多巴胺D1受体激动剂SKF38393对剥夺血清条件下PC12细胞的保护作用

目的 研究多巴胺D1受体激动剂SKF38393对剥夺血清所致PC12细胞损伤的神经保护作用及其与磷脂酰肌醇-3激酶/蛋白激酶B(phosphatidylinositol 3-kinases/protein kinase B,PI3K/Akt)、细胞外调节蛋白激酶(extracellular signal-regulated kinases,ERK)信号通路的关系.方法 将PC12细胞分为血清剥夺模型组、血清剥夺后加不同剂量SKF38393处理组(1 μmoL、3 μmoL、10 μmoL、30 μmoL和100 μmoL)及1%胎牛血清对照组,比较各组PC12细胞活性;PC12细胞分别加入不同剂量(同上)SKF38393处理40 min,以及以10 μmoL SKF38393处理不同时间(5 ～ 80 min),然后检测PC12细胞的Akt473及ERK1/2的磷酸化水平;PC12细胞分别加入PI3K/Akt信号通路抑制剂LY294002(50 μmoL)、ERK信号通路抑制剂PD98059(50 μmoL)或PD169316(10 μmoL),后再行SKF38393干预,比较各组PC12细胞活性.结果 与剥夺血清组比较,10 μmoL SKF38393即可显著增加PC12细胞的活性[(0.58 ± 0.02) vs (0.37 ± 0.01)],并且随着其剂量(30 μmoL、100 μmoL)的增加PC12细胞活性的增加可更明显[(0.62 ± 0.01)、(0.65 ± 0.02)],上述差异均有统计学意义(P ＜ 0.05).不同剂量SKF38393和不同时间的SKF38393处理PC12细胞后磷酸化的Akt和ERK的表达水平均明显高于剥夺血清组(P ＜ 0.05).与SKF38393组的PC12细胞活性(0.59 ± 0.01)比较,PD169316组细胞活性(0.41 ± 0.14)无明显差异(P ＞ 0.05),但LY294002组 (0.33 ± 0.01)和PD98059(0.33 ± 0.03)组细胞活性均更低(P ＜ 0.05),提示仅后二者可阻断SKF38393对PC12细胞损伤的保护作用.结论 SKF38393能保护剥夺血清所致的PC12细胞损伤,其保护作用可能与激活PI3K/Akt和ERK信号通路有关.     

Quercetin protects oligodendrocyte precursor cells from oxygen/glucose deprivation injury in vitro via the activation of the PI3K/Akt signaling pathway

The aim of this study was to investigate the protection of quercetin (QUE) on oligodendrocyte precursor cells (OPCs) from oxygen/glucose deprivation (OGD)-induced injury in vitro and explore whether the PI3K/Akt signaling pathway contributed to the protection provided by quercetin. The OGD condition was induced by including 2mM sodium dithionite (Na(2)S(2)O(4)) in glucose-free DMEM medium. The concentration of QUE in this study ranged from 3μM to 81μM. OPCs were identified by immunocytochemical staining. Cell viability was analyzed using the water soluble tetrazolium salt-8 (WST-8) and lactate dehydrogenase assay (LDH). The morphological changes of the nucleus were measured using Hoechst 33258 nuclear staining, and the ratio of apoptotic cells was determined by FITC annexin V- and propidium iodide (PI) flow cytometry assay kit. In addition, the levels of pro-apoptotic proteins such as cleaved-caspase-3 and Bax and the anti-apoptotic proteins p-Akt and Bcl-2 were quantified using western blotting. The results showed that the OPC cell survival rate was significantly increased by incubation in conditioned medium supplemented with QUE as measured by the WST-8 assay, while the LDH release rate was significantly decreased as analyzed by the LDH assay. Furthermore, apoptosis assay showed that the apoptosis ratio of OPCs was also dramatically reduced by QUE. Western blotting showed that the expression levels of Bax and cleaved-caspase-3 proteins were down-regulated, while Bcl-2 and p-Akt were up-regulated. Further study showed that the increase in p-Akt by QUE was reduced by the PI3K inhibitor LY294002. These results indicated that QUE effectively protected OPCs from OGD-induced injury and that the mechanism might be related to the activation of the PI3K/Akt signaling pathway.     

TNF-alpha stimulates caspase-3 activation and apoptotic cell death in primary septo-hippocampal cultures

Primary septo-hippocampal cell cultures were incubated in varying concentrations of tumor necrosis factor (TNF-alpha; 0.3-500 ng/ml) to examine proteolysis of the cytoskeletal protein alpha-spectrin (240 kDa) to a signature 145 kDa fragment by calpain and to the apoptotic-linked 120-kDa fragment by caspase-3. The effects of TNF-alpha incubation on morphology and cell viability were assayed by fluorescein diacetate-propidium iodide (FDA-PI) staining, assays of lactate dehydrogenase (LDH) release, nuclear chromatin alterations (Hoechst 33258), and internucleosomal DNA fragmentation. Incubation with varying concentrations of TNF-alpha produced rapid increases in LDH release and nuclear PI uptake that were sustained over 48 hr. Incubation with 30 ng/ml TNF-alpha yielded maximal, 3-fold, increase in LDH release and was associated with caspase-specific 120-kDa fragment but not calpain-specific 145-kDa fragment as early as 3.5 hr after injury. Incubation with the pan-caspase inhibitor, carbobenzosy- Asp-CH(2)-OC (O)-2-6-dichlorobenzene (Z-D-DCB, 50-140 microM) significantly reduced LDH release produced by TNF-alpha. Apoptotic-associated oligonucleosomal-sized DNA fragmentation on agarose gels was detected from 6 to 72 hr after exposure to TNF-alpha. Histochemical changes included chromatin condensation, nuclear fragmentation, and formation of apoptotic bodies. Results of this study suggest TNF-alpha may induce caspase-3 activation but not calpain activation in septo-hippocampal cultures and that this activation of caspase-3 at least partially contributes to TNF-alpha-induced apoptosis.     

P2 receptor‐mediated stimulation of the PI3‐K/Akt‐pathway in vivo

ATP acts as a growth factor as well as a toxic agent by stimulating P2 receptors. The P2 receptor‐activated signaling cascades mediating cellular growth and cell survival after injury are only incompletely understood. Therefore, the aim of the present study was to identify the role of the phosphoinositide 3 kinase (PI3‐K/Akt) and the mitogen‐activated protein kinase/extracellular signal regulated protein kinase (MAPK/ERK) pathways in P2Y receptor‐mediated astrogliosis after traumatic injury and after microinfusion of ADPβS (P2Y_1,12,13 receptor agonist) into the rat nucleus accumbens (NAc). Mechanical damage and even more the concomitant treatment with ADPβS, enhanced P2Y₁ receptor‐expression in the NAc, which could be reduced by pretreatment with the P2X/Y receptor antagonist PPADS. Quantitative Western blot analysis indicated a significant increase in phosphorylated (p)Akt and pERK1/2 2 h after ADPβS‐microinjection. Pretreatment with PPADS or wortmannin abolished the up‐regulation of pAkt by injury alone or ADPβS‐treatment. The ADPβS‐enhanced expression of the early apoptosis marker active caspase 3 was reduced by PPADS and PD98059, but not by wortmannin. Multiple immunofluorescence labeling indicated a time‐dependent expression of pAkt and pMAPK on astrocytes and neurons and additionally the colocalization of pAkt, pMAPK, and active caspase 3 with the P2Y₁ receptor especially at astrocytes. In conclusion, the data show for the first time the involvement of PI3‐K/Akt‐pathway in processes of injury‐induced astroglial proliferation and anti‐apoptosis via activation of P2Y₁ receptors in vivo, suggesting specific roles of P2 receptors in glial cell pathophysiology in neurodegenerative diseases. © 2008 Wiley‐Liss, Inc.     

PI3K/akt, JAK/STAT and MEK/ERK pathway inhibition protects retinal ganglion cells via different mechanisms after optic nerve injury

Recently we unexpectedly found that PI3K/akt, JAK/STAT and MEK/ERK pathway inhibitors enhanced retinal ganglion cell (RGC) survival after optic nerve (ON) axotomy in adult rat, a phenomenon contradictory to conventional belief that these pathways are pro-survival. In this study we showed that: (i) the RGC protection was pathway inhibition-dependent; (ii) inhibition of PI3K/akt and JAK/STAT, but not MEK/ERK, activated macrophages in the eye, (iii) macrophage removal from the eye using clodronate liposomes significantly impeded PI3K/akt and JAK/STAT inhibition-induced RGC survival and axon regeneration whereas it only slightly affected MEK/ERK inhibition-dependent protection; (iv) in the absence of recruited macrophages in the eye, inhibition of PI3K/akt or JAK/STAT did not influence RGC survival; and (v) strong PI3K/akt, JAK/STAT and MEK/ERK pathway activities were located in RGCs but not macrophages after ON injury. In retinal explants, in which supply of blood-derived macrophages is absent, MEK/ERK inhibition promoted RGC survival whereas PI3K/akt or JAK/STAT inhibition had no effect on RGC viability. However, MEK/ERK inhibition exerted opposite effects on the viability of purified adult RGCs at different concentrations in vitro, suggesting that this pathway may be bifunctional depending on the level of pathway activity. Our data thus demonstrate that inhibition of the PI3K/akt or JAK/STAT pathway activated macrophages to facilitate RGC protection after ON injury whereas the two pathways per se did not modulate RGC viability under the injury conditions (in the absence of the pathway activators). In contrast, the MEK/ERK pathway inhibition protected RGCs via macrophage-independent mechanism(s).     

Different dependence of lithium and valproate on PI3K/PKB pathway

Objectives: Acute treatment with valproate (VPA) or lithium (Li⁺) protects cerebellar granule cells (CGC) against apoptosis induced by low potassium (K⁺) (5 mM). As the protection induced by VPA is absolutely dependent on insulin, in contrast to the observed effects of Li⁺, we decided to study the different role of the PI3K/PKB pathway in the neuroprotective effects of both drugs.

Methods: We have studied the neuroprotection elicited by Li⁺ or VPA in cultures of rat CGC. We induced the apoptosis by switching to a medium with a low concentration of K⁺ or by adding C₂-ceramide to the cultures. We studied the effect of Li⁺ and VPA on viability and on the regulation of the PI3K/PKB pathway.

Results and conclusions: Insulin also protects against low K⁺-induced apoptosis in CGC, probably through its interaction with an insulin-like growth factor receptor. Moreover, whereas Li⁺ protects against the apoptosis induced by C₂-ceramide, VPA cannot, probably due to the inhibition of protein kinase B (PKB) caused in this apoptotic stimulus. These results suggest that VPA protects against low K⁺-induced apoptosis by acting on the PI3K/PKB pathway; however, VPA does not affect the increase of PKB activity caused by insulin in these cells. The protection by Li⁺ is independent of this transduction pathway. Moreover, Li⁺ blocks the caspase 3 activation induced by low K⁺, whereas neither VPA nor insulin affects this activation.     

Insulin-like growth factor-1 provides protection against psychosine-induced apoptosis in cultured mouse oligodendrocyte progenitor cells using primarily the PI3K/Akt pathway

Psychosine (galactosylsphingosine) is a toxic metabolite that accumulates in globoid cell leukodystrophy (GLD) due to the deficiency of galactocerebrosidase (GALC) activity. This results in subsequent programmed cell death of oligodendrocytes and demyelination in human patients and animal models. We investigated the potential role of insulin-like growth factor-1 (IGF-1) in modifying the apoptotic effect of psychosine in cultured mouse oligodendrocyte progenitor cells (OLP-II). We show that psychosine inhibits the phosphorylation of Akt and Erk1/Erk2 (Erk1/2), which are the main anti-apoptotic pathways of the IGF-1 receptor (IGF-1R). Although IGF-1 sustained phosphorylation of both of these pathways, it provided maximum protection to OLP-II cells from psychosine-induced cell death in a PI3K/Akt-dependent manner. The effects of IGF-1 were dose-dependent and resulted in increased IGF-1R autophosphorylation levels. Although relatively high concentrations of IGF-1 also resulted in the activation of the insulin receptor (IR), its effect was more significant on the IGF-1R.     

IGF-1通过PI3K/Akt通路抑制MPP~+诱导PC12细胞凋亡机制的研究

目的探讨胰岛素样生长因子-1(insulin-like growth factor-1,IGF-1)对1-甲基-4-苯基吡啶离子(1-methyl-4-phenylpyridinium,MPP+)诱导的PC12细胞凋亡的抑制作用及其潜在的作用机制。方法以250μmol/L的MPP+损伤PC12细胞作为帕金森病(Parkinson disease,PD)细胞模型。实验分组如下:空白对照组、MPP+组、IGF-1组、IGF-1+MPP+组、IGF-1+MPP++LY294002组。孵育24 h后采用AO-EB法检测细胞凋亡率;采用MTT法检测细胞存活率;孵育4 h之后采用Western blot免疫印迹法检测Akt、磷酸化-Akt(phospho-Akt,p-Akt)蛋白表达。结果 (1)100 nmol的IGF-1能够显著抑制MPP+所致的细胞凋亡,对PC12细胞具有保护作用;(2)总Akt含量蛋白表达水平各处理组之间差别无统计学意义(P>0.05),但磷酸化的Akt在IGF-1+MPP+组表达高于MPP+单独处理组(P<0.05)。结论 IGF-1可减少MPP+所致的细胞凋亡,其保护作用与上调磷酸化的Akt的表达相关。     

Involvement of PI3K/Akt/TOR pathway in stretch‐induced hypertrophy of myotubes

Skeletal muscle cells are hypertrophied by mechanical stresses, but the underlying molecular mechanisms are not fully understood. Two signaling pathways, phosphatidylinositol 3‐kinase (PI3K)/Akt to target of rapamycin (TOR) and extracellular signal–regulated kinase kinase (MEK) to extracellular signal–regulated kinase (ERK), have been proposed to be involved in muscle hypertrophy. In this study we examined the involvement of these pathways in primary cultures of chick skeletal myotubes subjected to passive cyclic stretching for 72 hours, a time that was sufficient to induce significant hypertrophy in our preparations. Hypertrophy was largely suppressed by wortmannin or rapamycin, inhibitors of PI3K or mTOR, respectively. Furthermore, phosphorylation of Akt was enhanced by stretching and suppressed by wortmannin. The MEK inhibitor, U0126, exerted a minimal influence on stretch‐induced hypertrophy. We found that cyclic stretching of myotubes activates the PI3K/Akt/TOR pathway, resulting in muscle hypertrophy. The MEK/ERK pathway may contribute negatively to spontaneous hypertrophy. Muscle Nerve, 2010     

bFGF-mediated redox activation of the PI3K/Akt pathway in retinal photoreceptor cells

In many retinal diseases, it is the death of photoreceptors that leads to blindness. In previous in vitro and in vivo studies, basic fibroblast growth factor (bFGF) has been shown to increase retinal cell survival. More recently, reactive oxygen species (ROS) have also been shown to promote cell survival, contrary to the traditional view that they are solely destructive molecules. Due to this possible link, we hypothesised that bFGF could stimulate the production of ROS, which in turn stimulates the protein kinase B (Akt) survival pathway. Flow cytometry was used to measure the fluorescence of oxidised dihydrorhodamine, a ROS indicator, in the murine 661W photoreceptor cell line under several different conditions. Expression of cyclooxygenase (Cox) enzymes was evaluated by immunohistochemistry, and the response of photoreceptor cells to exogenous bFGF in the explanted mouse retina was studied by confocal microscopy. Exogenous addition of bFGF to 661W cells resulted in an increase in ROS production that lasted for 24 h. When this ROS production was inhibited, bFGF-induced phosphorylation of Akt was prevented. Through the use of inhibitors and small interfering RNA in the cell line, the source of this production was shown to be Cox and to involve the activation of phospholipases A(2) + C. This pathway may also occur in the mouse retina, as we showed that the retina expressed Cox1&2, and that photoreceptors in explanted retina respond to bFGF by increasing their ROS levels. These results demonstrate that exogenous bFGF can stimulate ROS production through the activation of Cox, and activate the Akt pathway.     

MicRNA-124可能通过PI3K/Akt通路调节缺血脑组织细胞凋亡

目的探讨脑缺血环境下对micRNA-124表达的影响。方法采用Western blot、荧光定量PCR技术检测脑缺血后缺血皮质区不同时间点bax、bcl-2、caspase-3、ROCK1、micRNA-124蛋白或基因的表达水平。结果缺血脑组织细胞micRNA-124基因表达量与调控细胞凋亡指标bax、bcl-2、caspase-3增高一致;bax、bcl-2、caspase-3、ROCK1活化片段蛋白表达量逐渐升高,在随后观察的时点内持续处于高表达状态(P0.01)。结论 micRNA-124可能参与缺氧致脑组织细胞凋亡的过程,其机制可能是通过PI3K/Akt通路,激活或抑制bax、bcl-2、caspase-3、ROCK1其中一个或是多个基因调节缺氧脑组织细胞凋亡。     

Resveratrol attenuates brain damage in permanent focal cerebral ischemia via activation of PI3K/Akt signaling pathway in rats

ABSTRACT

Objective: The aim of this study was to evaluate the potential molecular mechanism of resveratrol (RSV) that attenuates brain damage from focal cerebral ischemia.

Methods and materials: To investigate whether phosphatidylinositol 3-kinase/Akt (PI3K/Akt) pathway was involved in RSV anti-inflammatory and neuroprotective properties. Middle cerebral artery occlusion (MCAO) animal model was used in this study. Adult male Sprague–Dawley (SD) rats underwent MCAO, and then received treatment with RSV or vehicle after the onset of ischemia. PI3K inhibitor LY294002 was injected intracerebroventricularly to inhibit the PI3K/Akt signaling pathway. Neurological deficit scores and cerebral water content were assessed 24 h after MCAO. The inflammatory factors interleukin (IL)-1β, tumor necrosis factor (TNFα), and cyclooxygenase-2 (COX2) mRNA level were examined by real-time PCR. The enzymatic activity of myeloperoxidase (MPO) was measured 24 h after MCAO. The protein expression of phospho-Akt and COX2 in ischemic brain were determined by western blot.

Results: RSV significantly reduced neurological deficit scores, cerebral water content and the enzymatic activity of MPO, all of which were abolished by LY294002 administration. Real-time PCR showed that RSV significantly suppressed the upregulation of the inflammatory factors IL-1β, TNFα, COX2 mRNA levels. RSV significantly inhibited upregulated the protein expression of COX2 24 h after MCAO, which effect was abolished by LY294002 administration.

Conclusion: RSV attenuated ischemic brain damage induced by cerebral artery occlusion mainly through PI3K/Akt signaling pathway.

Abbreviation: MCAO: Middle cerebral artery occlusion; RSV: resveratrol; PI3K/Akt: phosphatidylinositol 3-kinase/Akt; TNF: tumor necrosis factor; COX2: cyclooxygenase-2; MPO: myeloperoxidase; IL: interleukin.     

L-3-n-butylphthalide protects against vascular dementia via activation of the Akt kinase pathway

As a neuroprotective drug for the treatment of ischemic stroke, 3-n-butylphthalide, a celery seed ex- tract, has been approved by the State Food and Drug Administration of China as a clinical therapeutic drug for ischemic stroke patients. L-3-n-butylphthalide possesses significant efficacy in the treatment of acute ischemic stroke. The activated Akt kinase pathway can prevent the death of nerve cells and exhibit neuroprotective effects in the brain after stroke. This study provides the hypothesis that I-3-n- butylphthalide has a certain therapeutic effect on vascular dementia, and its mechanism depends on the activation of the Akt kinase pathway. A vascular dementia mouse model was established by cere- bral repetitive ischemia/reperfusion, and intragastrically administered I-3-n-butylphthalide daily for 28 consecutive days after ischemia/repedusion, or 7 consecutive days before ischemia/reperfusion. The Morris water maze test showed significant impairment of spatial learning and memory at 4 weeks after operation, but intragastric administration of I-3-n-butylphthalide, especially pretreatment with I-3-n- butylphthalide, significantly reversed these changes. Thionine staining and western blot analylsis showed that preventive and therapeutic application of I-3-n-butylphthalide can reduce loss of pyrami- dal neurons in the hippocampal CA1 region and alleviate nerve damage in mice with vascular demen- tia. In addition, phosphorylated Akt expression in hippocampal tissue increased significantly after I-3-n- butylphthalide treatment. Experimental findings demonstrate that I-3-n-butylphthalide has preventive and therapeutic effects on vascular dementia, and its mechanism may be mediated by upregulation of phosphorylated Akt in the hippocampus.     

Astrocytes protect oligodendrocyte precursor cells via MEK/ERK and PI3K/Akt signaling

Accumulating evidence suggest that trophic coupling among different cell types in the brain is required to maintain normal CNS function. Here we show that astrocytes secrete soluble factors that can be oligodendrocyte‐supportive. Oligodendrocyte precursor cells (OPCs) and astrocytes were prepared from neonatal rat brain and cultured separately. We conducted cell culture medium‐transfer experiments to examine whether astrocytes secrete OPC‐protective factors. Conditioned media from astrocytes protected OPCs against H₂O₂‐induced oxidative stress, starvation, and oxygen‐glucose deprivation. This protective effect may be mediated in part via ERK and Akt signaling pathways. Astrocyte‐conditioned media upregulated the phosphorylation levels of ERK and Akt in OPC cultures. Blockade of ERK or Akt signaling with U0126 or LY294002 cancelled the OPC‐protective effects of astrocyte‐conditioned media. Taken together, these data suggest that astrocytes are an important source for oligodendrocyte‐supportive factors. Coupling between these two major glial components in brain may be vital for sustaining white matter homeostasis. © 2009 Wiley‐Liss, Inc.     

ATP敏感性钾通道开放剂抑制PC12细胞凋亡的作用途径

Objective To investigate the effect of ATP-sensitive potassium channel (KATP) openers on ischemia-hypoxia-induced PC12 cell apoptosis and the mRNA and protein expression of Akt and Bcl-2, which should manifest the protective mechanism of KATP openers. Methods PC12 cells 3 days after passage were divided into group A (control group), B (ischemia-hypoxia group), C (KATP channel opener group) and D (KATP channel opener+blocker group). Apoptosis rate was detected using Annexin-v FITC/PI double staining flow cytometry; mRNA and protein levels of p-Akt and Bcl-2 were measured by immunofluorescent staining, Western-blotting and RT-PCR methods. Results After ischemia-hypoxia, number of apoptotic PC12 cells in group B, C and D gradually increased with time and peaked at 24h. Apoptotic cell numbers at each time point in group C were significantly different from that of group A, B and D (P<0.01). Apoptotic cell numbers in group B at different time points were not significantly different from that of group D (P>0.05). After ischemia-hypoxia, the mRNA and protein levels of p-Akt and Bcl-2 all increased and reached peak at 12h. The mRNA and protein levels of p-Akt and Bcl-2 in group C at different time points were significantly different from that of group A, B and D (P<0.05, or P<0.01). At contrast, no significant difference was seen in mRNA and protein levels of p-Akt and Bcl-2 between group B and D at different time points (P>0.05).Conclusion The protective mechanism of KATP openers on PC12 cells apoptosis after ischemia-hypoxia may be through activation of PI3K/Akt signaling pathway, which further activates the expression of downstream Bcl-2 gene.     

白藜芦醇通过激活PI3K/Akt信号通路减轻大鼠脑缺血再灌注损伤

目的 探讨PI3K/Akt信号通路在白藜芦醇减轻大鼠脑缺血再灌注损伤中的作用。方法 将48只成年SD大鼠随机分为假手术组、模型组、白藜芦醇组、LY294002组（Akt抑制剂）,每组12只。利用线栓法制备大鼠脑缺血再灌注损伤模型,造模后24 h进行大鼠神经功能损伤评分和检测脑梗死体积、脑组织髓过氧化物酶（MPO）的活性,免疫印迹法检测脑组织p-Akt、t-Akt的表达水平,ELISA法检测脑组织肿瘤坏死因子-α（TNF-α）的含量。结果 与假手术组相比,模型组大鼠神经功能损伤评分、脑梗死体积、缺血脑组织MPO活性和TNF-α含量均明显增高（P<0.05）,缺血脑组织p-Akt表达水平也明显增高（P<0.05）;与模型组相比,白藜芦醇显著降低大鼠神经功能损伤评分、脑梗死体积、缺血脑组织MPO活性和TNF-α含量（P<0.05）,也显著降低缺血脑组织p-Akt表达水平（P<0.05）;脑室内注射LY294002,显著抑制白藜芦醇的这些作用（P<0.05）。结论 白藜芦醇通过激活PI3K/Akt信号通路减轻大鼠脑缺血再灌注损伤。     

PI3K／Akt信号通路对神经元机械性损伤诱导的自噬调节作用

目的研究机械性神经元损伤后自噬的发生情况以及磷脂酰肌醇3激酶（P13K）／蛋白激酶B（Akt,即PKB）信号通路对其发挥的调节作用。方法小鼠皮层神经元原代培养2W后,采用机械性神经元损伤模型,通过蛋白印迹法（Westernblot）定量分析损伤后不同时间点自噬相关分子微管相关蛋白轻链3（LC3）I／II、Beclin-1和Akt蛋白磷酸化的表达情况;使用不同浓度的P13K抑制剂LY294002预处理神经元1h后给予机械性损伤,通过Westernblot来研究自噬相关分子LC3I／Ⅱ和Beclin-1的表达情况。结果自噬相关分子LC311于机械性神经元损伤后3h表达开始逐渐增加,而Beclin-1无明显变化;p-Akt的表达于损伤后3h达到高峰,此后逐渐恢复到正常水平;用P13K抑制剂LY294002预处理神经元,可以使损伤后神经元的自噬相关分子LC3lI和Beclin-1的表达上调。结论机械性神经元损伤可以诱导自噬发生,且PI3K／Akt信号通路在其中可能发挥调节作用。     

Galectin-3 protects against ischemic stroke by promoting neuro-angiogenesis via apoptosis inhibition and Akt/Caspase regulation

Post-stroke neurological deficits and mortality are often associated with vascular disruption and neuronal apoptosis. Galectin-3 (Gal3) is a potent pro-survival and angiogenic factor. However, little is known about its protective role in the cerebral ischemia/reperfusion (I/R) injury. We have previously shown significant up-regulation of Gal3 in the post-stroke rat brain, and that blocking of Gal3 with neutralizing antibody decreases the cerebral blood vessel density. Our current study demonstrates that intracerebral local delivery of the Gal3 into rat brain at the time of reperfusion exerts neuroprotection. Ischemic lesion volume and neuronal cell death were significantly reduced as compared with the vehicle-treated MCAO rat brains. Gal3 increased vessel density and neuronal survival after I/R in rat brains. Importantly, Gal3-treated groups showed significant improvement in motor and sensory functional recovery. Gal3 increased neuronal cell viability under in vitro oxygen–glucose deprivation conditions in association with increased phosphorylated-Akt, decreased phosphorylated-ERK1/2, and reduced caspase-3 activity. Gene expression analysis showed down regulation of pro-apoptotic and inflammatory genes including Fas-ligand, and upregulation of pro-survival and pro-angiogenic genes including Bcl-2, PECAM, and occludin. These results indicate a key role for Gal3 in neuro-vascular protection and functional recovery following ischemic stroke through modulation of angiogenic and apoptotic pathways.