME), MCAO with IGF-I receptor inhibitor and without exercise training (MAg), and MCAO with IGF-I receptor inhibitor and exercise training (MEAg). Rats in the ME and MEAg groups underwent treadmill training for 14 d, and rats in the MC and MAg groups served as controls. After the final intervention, rats were sacrificed under anesthesia, and samples were collected from the affected motor cortex, striatum, and plasma.
IGF-I and p-Akt levels in the affected motor cortex and the striatum of the ME group were significantly higher than those in the MC group, with significant decreases in infarct volume and improvements in motor function. However, IGF-I receptor inhibitor eliminated these effects and decreased the exercise ability. The brain IGF-I signaling strongly correlated with exercise ability.
Exercise-enhanced IGF-I entrance into ischemic brain and IGF-I signaling was related to exercise-mediated neuroprotection. IGF-1 signaling also affected the ability to exercise after brain ischemia.
Medicine and science in sports and exercise 05/2011; 43(12):2274-80. · 4.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to investigate the effects of hyperbaric oxygenation (HBO) after brain ischemia. Middle cerebral artery occlusion (MCAO) procedure was used to induce the brain ischemia. Rats were assigned to control or HBO group after brain ischemia. In order to examine the role of glutathione after HBO treatment, another group of brain ischemic rats were included to receive the glutathione synthesis inhibitor and HBO treatment. HBO was administered at a pressure of 3 atmospheres absolute for 1 h with 100% oxygen, starting at 3 h post brain ischemia in HBO groups. Animals in control group were placed in their home cage and exposed to normobaric room air. The infarct volume (IV), activation of astrocyte, and level of total glutathione and lipid peroxidation (LP) were assessed 24 h post-reperfusion. Significant reduction in IV was noted in HBO group when compared with control group. The activation of astrocyte was significantly increased in the right cerebral cortex and right striatum in the HBO group when compared with those of the control group. The glutathione level was higher with lower LP level in right cortex and right striatum after HBO as compared with those of the control. However, such effects of HBO treatment were markedly reduced by glutathione synthesis inhibitor administration. These results show that inhibiting glutathione synthesis dramatically reduces the effectiveness of HBO in acute transient focal cerebral ischemia.
[Show abstract][Hide abstract] ABSTRACT: Memory impairment is a frequent complication of brain ischemia. Neurogenesis is implicated in learning and memory and is regulated by the transcription factor c-Fos. Preconditioning intermittent hypoxia (IH) attenuates ischemia-related memory impairments, but it is not known whether post-ischemia IH intervention has a similar effect. We investigated the effects of post-ischemia IH on hippocampal neurogenesis and c-Fos expression as well as spatial learning and memory in rats.
Focal cerebral ischemia was induced in some rats by middle cerebral artery occlusion (MCAO), while other rats received sham MCAO surgery. Beginning a week later, half of the rats of each group received IH interventions (12% oxygen concentration, 4 hrs/d, for 7 d) and half received sham IH sessions. An additional group of rats received MCAO, IH, and injections of the neurogenesis-impairing agent 3'-AZT. Spatial learning and memory was measured in the Morris water maze, and hippocampal neurogenesis and c-Fos expression were examined. Hypoxia-inducible factor 1α (HIF-1α) and phosphorylated mitogen-activated protein kinase (pMAPK) were considered as possible mediators of IH-induced changes in neurogenesis and c-Fos expression. IH intervention following MCAO resulted in recovered spatial memory, increased hippocampal neurogenesis, and increased expression of c-Fos in newborn hippocampal cells. These effects were blocked by 3'-AZT. IH intervention following MCAO also was associated with increased hippocampal pMAPK and HIF-1α expression.
IH intervention following MCAO rescued ischemia-induced spatial learning and memory impairments, likely by inducing hippocampal neurogenesis and c-Fos expression through mediators including pMAPK and HIF-1α.
PLoS ONE 01/2011; 6(8):e24001. · 3.53 Impact Factor