Eun-Bum Kang

Treadmill exercise represses neuronal cell death in an aged transgenic mouse model of Alzheimer's disease.

The present study was undertaken to further investigate the protective effect of treadmill exercise on the hippocampal proteins associated with neuronal cell death in an aged transgenic (Tg) mice with Alzheimers disease (AD). To address this, Tg mouse model of AD, Tg-NSE/PS2m, which expresses human mutant PS2 in the brain, was chosen. Animals were subjected to treadmill exercise for 12 weeks from 24 months of age. The exercised mice were treadmill run at speed of 12 m/min, 60 min/day, 5 days/week on a 0% gradient for 3 months. Treadmill exercised mice improved cognitive function in water maze test. Treadmill exercised mice significantly reduced the expression of Aβ-42, Cox-2, and caspase-3 in the hippocampus. In parallel, treadmill exercised Tg mice decreased the phosphorylation levels of JNK, p38MAPK and tau (Ser404, Ser202, Thr231), and increased the phosphorylation levels of ERK, PI3K, Akt and GSK-3α/β. In addition, treadmill exercised Tg mice up-regulated the expressions of NGF, BDNF and phospho-CREB, and the expressions of SOD-1, SOD-2 and HSP-70. Treadmill exercised Tg mice up-regulated the expression of Bcl-2, and down-regulated the expressions of cytochrome c and Bax in the hippocampus. The number of TUNEL-positive cells in the hippocampus in mice was significantly decreased after treadmill exercise. Finally, serum TC, insulin, glucose, and corticosterone levels were significantly decreased in the Tg mice after treadmill exercise. As a consequence of such change, Aβ-dependent neuronal cell death in the hippocampus of Tg mice was markedly suppressed following treadmill exercise. These results strongly suggest that treadmill exercise provides a therapeutic potential to inhibit both Aβ-42 and neuronal death pathways. Therefore, treadmill exercise may be beneficial in prevention or treatment of AD.

Treadmill exercise represses neuronal cell death and inflammation during Aβ-induced ER stress by regulating unfolded protein response in aged presenilin 2 mutant mice

Alzheimer’s disease (AD) is characterized by the deposition of aggregated amyloid-beta (Aβ), which triggers a cellular stress response called the unfolded protein response (UPR). The UPR signaling pathway is a cellular defense system for dealing with the accumulation of misfolded proteins but switches to apoptosis when endoplasmic reticulum (ER) stress is prolonged. ER stress is involved in neurodegenerative diseases including AD, but the molecular mechanisms of neuronal apoptosis and inflammation by Aβ-induced ER stress to exercise training are not fully understood. Here, we demonstrated that treadmill exercise (TE) prevented PS2 mutation-induced memory impairment and reduced Aβ-42 deposition through the inhibition of β-secretase (BACE-1) and its product, C-99 in cortex and/or hippocampus of aged PS2 mutant mice. We also found that TE down-regulated the expression of GRP78/Bip and PDI proteins and inhibited activation of PERK, eIF2α, ATF6α, sXBP1 and JNK-p38 MAPK as well as activation of CHOP, caspase-12 and caspase-3. Moreover, TE up-regulated the expression of Bcl-2 and down-regulated the expressions of Bax in the hippocampus of aged PS2 mutant mice. Finally, the generation of TNFα and IL-1α and the number of TUNEL-positive cells in the hippocampus of aged PS2 mutant mice was also prevented or decreased by TE. These results showed that TE suppressed the activation of UPR signaling pathways as well as inhibited the apoptotic pathways of the UPR and inflammatory response following Aβ-induced ER stress. Thus, therapeutic strategies that modulate Aβ-induced ER stress through TE could represent a promising approach for the prevention or treatment of AD.

Neuroprotective effects of endurance exercise against neuroinflammation in MPTP-induced Parkinson's disease mice

Parkinsons disease (PD) is one of the main degenerative neurological disorders accompanying death of dopaminergic neurons prevalent in aged population. Endurance exercise (EE) has been suggested to confer neurogenesis and mitigate the degree of seriousness of PD. However, underlying molecular mechanisms responsible for exercise-mediated neuroprotection against PD remain largely unknown. Given the relevant interplay between elevated α-synuclein and neuroinflammation in a poor prognosis and vicious progression of PD and anti-inflammatory effects of EE, we hypothesized that EE would reverse motor dysfunction and cell death caused by PD. To this end, we chose a pharmacological model of PD (e.g., chronic injection of neurotoxin MPTP). Young adult male mice (7 weeks old) were randomly divided into three groups: sedentary control (C, n=10), MPTP (M, n=10), and MPTP + endurance exercise (ME, n=10). Our data showed that EE restored motor function impaired by MPTP in parallel with reduced cell death. Strikingly, EE exhibited a significant reduction in α-synuclein protein along with diminished pro-inflammatory cytokines (i.e., TNF-α and IL-1β). Supporting this, EE prevented activation of Toll like receptor 2 (TLR2) downstream signaling cascades such as MyD88, TRAF6 and TAK-1 incurred by in MPTP administration in the striatum. Moreover, EE reestablished tyrosine hydroxylase at levels similar to C group. Taken together, our data suggest that an EE-mediated neuroprotective mechanism against PD underlies anti-neuroinflammation conferred by reduced levels of α-synuclein. Our data provides an important insight into developing a non-pharmacological countermeasure against neuronal degeneration caused by PD.

Effect of treadmill exercise on PI3K/AKT/mTOR, autophagy, and Tau hyperphosphorylation in the cerebral cortex of NSE/htau23 transgenic mice

Purpose Neurofibrillary tangles, one of pathological features of Alzheimer’s disease, are produced by the hyperphosphorylation and aggregation of tau protein. This study aimed to investigate the effects of treadmill exercise on PI3K/AKT/mTOR signal transmission, autophagy, and cognitive ability that are involved in the hyperphosphorylation and aggregation of tau protein. Methods Experimental animals (NSE/htau23 mice) were divided into non-transgenic control group (Non-Tg-Control; CON; n = 7), transgenic control group (Tg-CON; n = 7), and transgenic exercise group (Tg-Treadmill Exercise; TE; n = 7). The Tg-TE group was subjected to treadmill exercise for 12 weeks. After the treadmill exercise was completed, the cognitive ability was determined by conducting underwater maze tests. Western blot was conducted to determine the phosphorylation status of PI3K/AKT/mTOR proteins and autophagy-related proteins (Beclin-1, p62, LC3-B); hyperphosphorylation and aggregation of tau protein (Ser199/202, Ser404, Thr231, PHF-1); and phosphorylation of GSK-3β, which is involved in the phosphorylation of tau protein in the cerebral cortex of experimental animals. Results In the Tg-TE group that was subjected to treadmill exercise for 12 weeks, abnormal mTOR phosphorylation of PI3K/AKT proteins was improved via increased phosphorylation and its activity was inhibited by increased GSK-3β phosphorylation compared with those in the Tg-CON group, which was used as the control group. In addition, the expression of Beclin-1 protein involved in autophagosome formation was increased in the Tg-TE group compared with that in the Tg-CON group, whereas that of p62 protein was reduced in the Tg-TE group compared with that in the Tg-CON group. Autophagy was activated owing to the increased expression of LC3-B that controls the completion of autophagosome formation. The hyperphosphorylation and aggregation (Ser199/202, Ser404, Thr231, PHF-1) of tau protein was found to be reduced in the Tg-TE group compared with that in the Tg-CON group. Furthermore, in the underwater maze test, the Tg-TE group showed a reduced escape time and distance compared with those of the Tg-CON group, suggesting that learning and cognitive ability were improved. Conclusion These findings suggest that aerobic exercise such as treadmill exercise might be an effective approach to ameliorate the pathological features (or neurofibrillary tangles) of Alzheimer’s disease.

Treadmill exercise decreases amyloid-β burden possibly via activation of SIRT-1 signaling in a mouse model of Alzheimer's disease

ABSTRACT Accumulation of amyloid‐&bgr; (A&bgr;) correlates significantly with progressive cognitive deficits, a main symptom of Alzheimers disease (AD). Although treadmill exercise reduces A&bgr; levels, the molecular mechanisms underlying the effects are not fully understood. We hypothesize that treadmill exercise decreases A&bgr; production and alleviates cognitive deficits by activating the non‐amyloidogenic pathway via SIRT‐1 signaling. Treadmill exercise improved cognitive deficits and alleviated neurotoxicity. Most importantly, treadmill exercise increased SIRT‐1 level, which subsequently resulted in increased ADAM‐10 level by down‐regulation of ROCK‐1 and upregulation of RAR&bgr;, ultimately facilitating the non‐amyloidogenic pathway. Treadmill exercise‐induced activation in SIRT‐1 level also elevated PGC‐1&agr; level and reduced BACE‐1 and C‐99 level, resulting in inhibition of the amyloidogenic pathway. Treadmill exercise may thus inhibit A&bgr; production via upregulation of SIRT‐1, which biases amyloid precursor protein processing toward the non‐amyloidogenic pathway. This study provides novel and valuable insight into the molecular mechanisms possibly by which treadmill exercise reduces A&bgr; production. HighlightsTreadmill exercise increased SIRT‐1 levels, resulting in increased ADAM‐10 by downregulating ROCK‐1 and upregulating RAR&bgr;.Treadmill exercise increased PGC‐1&agr; levels, which reduced BACE‐1 and C‐99 expression.Treadmill exercise inhibits A&bgr; production possibly by activating non‐amyloidogenic pathway via SIRT‐1/PGC‐1&agr; signaling.

Neuroprotective Effects of Endurance Exercise against High Fat Diet‐Induced Hippocampal Neuroinflammation

Obesity contributes to systemic inflammation, which is associated with the varied pathogenesis of neurodegenerative diseases. Growing evidence has demonstrated that endurance exercise (EE) mitigates obesity‐induced brain inflammation. However, exercise‐mediated anti‐inflammatory mechanisms remain largely unknown. We investigated how treadmill exercise (TE) reverses obesity‐induced brain inflammation, mainly focusing on toll‐like receptor‐4 (TLR‐4)‐dependent neuroinflammation in the obese rat brain after 20 weeks of a high‐fat diet (HFD). TE in HFD‐fed rats resulted in a significant lowering in the homeostasis model assessment of insulin resistance index, the area under the curve for glucose and abdominal visceral fat, and also improved working memory ability in a passive avoidance task relative to sedentary behaviour in HFD‐fed rats, with the exception of body weight. More importantly, TE revoked the increase in HFD‐induced proinflammatory cytokines (tumour necrosis factor α and interleukin‐1β) and cyclooxygenase‐2, which is in parallel with a reduction in TLR‐4 and its downstream proteins, myeloid differentiation 88 and tumour necrosis factor receptor associated factor 6, and phosphorylation of transforming growth factor β‐activated kinase 1, IkBα and nuclear factor‐κB. Moreover, TE reduced an indicator of microglia activation, ionised calcium‐binding adapter molecule‐1, and also decreased glial fibrillary acidic protein, an indicator of gliosis formed by activated astrocytes in the cerebral cortex and the hippocampal dentate gyrus, compared to HFD‐fed sedentary rats. Finally, EE up‐regulated the expression of anti‐apoptotic protein, Bcl‐2, and suppressed the expression of pro‐apoptotic protein, Bax, in the hippocampus compared to HFD‐fed sedentary rats. Taken together, these data suggest that TE may exert neuroprotective effects as a result of mitigating the production of proinflammatory cytokines by inhibiting the TLR4 signalling pathways. The results of the present study suggest that the unique combination of the beneficial effects of TE on the restoration of the blood profile and the anti‐inflammatory and anti‐apoptotic effects on cognitive function should inspire further investigations into its therapeutic potential for metabolic disorders and neurodegenerative diseases.

The effects of senior brain health exercise program on basic physical fitness, cognitive function and BDNF of elderly women - a feasibility study.

[Purpose] This study was to investigate the impacts of senior brain heath exercise (SBHE) program for 12 weeks to basic active physical fitness, cognitive function and brain derived neurotrophic factor (BDNF) in elderly women. [Methods] Subject of this study is total of 24 women in the age of 65-79 who can conduct normal daily activity and communication but have not participated in regular exercise in recent 6 months. The study groups were divided into an exercise group (EG, n=13) and a control group (CG, n=11). The exercise program was consisted of SBHE, and training frequency was 4 times weekly, of which training time was a total of 50 minutes each time in level of intensity of 9-14 by rating of perceived exertion (RPE). [Results] First, 12-week SBHE program has shown statistical increase in basic physical fitness in the EG comparing with the CG, such as lower body strength, upper body strength and aerobic endurance, but not in flexibility, agility and dynamic balance. Second, in the case of Mini-mental state examination Korean version (MMSE-K) and BDNF, it showed that there was a statistically significant increase in the EG comparing with the CG. [Conclusion] In this study, 12-week SBHE program has resulted in positive effect on change of basic physical fitness (strength and aerobic endurance), cognitive function and BDNF. If above program adds movements that can enhance flexibility, dynamic balance and agility, this can be practical exercise program to help seniors maintain overall healthy lifestyle.

Effects of treadmill exercise on PI3K/AKT/GSK-3β pathway and tau protein in high-fat diet-fed rats

[Purpose] This study aimed to clearly evaluate the effects of obesity on cerebral health. Thus, we induced obesity in rats using a long-term high-fat diet (HFD), then investigated its effects on insulin signaling and tau hyperphosphorylation. Additionally, we examined the effects of 8 weeks of treadmill exercise (TE) on insulin signaling and tau hyperphosphorylation. [Methods] Rats were separated into Normal Diet-Control, HFD-Control, and HFD-TE groups. TE loads were gradually increased. A passive avoidance test was used to evaluate cognitive function. Western blots were used to examine the abundance of the insulin receptor,phosphoinositide 3-kinase, protein kinase B, glycogen synthase kinase-3β, and tau proteins in the cerebral cortex; immunohistochemical analyses were used to examine the abundance of hyperphosphorylated tau in the cerebral cortex. [Results] TE in HFD-fed rats resulted in a significant lowering of bodyweight, abdominal visceral fat (AVF), the area under the glucose response curve, and the homeostatic model assessment-insulin resistance index, while it improved working memory. In addition, TE in HFD-fed rats decreased tau hyperphosphorylation and aggregation, while increasing insulin signaling-related protein activity. [Conclusion] After a 20-week HFD, the experimental animals exhibited increased weight, as well as impaired insulin resistance and blood glucose metabolism. HFD rats demonstrated abnormal insulin signaling and tau hyperphosphorylation in the cerebral cortex, as well as memory impairments that suggested reduced cerebral function. However, TE reduced AVF, improved insulin resistance in the peripheral tissues by increasing insulin sensitivity, and alleviated memory impairments by restoring insulin signaling and reducing tau hyperphosphorylation in the cerebral cortex.

The Effect of Exercise Training on Aβ-42, BDNF, GLUT-1 and HSP-70 Proteins in a NSE/ APPsw-transgenic Model for Alzheimer`s Disease.

Mutations in the APP gene lead to enhanced cleavage by and , and increased formation, which are closely associated with Alzheimer`s disease (AD)-like neuropathological changes. Recent studies have shown that exercise training can ameliorate pathogenic phenotypes (, BDNF, GLUT-1 and HSP70) in experimental models of Alzheimer`s disease. Here, we have used NSE/APPsw transgenic mice to investigate directly whether exercise training ameliorates pathogenic phenotypes within Alzheimer`s brains. Sixteen weeks of exercise training resulted in a reduction of peptides and also facilitated improvement of cognitive function. Furthermore, GLUT -1 and BDNF proteins produced by exercise training may protect brain neurons by inducing the concomitant expression of genes that encode proteins (HSP-70) which suppress stress induced neuron cell damages from APPsw transgenic mice. Thus, the improved cognitive function by exercise training may be mechanistically linked to a reduction of peptides, possibly via activation of BDNF, GLUT-1, and HSP-70 proteins. On the basis of the evidences presented in this study, exercise training may represent a practical therapeutic management strategy for human subjects suffering from Alzheimer`s disease.

Effect of Resistance Exercise on Muscle Metabolism and Autophagy in sibm.

Purpose Sporadic inclusion body myositis (sIBM), a muscular degenerative disease in the elderly, is an inflammatory myopathy characterized by muscle weakness in the wrist flexor, quadriceps, and tibialis anterior muscles. We aimed to identify the therapeutic effect of resistance exercise (RE) in improving sIBM symptoms in an sIBM animal model. Methods Six-week-old male Wistar rats were divided into a sham group (sham, n = 12), chloroquine—control group (CQ-con, n = 12), and chloroquine—RE group (CQ-RE, n = 12). The rats were subjected to 1 wk of exercise adaptation and 8 wk of exercise (three sessions per week). Protein expression was measured by Western blotting. Rimmed vacuoles (RV) were identified by hematoxylin and eosin staining and modified Gömöri trichrome staining, and amyloid deposition was examined by Congo red staining. Results The effects of CQ and RE differed depending on myofiber characteristics. Soleus muscles showed abnormal autophagy in response to CQ, which increased RV generation and amyloid-&bgr; accumulation, resulting in atrophy. RE generated RV and decreased amyloid deposition in soleus muscles and also improved autophagy without generating hypertrophy. This reduced the atrophy signal transduction, resulting in decreased atrophy compared with the CQ-con group. Despite no direct effect of CQ, flexor hallucis longus muscles showed loss of mass because of reduced activity or increased inflammatory response; however, RE increased the hypertrophy signal, resulting in reduced autophagy and atrophy. Conclusions These results demonstrate that RE had a preventive effect on sIBM induced by CQ treatment in an animal model. However, because the results were from an animal experiment, a more detailed study should be conducted over a longer period, and the effectiveness of different RE programs should also be investigated.