Bilirubin induces apoptosis and necrosis in human NT2-N neurons

Studies on primary cultures of newborn rodent neurons have suggested that neuronal death induced by unconjugated bilirubin (UCB) is mainly apoptotic in nature. We exposed a human teratocarcinoma-derived cell line, NT2-N neurons, to different concentrations of UCB and albumin at a 1.5 molar ratio and used multiple, independent measures of cell damage to evaluate neuronal injury after 6, 24, and 48 h. Low doses of UCB (0.66, 2, and 5 microM) induced a moderate loss of 3-4[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide (MTT) cleavage accompanied by delayed morphologic changes consistent with apoptosis (2 and 5 microM). Moderate concentrations of UCB (10 and 25 microM) resulted in early (6 h) necrosis in a subset of neurons, while remaining neurons underwent progressive impairment of MTT cleavage and increasing lactate dehydrogenase (LDH) release accompanied by predominantly delayed apoptosis. High concentrations of UCB (100 microM) induced severe impairment of MTT cleavage, extensive LDH release, and morphologic changes consistent with necrosis within 6 h. Used as a positive control for apoptosis, 2 microM STS induced progressive impairment of MTT cleavage and morphologic changes consistent with apoptosis over the entire observation period. DNA electrophoresis at 48 h was compatible with apoptosis both after treatment with STS and UCB concentrations 相似文献   

Reassessment of the unbound concentrations of unconjugated bilirubin in relation to neurotoxicity in vitro

Most studies of the cellular toxicity of unconjugated bilirubin (UCB) have been performed at concentrations of unbound UCB (BF) that exceed those in the plasma of neonates with bilirubin encephalopathy. We assessed whether UCB could be toxic to neurons and astrocytes at clinically relevant BF values (相似文献   

Synergistic protection of a general caspase inhibitor and MK-801 in bilirubin-induced cell death in human NT2-N neurons

Unconjugated bilirubin (UCB) induces both apoptosis and necrosis in neurons. To investigate the role of caspases and excitotoxicity in UCB-induced cell death, we exposed NT2-N neurons to 5 microM UCB (a concentration known to induce apoptosis) or 2 microM staurosporine (positive apoptosis control) and investigated the effects of treatments with the specific caspase-3 inhibitor, zDEVD.FMK (20 and 100 microM), or the general caspase inhibitor, zVAD.FMK (20 and 100 microM), and/or the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 (10 microM) during a 24- or 48-h exposure. UCB increased caspase-3 activity 2.3-fold after 6 h. Despite this, treatment with zDEVD.FMK did not prevent cell death. zVAD.FMK enhanced neuronal survival by reducing apoptotic nuclear fragmentation, while MK-801 enhanced survival by reducing apoptotic nuclear condensation; both without affecting the MTT assays. Combined treatment reduced both apoptotic morphologies (without affecting necrosis), and this effect was also reflected in the MTT assays [corrected] We conclude that NMDA receptor-mediated pathways and caspase-mediated pathways are involved in UCB-induced cell death in human NT2-N neurons. Concomitant inhibition of both pathways results in synergistic protection.     

Aging confers different sensitivity to the neurotoxic properties of unconjugated bilirubin.

The pathogenesis of bilirubin encephalopathy appears to result from accumulation of unconjugated bilirubin (UCB), which, in turn, may cause mitochondrial perturbation, release of intermembrane proteins, and, ultimately, cell death. Aging imparts to cells a different susceptibility to this toxic stimulus, as neonates are particularly vulnerable to the accumulation of UCB in the CNS. In this paper, we further characterize UCB-induced toxicity in isolated neuronal and glial cells according to age in culture. In addition, we investigate sensitivity of mitochondria derived from young and old rats to UCB-induced membrane permeabilization and, finally, evaluate whether age-dependent changes in UCB toxicity are accompanied by alterations in the mitochondrial content of cytochrome c. The results showed that UCB is more toxic to immature neural cells after 4-5 d in culture (p < 0.001), whereas neurons were more sensitive than astrocytes (p < 0.05). In fact, approximately 40% of cells were apoptotic in immature cultures compared with 20% in mature cultures. Unexpectedly, mitochondrial swelling and subsequent efflux of cytochrome c induced by UCB were 2-fold greater in organelles derived from older rats (p < 0.01). In conclusion, UCB toxicity of isolated rat neuronal and glial cells is modulated by age in culture in that immature cells are more susceptible. Mitochondria derived from younger rats are nevertheless more resistant to membrane permeabilization and cytochrome c release induced by UCB. The data indicate that the cells of young animals are relatively resistant to UCB toxicity, through a protective mechanism at the mitochondrial level; however, this is not sufficient to prevent apoptosis of cells in the young animal. Thus, although playing a role, direct mitochondrial injury may not be the sole mechanism of UCB cytotoxicity.     

胰岛素样生长因子-1对新生大鼠神经细胞氧化损伤保护作用的研究

目的 探讨氧化应激状态下,胰岛素样生长因子-1（IGF-1）对新生大鼠神经细胞氧化损伤的保护作用。方法 原代培养新生大鼠大脑皮层神经元、少突胶质细胞及星形胶质细胞,不同浓度H2O2（0~60 μM）诱导氧化应激细胞模型,LDH 法检测各种神经细胞损伤程度,MTT 法检测各种神经细胞活力;不同浓度H2O2（0~80 μM）诱导氧化应激神经元细胞模型,Western blot 检测IGF-1（25 ng/mL）施加前后神经元细胞内Akt 的磷酸化水平。结果 与未经H2O2 处理组相比,不同浓度H2O2 处理细胞24 h 后,大脑皮层神经元、少突胶质细胞及星形胶质细胞损伤程度均有升高、细胞活力均有降低;但神经元变化更为显著,与少突胶质细胞和星形胶质细胞相比,差异有统计学意义（均P2O2 处理大脑皮层神经元5 min 后,相比于未经H2O2 处理组,可见Akt 磷酸化水平呈H2O2 浓度依赖性降低（均P2O2 导致的神经元细胞Akt 磷酸化,与未经H2O2 处理组比较,差异无统计学意义（P>0.05）,但是对高浓度H2O2 导致的Akt 磷酸化作用无明显效果,其磷酸化水平均低于未经H2O2 处理组（均P2O2 处理1 h 后,再加入25 ng/mL 的IGF-1,IGF-1 处理前后Akt 磷酸化水平均已恢复至未经H2O2 处理时的水平（均P>0.05）。结论 大脑皮层神经元对H2O2 诱导的氧化应激损伤较其他神经细胞敏感;IGF-1 对皮层神经元氧化应激损伤具有保护作用。     

Hypoxic injury to developing glial cells: protective effect of high glucose

Hypoxic injury to differentiating glial cells is a critical event in the development of periventricular leukomalacia, the major hypoxic-ischemic lesion of the premature infant. This study has addressed the effects of hypoxia on differentiating glial cells, primarily astrocytes. Primary cultures of dissociated newborn rat brain, which are composed predominantly of differentiating astroglia, were used. Efflux of lactate dehydrogenase, an enzyme enriched in astroglia, was used to quantitate cellular injury. Three major findings are reported. First, differentiating astrocytes were resistant to hypoxic injury for many hours, although by 24 h of hypoxia severe cellular injury (lactate dehydrogenase efflux of 86% of total and morphologic changes) was obvious. Second, increase of glucose in the culture medium from the approximately physiological concentration of 5.6 to 15 mM had a marked protective effect versus hypoxia, i.e. lactate dehydrogenase efflux was totally prevented during 24 h of hypoxia in 15 mM glucose. Third, the protective effect of high glucose appeared to be related to increased utilization by glycolysis, because there was a direct correlation between the resistance to hypoxic cellular injury and the amount of lactate generated and of glucose consumed by the cells. Thus, the cells with the lowest lactate dehydrogenase efflux (and highest glucose supplementations) had medium lactate concentrations as high as 32-36 mM. These concentrations of lactate are approximately double the reported threshold concentration of lactate considered to produce cellular necrosis in in vivo models of hypoxic injury, primarily in mature animals. The data raise the possibility that hypoxic injury to differentiating glia can be prevented or ameliorated by increase in glucose availability.     

Activity of enzymes involved in energy production in the small intestine during suckling-weaning transition of pigs

The effect of weaning on a potential metabolic capacity of key enzymes involved in the energy production by porcine enterocytes was investigated. The activity of citrate synthase, isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, glutamate dehydrogenase, alanine aminotransferase and aspartate aminotransferase was determined in the small intestine epithelium of piglets during suckling-weaning transition. Investigations were performed on 5-week-old (suckling), 6-week-old (1st week after weaning) and 7-week-old (2nd week after weaning) piglets. The activity of glutamate dehydrogenase decreased (p < 0.05) during the 1st week after weaning, and remained numerically lower during the 2nd week after weaning than in suckling piglets. The activities of isocitrate dehydrogenase and alanine aminotransferase showed the same pattern as the glutamate dehydrogenase activity and decreased numerically during the 1st and 2nd weeks. The activities of citrate synthase and alpha-ketoglutarate dehydrogenase were numerically lower in post-weaned piglets (1st and 2nd weeks) than in suckling piglets. In contrast, the activity of aspartate aminotransferase was high and remained unchanged from week 5 to the 2nd week post-weaning. The activities of alanine and aspartate aminotransferase were positively correlated in suckling piglets (r = 0.98, p < 0.05) and at the 1st week after weaning (r = 0.99, p < 0.01). Also, both aminotransferases were positively correlated to the activity of alpha-ketoglutarate dehydrogenase in suckling piglets (r = 0.95, p < 0.05 and r = 0.95, p < 0.05) and to the activity of isocitrate dehydrogenase during the 1st week after weaning (r = 0.99, p < 0.001 and r = 0.99, p < 0.01). The results indicate additional capacity of the tricarboxylic acid (TCA) cycle for transformation of alpha-ketoglutarate from other sources than acetyl-CoA such as glutamine, glutamate and other amino acids. Further, the high activity of aspartate aminotransferase also suggests a high capacity of porcine small intestinal epithelium to provide the TCA cycle with oxaloacetate during the suckling-weaning transition.     

Myocardial carbohydrate, ketone, and fatty acid uptake in conscious lambs with aortopulmonary shunts.

A left to right shunt increases myocardial work and is often accompanied by increased catecholamine levels. Because both increased myocardial work and increased catecholamine levels may induce increased fatty acid utilization, which could increase resting myocardial oxygen consumption and therefore unfavorably affect coronary reserve, we studied myocardial uptake of glucose, pyruvate, lactate, beta-OH-butyrate, acetoacetate, FFA, and triglycerides in 12 7-wk-old lambs with aortopulmonary left to right shunts (58 +/- 2% of left ventricular output, mean +/- SEM) and in 10 control lambs 2 wk after surgery. Despite the shunt, systemic blood flow in the shunt lambs was maintained at the same level as in the control lambs. This was accomplished by an increased heart rate and stroke volume. Furthermore, the shunt was accompanied by an increased myocardial oxygen consumption in the shunt lambs (834 +/- 70 versus 528 +/- 43 mumol O2.min-1 x 100 g-1; p less than 0.05). There were no significant differences in arterial substrate concentrations between the two groups. The same was true for arteriovenous differences across the myocardium, with the exception of lactate, which was substantially higher in shunt than in control lambs (72 +/- 25 versus 18 +/- 23 mumol/L; p less than 0.05). As a consequence, myocardial lactate uptake in the shunt lambs was increased 15-fold (18 +/- 6 versus 1 +/- 2 mumol.min-1 x 100 g-1; p less than 0.02), whereas uptake of the other substrates merely paralleled the increased myocardial blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)     

Late gestation alterations in fetal pulmonary lactate metabolism in vivo

We have previously shown that lactate is produced by the ovine fetal lung. Inasmuch as factors that might affect lactate production, such as pulmonary glucose and oxygen uptake, change late in gestation we investigated whether pulmonary lactate metabolism also changes. Eleven chronically catheterized fetal lambs were studied over 119-141 d gestation. Lactate, glucose, and oxygen concentrations were measured in the pulmonary artery (PA) and vein while lung blood flow was determined using labeled microspheres. Between early studies (less than or equal to 127 d) and studies near term (greater than or equal to 134 d) PA lactate levels did not change, but due to increasing pulmonary blood flow, lung lactate delivery rose 51% (p less than 0.05). Because of a decline in PA glucose, lactate also made up a larger fraction of the major nonnitrogenous substrate in PA blood near term (p less than 0.001). Despite this, no net pulmonary uptake of lactate occurred. Lactate production continued, but decreased by 80% between early and late studies (p less than 0.05) and the maximum fraction of glucose uptake that could be accounted for by lactate production dropped from 0.78 to 0.20 (p less than 0.025). Correlations were found between lung lactate production and glucose uptake also correlated with PA glucose (p less than 0.05). No relationships were observed between lactate production and PA oxygen content, oxygen delivery, lactate concentration, or lactate delivery. The decreasing fraction of glucose uptake explained by lactate production suggests that metabolism of pulmonary glucose is altered near term. The correlation between decreasing glucose delivery and declining lactate production also suggests that glucose itself influences this change.     

星形胶质细胞外泌体对缺氧缺血神经元的保护作用

目的 探索星形胶质细胞外泌体对缺氧缺血神经元的影响。方法 体外培养大鼠星形胶质细胞,通过差速离心法获取细胞上清液中的外泌体。采用透射电镜、Nanosight和Western blot鉴定外泌体;采用BCA法检测外泌体蛋白浓度。体外培养大鼠神经元,分为对照组、外泌体组、氧糖剥夺（OGD）组和OGD+外泌体组（n=3）。OGD组和OGD+外泌体组给予无糖培养基和缺氧处理;外泌体组和OGD+外泌体组分别给予终浓度为22 μg/mL的外泌体处理,对照组和OGD组给予等体积PBS处理。采用ELISA法检测神经元乳酸脱氢酶（LDH）水平;TUNEL法检测神经元凋亡指数。结果 外泌体鉴定结果显示差速离心法提取的外泌体符合外泌体特点;与对照组和外泌体组相比,OGD组LDH值和凋亡指数显著增加（P < 0.05）;与OGD组相比,OGD+外泌体组LDH值和凋亡指数均显著降低（P < 0.05）。结论 星形胶质细胞来源的外泌体对神经元缺氧缺血损伤有保护作用。     

Ventricle-specific metabolic differences in the newborn piglet myocardium in vivo and during arrested global ischemia

Ventricular dysfunction is reported greater in the left (LV) versus right ventricle (RV) in infants following surgically induced ischemia. Ventricle-specific differences in baseline metabolism may alter response to ischemia thus affecting postischemic functional recovery. This study identifies ventricle-specific metabolic differences in the newborn (piglet) heart at baseline (working) and during ischemia (arrested). Baseline LV citrate synthase (CS) and hydroxyacyl-CoA dehydrogenase (HAD) activities were 15% and 18% lower (p < 0.02), whereas creatine kinase (CK) and phosphofructokinase (PFK) activities were 40% and 23% higher (p < 0.04) than the RV. Baseline LV glycogen reserves were also 55% higher (p = 0.004). By 15 min of ischemia, LV ATP was 20% lower (p < 0.05), lactate was 51% higher (p = 0.001), and hydrogen ions (H) were 43% higher (p = 0.03) compared with the RV. These differences persisted for the entire ischemic period (p < 0.02). After 45 min of ischemia, the LV used 58% less (p < 0.05) glycogen than the RV. These findings demonstrate that the enhanced glycolytic capacity of the newborn LV was accompanied by greater anaerobic end-product accumulation and lower energy levels during ischemia. This profile may offer one explanation for greater LV-dysfunction relative to the RV in children following ischemia.     

Assessment of antioxidant reserves and oxidative stress in cerebrospinal fluid after severe traumatic brain injury in infants and children

Studies in experimental traumatic brain injury (TBI) support a key role for oxidative stress. The degree of oxidative injury in clinical TBI, however, remains to be defined. We assessed antioxidant defenses and oxidative stress in pediatric TBI by applying a comprehensive battery of assays to cerebrospinal fluid samples. Using a protocol approved by our institutional review board, 87 cerebrospinal fluid samples from 11 infants and children with severe TBI (Glasgow Coma Scale score < or = 8) and 8 controls were studied. Cerebrospinal fluid was drained as standard care after TBI. CSF was assessed on d 1, 2, and 5-7 after ventricular drain placement. Biochemical markers of oxidative stress included F(2)-isoprostane and protein sulfhydryl (detected by ELISA and fluorescence assay, respectively). Antioxidant defenses were measured by determination of total antioxidant reserve (via chemiluminescence assay), and ascorbate (via HPLC) and glutathione (via fluorescence assay) concentrations. Free radical production (ascorbate radical) was assessed by electron paramagnetic resonance spectroscopy. F(2)-isoprostane was markedly increased versus control, maximal on d 1 (93.8 +/- 30.8 pg/mL versus 7.6 +/- 5.1 pg/mL, p < 0.05). Total antioxidant reserve was reduced versus control. Reduction was maximal on d 5-7 (81.8 +/- 3.7 microM versus 178.9 +/- 2.2 microM, p < 0.05). Ascorbate was remarkably reduced (53.8 +/- 8 microM versus 163.8 +/- 21 microM on d 1, p < 0.05). Ascorbate depletion was likely associated with its free radical oxidation, as evidenced by electron paramagnetic resonance spectroscopy. Glutathione levels increased on d 1, then decreased versus control (0.19 +/- 0.05 microM versus 1.2 +/- 0.16 microM, p < 0.05). This is the first comprehensive study of antioxidant reserve and oxidative injury in clinical TBI. Progressive compromise of antioxidant defenses and evidence of free radical-mediated lipid peroxidation are noted. These markers could be used to monitor antioxidant strategies in clinical trials.     

Cytotoxicity is predicted by unbound and not total bilirubin concentration

Although it has been suggested that the unbound, free, (B(f)) rather than total (B(T)) bilirubin level correlates with cell toxicity, direct experimental evidence supporting this conclusion is limited. In addition, previous studies never included a direct measurement of B(f), using newer, accurate methods. To test "the free bilirubin hypothesis", in vitro cytotoxicity was assessed in four cell lines exposed to different B(f) concentrations obtained by varying B(T)/Albumin ratio, using serum albumins with different binding affinities, and/or displacing unconjugated bilirubin (UCB) from albumin with a sulphonamide. B(f) was assessed by the modified, minimally diluted peroxidase method. Cytotoxicity varied among cell lines but was invariably related to B(f) and not B(T). Light exposure decreased toxicity parallel to a decrease in B(f). In the absence of albumin, no cytotoxicity was found at a B(f) of 150 nM whereas in the presence of albumin a similar B(f) resulted in a 40% reduction of viability indicating the importance of total cellular uptake of UCB in eliciting toxic effect. In the presence of albumin-bound UCB, bilirubin-induced cytotoxicity in a given cell line is accurately predicted by B(f) irrespective of the source and concentration of albumin, or total bilirubin level.     

谷氨酸诱导骨髓间质干细胞凋亡及其对Smac基因转录影响

目的观察谷氨酸能否诱导骨髓间充质干细胞(BMSCs)凋亡,探讨Smac基因是否参与谷氨酸诱导的BMSCs凋亡。方法原代培养大鼠BMSCs,加谷氨酸培养后,四甲基偶氮唑蓝(MTT)法检测分别经10、30、50mmol/L谷氨酸作用24h后BMSCs存活率,并用PI/Annexin-V双染法流式细胞仪计数各组凋亡细胞比例,通过逆转录聚合酶链反应观察经30、50mmol/L谷氨酸作用24h后Smac基因mRNA表达变化。结果谷氨酸诱导组BMSCs凋亡率较对照组升高(P<0.05),且随谷氨酸浓度增加,凋亡细胞百分率也相应增加;RT-PCR法发现谷氨酸作用后,BMSCsSmac基因表达较对照组升高(P<0.05),且随谷氨酸浓度增加,Smac基因表达也增加。结论谷氨酸能诱导BMSCs凋亡,Smac基因可能参与谷氨酸诱导的BMSCs凋亡。     

Characterization of the neuroprotective effect of the cannabinoid agonist WIN-55212 in an in vitro model of hypoxic-ischemic brain damage in newborn rats

Brain slices from 7-d-old Wistar rats were exposed to oxygen-glucose deprivation (OGD) for 30 min. OGD slices were incubated with vehicle or with the CB1/CB2 cannabinoid agonist WIN55212 (50 microM), the CB1 agonist arachidonyl-2-chloroethylamide (ACEA) (50 microM), or the CB2 agonist JW133 (50 microM), alone or combined with the CB1 and CB2 receptor antagonist SR 141716 (50 microM) or SR 144528 (50 microM), respectively. Neuronal damage was assessed by histologic analysis and spectrophotometric determination of lactate dehydrogenase (LDH) efflux into the incubation medium. Additionally, medium glutamate levels were determined by high-performance liquid chromatography (HPLC) and those of tumor necrosis factor alpha (TNF-alpha) by enzyme-linked immunosorbent assay. Finally, inducible nitric oxide synthase (iNOS) and CB1/CB2 receptor expression were determined in slices homogenate by Western blot. Both CB1 and CB2 receptors were expressed in slices. OGD increased CB1 expression, cellular damage, LDH efflux, glutamate and TNF-alpha release, and inducible nitric oxide synthase (iNOS) expression; WIN55212 inhibited all these actions. SR141716 and SR144528 inhibited the effect of R(+)-WIN-55212-2 (WIN), as well as the reduction of LDH efflux by ACEA and JW133, respectively. In conclusion, WIN55212 afforded robust neuroprotection in the forebrain slices exposed to OGD, by acting on glutamatergic excitotoxicity, TNF-alpha release, and iNOS expression; this neuroprotective effect seemed to be mediated by CB1 and CB2 receptors.     

Activities of enzymes involved in glutamine metabolism in connection with energy production in the gastrointestinal tract epithelium of newborn, suckling and weaned piglets

Changes in the activity of enzymes involved in glutaminolysis and energy metabolism in the entire gastrointestinal (GI) tract of developing piglets are presented for the first time. The activities of glutaminase, glutamate dehydrogenase, oxoglutarate dehydrogenase, isocitrate dehydrogenase and alanine aminotransferase in the epithelium along the gastrointestinal tract from newborn, suckling (2-4 weeks old) and weaned (9 weeks old) piglets were investigated. The activity of glutaminase in the epithelium from the small intestine and colon was higher (p < 0.05) in weaned piglets than in newborn and suckling piglets. In addition, glutamate dehydrogenase and alanine aminotransferase activities in the small intestinal epithelium were higher (p < 0.05) for weaned piglets than for newborns. The activity of oxoglutarate dehydrogenase in the epithelium of the small intestine was significantly lower in newborn and suckling piglets compared with weaned individuals. The activity of isocitrate dehydrogenase in the epithelium along the gastrointestinal tract was higher (p < 0.05) for suckling and weaned piglets than for newborn piglets. The present data indicate that the utilization of substrates for energy production differs markedly between the stomach, small intestine and colon of growing piglets. Also, the capacity of enzymes in the epithelium of the GI tract to utilize acetyl-CoA as an energy substrate in the tricarboxylic acid cycle increased with piglet age. The epithelium of the GI tract of the newborn, suckling and weaned piglets showed a high capacity to metabolize alpha-ketoglutarate.     

Caspase-3,-8,-9在铜诱导大鼠原代皮层神经元凋亡中的作用研究

目的通过建立体外铜诱导神经元模型,观察醋酸铜对大鼠原代皮层神经元凋亡及活化caspase-3,caspase-8和caspase-9蛋白表达的影响,探索高浓度铜导致大鼠神经元损伤的作用机制。方法采用不同浓度(20,40,80μM)醋酸铜诱导体外培养72h的大鼠原代皮层神经元;MTT法检测神经元活力,Hoechst33258染色和流式Annexin-V/PI法检测神经元凋亡,Western blot法检测不同浓度和时间点活化的caspase-3、caspase-8和caspase-9蛋白表达。结果体外培养的原代皮层神经元经醋酸铜诱导48h后,凋亡率上升,细胞活力呈浓度梯度下降,活化的caspase-8和caspase-9在铜诱导4h20μM组开始升高,48h各浓度组表达最高,呈时间与浓度梯度依赖;活化caspase-3在铜诱导24h20μM组才开始升高,激活的时间晚于caspase-8和caspase-9,48h各浓度组表达最高。结论过量铜可导致体外培养大鼠原代皮层神经元发生凋亡,caspase-3、caspase-8和caspase-9级联反应在铜诱导皮层神经元凋亡过程中发挥重要调控作用。     

Food proteins and gut mucosal barrier. III. The influence of lactation and prolactin on the in vitro binding and uptake of bovine serum albumin and ovalbumin in the rat jejunum

The everted gut sac technique was used to study adaptive changes in small intestinal handling and uptake of radiolabeled bovine serum albumin and ovalbumin during lactation in rats. Binding and uptake of both proteins by the gut sacs of lactating animals were significantly less, compared to controls (p less than 0.001, after 30 min of incubation). This change was reversible after lactation ceased. The differences could not be explained by oral immunization since there were no specific antibodies found in sera, mucosal extracts, or breast milk; prior exposure to the protein did not alter the observed differences. No differences in mucosal breakdown of bovine serum albumin could be demonstrated by precipitation with trichloroacetic acid (10%); an increase in breakdown of ovalbumin in the lactating animals was shown under the same conditions. The injection of prolactin produced differences in bovine serum albumin binding and uptake similar to the ones observed in the lactating group (p less than 0.01, after 30 min of incubation, compared to solvent-injected controls). Since food protein antigen binding, breakdown and uptake are functions of the local intestinal host defense, these findings suggest that there are adaptive changes of the gut mucosal barrier during lactation which decrease the transfer of dietary antigens from mother to infant. The adaptation of the maternal intestinal host defense was shown to be influenced by prolactin.     

Caspase-3,-8,-9在铜诱导大鼠原代皮层神经元凋亡中的作用研究

目的:通过建立体外铜诱导神经元模型,观察醋酸铜对大鼠原代皮层神经元凋亡及活化caspase-3,caspase-8和caspase-9蛋白表达的影响,探索高浓度铜导致大鼠神经元损伤的作用机制。方法:采用不同浓度（20,40,80 μM）醋酸铜诱导体外培养72 h的大鼠原代皮层神经元;MTT法检测神经元活力,Hoechst33258染色和流式Annexin-V/PI法检测神经元凋亡,Western blot法检测不同浓度和时间点活化的caspase-3、caspase-8和caspase-9蛋白表达。结果:体外培养的原代皮层神经元经醋酸铜诱导48 h后,凋亡率上升,细胞活力呈浓度梯度下降,活化的caspase-8和caspase-9在铜诱导4 h 20 μM组开始升高,48 h各浓度组表达最高,呈时间与浓度梯度依赖;活化caspase-3在铜诱导24 h 20 μM组才开始升高,激活的时间晚于caspase-8和caspase-9,48 h各浓度组表达最高。结论:过量铜可导致体外培养大鼠原代皮层神经元发生凋亡,caspase-3、caspase-8和caspase-9级联反应在铜诱导皮层神经元凋亡过程中发挥重要调控作用。［中国当代儿科杂志,2009,11（11）：917-922］     

炎症因子诱导星形胶质细胞凋亡及机制探讨

目的：探讨LPS,IL-1β,TNF-α所致星形胶质细胞(AC)凋 亡的机制及途径。方法：原代培养的新生SD大鼠前脑AC分为正常对照组、 炎症组(LPS+IL 1β+TNF α)与预处理组(L-NMMA预处理30 min后加入LPS+TNF-α+IL-1 β)。培养72h后,MTT测定AC活力;分光光度仪测定细胞培养上清中NO2-/NO3-含量;电镜、流式细胞术检测细胞凋亡;Western Blot检测胞浆内细胞色素C的表达;原位杂 交检测AC Caspase-3 mRNA表达。结果：预处理组细胞活力明显高于炎症 组(0.81±0.29 vs 0.46±0.15),差异有显著性(P<0.01)。炎症 组AC活力与其分泌的一氧化氮(NO)呈负相关(r=-0.604,P<0.05)。预处理 组凋亡率［(15.2±7.9)%］低于炎症组［(29.7±10.4)%］,P<0.0 5。预处理组胞浆内细胞色素C的含量较炎症组明显减少(14 784±2 096 vs 31 049± 3 784),P<0.01。炎症组的Caspase 3 mRNA表达强于预处理组。结论：①LPS,IL-1β,TNF-α可导致细胞活力下降。其细胞活力的下降与其分泌的NO增多有关。②增多的NO可导致AC凋亡;NO导致的AC凋亡可能与细胞色素C凋亡途径有关。