Effects of genistein on neuronal apoptosis,and expression of Bcl-2 and Bax proteins in the hippocampus of ovariectomized rats

Genistein is one of several isoflavones that has a structure similar to 17β-estradiol, has a strong antioxidant effect, and a high affinity to estrogen receptors. At 15 weeks after ovariectomy, the expression of Bcl-2 in the hippocampus of rats decreased and Bax expression increased, with an obvious upregulation of apoptosis. However, intraperitoneal injection of genistein or 17β-estradiol for 15 consecutive weeks from the second day after operation upregulated Bcl-2 protein expression downregulated Bax protein expression, and attenuated hippocampal neuron apoptosis. Our experimental findings indicate that long-term intervention with genistein can lead to a decrease in apoptosis in hippocampal neurons following ovadectomy, upregulate the expression of Bcl-2, and downregulate the expression of Bax. In addition, genistein and 17β-estradiol play equal anti-apoptotic and neuroprotective roles.

Intermittent hypoxia attenuates ischemia/reperfusion induced apoptosis in cardiac myocytes via regulating Bcl-2/Bax expression

Intermittent hypoxia has been shown to provide myocardial protection against ishemia/reperfusion-induced injury.Cardiac myocyte loss through apoptosis has been reported in ischemia/reperfusion injury. Our aim was to investigate whether intermittent hypoxia could attenuate ischemia/reperfusion-induced apoptosis in cardiac myocytes and its potential mechanisms. Adult male Sprague-Dawley rats were exposed to hypoxia simulated 5000 m in a hypobaric chamber for 6 h/day, lasting 42 days. Normoxia group rats were kept under normoxic conditions. Isolated perfused hearts from both groups were subjected to 30 min of global ischemia followed by 60 min reperfusion.Incidence of apoptosis in cardiac myocytes was determined by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and DNA agarose gel electrophoresis. Expressions of apoptosis related proteins,Bax and Bcl-2, in cytosolic and membrane fraction were detected by Western Blotting. After ischemia/reperfusion,enhanced recovery of cardiac function was observed in intermittent hypoxia hearts compared with normoxia group.Ischemia/reperfusion-induced apoptosis, as evidenced by TUNEL-positive nuclei and DNA fragmentation, was significantly reduced in intermittent hypoxia group compared with normoxia group. After ischemia/reperfusion,expression of Bax in both cytosolic and membrane fractions was decreased in intermittent hypoxia hearts compared with normoxia group. Although ischemia/reperfusion did not induce changes in the level of Bcl-2 expression in cytosolic fraction between intermittent hypoxia and normoxia groups, the expression of Bcl-2 in membrane fraction was upregulated in intermittent hypoxia group compared with normoxia group. These results indicated that the cardioprotection of intermittent hypoxia against ischemia/reperfusion injury appears to be in part due to reduce myocardial apoptosis. Intermittent hypoxia attenuated ischemia/reperfusion-induced apoptosis via increasing the ratio of Bcl-2/Bax, especially in membrane fraction.

Propofol blocks apoptosis and Bcl-2 and Bax expression induced by hypoxia-reoxygenation in primary cultures of rat hippocampal astrocytes

BACKGROUND： Cerebral hippocampal astrocytes are more sensitive.to ischemic injury than neurons. Hypoxic-ischemic brain injury induces profound astrocyte apoptosis, and propofol may protect against astrocyte apoptosis. OBJECTIVE： To verify the protective effects of propofol against astrocyte apoptosis and to investigate anti-apoptotic Bcl-2 and pro-apoptotic Bax expression in primary cultures of rat hippocampal astrocytes exposed to hypoxia-reoxygenation for different periods of time following propofol treatment. DESIGN, TIME, AND SETTING： In vitro neural immunocytochemistry was performed at the Central Laboratory of Yunyang Medical College between September 2007 and March 2008.MATERIALS： A total of 30 Wistar rats, aged 1-3 days, wJth equal numbers of males and females, were included for isolation and culture of .hippocampal astrocytes. METHODS： Hippocampal astrocytes were purified and cultured for 3 weeks and treated with four culture conditions： 50 μL Hank＇s solution （normal control）; 0.2 mL/L Intralipid; 50 μL Hank＇s solution for 10 minutes followed by hypoxic incubation for 4 hours and normoxic incubation for 12, 24, 36, 48, 60 or 72 hours; propofol （250 μmol/L final） for 10 minutes followed by hypoxic incubation for 4 hours and normoxic incubation for 12, 24, 36, 48, 60 and 72 hours. MAIN OUTCOME MEASURES： （1） Morphologic changes in hippocampal astrocytes. （2） Levels of astrocyte apoptosis and Bcl-2 and Bax expression. RESULTS： Hypoxia and reoxygenation increased apoptosis over time, with Bcl-2 expression peaking at 24 hours and decreasing gradually （P 〈 0.01 ）; Bax expression peaked at 72 hours （P 〈 0.01）; the ratio of Bcl-2/Bax was 1.4, 0.8, and 0.6, respectively, at 24, 48 and 72 hours. Non-apoptotic astrocytes showed significant proliferation and swelling. Propofol treatment decreased apoptosis after hypoxia-reoxygenation （P 〈 0.01）, as well as Bct-2 and Bax expression （P 〈 0.05, P 〈 0.01）, with Bcl-2/Bax ratios of 1.6-1.8. Propofol treatmentalso blocked astrocyte proliferation and swelling. No apoptotic cells or Bcl-2/Bax expression was detected in astrocytes cultured in Hank＇s or Intralipid solution. CONCLUSION： Propofol protects astrocytes against injury caused by hypoxia and reoxygenation via a mechanism that involves maintaining high ratios of Bcl-2/Bax.

Medium-intensity acute exhaustive exercise induces neural cell apoptosis in the rat hippocampus

The present study assessed the influence of medium-intensity （treadmill at a speed of 19.3 m/min until exhaustion） and high-intensity （treadmill at a speed of 26.8 m/min until exhaustion） acute exhaustive exercise on rat hippocampal neural cell apoptosis. TUNEL staining showed significantly increased neural cell apoptosis in the hippocampal CA1 region of rats after medium- and high-intensity acute exhaustive exercise, particulady the medium-intensity acute exhaustive exercise, when compared with the control. Immunohistochemistry showed significantly increased expression of the antiapoptotic protein Bcl-2 and the proapoptotJc proteJn Bax in the hippocampal CA1 region of rats after medium- and high-intensity acute exhaustive exercise. Additionally, the ratio of Bax to Bcl-2 increased in both exercise groups. In particular, the medium-intensity acute exhaustive exercise group had significantly higher Bax and Bcl-2 protein expression and a higher Bax/Bcl-2 ratio. These findings indicate that acute exhaustive exercise of different intensities can induce neural cell apoptosis in the hippocampus, and that medium-intensity acute exhaustive exercise results in greater damage when compared with high-intensity exercise.

Effects of vitamin C supplementation on leadinduced apoptosis in adult rat hippocampus

BACKGROUND： Lead has caused widespread pollution in the environment due to the numerous industrial applications. One principle target for lead in the human body is the central nervous system However, research has demonstrated that neurotoxic effects of lead can be ameliorated by antioxidant agents, such as vitamin C. OBJECTIVE： To investigate the protective effects of vitamin C supplementation against lead-induced apoptosis in the adult rat hippocampus, as well as changes in pro-apoptotic protein Bax expression. DESIGN, TIME AND SETTING： A randomized, controlled, animal study was performed at the College of Medicine, Iran University of Medical Sciences from December 2007 to April 2009. MATERIALS： Lead acetate and vitamin C were purchased from Sigma, USA. METHODS： Thirty male rats were randomly assigned to three groups, with 10 rats in each group： control, lead, and lead ＋ vitamin C. Rats from the lead group received intraperitoneal administration of lead 20 mg/kg per day for 7 days. Rats from the lead ＋ vitamin C group received ascorbic acid 500 mg/kg per day in addition to lead acetate （as per the lead group）. MAIN OUTCOME MEASURES： After 7 days of vitamin C administration, hippocampal cell apoptosis was observed using uranyl acetate and lead citrate stainings, hippocampal Bax protein expression was detected by Western blot analysis, and blood lead levels were measured by atomic absorption spectrometry. RESULTS： Vitamin C supplementation significantly reduced lead-induced hippocampal cell apoptosis and decreased hippocampal Bax protein expression. However, vitamin C treatment did not significantly decrease blood lead levels. CONCLUSION： Vitamin C significantly decreased Bax expression and reduced lead-induced hippocampal cell apoptosis.

慢性低O_2高CO_2对大鼠海马Bcl-2、Bax基因表达和细胞凋亡的影响

目的:探讨慢性低O2高CO2对大鼠海马神经细胞凋亡的诱发作用及对Bcl-2、Bax基因表达的影响。方法:雄性SD大鼠50只,随机均分成5组:正常对照组(NC)、低O2高CO21周组(1HH)、2周组(2HH)、3周组(3HH)和4周组(4HH)。采用TUNEL法检测海马神经细胞凋亡;以RT-PCR检测海马Bcl-2mRNA和BaxmRNA的表达。结果:随着低O2高CO2时间延长,凋亡指数(AI)及BaxmRNA水平进行性升高;Bcl-2mRNA先升高后下降(均P<0.01)。AI与BaxmRNA之间呈显著正相关(r=0.814,P<0.01),而与Bcl-2mRNA/BaxmRNA比值之间呈显著负相关(r=-0.405,P<0.01)。结论:慢性低O2高CO2可以诱发大鼠海马神经细胞凋亡,Bcl-2/Bax比值下降是促进凋亡的重要因素。