Effect of CNTF on low-affinity NGF receptor expression by cultured neurons from different rat brain regions.

Our previous work indicated that in E14 embryonic rat spinal cord cultures ciliary neuronotrophic factor (CNTF) exerted (1) a survival-promoting effect on motor neurons and on a large population of unidentified neurons, and (2) a regulatory role on the expression of ChAT and low affinity NGF receptor (LNGFR) in a population of small/medium-sized neurons. In the present study, we examined the effect of CNTF on the expression of LNGFR in cultures of different regions from the E18 embryonic rat brain, namely cortex, septum, striatum, mesencephalon, hippocampus, brainstem, and cerebellum. The number of LNGFR-positive neurons (stained with the 192-IgG monoclonal antibody) was determined in untreated cultures and in cultures treated for 6 days (0-6) with human recombinant CNTF. To distinguish between effects on survival and on LNGFR expression, experiments were performed in which CNTF was administered only for the last 48 h of the culture (from days 4-6). LNGFR positive neurons were found in the cultures of all the regions examined. In each one of them, CNTF increased the number of LNGFR-positive neurons by three- to fourfold after 6 days of treatment. In the striatum, septum, mesencephalon, and cerebellum, the effect of CNTF was shown to be on the regulation of LNGFR expression and not on survival. In cultures from the cortex, hippocampus and brainstem, a survival-promoting role of CNTF could be demonstrated. The effect of CNTF was dose dependent, with half-maximal effects (ED50) achieved at 2-4.5 TU/ml for all the brain regions. Maximal effects were reached at 100-250 TU/ml. From these results, we conclude that (1) there exists a wide spectrum of CNTF-responsive neurons in the central nervous system, and (2) CNTF plays an important and widespread role in regulating the expression of the LNGFR in neurons.     

Effects of ciliary neurotrophic factor on excitotoxicity and calcium-ionophore A23187-induced cell death in cultured embryonic striatal neurons

Ciliary neurotrophic factor (CNTF) has a protective effect on the striatum in animal models of Huntington's disease. However, the mechanism through which it exerts its effect is not clear. In this study, we show that there is a concentration-dependent direct protective effect of CNTF against N-methyl-D-aspartate-mediated excitotoxicity on striatal neurons in vitro. The CNTF has to be added more than half an hour before the insult for the effect to occur and its effect is eliminated by the presence of the protein synthesis inhibitor cycloheximide. This suggests that the protective mechanism of CNTF does not involve acute interference with the glutamate receptors, but probably requires gene/protein expression. We have also shown that the effect of CNTF against glutamate-induced excitotoxicity is dependent on the concentration of glutamate with a protective effect more evident at a low grade excitotoxic insult. Finally, we saw no effect of CNTF on calcium ionophore A23187-induced toxicity in striatal cultures, indicating that the growth factor does not promote survival by enhancing general defenses against raised intracellular levels of calcium.     

Differential regulation of ciliary neurotrophic factor and its receptor in the rat hippocampus following transient global ischemia

To investigate a potential role of ciliary neurotrophic factor (CNTF) in transient global ischemia, we have studied the postischemic regulatory changes in the expression of CNTF and its receptor, the ligand-binding alpha-subunit (CNTFRalpha). Immunoblot analysis demonstrated CNTF levels were slightly upregulated already during the first day after ischemia and then increased markedly by more than 10-fold until 2 weeks postischemia. Immunoreactivity for CNTF became detectable 1 day after ischemia and was localized in reactive astrocytes. The intensity of the immunolabeling was maximal in CA1 during the phase of neuronal cell death (days 3-7 postischemia) and in the deafferented inner molecular layer of the dentate gyrus. Upregulation of CNTF expression was less pronounced in CA3 and absent in the stratum lacunosum moleculare and the outer molecular layer of the dentate gyrus and thus did not simply correlate with astroliosis as represented by upregulation of glial fibrillary acidic protein (GFAP). As shown by in situ hybridization, expression of CNTFRalpha mRNA was restricted to neurons of the pyramidal cell and granule cell layers in control animals. Following ischemia, reactive astrocytes, identified by double labeling with antibodies to GFAP, transiently expressed CNTFRalpha mRNA with a maximum around postischemic day 3. This astrocytic response was most pronounced in CA1 and in the hilar part of CA3. These results show that CNTF and its receptor are differentially regulated in activated astrocytes of the postischemic hippocampus, indicating that they are involved in the regulation of astrocytic responses and the neuronal reorganizations occurring after an ischemic insult.     

2型糖尿病患者血清睫状神经营养因子水平的变化及其临床意义

目的 探讨血清睫状神经营养因子（CNTF）水平与T2DM及肥胖的相关性与临床意义.方法 选择44名糖耐量正常（NGT组）者和44例新诊断T2 DM（T2 DM组）患者按BMI各自分为超重（Ob）和正常体重（Nob）亚组.ELISA法测定血清CNTF水平.结果 T2DM组血清CNTF的浓度较NGT组降低（P＜0.05）.相关分析显示,T2DM组中CNTF与TC、HbA1c、FPG、HOMA-IR呈负相关.HOMA-IR是血清CNTF的独立相关因素.结论 T2DM患者CNTF水平降低,与TC、HbA1c、FPG、HOMA-IR呈负相关,HOMA-IR是CNTF.独立相关因素.     

大鼠脑血肿周围组织STAT 3的表达、细胞凋亡的变化与CNTF的影响

目的 观察大鼠脑血肿周围组织STAT3, Bcl-2, Caspase-3的表达情况,并探讨睫状神经营养因子(CNTF)对出血性脑卒中的治疗作用及其可能机制.方法 实验大鼠随机分为假手术组、模型组、CNTF治疗组,采用自体股动脉血注入大鼠尾壳核建立脑出血模型,CNTF治疗组于术后经尾静脉注射CNTF.分别于术后12h、24h、3d、5d 4个时间点取脑组织,应用免疫组化方法检测血肿周围组织STAT3, Bcl-2, caspase-3的表达情况.结果 CNTF治疗组大鼠脑血肿周围组织STAT3, Bcl-2的表达明显高于其他组,Caspase-3的表达水平比模型组低.结论 CNTF对脑出血后损伤神经细胞具有保护作用,其可能的机制为通过上调STAT3的表达,使Bcl-2的表达升高,从而减少出血灶周围细胞的凋亡.     

CNTF和Ad-BDNF对视神经夹伤后视网膜神经节细胞存活的影响

目的:观察大鼠视神经夹伤后玻璃体腔内注射睫状神经营养因子(CNTF)和腺病毒介导脑源性神经营养因子(Ad-BDNF)对视神经损伤后视网膜神经节细胞(RGC)存活的影响。方法:制作大鼠视神经定量夹伤模型,玻璃体腔内注射CNTF和Ad-BDNF,经上丘荧光金(FG)逆行标记RGC,计数视网膜铺片上的RGC并行统计学分析。结果:正常SD大鼠视网膜上RGC密度为2155±265个/mm2(n=12),视神经夹伤后RGC在1~2wk内下降速率最快,到3,4wk时RGC细胞数量虽仍有减少但下降速度已经明显减慢。CNTF组在视神经夹伤后1wk时视网膜RGC数显著高于对照组,但2~4wk的结果和对照组比较差异不明显。Ad-BDNF组视神经夹伤后1~4wk视网膜RGC数均显著高于对照组。结论:CNTF治疗组玻璃体腔内一次性注射CNTF可以在损伤早期2wk内为损伤的RGC提供神经营养因子,减少RGC的早期死亡。Ad-BDNF治疗组的这种保护作用可以持续到损伤后4wk,能够为RGC提供长时间地营养支持,但这种作用比较局限,可能与单一营养因子作用有关。