缺血缺氧对体外培养星形胶质细胞细胞周期和周期相关蛋白的影响

目的 观察缺血缺氧损伤对星形胶质细胞细胞周期及细胞周期相关蛋白的影响。方法 用流式细胞仪及Brdu掺入法检测缺血缺氧后不同时间点星形胶质细胞细胞周期变化和细胞的增殖活力；用荧光免疫细胞化学技术测定增殖细胞核抗原(PCNA)及细胞周期蛋白cyclin D1的表达水平。结果 体外缺血缺氧损伤后S期星形胶质细胞较正常组明显增加，6h达高峰，Brdu掺入法显示损伤后6h星形胶质细胞的增殖活力最高，而随后S期细胞数目及细胞增殖活力都呈下降趋势。PCNA阳性反应损伤后表达增加，6h表达最高，而cyclin D1的表达在损伤后逐渐增加，在24h时达高峰。结论 缺血缺氧损伤激活星形胶质细胞，使其进入新的细胞周期，出现细胞的增殖反应；PCNA及cyclin D1参与了损伤后星形胶质细胞的修复和增殖；细胞周期事件与星形胶质细胞的增殖活化密切相关。     

沉默Cdk5对星形胶质细胞活化增殖和细胞周期的影响

目的 观察沉默细胞周期蛋白依赖性激酶5(Cdk5)对星形胶质细胞活化增殖和细胞周期的影响。方法 培养及鉴定SD大鼠星形胶质细胞,设计合成针对星形胶质细胞Cdk5的小干扰RNA(siRNA),将Cdk5 siRNA转染入星形胶质细胞,通过Real-time PCR和Western blot检测沉默效率; 分为对照组及Cdk5 siRNA干预组,在不同时间点(3、6、12及24 h)采用Edu染色及流式细胞术检测细胞增殖及细胞周期情况。结果 成功利用Cdk5 siRNA沉默星形胶质细胞Cdk5; Edu染色显示Cdk5 siRNA干预组干预3、6、12 h Edu染色阳性率较对照组显著降低(P<0.01); 流式细胞术显示 Cdk5 siRNA干预组干预3、6、12 h处于S期的星形胶质细胞比例较对照组显著降低(P<0.05)。结论 沉默Cdk5可抑制星形胶质细胞的增殖及细胞周期进展,提示Cdk5在星形胶质细胞增殖过程中起到重要作用。     

缺血缺氧对体外培养星形胶质细胞细胞周期和增殖的影响

目的 观察缺血缺氧损伤对星形胶质细胞细胞周期和增殖的影响。方法 用流式细胞仪检测缺血缺氧后不同时问点星形胶质细胞细胞周期变化，并用荧光免疫细胞化学技术测定胶质细胞纤维酸性蛋白(GFAP)和增殖细胞核抗原(PCNA)的表达水平。结果 体外缺血缺氧损伤后星形胶质细胞S期较正常组明显增高，6h达高峰，而随后则呈下降趋势。PCNA阳性反应损伤后表达均增加，6h表达最高；在缺血缺氧早期，GFAP阳性染色增强，6h最高；缺血缺氧12h后GFAP阳性染色变弱。结论 缺血缺氧损伤后星形胶质细胞活化进入增殖期；PCNA参与了损伤后星形胶质细胞的修复和增殖；细胞周期事件与星形胶质细胞的活化密切相关。     

NPPB对星形胶质细胞增殖的抑制作用

目的观察体积调节性阴离子通道阻滞剂NPPB对体外培养星形胶质细胞增殖的影响。方法采用原代培养的大鼠大脑皮层星形胶质细胞,实验分为对照组(正常培养基培养)与NPPB干预组;在不同时间点(0、6、12、24、48h),应用流式细胞技术以及免疫细胞荧光双标法(Brdu/DAPI)检测各实验组星形胶质细胞增殖及细胞周期进展的情况。结果与对照组相比,NPPB干预组在12、24h时星形胶质细胞增殖率较正常对照组降低(P<0.05),同时处于S期细胞的百分率亦相对正常对照组明显下降(P<0.01)。结论体积调节性氯离子通道阻滞剂NPPB可以显著抑制体外培养星形胶质细胞增殖及细胞周期进展,提示VRAC通道参与了体外培养星形胶质细胞的增殖。     

活化小胶质细胞对PC12细胞中CREB激活程度影响的研究

目的探讨小胶质细胞活化后是否影响神经细胞（PC12细胞）中cAMP反应蛋白元件结合蛋白（CREB）的活化程度。方法原代细胞培养法培养小胶质细胞。传代培养PC12细胞．IFN-1激活小胶质细胞后利用转移筛网使其与PC12细胞共育，经不同时间段（15min、2h、24h）共育后Westernblot检测PC12细胞的总CREB和磷酸化CREB，考察CREB活化程度。结果激活小胶质细胞与PC12细胞共育后15min。即有CREB活化程度的显著增高．同PC12细胞组相比差异显著（P〈0．05），此后随时间延长其活化程度逐渐下降，2h时已无统计学差异，24h时甚至略低于PC12细胞组。结论激活小胶质细胞能够在短时间内迅速一过性提高神经细胞中活化CREB含量，为增强神经细胞抗损伤能力奠定基础。     

外周炎症性疼痛刺激诱发中枢神经系统小胶质细胞增殖活化

目的 观察外周疼痛刺激后,中枢神经系统小胶质细胞形态和功能特征的变化,方法 采用福尔马林疼痛动物模型,刺激后2、4、8h,1,3d,1,2及4周后处死,制成腰脊髓和脑干切片。小胶质细胞特异表达补体C3受体（单克隆抗体OX－42）,活化型小胶质细胞表达Ⅱ类主要组织相容性复合物Ia(单克隆抗体OX－6）,定性和定量的免疫组化方法显示中枢小胶质细胞及疼痛刺激下形态的转化。结果 福尔马林刺激侧腰脊髓后角和脑干薄束核内小胶质细胞的增殖活化,注射后1d开始出现,3d后明显,1周达到高峰,2周后增殖活化反应开始消退。本研究增殖活化的小胶质细胞表现为激活型,而非活化型或吞噬型。结论 福尔马林注射引起的疼痛刺激或外周炎症反应可能诱发中枢小胶质细胞增殖活化。小胶质细胞的增殖活化可能是慢性疼痛长期持续的原因之一。     

重组人粒细胞集落刺激因子对实验性脑出血大鼠星形胶质细胞表达的影响

背景：星形胶质细胞是中枢神经系统的主要成分之一,具有对各种损伤产生强烈反应的特性,脑出血后星形胶质细胞大量表达、活性增强,这种由常态转变为反应性状态的星形胶质细胞的病理生理学意义是目前研究热点。 目的:探讨重组人粒细胞集落刺激因子对脑出血后星形胶质细胞表达的影响。 设计、时间及地点：随机对照动物实验,于2006-03/11在泸州医学院中心实验室完成。 材料：清洁级健康雄性SD大鼠50只,随机分为3组：假手术组10只、模型组20只、实验组20只。重组人粒细胞集落刺激因子为深圳新鹏生物工程有限公司产品。 方法：模型组、实验组利用鼠脑立体定向仪、采用断尾取自体血法制备脑出血动物模型,假手术组用等量生理盐水代替自体血,余干预措施与模型组一致。造模1 h后,实验组大鼠腹腔注射重组人粒细胞集落刺激因子 60 μg/kg,余2组未注射任何物质。 主要观察指标：分别于干预后6 h,24 h,48 h,72 h,7 d采用免疫组织化学ABC法检测胶质纤维酸性蛋白阳性细胞的表达。 结果：假手术组未见胶质纤维酸性蛋白阳性细胞的表达。模型组干预6 h即有少量胶质纤维酸性蛋白阳性细胞表达,48 h后开始增多,至72 h胶质纤维酸性蛋白阳性细胞数量达高峰(P < 0.05),7 d后仍有大量胶质纤维酸性蛋白阳性细胞表达,但较72 h时有所减少。实验组干预6 h时胶质纤维酸性蛋白阳性细胞的表达与模型组相似,干预24 h,48 h,72 h,7 d时胶质纤维酸性蛋白阳性细胞较模型组明显减少( P < 0.05),细胞变形程度减轻。 结论：重组人粒细胞集落刺激因子能够抑制脑出血后星形胶质细胞的过度活化,可能对损伤脑组织重建和功能恢复起重要作用。     

大鼠坐骨神经切断后腰脊髓腹角内胶质细胞和神经元的可塑性变化

目的：探讨大鼠单侧坐骨神经切断后腰脊髓腹角胶质细胞和运动神经元的反应及其相互关系。方法：用免疫组织化学技术、HE染色和Tunnel法，观察坐骨神经切断后1，6，12，24h及3，7和14d腰脊髓腹角胶质原纤维酸性蛋白(GFAP)标记的星形胶质细胞、OX-42标记的小胶质细胞及运动神经元的变化。结果：坐骨神经切断侧腰脊髓腹角可见星形胶质细胞和小胶质细胞活化，星形胶质细胞的活化早于小胶质细胞；后期运动神经元发生凋亡，HE染色显示凋亡细胞周围为反应性OX-42阳性小胶质细胞和GFAP阳性星形胶质细胞包绕。结论：研究结果提示，坐骨神经切断后切断侧腰脊髓腹角活化的胶质细胞与凋亡的运动神经元之间关系密切。     

ROCK抑制剂Y27632对小胶质细胞活化增殖和细胞周期的影响

目的观察ROCK抑制剂Y27632对小胶质细胞活化增殖和细胞周期的影响。方法采用小胶质细胞系BV2细胞复苏后传代培养,分为对照组和Y27632干预组;在不同时间点(0、3、6、12、和24h),采用brdu标记法和流式细胞术检测各实验组细胞增殖率变化及细胞周期进展情况。结果干预3h后各组的S期细胞率都逐渐增加,但Y27632干预组的S期细胞率较正常组明显增加,6h时达高峰(P<0.01);Brdu掺入法显示干预6h时BV2细胞的增殖活力最高,在各个时间点Y27632干预组的Brdu阳性率都较对照组高,6h时最为显著(P<0.01)。结论 ROCK抑制剂Y27632可促进小胶质细胞系BV2细胞的活化增殖和细胞周期进展,提示Rho/ROCK信号通路在小胶质细胞的增殖过程中起着重要的作用。     

精氨酸加压素对星形胶质细胞凋亡的影响

目的 探讨不同浓度精氨酸加压素(arginine vasopressin,AVP)对原代培养大鼠星形胶质细胞凋亡的影响,以及p38 MAPK途径在该过程中的作用.方法 采用大鼠大脑皮质分离星形胶质细胞,以500 nmol/LAVP处理星形胶质细胞1、6、12、24 h,以及500 nmol/L AVP分别与V1a受体(V1.R)拮抗剂、SB 203580共同处理星形胶质细胞1、6、12、24 h,采用MTT法测定星形胶质细胞存活率变化;以50、100、500 nmol/L AVP对星形胶质细胞分别处理1、6、12、24 h,以及500 nmol/L AVP分别与V1a受体(V1aR)拮抗剂、SB 203580共同处理星形胶质细胞1、6、12、24 h,采用TUNEL法检测星形胶质凋亡情况.结果 以500 nmol/L AVP干预6、12、24 h后,星形胶质细胞存活率下降(P＜0.01),而V1aR拮抗剂、SB 203580与500 nmol/L AVP共同干预星形胶质细胞后,各时间点存活率与对照组比较无统计学差异(P＞0.05).以50、100 nmol/L AVP分别干预1、6、12、24 h未发现星形胶质细胞凋亡数增加(P＞0.05),而500 nmol/L AVP干预6、12、24 h后,星形胶质细胞凋亡细胞增多,24 h达高峰(P＜0.01).V1aR拮抗剂、SB 203580与500 nmol/L AVP共同干预后,各时间点细胞凋亡数未见显著增加(P＞0.05).结论 高浓度AVP能导致星形胶质存活率下降,细胞凋亡增多;V1aR拮抗剂及p38MAPK抑制剂能抑制高浓度AVP诱导的星形胶质细胞凋亡,可能对减轻脑损伤过程中AVP造成的继发损害具有一定作用.     

Optogenetic stimulation of astrocytes in the posterior hypothalamus increases sleep at night in C57BL/6J mice

A distributed network of neurons regulates wake, non‐rapid eye movement (NREM) sleep, and REM sleep. However, there are also glia in the brain, and there is growing evidence that neurons and astroglia communicate intimately to regulate behaviour. To identify the effect of optogenetic stimulation of astrocytes on sleep, the promoter for the astrocyte‐specific cytoskeletal protein, glial fibrillary acidic protein (GFAP) was used to direct the expression of channelrhodopsin‐2 (ChR2) and the linked reporter gene, enhanced yellow fluorescent protein (EYFP), in astrocytes. rAAV‐GFAP‐ChR2 (H134R)‐EYFP or rAAV‐GFAP‐EYFP was microinjected (750 nL) into the posterior hypothalamus (bilateral) of mice. Three weeks later baseline sleep was recorded (0 Hz) and 24 h later optogenetic stimulation applied during the first 6 h of the lights‐off period. Mice with ChR2 were given 5, 10 or 30 Hz stimulation for 6 h (10‐ms pulses; 1 mW; 1 min on 4 min off). At least 36 h elapsed between the stimulation periods (5, 10, 30 Hz) and although 0 Hz was always first, the order of the other three stimulation rates was randomised. In mice with ChR2 (n = 7), 10 Hz, but not 5 or 30 Hz stimulation increased both NREM and REM sleep during the 6‐h period of stimulation. Delta power did not increase. In control mice (no ChR2; n = 5), 10 Hz stimulation had no effect. This study demonstrates that direct stimulation of astrocytes powerfully induces sleep during the active phase of the sleep–wake cycle and underlines the inclusion of astrocytes in network models of sleep–wake regulation.     

Astrocyte proliferation in the chick auditory brainstem following cochlea removal

Astrocytes in the central nervous system (CNS) respond to injury and disease by proliferating and extending processes. The intermediate filament protein of astrocytes, glial fibrillary acidic protein (GFAP) also increases in astrocytes. These cells are called “reactive astrocytes” and are thought to play a role in CNS repair. We have previously demonstrated rapid increases (< 6 hours) in GFAP-immunoreactive and silver-impregnated glial processes in the chick cochlear nucleus, nucleus magnocellularis (NM), following cochlea removal or activity blockade of the eighth nerve. It was not known whether these changes were the result of glial proliferation, glial hypertrophy, or both. The present study examined the time course of astrocyte proliferation in NM following cochlea removal. Postnatal chicks received unilateral cochlea removal and survived for 6, 12, 18, 24, 36, 48, and 72 hours. Bromodeoxyuridine was used to label proliferating cells. The volume and number of labeled cells in NM was calculated for both the experimental and control sides of the brains for experimental animals was well as for unoperated control animals. A subset of astrocytes continuously divide in the normal posthatch chick brainstem. The percentage of labeled nuclei increases within NM 36 hours following cochlea removal and is robust by 48 hours. This increase is due to astrocyte proliferation within, rather than migration to, NM. These resulis indicate that rapid increases in GFAP following reduced activity are independent of cell proliferation. The time course of astrocyte proliferation suggests that cellular degeneration within the nucleus may play a role in upregulating astrocyte proliferation. © 1994 Wiley-Liss, Inc.     

Bidirectional regulation by “star forces”: Ionotropic astrocyte's optical stimulation suppresses synaptic plasticity,metabotropic one strikes back

The role of astrocytes in modulating synaptic plasticity is an important question that until recently was not addressed due to limitations of previously existing technology. In the present study, we took an advantage of optogenetics to specifically activate astrocytes in hippocampal slices in order to study effects on synaptic function. Using the AAV-based delivery strategy, we expressed the ionotropic channelrhodopsin-2 (ChR2) or the metabotropic Gq-coupled Opto-a1AR opsins specifically in hippocampal astrocytes to compare different modalities of astrocyte activation. In electrophysiological experiments, we observed a depression of basal field excitatory postsynaptic potentials (fEPSPs) in the CA1 hippocampal layer following light stimulation of astrocytic ChR2. The ChR2-mediated depression increased under simultaneous light and electrical theta-burst stimulation (TBS). Application of the type 2 purinergic receptor antagonist suramin prevented depression of basal synaptic transmission, and switched the ChR2-dependent depression into potentiation. The GABA_B receptor antagonist, phaclofen, did not prevent the depression of basal fEPSPs, but switched the ChR2-dependent depression into potentiation comparable to the values for TBS in control slices. In contrast, light stimulation of Opto-a1AR expressed in astrocytes led to an increase in basal fEPSPs, as well as a potentiation of synaptic responses to TBS significantly. A specific blocker of the Gq protein downstream target, the phospholipase C, U73122, completely prevented the effects of Opto-a1AR stimulation on basal fEPSPs or Opto + TBS responses. To understand molecular basis for the observed effects, we performed an analysis of gene expression in these slices using quantitative PCR approach. We observed a significant upregulation of “immediate-early” gene expression in hippocampal slices after light activation of Opto-a1AR-expressing astrocytes alone (cRel, Arc, Fos, JunB, and Egr1) or paired with TBS (cRel, Fos, and Egr1). Activation of ChR2-expressing hippocampal astrocytes was insufficient to affect expression of these genes in our experimental conditions. Thus, we concluded that optostimulation of astrocytes with ChR2 and Opto-a1AR optogenetic tools enables bidirectional modulation of synaptic plasticity and gene expression in hippocampus.     

Two types of Na(+)-currents in cultured rat optic nerve astrocytes: changes with time in culture and with age of culture derivation.

Na+ channel expression was studied in cultures of rat optic nerve astrocytes using whole-cell voltage-clamp recordings. Astrocytes from postnatal day 7 rat optic nerve (RON) expressed two distinct types of Na+ currents, which had significantly different h infinity curves. Stellate, GFAP+/A2B5+ astrocytes showed currents with h infinity curve midpoints close to -65 mV, similar to Na+ currents in most neurons. In contrast, flat fibroblast-like GFAP+/A2B5- astrocytes showed Na+ currents with h infinity midpoints around -85 mV, almost 20 mV more hyperpolarized than in neurons or A2B5+ astrocytes. Interestingly, Na+ current expression was maintained in A2B5+ astrocytes but began to decrease in A2B5- astrocytes after 6 days in vitro (DIV) and fell to or below the level of detection (i.e., 1 pA/pF) at 12 DIV. Astrocytes cultured from neonatal rats (P0) are almost exclusively GFAP+/A2B5-. These cells did not display measurable Na+ currents when studied at 2 DIV; however, Na+ current was observed after 5 DIV in A2B5- astrocytes from these neonatal (P0) cultures. These findings were substantiated by immunocytochemical experiments using 7493, an antibody raised against purified rat brain Na+ channels; in P0-derived astrocyte cultures 7493 antibody staining was initially lacking (up to 3 DIV), but it was prominent in cultures after 5 DIV, suggesting that Na+ current expression in RON astrocytes occurs postnatally.     

Prolactin concurrently activates Src-PLD and JAK/Stat signaling pathways to induce proliferation while promoting differentiation in embryonic astrocytes

In normal development, embryonic astrocytes progress through their cell lineage by acquiring differentiation, by apoptosis, and by proliferation. In this study, we show that embryonic astrocytes may maintain and make gains in differentiation as they simultaneously progress through one cell cycle when induced by prolactin (PRL). Prolactin induced the majority of astrocytes to incorporate bromodeoxyuridine (BrdU) with a four-fold increase over controls after 18 h of exposure. Investigating possible mitogenic signaling pathways we show for the first time that prolactin is coupled to a sustained phospholipase D (PLD) activation, with an efficacy similar to the phorbol ester and astrocytic mitogen 12-tetradecanoylphorbol-13-acetate (TPA). Both cyclosporine and suramin abolished this activation. Staurosporine and calphostin C also inhibited the PRL effect by 50%, consistent with involvement of protein kinase C-(PKC)-alpha, the major PKC isoform in astrocytes. Genistein and PP1 blocked the activation indicating additional regulation by cytosolic tyrosine kinases. This profile of PLD activation was suggestive of a PLD I isoform and a mitogenic response. Upon completion of the cell cycle, analysis of glia fibrillary acidic protein (GFAP) and vimentin abundance, and glutamine synthetase (GS) activity showed that astrocytes had gained in expression of differentiation markers. Moreover, the intensity of GFAP immunofluorescence was greater per cell, as was the length of the cell processes. In exploring the signaling for prolactin-induced differentiation we found that prolactin activated the tyrosine kinase Janus kinase (JAK) 2 and significantly stimulated tyrosine, phosphorylation of the prolactin receptor. Stat 1 and 3 were also activated presumably downstream to JAK2 activation. A rapid translocation of the cytosolic Stats over the nucleus was seen in nearly every astrocyte corresponding well with the gains in GFAP per cell. The Stats translocation did not depend on MEK-ERK inhibition by PD98059, inhibition of p38 by 1 microm SB203580, or Src kinase family inhibition by PP1. Our results demonstrate the ability of PRL to concurrently induce activation of PLD, a mitogenic signaling pathway in astrocytes, and prolonged stimulation of Stat1, compatible with the increased GFAP upregulation and cell differentiation. Considered together this data may provide an explanation on the fast gain in both numbers and differentiation in the astrocytic population during development (HD 09402, CRF).     

脂多糖刺激的星形胶质细胞可能通过IL-6介导PC12细胞增殖双重性

目的：研究脂多糖（LPS）刺激的星形胶质细胞（AC）条件培养液（ACM）对PC12细胞生长的影响及其可能的因子。方法：在原代培养的AC中加入不同浓度的LPS作用24h，收集条件培养液，观察ACM对PC12细胞生长的影响，分析AC分泌的细胞因子的变化，研究IL-6中和抗体后处理的ACM对PC12细胞生长的影响。结果：ACM可促进PCI2细胞的增殖，0．1mg·mL^-1 LPS刺激组作用最强。LPS可促进AC分泌IL-6，并呈剂量依赖性。IL-6中和抗体可阻断这种效应。结论：AC对PC12的生长具有双重性，IL-6可能是关键的因素之一。     

Inhibition of cysteine cathepsin B and L activation in astrocytes contributes to neuroprotection against cerebral ischemia via blocking the tBid‐mitochondrial apoptotic signaling pathway

The roles of cathepsins in the ischemic astrocytic injury remain unclear. Here, we test the hypothesis that activation of cathepsin B and L contributes to the ischemic astrocyte injury via the tBid‐mitochondrial apoptotic signaling pathways. In the rat models of pMCAO, CA‐074Me or Clik148, a selective inhibitor of cathepsin B or cathepsin L, reduced the infarct volume, improved the neurological deficits and increased the MAP₂ and GFAP levels. In OGD‐induced astrocyte injury, CA‐074Me or Clik148 decreased the LDH leakage and increased the GFAP levels. In the ischemic cortex or OGD‐induced astrocytes injury, Clik148 or CA‐074Me reversed pMCAO or OGD‐induced increase in active cathepsin L or cathepsin B at 3 h or 6 h, increase in tBid, reduction in mitochondrial cytochrome‐c (Cyt‐c) and increase in cytoplastic Cyt‐c and active caspase‐3 at 12–24 h of the late stage of pMCAO or OGD. CA‐074Me or Clik148 also reduced cytosolic and mitochondrial tBid, increased mitochondrial Cyt‐c and decreased cytoplastic Cyt‐c and active caspase‐3 at 6 h of the early stage of Bid activation. CA‐074Me or Clik148 blocked the pMCAO‐induced release of cathepsin B or L from the lysosomes into the cytoplasm and activation of caspase‐3 in ischemic astrocytes at 12 h after ischemia. Concurrent inhibition of cathepsin B and cathepsin L provided better protection on the OGD‐induced astrocytic apoptosis than obtained with separate use of each inhibitor. These results suggest that inhibition of the cysteine cathepsin B and cathepsin L activation in ischemic astrocytes contributes to neuroprotection via blocking the tBid‐mitochondrial apoptotic signaling pathway. GLIA 2014;62:855–880     

Secretion of tenascin-C by cultured astrocytes: regulation of cell proliferation and process elongation

Tenascin-C (TNC), an extracellular matrix glycoprotein, is involved in tissue morphogenesis like embryogenesis, wound healing or tumorigenesis. Quiescent astroglia in long-term primary cultures are known to show rapid morphological changes after subculture and serum deprivation/re-addition (SSDR). To elucidate roles of TNC in the morphogenetic processes of cultured astrocytes, we have revealed morphological changes in association with soluble TNC contents in the medium and expression of TNC mRNA, TNC, glial fibrillary acidic protein (GFAP) and integrin β1, one of its cell surface receptors, in glial cells after SSDR. Soluble TNC in the medium rapidly increased in amount at 4 h when GFAP-positive cells expressed TNC mRNA, TNC and integrin β1. Cellular proliferation and growth occurred in colonies expressing TNC mRNA, TNC and integrin β1 during the first 24 h. During the next 24 h, process elongation and cell migration occurred in association with increased GFAP expression and re-elevation of soluble TNC in the medium. Cell bodies became flat and larger with increased GFAP and reduced TNC expression at 72 h, while cultures became confluent with reduced GFAP and TNC expression at 96 h after SSDR. Functional blocking with anti-TNC antibody reduced cell proliferation and induced morphological change from a process-bearing slender shape to a flat and wide shape presumably due to increased cell adhesion.

These findings strongly support the idea that endogenous TNC produced and released by astrocytes in response to serum stimulation induces their proliferation and process elongation through a paracrine/autocrine mechanism.     

Chemical stimulation of the ST36 acupoint reduces both formalin-induced nociceptive behaviors and spinal astrocyte activation via spinal alpha-2 adrenoceptors

Spinal astrocytes have emerged as important mechanistic contributors to pathological and chronic pain. Recently, we have demonstrated that injection of diluted bee venom (DBV) into the Zusanli (ST36) acupoint produces a potent anti-nociceptive effect via the activation of spinal alpha-2 adrenoceptors. However, it is unclear if this anti-nociceptive effect is associated with alterations in spinal astrocytes. Thus, the present study was designed to determine: (1) whether DBV's anti-nociceptive effect in the formalin test involves suppression of spinal astrocyte activation; (2) whether DBV-induced astrocyte inhibition is mediated by spinal alpha-2 adrenoceptors; and (3) whether this glial modulation is potentiated by intrathecal administration of the glial metabolic inhibitor, fluorocitrate (FC) in combination with DBV injection. DBV was injected directly into the ST36 acupoint, and spinal expression of the astrocytic marker, glial fibrillary acidic protein (GFAP), was assessed together with effects on formalin-induced nociception. DBV treatment reduced pain responses in the late phase of the formalin test and significantly blocked the formalin-evoked increase in spinal GFAP expression. These effects of DBV were prevented by intrathecal pretreatment with selective alpha-2A and alpha-2C adrenoceptor antagonists. Moreover, low dose intrathecal injection of FC in conjunction with low dose DBV injection into the ST36 acupoint synergistically suppressed pain responses and GFAP expression. These results demonstrate that DBV stimulation of the ST36 acupoint inhibits the formalin-induced activation of spinal astrocytes and nociceptive behaviors in this inflammatory pain model and this inhibition is associated with the activation of spinal alpha-2 adrenoceptors.