强制运动促进成年大鼠海马齿状回神经发生并提高学习能力

为了探讨强制运动对成年大鼠海马齿状回（dentate gyrus,DG）神经发生的影响,强制大鼠在马达驱动的转轮中跑步,用5-溴-2-脱氧尿苷（5-bromo-2-deoxyuridine,BrdU）标记增殖细胞,巢蛋白（neuroepthelial stem cell protein,nestin）标记神经干细胞／前体细胞,然后用免疫细胞化学技术检测大鼠DG中BrdU及nestin阳性细胞。为了解强制运动后DG增殖细胞的功能意义,采用Y-迷宫检测大鼠的学习能力。结果表明,强制运动组DG中BrdU及nestin阳性细胞数均日月显多于对照组（P〈0．05）：强制运动对DG神经发生的效应有强度依赖性。Y-迷宫检测结果显示,强制运动能明显改善大鼠的学习能力。结果提示,在转轮中进行强制跑步能促进成年火鼠DG的神经发生,并改善学习能力。     

Selenium mediates exercise-induced adult neurogenesis and reverses learning deficits induced by hippocampal injury and aging

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Quetiapine attenuates spatial memory impairment and hippocampal neurodegeneration induced by bilateral common carotid artery occlusion in mice

Quetiapine, a new atypical antipsychotic drug, has beneficial effects on cognitive impairment and neuropathological changes in treating chronic neurodegenerative diseases. Our previous studies have demonstrated that quetiapine may have neuroprotective properties. In the present study, we investigated the effects of a 2-week pre-administration of quetiapine (10 mg/kg/day, i.p.) on spatial memory impairment and hippocampal neurodegeneration induced by 60-minute bilateral common carotid artery occlusion (CCAO). Following a 7-day recovery phase from CCAO, the spatial memory of the mice was tested using a modified water maze test. After the behavioural test, the mice were sacrificed and brain sections were stained with NeuN (a neuron-specific soluble nuclear antigen), cresyl violet (Nissl), and Fluoro-Jade B. CCAO significantly induced spatial memory impairment and caused neurodegeneration in the hilus of hippocampus, while quetiapine significantly attenuated these changes. This is the first study showing that quetiapine significantly attenuates CCAO-induced spatial memory impairment and this improvement parallels the alleviative effects of quetiapine on CCAO-induced neurodegeneration in the hilus of hippocampus. The results suggest that quetiapine may have defending effects on the impairments induced by cerebral ischemia, which enhances our understanding about the mechanisms of quetiapine.     

Social isolation rearing-induced impairment of the hippocampal neurogenesis is associated with deficits in spatial memory and emotion-related behaviors in juvenile mice

Experiences during brain development may influence the pathogenesis of developmental disorders. Thus, social isolation (SI) rearing after weaning is a useful animal model for studying the pathological mechanisms of such psychiatric diseases. In this study, we examined the effect of SI on neurogenesis in the hippocampal dentate gyrus (DG) relating to memory and emotion-related behaviors. When newly divided cells were labeled with 5-bromo-2'-deoxyuridine (BrdU) before SI, the number of BrdU-positive cells and the rate of differentiation into neurons were significantly decreased after 4-week SI compared with those in group-housed mice. Repeated treatment of fluoxetine prevented the SI-induced impairment of survival of newly divided cells and ameliorated spatial memory impairment and part of aggression in SI mice. Furthermore, we investigated the changes in gene expression in the DG of SI mice by using DNA microarray and real-time PCR. We finally found that SI reduced the expression of development-related genes Nurr1 and Npas4 . These findings suggest that communication in juvenile is important in the survival and differentiation of newly divided cells, which may be associated with memory and aggression, and raise the possibility that the reduced expression of Nurr1 and/or Npas4 may contribute to the impairment of neurogenesis and memory and aggression induced by SI.     

Strength exercise suppresses STZ-induced spatial memory impairment and modulates BDNF/ERK-CAMKII/CREB signalling pathway in the hippocampus of mice

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that has generated scientific interest because of its prevalence in the population. Studies indicate that physical exercise promotes neuroplasticity and improves cognitive function in animal models and in human beings. The aim of the present study was to investigate the effects of strength exercise on the hippocampal protein contents and memory performance in mice subjected to a model of sporadic AD induced by streptozotocin (STZ). Swiss mice received two injections of STZ (3 mg/kg, intracerebroventricular). After 21 days, they began physical training using a ladde. Mice performed this protocol for 4 weeks. After the last exercise training session, mice performed the Morris Water Maze test. The samples of hippocampus were excised and used to determine protein contents of brain-derived neurotrophic factor (BDNF), extracellular signal-regulated kinase-Ca²⁺ (ERK), calmodulin-dependent protein kinase (CAMKII) and cAMP-response element-binding protein (CREB) signalling pathway. Strength exercise was effective against the decrease in the time spent and distance travelled in the target quadrant by STZ-injected mice. Strength exercise was also effective against the reduction of mature BDNF, tropomyosin receptor kinase B and neuronal nuclear antigen (NeuN) hippocampal protein levels in STZ mice. The decrease in the hippocampal ratio of pERK/ERK, pCAMKII/CAMKII and pCREB/CREB induced by STZ was reversed by strength exercise. Strength exercise decreased Bax/Bcl2 ratio in the hippocampus of STZ-injected mice. The present study demonstrates that strength exercise modulated the hippocampal BDNF/ERK-CAMKII/CREB signalling pathway and suppressed STZ-induced spatial memory impairment in mice.     

Behavioral deficits induced by lead exposure are accompanied by serotonergic and cholinergic alterations in the prefrontal cortex

The effects of long-term lead (Pb) exposure producing a blood Pb concentration of lower than 20 μg/dL, i.e. below that associated with overt neurological deficits in occupationally exposed individuals, was studied in adult rats. In order to assess gender differences, we performed parallel behavioral experiments in male and female rats. Exposure to Pb acetate (50 ppm in drinking water) for 6 months induced motor and cognitive alterations, however these effects were gender- and task-dependent. Chronic lead exposure impaired spatial learning assessed in the Morris water maze test (MWM) in both genders, whereas it only induced hyperactivity in the open field and impaired motor coordination in the rotarod test, only in male rats. Hyperactivity in male rats was accompanied by an increase in extracellular level of acetylcholine in the prefrontal cortex. Extracellular dopamine concentration in the prefrontal cortex was unaffected by lead exposure whereas serotonin concentration in the same brain area was significantly decreased in both male and female rats exposed to lead. These results unveil new molecular mechanisms underlying neuropsychiatric alterations induced by chronic lead exposure.     

The effect of training on endurance and the cardiovascular responses of individuals with paraplegia during dynamic exercise induced by functional electrical stimulation

Endurance for dynamic exercise, cardiac output, blood pressure, heart rate, ventilation, and oxygen consumption was measured in eight individuals with paraplegia at the end of 4-min bouts of exercise on a friction braked cycle ergometer. Movement of the subjects' legs was induced by electrically stimulating the quadriceps, gluteus maximus and hamstring muscles with a computer-controlled biphasic square--wave current at a frequency of 30 Hz. The friction braked cycle ergometer was pedalled at work rates which varied between 0 and 40 W. Measurements were repeated after 3 and 6 months to assess the affect of training. After 3 months of training it was found that endurance increased from 8 min at a work rate of 0 W to 30 min at a work rate of 40 W. Compared to the cardiovascular responses in non-paralyzed subjects, computerized cycle ergometry was found to be associated with higher relative stresses for a given level of absolute work. Mean blood pressure, for example, increased by over 30% during maximal work in individuals with paralysis compared to the typical response obtained for able-bodied subjects. Analysis of the data showed that instead of the 20-30% metabolic efficiency commonly reported for cycle ergometry, the calculated metabolic efficiency during computer-controlled cycle ergometry was only 3.6%.     

PERK inhibition attenuates the abnormalities of the secretory pathway and the increased apoptotic rate induced by SIL1 knockdown in HeLa cells

Loss-of-function mutations in the SIL1 gene are linked to Marinesco-Sjögren syndrome (MSS), a rare multisystem disease of infancy characterized by cerebellar and skeletal muscle degeneration. SIL1 is a ubiquitous adenine nucleotide exchange factor for the endoplasmic reticulum (ER) chaperone BiP. The complexity of mechanisms by which loss of SIL1 causes MSS is not yet fully understood. We used HeLa cells to test the hypothesis that impaired protein folding in the ER due to loss of SIL1 could affect secretory trafficking, impairing the transport of cargoes essential for the function of MSS vulnerable cells. Immunofluorescence and ultrastructural analysis of SIL1-knocked-down cells detected ER chaperone aggregation, enlargement of the Golgi complex, increased autophagic vacuoles, and mitochondrial swelling. SIL1-interefered cells also had delayed ER-to-plasma membrane transport with retention of Na⁺/K⁺-ATPase and procollagen-I in the ER and Golgi, and increased apoptosis. The PERK pathway of the unfolded protein response was activated in SIL1-interfered cells, and the PERK inhibitor GSK2606414 attenuated the morphological and functional alterations of the secretory pathway, and significantly reduced cell death. These results indicate that loss of SIL1 is associated with alterations of secretory transport, and suggest that inhibiting PERK signalling may alleviate the cellular pathology of SIL1-related MSS.     

Alisol A attenuates high‐fat‐diet‐induced obesity and metabolic disorders via the AMPK/ACC/SREBP‐1c pathway

Obesity and its associated metabolic disorders such as diabetes, hepatic steatosis and chronic heart diseases are affecting billions of individuals. However there is no satisfactory drug to treat such diseases. In this study, we found that alisol A, a major active triterpene isolated from the Chinese traditional medicine Rhizoma Alismatis, could significantly attenuate high‐fat‐diet‐induced obesity. Our biochemical detection demonstrated that alisol A remarkably decreased lipid levels, alleviated glucose metabolism disorders and insulin resistance in high‐fat‐diet‐induced obese mice. We also found that alisol A reduced hepatic steatosis and improved liver function in the obese mice model.In addition, protein expression investigation revealed that alisol A had an active effect on AMPK/ACC/SREBP‐1c pathway. As suggested by the molecular docking study, such bioactivity of alisol A may result from its selective binding to the catalytic region of AMPK.Therefore, we believe that Alisol A could serve as a promising agent for treatment of obesity and its related metabolic diseases.     

Neuroprotection by dipeptidyl-peptidase-4 inhibitors and glucagon-like peptide-1 analogs via the modulation of AKT-signaling pathway in Alzheimer’s disease

Alzheimer’s disease (AD) is the most common reason for progressive dementia in the elderly. It has been shown that disorders of the mammalian/mechanistic target of rapamycin (mTOR) signaling pathways are related to the AD. On the other hand, diabetes mellitus (DM) is a risk factor for the cognitive dysfunction. The pathogenesis of the neuronal impairment caused by diabetic hyperglycemia is intricate, which contains neuro-inflammation and/or neurodegeneration and dementia. Glucagon-like peptide-1 (GLP1) is interesting as a possible link between metabolism and brain impairment. Modulation of GLP1 activity can influence amyloid-beta peptide aggregation via the phosphoinositide-3 kinase/AKT/mTOR signaling pathway in AD. The GLP1 receptor agonists have been shown to have favorable actions on the brain such as the improvement of neurological deficit. They might also exert a beneficial effect with refining learning and memory on the cognitive impairment induced by diabetes. Recent experimental and clinical evidence indicates that dipeptidyl-peptidase-4 (DPP4) inhibitors, being currently used for DM therapy, may also be effective for AD treatment. The DPP-4 inhibitors have demonstrated neuroprotection and cognitive improvements in animal models. Although further studies for mTOR, GLP1, and DPP4 signaling pathways in humans would be intensively required, they seem to be a promising approach for innovative AD-treatments. We would like to review the characteristics of AD pathogenesis, the key roles of mTOR in AD and the preventive and/ or therapeutic suggestions of directing the mTOR signaling pathway.     

Aloperine attenuated neuropathic pain induced by chronic constriction injury via anti-oxidation activity and suppression of the nuclear factor kappa B pathway

Objective

To investigate whether aloperine (ALO) has antinociceptive effects on neuropathic pain induced by chronic constriction injury, whether ALO reduces ROS against neuropathic pain, and what are the mechanisms involved in ALO attenuated neuropathic pain.

Methods

Mechanical and cold allodynia, thermal and mechanical hyperalgesia and spinal thermal hyperalgesia were estimated by behavior methods such as Von Frey filaments, cold-plate, radiant heat, paw pressure and tail immersion on one day before surgery and days 7, 8, 10, 12 and 14 after surgery, respectively. In addition, T-AOC, GSH-PX, T-AOC and MDA in the spinal cord (L4/5) were measured to evaluate anti-oxidation activity of ALO on neuropathic pain. Expressions of NF-κB and pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) in the spinal cord (L4/5) were analyzed by using Western blot.

Results

Administration of ALO (80 mg/kg and 40 mg/kg, i.p.) significantly increased paw withdrawal threshold, paw pressure, paw withdrawal latencies, tail-curling latencies, T-AOC, GSH-PX and T-SOD concentration, reduced the numbers of paw lifts and MDA concentration compared to CCI group. ALO attenuated CCI induced up-regulation of expressions of NF-κB, TNF-α, IL-6, IL-1β at the dose of 80 mg/kg (i.p.). Pregabalin produced similar effects serving as positive control at the dose of 10 mg/kg (i.p.).

Conclusion

ALO has antinociceptive effects on neuropathic pain induced by CCI. The antinociceptive effects of ALO against neuropathic pain is related to reduction of ROS, via suppression of NF-κB pathway.     

Synergistic activation of JNK/SAPK induced by TNF-alpha and IFN-gamma: apoptosis of pancreatic beta-cells via the p53 and ROS pathway

IFN-γ and TNF-α are major proinflammatory cytokines implicated in islet β-cell destruction, which results in type-1 diabetes; however, the underlying mechanism is not clear. Using pancreatic β-cell line MIN6N8 cells, co-treatment with TNF-α and IFN-γ, but neither cytokine alone, synergistically induced apoptosis, correlated with the activation of the JNK/SAPK, which resulted in the production of reactive oxidative species (ROS) and loss of mitochondrial transmembrane potential (ΔΨm). Additionally, cells transfected with wild-type JNK1 became more susceptible to apoptosis induced by TNF-α/IFN-γ through ROS production and loss of Δψm, while cascading apoptotic events were prevented in dominant-negative JNK1-transfected or JNK inhibitor SP600125-treated cells. As the antioxidant, N-acetyl-cysteine, failed to completely suppress apoptosis induced by TNF-α/IFN-γ, an additional pathway was considered to be involved. The level of p53 was significantly increased through synergistic activation of JNK by TNF-α/IFN-γ. Furthermore, the synergistic effect of TNF-α/IFN-γ on apoptosis and ROS production was further potentiated by the overexpression of wild-type p53, but not with mutant p53. This synergistic activation of JNK/SAPK by TNF-α/IFN-γ was also induced in insulin-expressing pancreatic islet cells, and increased ROS production and p53 level, which was significantly inhibited by SP600125. Collectively, these data demonstrate that TNF-α/IFN-γ synergistically activates JNK/SAPK, playing an important role in promoting apoptosis of pancreatic β-cell via activation of p53 pathway together with ROS.     

20‐HETE synthesis inhibition attenuates traumatic brain injury–induced mitochondrial dysfunction and neuronal apoptosis via the SIRT1/PGC‐1α pathway: A translational study

Objectives20‐hydroxyeicosatetraenoic acid (20‐HETE) is a metabolite of arachidonic acid catalysed by cytochrome P450 enzymes and plays an important role in cell death and proliferation. We hypothesized that 20‐HETE synthesis inhibition may have protective effects in traumatic brain injury (TBI) and investigated possible underlying molecular mechanisms.Materials and methodsNeurologic deficits, and lesion volume, reactive oxygen species (ROS) levels and cell death as assessed using immunofluorescence staining, transmission electron microscopy and Western blotting were used to determine post‐TBI effects of HET0016, an inhibitor of 20‐HETE synthesis, and their underlying mechanisms.ResultsThe level of 20‐HETE was found to be increased significantly after TBI in mice. 20‐HETE synthesis inhibition reduced neuronal apoptosis, ROS production and damage to mitochondrial structures after TBI. Mechanistically, HET0016 decreased the Drp1 level and increased the expression of Mfn1 and Mfn2 after TBI, indicating a reversal of the abnormal post‐TBI mitochondrial dynamics. HET0016 also promoted the restoration of SIRT1 and PGC‐1α in vivo, and a SIRT1 activator (SRT1720) reversed the downregulation of SIRT1 and PGC‐1α and the abnormal mitochondrial dynamics induced by 20‐HETE in vitro. Furthermore, plasma 20‐HETE levels were found to be higher in TBI patients with unfavourable neurological outcomes and were correlated with the GOS score.ConclusionsThe inhibition of 20‐HETE synthesis represents a novel strategy to mitigate TBI‐induced mitochondrial dysfunction and neuronal apoptosis by regulating the SIRT1/PGC‐1α pathway.     

Bortezomib attenuates renal interstitial fibrosis in kidney transplantation via regulating the EMT induced by TNF‐α‐Smurf1‐Akt‐mTOR‐P70S6K pathway

Allograft interstitial fibrosis was characterized by massive extracellular matrix deposition caused by activated fibroblasts and myofibroblasts. Epithelial‐mesenchymal transition (EMT) is recognized as an important source of myofibroblasts contributing to the pathogenesis of allograft interstitial fibrosis. Smad ubiquitination regulatory factor 1 (Smurf1) has been recently reported to be involved in the progression of EMT. Our study was to detect the effect of Bortezomib and Smurf1 in the EMT and allograft interstitial fibrosis. Biomarkers of EMT, as well as Smurf1, were examined in human proximal tubular epithelial cells (HK‐2) treated with tumour necrosis factor‐alpha (TNF‐α) in various doses or at various time points by Western Blotting or qRT‐PCR. We knockdown or overexpressed Smurf1 in HK‐2 cells. Furthermore, rat renal transplant model was established and intervened by Bortezomib. Allograft tissues from human and rats were also collected and prepared for HE, Masson's trichrome, immunohistochemical staining and western blotting assays. As a result, we found that TNF‐α significantly promoted the development of EMT in a time‐dependent and dose‐dependent manner through Smurf1/Akt/mTOR/P70S6K signalling pathway. More importantly, Bortezomib alleviated the progression of EMT and allograft interstitial fibrosis in vivo and in vitro by inhibiting the production of TNF‐α and expression of Smurf1. In conclusion, Smurf1 plays a critical role in the development of EMT induced by TNF‐α. Bortezomib can attenuate the Sumrf1‐mediated progression of EMT and renal allograft interstitial fibrosis, which could be suggested as a novel choice for the prevention and treatment of renal allograft interstitial fibrosis.     

Pinitol attenuates LPS‐induced pneumonia in experimental animals: Possible role via inhibition of the TLR‐4 and NF‐κB/IκBα signaling cascade pathway

Pneumonia is a chronic disorder of the respiratory system associated with worsening quality of life and a significant economic burden. Pinitol, a plant cyclic polyol, has been documented for immune‐inflammatory potential. The aim of present investigation was to evaluate the potential and possible mechanism of action of pinitol against lipopolysaccharide (LPS)‐induced pneumonia in the experimental animal model. Pneumonia was induced in Sprague‐Dawley rats by intratracheal administration of LPS (2 mg/kg). Animals were treated with either vehicle or dexamethasone or pinitol (5 or 10 or 20 mg/kg). Potential of pinitol against LPS‐induced pulmonary insult was assessed based on behavioral, biochemical, molecular, and ultrastructural studies. Intratracheal instillation of LPS induced significant (P < .05) inflammatory infiltration in bronchoalveolar lavage fluid (BALF) and lung tissue reflected by elevated pleural effusion volume, lung edema, BALF polymorphonuclear leukocytes count and lung myeloperoxidase levels, which was attenuated by pinitol (10 and 20 mg/kg) administration. Pinitol also markedly (P < .05) inhibited LPS‐induced alterations in electrocardiographic, hemodynamic changes, right ventricular, and lung function tests. The LPS‐induced downregulated nuclear factor erythroid 2–related factor 2 (Nrf‐2) and heme oxygenase‐1 (HO‐1), whereas upregulated transforming growth factor‐β (TGF‐β), tumor necrosis factor‐α (TNF‐α), interleukin‐1β (IL‐1β), IL‐6, NOD‐, LRR‐, and pyrin domain‐containing protein 3 (NLRP3), and inducible nitric oxide synthase (iNOs) lung messenger RNA expressions were significantly (P < .05) inhibited by pinitol. Western blot analysis suggested pinitol markedly (P < .05) decreased nuclear factor‐κB (NF‐κB), inhibitor of nuclear factor κB (IkBα), toll‐like receptor 4 (TLR‐4), and cyclooxygenase‐II (COX‐II) protein expressions in the lung. These findings were further supported by histological and ultrastructural analyses of lung tissue that show pinitol significantly (P < .05) ameliorates LPS‐induced aberrations in lung tissue. In conclusion, pinitol attenuated LPS‐induced pneumonia via inhibition of TLR‐4 to downregulate the NF‐κB/IκBα signaling cascade and thus ameliorated the production of proinflammatory cytokines (TNF‐α, ILs, NLRP3, and TGF‐β), inflammatory mediators (COX‐II and iNOs) and elevated oxidative stress (Nrf‐2 and HO‐1).