PPARs激动剂罗格列酮对大鼠癫痫持续状态海马神经元的保护作用

目的探讨罗格列酮(RSG)对大鼠癫痫持续状态(SE)后海马神经元凋亡的影响及其可能作用机制。方法采用免疫组化法对氯化锂-匹罗卡品诱发癫痫大鼠模型脑内Bcl-2、Bax及TUNEL阳性细胞的表达进行测定,并研究RSG对癫痫影响及可能机制。结果模型组(M组)海马区TUNEL、Bcl-2、Bax较对照组(N组)明显增多(P0.05);RSG组Bax、TUNEL较M组明显减少(P0.05),Bcl-2阳性细胞、Bcl-2/Bax比率较M组明显增多(P0.05)。结论SE后脑内TUNEL、Bcl-2、Bax表达明显增加;RSG能够减轻海马TUNEL、Bax的表达,增加海马Bcl-2的表达从而增加Bcl-2/Bax比率。RSG可能具有减轻癫痫发作和保护神经元的作用。     

Absence of age-related changes in nigral dopaminergic neurons of Asian Indians: Relevance to lower incidence of Parkinson's disease

Age-related loss of melanized nigral neurons reported in the British Caucasians is not observed in Asian Indian, American and French adults. In the Americans, loss of dopaminergic phenotype occurs from midlife, without frank neurodegeneration. Here, we investigated whether nigral dopaminergic neurons in Asian Indians are lost with age or undergo morphological or biochemical dysfunction. Using unbiased stereology we estimated volume, number of melanized, borderline/non-melanized (n=34, 28 gestational weeks to 80 years) and tyrosine hydroxylase (TH)–Nurr1 co-labeled neurons (n=32, 28 gestational weeks to 80 years) in substantia nigra pars compacta. We quantified Nurr1 and TH proteins by immunoblotting (n=18, 28 gestational weeks to 69 years) and apoptotic neurons by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) staining. Nuclear and soma size was estimated by morphometry. There was no age-related decline in volume, neuronal density, neuronal numbers and TH-Nurr1 co-labeled neurons. TH and Nurr1 protein expression remained stable. Lack of TUNEL-TH co-labeled cells confirmed absence of neuronal apoptosis. The neuronal size remained unaltered. Our findings of preserved nigral dopaminergic neurons suggest no age-related loss of nigral function in Asian Indians, unlike the Americans. This may explain the lower incidence of Parkinson's disease in Asian Indians.     

Lack of Teratogenicity of 3-Chloro-4-(Dichloromethyl)-5-Hydroxy-2 (5H)-Furanone (MX) in Embryonic Mouse Palate Culture in vitro

3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5 H )-furanone (MX) is known as a by-product of wood pulp manufacture and a contaminant of chlorinated drinking water. Since our previous studies (Teramoto et al., 1998, 1999) demonstrated in a micromass in vitro test a strong inhibitory effect of MX on rat embryo cell differentiation, the potential teratogenicity was investigated in this study by using a suspension organ culture system. Twelve-day mouse embryo palatal explants were cultivated for 72 hr in the MX-containing medium at a concentration of 0, 1, 10, 100 or 300 μg/ml and examined for closure of the palatal shelves. All control explants showed almost complete closure of the palatal shelves. Similar results were also obtained in the MX-treated explants at concentrations up to and including 100 μg/ml. Immunohistochemistry revealed no difference between the control and MX-treated explants in distribution of PCNA-and TUNEL-positive cells in the palatal mesenchyme and medial edge epithelium, respectively. When the MX concentration was raised to 300 μg/ml, palatal shelves remained wide open. However, histopathology revealed extensive pyknosis of the mesenchymal cells and loss of the epithelium. These results may indicate that MX is cytotoxic against the mouse palate at a high concentration, and that it has no cleft-palate inducing effects in mice.     

EGCG inhibits activation of the insulin-like growth factor (IGF)/IGF-1 receptor axis in human hepatocellular carcinoma cells

The receptor tyrosine kinase (RTK) insulin like growth factor-1 (IGF-1)/IGF-1 receptor (IGF-1R) axis plays an important role in the development of hepatocellular carcinoma (HCC). EGCG inhibits activation of the various types of RTKs and that this is associated with inhibition of multiple downstream signaling pathways. In this study we examined the effects of EGCG on activity of the IGF/IGF-1R axis in HepG2 human HCC cells which express constitutive activation of this axis. The level of phosphorylated (i.e. activated) form of the IGF-1R protein (p-IGF-1R) was increased in a series of human HCC cell lines when compared with the Hc normal human hepatocytes. EGCG preferentially inhibited growth of HepG2 cells when compared with Hc cells. Treatment of HepG2 cells with EGCG induced apoptosis and caused a decrease in the p-IGF-1R protein and its downstream signaling molecules including the p-ERK, p-Akt, p-Stat-3, and p-GSK-3β proteins, both in the absence or presence of ligand stimulation. EGCG also decreased the levels of both IGF-1 and IGF-2 proteins and mRNAs, but increased the levels of the IGFBP-3 protein. These findings suggest that EGCG can overcome the stimulatory effects of IGFs on the IGF-1R dependent signaling pathway, thus expanding the roles of EGCG as an inhibitor of critical RTKs involved in HCC cell proliferation. These results provide further evidence that EGCG may be useful in the chemoprevention or treatment of liver cancer.     

Chronic cerebral hypoperfusion induces white matter lesions and loss of oligodendroglia with DNA fragmentation in the rat

Cerebrovascular white matter lesions represent an age-related neurodegenerative condition that appears as a hyperintense signal on magnetic resonance images. These lesions are frequently observed in aging, hypertension and cerebrovascular disease, and are responsible for cognitive decline and gait disorders in the elderly population. In humans, cerebrovascular white matter lesions are accompanied by apoptosis of oligodendroglia, and have been thought to be caused by chronic cerebral ischemia. In the present study, we tested whether chronic cerebral hypoperfusion induces white matter lesions and apoptosis of oligodendroglia in the rat. Doppler flow meter analysis revealed an immediate reduction of cerebral blood flow ranging from 30% to 40% of that before operation; this remained at 52–64% between 7 and 30 days after operation. Transferrin-immunoreactive oligodendroglia decreased in number and the myelin became degenerated in the medial corpus callosum at 7 days and thereafter. Using the TUNEL method, the number of cells showing DNA fragmentation increased three- to eightfold between 3 and 30 days post-surgery compared to sham-operated animals. Double labeling with TUNEL and immunohistochemistry for markers of either astroglia or oligodendroglia showed that DNA fragmentation occurred in both of these glia. Messenger RNA for caspase-3 increased approximately twofold versus the sham-operated rats between 1 and 30 days post-surgery. Immunohistochemistry revealed up-regulation of caspase-3 in the oligodendroglia of the white matter, and also in the astroglia and neurons of the gray matter. Molecules involved in apoptotic signaling such as TNF- and Bax were also up-regulated in glial cells. These results indicate that chronic cerebral hypoperfusion induces white matter degeneration in association with DNA fragmentation in oligodendroglia.     

Trans-neuronal regulation of cortical apoptosis in the adult rat olfactory system

Previous work has identified a population of neurons within the anterior piriform cortex that undergo rapid apoptosis following de-afferentation by olfactory bulbectomy in adult rats. The specific initiation signal for apoptosis in this paradigm is unknown, but may include an activity-dependent trans-neuronal cascade. The present report examined the effect of adult-onset unilateral naris occlusion, which reduces olfactory bulb afferent excitation of piriform cortex, on apoptosis (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling [TUNEL]) in the rat anterior piriform cortex. Adult Long-Evans hooded rats received unilateral naris occlusion or a control manipulation and were sacrificed after 1, 5, 7, 10 or 20 days later. For comparison, a second group of rats received a unilateral bulbectomy and were sacrificed 24 h later. Counts of TUNEL-stained cell profiles were performed for layers I/II and layer III of the anterior piriform cortex ipsilateral and contralateral to the manipulation. The results confirmed that unilateral bulbectomy produced a dramatic increase in TUNEL labeling in layers I/II of the ipsilateral piriform cortex 24 h after bulbectomy. Unilateral naris closure also produced enhanced TUNEL labeling, although the magnitude of the effect was less than that produced by bulbectomy, and enhanced TUNEL labeling was apparent both ipsilateral and contralateral to the sealed naris compared to controls. Deprivation-induced TUNEL labeling was detectable by 24 h post-closure, peaked at 5 days and was no different from controls by 20 days post-closure. Neither bulbectomy nor naris closure affected TUNEL labeling in layer III. Together, these results suggest that there is a population of superficial cells in piriform cortex whose survival is tightly regulated by sensory input.     

金雀异黄素对人乳癌细胞MCF-7增殖和凋亡的影响

目的：采用离体细胞培养的方法，研究大豆异黄酮的主要成分金雀异黄素(GEN)对人乳腺癌MCF-7细胞的增殖抑制作用及其作用机理。方法：MCF-7细胞接受不同浓度的GEN处理，MTT比色法测定GEN抑制MCF-7细胞的量效关系；细胞分裂指数试验用于评价GEN对该细胞的恶性增殖的抑制作用；细胞形态学观察及原位细胞凋亡检测法(TUNEL)用于检测细胞凋亡。结果：GEN的IC30与IC50分别为17．5μmol／L及32．0μmol／L，GEN对MCF-7具有明显的抑制作用，且该抑制作用呈剂量反应关系；各剂量GEN均可抑制MCF-7细胞分裂并且呈剂效关系；细胞形态学观察及TUNEL检测发现GEN处理48h及96h后有明显的凋亡细胞出现，并呈现剂效关系，而本次实验未发现其时效关系。结论：GEN可抑制离体培养MCF-7细胞的增殖，其作用机理可能与GEN诱导细胞凋亡的途径有关。     

耳蜗半薄切片细胞凋亡检测

目的尝试在耳蜗半薄切片上用TUNEL方法检测耳蜗组织的细胞凋亡.方法基因敲除Smad5小鼠耳蜗,分别作常规石蜡切片和环氧树脂包埋的半薄切片,用TUNEL方法检测耳蜗组织的细胞凋亡.结果在半薄切片上Smad5基因敲除小鼠,耳蜗内有大量的凋亡细胞产生,主要集中在螺旋神经节细胞、血管纹上的细胞,以及基底膜上的间皮细胞等,而且能够更清楚的显示凋亡的毛细胞.而在石蜡切片上只在螺旋神经节细胞、血管纹上的细胞,以及基底膜上的间皮细胞检出凋亡细胞,但是毛细胞没有凋亡细胞的检出.结论用TUNEL方法检测耳蜗组织的细胞凋亡半薄切片明显好于石蜡切片.     

曲安奈德对培养的人视网膜色素上皮细胞的毒性作用

目的探讨曲安奈德(triamcinolone acetonide,TA)对视网膜色素上皮细胞可能潜在的毒性作用。方法质量浓度0mg·L-1、10mg·L-1、30mg·L-1、300mg·L-1TA分别作用ARPE19细胞24h和72h后通过TUNEL和电镜观察2种方法从形态和功能方面观察TA对ARPE19细胞生长的影响。结果(1)TUNEL法:质量浓度10mg·L-1TA不影响ARPE19细胞的生长,但是随着质量浓度增大,细胞凋亡程度逐渐增强(t=2.921,P<0.01),随着时间延长,ARPE19细胞的凋亡指数逐渐增大(t=2.306,P<0.01);(2)电镜:质量浓度10mg·L-1TA作用后ARPE19细胞状态良好,但是随着质量浓度增加,细胞走向凋亡的形态越明显,微绒毛消失,核染色质边集,凋亡小体形成。结论一定浓度的TA能够诱导视网膜色素上皮细胞的凋亡,而且这种凋亡效应呈浓度和时间依赖关系。因此,TA对视网膜色素上皮细胞可能有潜在毒性。