Developmental regulation of glucose transporters GLUT3, GLUT4 and GLUT8 in the mouse cerebellar cortex

Glucose uptake into the mammalian nervous system is mediated by the family of facilitative glucose transporter proteins (GLUT). In this work we investigate how the expression of the main neuronal glucose transporters (GLUT3, GLUT4 and GLUT8) is modified during cerebellar cortex maturation. Our results reveal that the levels of the three transporters increase during the postnatal development of the cerebellum. GLUT3 localizes in the growing molecular layer and in the internal granule cell layer. However, the external granule cell layer, Purkinje cell cytoplasm and cytoplasm of the other cerebellar cells lack GLUT3 expression. GLUT4 and GLUT8 have partially overlapping patterns, which are detected in the cytoplasm and dendrites of Purkinje cells, and also in the internal granule cell layer where GLUT8 displays a more diffuse pattern. The differential localization of the transporters suggests that they play different roles in the cerebellum, although GLUT4 and GLUT8 could also perform some compensatory or redundant functions. In addition, the increase in the levels and the area expressing the three transporters suggests that these roles become more important as development advances. Interestingly, the external granule cells, which have been shown to express the monocarboxylate transporter MCT2, express none of the three main neuronal GLUTs. However, when these cells migrate inwardly to differentiate in the internal granule cells, they begin to produce GLUT3, GLUT4 and GLUT8, suggesting that the maturation of the cerebellar granule cells involves a switch in their metabolism in such a way that they start using glucose as they mature.     

Toll-like receptor 2 and facial motoneuron survival after facial nerve axotomy

We have previously demonstrated that CD4⁺ Th2 lymphocytes are required to rescue facial motoneuron (FMN) survival after facial nerve axotomy through interaction with peripheral antigen presenting cells, as well as CNS resident microglia. Furthermore, the innate immune molecule, toll-like receptor 2 (TLR2), has been implicated in the development of Th2-type immune responses and can be activated by intracellular components released by dead or dying cells. The role of TLR2 in the FMN response to axotomy was explored in this study, using a model of facial nerve axotomy at the stylomastoid foramen in the mouse, in which blood–brain-barrier (BBB) permeability does not occur. After facial nerve axotomy, TLR2 mRNA was significantly upregulated in the facial motor nucleus and co-immunofluorescence localized TLR2 to CD68⁺ microglia, but not GFAP⁺ astrocytes. Using TLR2-deficient (TLR2^−/−) mice, it was determined that TLR2 does not affect FMN survival levels after axotomy. These data contribute to understanding the role of innate immunity after FMN death and may be relevant to motoneuron diseases, such as amyotrophic lateral sclerosis (ALS).     

大鼠面神经切断及修复后面神经核内STAT3的变化

目的：探讨面神经损伤及修复条件下，面神经核运动神经元STAT3 mRNA和蛋白的变化规律。方法：采用原位杂交和免疫组化染色法，观察成年大鼠面神经切断和即刻端端吻合后面神经核STAT3 mRNA和蛋白的时程变化。结果：面神经切断后损伤侧面神经核STAT3 mRNA信号的强度增加，在术后第21d和35d，面神经单纯切断组和面神经切断后端端吻合组间STAT3 mRNA信号的强度相差显著（P＜0．05）。结论：面神经损伤后，面神经核运动神经元内由STAT3介导的细胞因子的信号转导增加。在面神经无再生状态下，STAT3表达上调呈持续性；而在面神经再生状态下，随着面神经的成功再生，STAT3可逐渐恢复至正常水平。     

低氧预适应上调大鼠海马神经元和星形胶质细胞在急性缺氧时的葡萄糖转运蛋白的活性和基因表达

目的 研究低氧预适应对海马神经元和星形胶质细胞在急性缺氧暴露时的葡萄糖转运蛋白的活性和基因表达的影响。方法 培养大鼠海马神经元和星形胶质细胞,每天间歇暴露于低氧混合气体（1% O2、10% CO2、89% N2）20min,连续6d。最后1次低氧暴露24h后,将细胞暴露于无氧混合气体（10% CO2、90% N2）6h,然后立即检测[3H]-2-脱氧葡萄糖（2-DG）的摄取率、GLUT1和GLUT3的mRNA水平及神经元的存活率。结果 低氧预适应上调急性缺氧时神经元和星形胶质细胞的2-DG吸收率、星形胶质细胞GLUT1 mRNA的表达及神经元GLUT1和GLUT3 mRNA的表达,提高神经元存活率,这一作用可被细胞松弛素B消除。结论 低氧预适应上调海马神经元和星形胶质细胞在急性缺氧时的葡萄糖摄取率和葡萄糖转运蛋白的基因表达。     

GLUT11, but not GLUT8 or GLUT12, is expressed in human skeletal muscle in a fibre type-specific pattern

Nine novel sugar transporter-like proteins have been discovered in the past 5 years. The mRNA for three of these, the glucose transporters (GLUT) GLUT8, GLUT11 and GLUT12, have been detected in human skeletal muscle. In the present study, we examined the pattern of expression and localization of the GLUT isoforms 8, 11 and 12 in human skeletal muscle using an immunohistochemical approach. Biopsies of human skeletal muscle from sedentary or trained healthy adults, from fetal muscle (24 weeks of gestation), from obese type-2 diabetic subjects, and from patients suffering from polymyositis or amyotrophic lateral sclerosis (ALS) were studied. GLUT8 and 12 immunoreactivity was below detection level in both developing and adult muscle fibres. GLUT11 immunoreactivity, however, was present in slow-twitch muscle fibres, but not in fast twitch fibres. Since, in contrast, GLUT4 was expressed in all investigated muscle fibres, the pattern of expression of GLUT11 differs from that of GLUT4, suggesting a specialized function for GLUT11 with a regulation independent from that of GLUT4. Obesity, type-2 diabetes, training, conditions of de- and reinnervation (ALS) and regeneration (polymyositis) failed to induce GLUT8 or -12 expression. Likewise, the fibre type-dependent pattern of GLUT11 immunoreactivity was unaltered. However, some slow muscle fibres lose their GLUT11 immunoreactivity under regeneration. Our results indicate that GLUT11 immunoreactivity, in contrast to that of GLUT4, is expressed exclusively in slow-twitch muscle fibres and is unaffected by physiological and pathophysiological conditions except in primary myopathy. GLUT8 and GLUT12 do not appear to be of importance in human muscle under physiological and pathophysiological conditions.     

Regulation of GLUT4 protein and glycogen synthase during muscle glycogen synthesis after exercise

The pattern of muscle glycogen synthesis following its depletion by exercise is biphasic. Initially, there is a rapid, insulin independent increase in the muscle glycogen stores. This is then followed by a slower insulin dependent rate of synthesis. Contributing to the rapid phase of glycogen synthesis is an increase in muscle cell membrane permeability to glucose, which serves to increase the intracellular concentration of glucose-6-phosphate (G6P) and activate glycogen synthase. Stimulation of glucose transport by muscle contraction as well as insulin is largely mediated by translocation of the glucose transporter isoform GLUT4 from intracellular sites to the plasma membrane. Thus, the increase in membrane permeability to glucose following exercise most likely reflects an increase in GLUT4 protein associated with the plasma membrane. This insulin-like effect on muscle glucose transport induced by muscle contraction, however, reverses rapidly after exercise is stopped. As this direct effect on transport is lost, it is replaced by a marked increase in the sensitivity of muscle glucose transport and glycogen synthesis to insulin. Thus, the second phase of glycogen synthesis appears to be related to an increased muscle insulin sensitivity. Although the cellular modifications responsible for the increase in insulin sensitivity are unknown, it apparently helps maintain an increased number of GLUT4 transporters associated with the plasma membrane once the contraction-stimulated effect on translocation has reversed. It is also possible that an increase in GLUT4 protein expression plays a role during the insulin dependent phase.     

面神经截端收集液对运动神经元促进作用

为了检测面神经截端收集液（本文内称神经再生液）对运动神经元的营养活性，藉以探讨面神经再生微环境在神经再生中的作用，同时检验穴位针刺对面神经再生微环境的影响。作者建立兔面神经再生微环境的动物模型，并分为针刺组和末针刺组，5d后收集神经再生液，与纯化的运动神经元一起培养，通过动态观察胞体面积、突起长度及MTT法检验各组神经元的细胞活性。结果发现实验组（包括针刺组和未针刺组）神经元的胞体面积、突起长度及OD值总体上大于对照组；但针刺组和未针刺组两组无明显差异。作者提出面神经再生液对运动神经元有营养活性作用；尚不能证实针刺对面神经再生微环境有积极的影响作用。     

VEGF enhances intraneural angiogenesis and improves nerve regeneration after axotomy

Whilst there is an increased understanding of the cell biology of nerve regeneration, it remains unclear whether there is a direct interrelationship between vascularisation and efficacy of nerve regeneration within a nerve conduit. To establish this is important as in clinical surgery peripheral nerve conduit grafting has been widely investigated as a possible alternative to the use of nerve autografts. The aim of this study was to assess whether vascular endothelial growth factor (VEGF), a highly specific endothelial cell mitogen, can enhance vascularisation and, indirectly, axonal regeneration within a silicone nerve regeneration chamber. Chambers containing VEGF (500–700 ng/ml) in a laminin‐based gel (Matrigel) were inserted into 1 cm rat sciatic nerve defects and nerve regeneration examined in relation to angiogenesis between 5 and 180 d. Longitudinal sections were stained with antibodies against endothelial cells (RECA‐1), axons (neurofilament) and Schwann cells (S‐100) to follow the progression of vascular and neural elements. Computerised image analysis demonstrated that the addition of VEGF significantly increased blood vessel penetration within the chamber from d 5, and by d 10 this correlated with an increase of axonal regeneration and Schwann cell migration. The pattern of increased nerve regeneration due to VEGF administration was maintained up to 180 d, when myelinated axon counts were increased by 78% compared with plain Matrigel control. Furthermore the dose‐response of blood vessel regeneration to VEGF was clearly reflected in the increase of axonal regrowth and Schwann cell proliferation, indicating the close relationship between regenerating nerves and blood vessels within the chamber. Target organ reinnervation was enhanced by VEGF at 180 d as measured through the recovery of gastrocnemius muscle weights and footpad axonal terminal density, the latter showing a significant increase over controls (P < 0.05). The results demonstrate an overall relationship between increased vascularisation and enhanced nerve regeneration within an acellular conduit, and highlight the interdependence of the 2 processes.     

Glucose transport in human peripheral blood lymphocytes influenced by type 2 diabetes mellitus

Introduction: The objective of this study was to evaluate glucose transport into lymphocytes in healthy subjects and patients with type 2 diabetes mellitus (DM) treated either with diet only or with insulin and to propose peripheral blood lymphocytes as a convenient model for cellular glucose transport studies. Materials and Methods: Sixty subjects with type 2 DM, 30 treated with diet only and 30 with insulin, were investigated. Thirty healthy subjects matched for age, weight, and sex served as a control group. Deoxy-D-glucose, 2-[³H(G)] transport was studied in isolated peripheral blood lymphocytes. Expression of glucose transporters was ascertained by immunocytochemical identification and by Western blotting. Results: In lymphocytes from the control group, deoxy-D-glucose uptake increased gradually with the duration of the experiment. In diabetics treated with insulin, the maximal increase in deoxy-D-glucose uptake was observed after 30 min of the investigation, followed by a plateau phase. In diabetics treated with diet, deoxy-D-glucose uptake increased slowly during the first 30 min. The presence of GLUT1 and GLUT3 in lymphocytes was confirmed in this study. Conclusions: Glucose transport into lymphocytes is altered in type 2 DM. In lymphocytes from diabetics, the dynamics of deoxy-D-glucose uptake significantly differed from that in healthy subjects. There was also a significant difference between the diabetic groups, representing different modes of therapy and stages of the disease. Glucose transport into lymphocytes is apparently influenced by DM as well as by the mode of therapy. We suggest that peripheral blood lymphocytes may become a promising model for studies on glucose transport in diabetes.     

Induced NG2 expressing microglia in the facial motor nucleus after facial nerve axotomy

Chondroitin sulfate proteoglycan (NG2) expressing cells, ubiquitously distributed in the CNS respond to injured or diseased neurons; however, their behaviors toward injured neurons have remained to be fully explored. In the present study, along with astrocytic and microglial responses, NG2 expressing cells reacted swiftly and robustly in the facial motor nucleus (FMN) subjected to axotomy. With time, hypertrophic NG2 expressing cells gradually adhered to and enwrapped the axotomized motoneurons. Tight encapsulations around axotomized motoneurons were eventually formed at 7, 14, and 28 days after axotomy. NG2 positive processes appeared to interpose between synapsin-1 immunoreactive nerve terminals and surfaces of axotomized motoneurons. Double labeling results showed that NG2 expressing cells encapsulating axotomized facial motoneurons were mainly microglia marked by OX42 and lectin; only a few of them were positive to platelet-derived growth factor-α receptor and none of them positive to ED-1. No Rhodamine particle was detected in the FMN ipsilateral to axotomy after venous injection of the particles. The results suggest that activated microglia in lesioned FMN were induced to express NG2 molecules. It is concluded that axotomized FMN showed two types of NG2 expressing cells namely constitutive NG2 cells and induced-NG2 expressing microglia.     

The effects of delayed nerve repair on neuronal survival and axonal regeneration after seventh cervical spinal nerve axotomy in adult rats

It has been proposed clinically that delayed surgery after traumatic brachial plexus injury may adversely affect functional outcome. In the present experimental study the neuroprotective and growth-promoting effects of early and delayed nerve grafting following proximal seventh cervical spinal nerve (C7) axotomy were examined. The ventral branch of C7 spinal nerve was transected and axons projecting out of the proximal nerve stump were labelled with Fast Blue (FB). At the same time, the biceps brachii muscle was denervated by transecting the musculocutaneous nerve at its origin. Neuronal survival and muscle atrophy were then assessed at 1, 4, 8 and 16 weeks after permanent axotomy. In the experimental groups, a peripheral nerve graft was interposed between the transected C7 spinal nerve and the distal stump of the musculocutaneous nerve at 1 week [early nerve repair (ENR)] or 8 weeks [delayed nerve repair (DNR)] after axotomy. Sixteen weeks after nerve repair had been performed, a second tracer Fluoro-Ruby (FR) was applied distal to the graft to assess the efficacy of axonal regeneration. Counts of FB-labelled neurons revealed that axotomy did not induce any significant cell loss at 4 weeks, but 15% of motoneurons and 32% of sensory neurons died at 8 weeks after injury. At 16 weeks, the amount of cell loss in spinal cord and dorsal root ganglion (DRG) reached 29 and 50%, respectively. Both ENR and DNR prevented retrograde degeneration of spinal motoneurons and counteracted muscle atrophy, but failed to rescue sensory neurons. Due to substantial cell loss at 8 weeks, the number of FR-labelled neurons after DNR was significantly lower when compared to ENR. However, the proportion of regenerating neurons among surviving motoneurons and DRG neurons remained relatively constant indicating that neurons retained their regenerative capacity after prolonged axotomy. The results demonstrate that DNR could protect spinal motoneurons and reduce muscle atrophy, but had little effect on sensory DRG neurons. However, the efficacy of neuroprotection and axonal regeneration will be significantly affected by the amount of cell loss already presented at the time of nerve repair.     

Deletion of Glucose Transporter GLUT8 in Mice Increases Locomotor Activity

Transport of glucose into neuronal cells is predominantly mediated by the glucose transporters GLUT1 and GLUT3. In addition, GLUT8 is expressed in some regions of the brain. By in situ hybridization we detected GLUT8-mRNA in hippocampus, thalamus, and cortex. However, its cellular and physiological function is still unknown. Thus, GLUT8 knockout (Slc2a8 -/-) mice were used for a screening approach in the modified hole board (mHB) behavioral test to analyze the role of GLUT8 in the central nervous system. Slc2a8 -/- mice showed increased mean velocity, total distance traveled and performed more turns in the mHB test. This hyperactivity of Slc2a8 -/- mice was confirmed by monitoring locomotor activity in the home cage and voluntary activity in a running wheel. In addition, Slc2a8 -/- mice showed increased arousal as indicated by elevated defecation, reduced latency to the first defecation and a tendency to altered grooming. Furthermore, the mHB test gave evidence that Slc2a8 -/- mice exhibit a reduced risk assessment because they performed less rearings in an unprotected area and showed significantly reduced latency to stretched body posture. Our data suggest that behavioral alterations of Slc2a8 -/- mice are due to dysfunctions in neuronal processes presumably as a consequence of defects in the glucose metabolism.     

Increased insulin-stimulated glucose uptake in athletes: the importance of GLUT4 mRNA,GLUT4 protein and fibre type composition of skeletal muscle

In the present study the expression of GLUT4 and fibre type composition were examined in biopsies from skeletal muscle in seven male athletes and eight male sedentary subjects. Estimated maximal oxygen uptake was increased in the trained group when compared with the sedentary group (74.0 ± 3.9 vs. 42.9±5.1 ml kg^-1 min^-1; P < 0.01). A biopsy of vastus lateralis muscle was taken in the fasting state, 36 h after the last bout of exercise. A second muscle biopsy was obtained following 4 h of a hyperinsulinaemic (2 mU kg^-1 min^-1), euglycaemic clamp. The rate of insulin-stimulated glucose uptake was increased in the trained subjects (17.34±0.53 vs. 13.53±0.79 mg kg^-1 min^-1, P < 0.01). In parallel, the steady state levels of GLUT4 protein and mRNA per DNA were higher in muscle biopsies obtained in the basal state from athletes than in sedentary controls, 21 and 71% respectively (P < 0.05). In the total group of participants, GLUT4 protein per DNA in the basal state and insulin-stimulated glucose uptake rate correlated positively, (r = 0.51, P = 0.05). In the insulin-stimulated state we did not find any significant correlation between GLUT4 protein per DNA and glucose uptake rate (r = 0.13, n.s.). No significant relationships between GLUT4 protein abundance per DNA and muscle fibre type distribution were observed. A significantly negative correladon was found between type 2B fibre area and insulin-stimulated glucose uptake (r =–0.63, P < 0.05). In conclusion, the abundance of GLUT4 protein and mRNA, respectively, is increased in skeletal muscle from endurance trained subjects compared to sedentary subjects. However, factors other than GLUT4 immunoreactive protein abundance seem to be determinant for the increased insulin-stimulated whole body glucose uptake in endurance trained subjects.     

PDGF and its receptors following facial nerve axotomy in rats: expression in neurons and surrounding glia

We investigated the expression of platelet-derived growth factor (PDGF) and its receptors in rat facial nuclei following axotomy by in situ hybridization and immunohistochemistry. Facial nuclei were examined on days 3, 6, 12, 19 and 26 postoperatively (p.o.). Strong immunoreactivity for PDGF was found in facial neurons and surrounding astrocytes on the ipsilateral side of the brainstem already after 3 days p.o. and persisted at a high level until day 26 p.o. in rats with a facial nerve cut injury. After crushing of the facial nerve, a similar increase was seen in PDGF immunoreactivity which, however, decreased after day 19 p.o., when reinnervation had occurred. Reactive gliosis appeared on the operated side and was confirmed by an increase in intensity of GFAP staining. The kinetics of PDGF A-chain mRNA expression corresponded to the PDGF immunoreactivity, whereas the B-chain mRNA was present only in the neurons. The PDGF -receptor immunoreactivity as well as the mRNA were detected in scattered glial cells. The density of the PDGF -receptor mRNA expressing glial cells was higher on the injured side, but the intensity of the expression per cell did not change after axotomy. An increase in PDGF -receptor immunoreactivity was seen in the ipsilateral facial nuclei after 3–6 days p.o., however, the increase in the mRNA could not be detected. The staining persisted until day 26 p.o., when transected facial neurons showed heavier staining than those that had been crushed. Furthermore, both mRNA and protein of the -receptor were expressed in the blood vessels after 3–6 days p.o., increasing with time. These results imply a role for PDGF in the regeneration process following nerve injury.     

大鼠脂肪细胞中14-3-3蛋白与葡萄糖转运子4的相互作用

目的研究在大鼠脂肪细胞中,14-3-3蛋白与葡萄糖转运子4(GLUT4)之间是否存在相互作用。方法用胶原酶I消化雄性SD大鼠附睾上的脂肪垫,获得分离的脂肪细胞。在纯化的细胞中,采用低渗裂解和甘油梯度速率沉降技术获得3个含有GLUT4的组分:T、H和L。用交联了1F8(GLUT4特异性单抗)的琼脂糖微珠对脂肪细胞总提取物以及上述3个组分分别进行免疫吸附实验,经吸附后在上清液和微珠的洗脱液中分别进行14-3-3蛋白和GLUT4的免疫印迹分析。结果在脂肪细胞的总提取物以及上述GLUT4的3个组分T、H和L中,14-3-3蛋白都能够与GLUT4发生免疫共沉淀。共沉淀下来的14-3-3蛋白在免疫印迹分析时显示为2个条带,其相对分子质量分别约为29 ku和60 ku,提示14-3-3蛋白可能以二聚体的形式与GLUT4发生相互作用。结论在生理条件下,14-3-3蛋白与GLUT4在大鼠脂肪细胞中存在相互作用。     

Survival and regeneration of cutaneous and muscular afferent neurons after peripheral nerve injury in adult rats

Peripheral nerve injury induces the retrograde degeneration of dorsal root ganglion (DRG) cells, which affects predominantly the small-diameter cutaneous afferent neurons. This study compares the time-course of retrograde cell death in cutaneous and muscular DRG cells after peripheral nerve transection as well as neuronal survival and axonal regeneration after primary repair or nerve grafting. For comparison, spinal motoneurons were also included in the study. Sural and medial gastrocnemius DRG neurons were retrogradely labeled with the fluorescent tracers Fast Blue (FB) or Fluoro-Gold (FG) from the homonymous transected nerves. Survival of labeled sural and gastrocnemius DRG cells was assessed at 3 days and 1–24 weeks after axotomy. To evaluate axonal regeneration, the sciatic nerve was transected proximally at 1 week after FB-labeling of the sural and medial gastrocnemius nerves and immediately reconstructed using primary repair or autologous nerve grafting. Twelve weeks later, the fluorescent tracer Fluoro-Ruby (FR) was applied 10 mm distal to the sciatic lesion in order to double-label sural and gastrocnemius neurons that had regenerated across the repair site. Counts of labeled gastrocnemius DRG neurons did not reveal any significant retrograde cell death after nerve transection. In contrast, sural axotomy induced a delayed loss of sural DRG cells, which amounted to 22% at 4 weeks and 43–48% at 8–24 weeks postoperatively. Proximal transection of the sciatic nerve at 1 week after injury to the sural or gastrocnemius nerves neither further increased retrograde DRG degeneration, nor did it affect survival of sural or gastrocnemius motoneurons. Primary repair or peripheral nerve grafting supported regeneration of 53–60% of the spinal motoneurons and 47–49% of the muscular DRG neurons at 13 weeks postoperatively. In the cutaneous DRG neurons, primary repair or peripheral nerve grafting increased survival by 19–30% and promoted regeneration of 46–66% of the cells. The present results suggest that cutaneous DRG neurons are more sensitive to peripheral nerve injury than muscular DRG cells, but that their regenerative capacity does not differ from that of the latter cells. However, the retrograde loss of cutaneous DRG cells taking place despite immediate nerve repair would still limit the recovery of cutaneous sensory functions.     

Cortically and lingually induced postsynaptic potentials in trigeminal motoneurons after axotomy

Summary The membrane properties and the efficacy of excitatory and inhibitory synapses were studied in cat masseteric motoneurons (Mass Mns) after axotomy. In axotomized Mass Mns the slope of the primary range in the frequency-current relationship showed a higher gain than that of normal Mass Mns. The safety of antidromic invasion was increased and the initial segment component of antidromic action potentials could not be separated from the somadendritic component. In normal Mass Mns a single shock delivered to the orbital gyrus or the lingual nerve induced long-lasting inhibitory postsynaptic potentials (IPSPs). In two-thirds of Mass Mns explored 30 days after axotomy, a single shock delivered to the orbital gyrus or the lingual nerve evoked a mixture of inhibitory and excitatory synaptic potentials. In Mass Mns 50 days after axotomy, we have demonstrated that the major fraction of the total sample of explored Mass Mns showed long-lasting excitatory postsynaptic potentials followed by IPSPs. The results suggest that in Mass Mns, axotomy is followed by the decline of synaptic efficacy of inhibitory rather than of excitatory synapses.     

胶质细胞源性神经营养因子/PI3K/AKT通路参与电针促进面神经压榨损伤模型兔的面神经再生

文题释义： 胶质细胞源性神经营养因子(glial cell-derived neurotrophic factor，GDNF)：是于1993年发现的由二硫键结合的同源二聚体蛋白质，含有134个氨基酸，分子质量为33-35 kD，是神经营养因子中的一种，属于转化生长因子超家族的远系成员，在全身各组织中均有表达，尤其在中枢神经系统内分布较广，具有显著的提高多巴胺能神经元存活与分化、抑制运动神经元凋亡、营养外周神经元、调整细胞间信息等作用。 PI3K：是由Sugimoto和Macara等(1984)发现的一种胞内磷脂酰肌醇激酶，由一个催化亚基(110 kD，p110 )和一个调节亚基(85 kD，p85 )构成，可特异地使肌醇环上的3位羟基磷酸化，其产物是在3位上有磷酸根的多磷酸肌醇脂，包括3，4-二磷酸磷脂酰肌醇(PI-3，4-P2)和3，4，5-三磷酸磷脂酰肌醇(PI-3，4，5-P3)等，它们都是位于质膜上的第二信使。PI3K是许多生命活动中关键的信号分子，PI3K介导的信号转导通路调节细胞的分裂、分化、凋亡等活动。 背景：多穴位电针治疗周围性面瘫的机制不明。胶质细胞源性神经营养因子(glial cell-derived neurotrophic factor，GDNF)是促进体外运动神经元存活的最有效因子，PI3K/AKT信号通路在保护受损神经元方面发挥着重要作用。目前暂没有GDNF/PI3K/AKT通路参与电针促进兔周围面神经再生的研究。 目的：观察电针对周围面神经压榨损伤后再生的影响，并从GDNF/PI3K/AKT介导的信号通路角度探讨电针对面神经元的保护机制。 方法：成年健康新西兰大白兔由西南医科大学动物实验中心提供，随机分成正常组和模型组。模型组制备右侧面神经颊支压榨性损伤的病理模型，造模成功后随机分为模型对照组和电针组，模型对照组自然康复，电针组取右侧翳风、颊车、四白、地仓、阳白、颧髎穴位进行电针治疗，1次/d，每次30 min。观察动物面瘫症状的改善情况并进行评分；正常组直接取材，模型组分别于术后 1，4，7，14，28 d取含面神经元的脑桥组织，进行苏木精-伊红染色观察神经元形态，尼氏染色观察尼氏小体，免疫组化测定GDNF的阳性表达，Western blotting检测3组各时间点面神经元组织中GDNF、PI3K、AKT、P-AKT的蛋白表达。实验方案经西南医科大学动物伦理学委员会批准，批准号为20170120001。 结果与结论：①与模型对照组相比，电针组动物的面瘫症状(患侧口角歪斜下垂，触须倒伏且运动减弱，眼睑上抬不能)恢复较快且完全；②电针组面神经元形态学改变、尼氏体变化均较模型对照组病理变化轻；③术后各时间点，面神经元GDNF免疫反应较强，阳性细胞数多于模型对照组(除术后1 d，其余各时间点P < 0.001)，且面神经元组织中GDNF、PI3K和P-AKT蛋白表达明显增高(P < 0.05/0.01/0.001)。提示：电针可有效治疗由压榨面神经颊支引起的周围性面瘫，促进面神经元形态恢复，其面神经元保护机制可能与上调GDNF在面神经元中的表达，激活PI3K/AKT信号通路有关。 ORCID: 0000-0002-9531-7400(李雷激) 中国组织工程研究杂志出版内容重点：干细胞；骨髓干细胞；造血干细胞；脂肪干细胞；肿瘤干细胞；胚胎干细胞；脐带脐血干细胞；干细胞诱导；干细胞分化；组织工程