Hypoxia-induced Bax and Bcl-2 protein expression, caspase-9 activation, DNA fragmentation, and lipid peroxidation in mitochondria of the cerebral cortex of newborn piglets: the role of nitric oxide

Protein S-Nitrosylation Regulates Postmortem Beef Apoptosis through the Intrinsic Mitochondrial Pathway

The objective of the present study was to investigate the regulatory mechanism of protein S-nitrosylation on early postmortem beef muscle apoptosis. Beef semimembranosus (SM) muscles at 45 min postmortem were treated with nitric oxide (NO) donor, control (NaCl solution), or nitric oxide synthase (NOS) inhibitor for 24 h at 4 °C. Bcl-2 expression and mitochondrial membrane potential were significantly increased by the NO donor treatment at 6 h postmortem, while the NOS inhibitor group exhibited a lower Bcl-2 level and mitochondrial membrane potential in comparison with the control (P < 0.05). The cytochrome c expression analysis highlighted that NO donor incubation repressed cytochrome c release from mitochondria to the cytoplasm. Further, S-nitrosylation levels of caspase-3 and caspase-9 were elevated after incubation with the NO donor (P < 0.05), leading to decreased caspase-3 and caspase-9 activities (P < 0.05). The aforementioned findings imply that protein S-nitrosylation mediates postmortem apoptosis of beef SM through the mitochondrial apoptotic pathway.

Piperine as a neuroprotective functional component in rats with cerebral ischemic injury

Long pepper (Piper longum L.) and black pepper (Piper nigrum L.) plants are commonly used as spices around the world and have also been postulated to have medicinal effects. Piperine, as the major alkaloid of P. nigrum and P. longum, has gained wide attention of the medical community and culinary enthusiasts. This study seeks to determine the effects of piperine on neuronal apoptosis in peri-infarcted cerebral cortices of rats with permanent middle cerebral artery occlusion (pMCAO) injury. Evaluation of the different behavioral components was conducted after pMCAO. 2, 3, 5-Triphenyltetrazolium chloride (TTC) was used to evaluate the area of cortical ischemia. Gross histopathological changes, as well as microscopic neuronal changes, were observed in brain tissue samples. The protein expression of Caspase-3, Caspase-9, Bax, Bcl-2, and Cytochrome C (Cyt-c) was analyzed using western blotting. The findings reveal that rats that received piperine treatment show markedly decreased neurological deficit, less ischemia-induced cellular damage, as well as smaller areas of cerebral infarction, with less severe macro and microcellular cerebral structural changes. Western blotting analysis reveals that piperine administration inhibits Bax, while enhancing Bcl-2 expression. The protein expression of Caspase-3, Caspase-9, and Cyt-c was also found to be significantly inhibited. We conclude that piperine may provide several beneficial neuroprotective effects that warrant further investigation.

The role of taurine in improving neural stem cells proliferation and differentiation

OBJECTIVES

Taurine is one of the most abundant amino acids in the central nervous system and has important functions in the promotion of brain development. This study aimed to determine the mechanistic role of taurine in improving neuronal proliferation, stem cell proliferation, and neural differentiation.

METHODS

The data for this review were primarily retrieved from the PubMed database from 1985 to 2015 in English. The search string included the keywords taurine, brain development, neuronal, stem cell, proliferation, differentiation, and others. Relevant publications were identified, retrieved, and reviewed.

RESULTS

This review introduces the source, function, and mechanisms of taurine in brain development and provides additional detail regarding the mechanistic role of taurine in improving neuronal proliferation, stem cell proliferation, and neural differentiation. Many studies concerning these aspects are discussed.

CONCLUSIONS

Taurine plays an important role in brain development, including neuronal proliferation, stem cell proliferation, and differentiation, via several mechanisms. Taurine can be directly used in clinical applications to improve brain development because it has no toxic effects on humans.

Neuroprotective effect and mechanism of Mu-Xiang-You-Fang on cerebral ischemia-reperfusion injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

The present study is to investigate the neuroprotective effect of Mu-Xiang-You-Fang (MXYF), a classic Traditional Chinese Medicine used by Chinese minorities to treat stroke, on cerebral ischemia-reperfusion (I/R) injury and the related signaling pathways.

MATERIALS AND METHODS

Male Sprague-Dawley rats were divided into 6 groups: sham group, I/R group, nimodipine and MXYF (58, 116 and 232mg/kg respectively) groups. Cerebral ischemia model was induced by middle cerebral artery occlusion for 2h followed by reperfusion for 48h. Neurological functional score was evaluated according to the method of Zea longa's score and the infarct area was determined by 2,3,5-triphenyltetrazolium chloride (TTC) staining at 48h after reperfusion. The protein expression of cytochrome c (cyt-c), Bcl-2, Bax, caspase-9, caspase-3 and caspase-7 were analyzed by western blot and the mRNA expression of Caspase-9, Caspase-3 and Caspase-7 were determined by the reverse transcription-polymerase chain reaction.

RESULTS

Oral administration of MXYF (116 and 232mg/kg) significantly reduced the neurological functional score and attenuated the cerebral infarct area. Western blot analysis showed that the expression of Bcl-2 is enhanced and Bax expression is inhibited after treatment with MXYF (116 and 232mg/kg), leading to significant increase of the ratio between Bcl-2 and Bax. Furthermore, the protein expression of cyt-c, caspase-9, caspase-3 and caspase-7 was significantly inhibited while the mRNA expression of caspase-9, caspase-3 and caspase-7 but not cyt-c was markedly inhibited in the MXYF (116 and 232mg/kg) treatment groups compared with the I/R group.

CONCLUSIONS

The above data suggested that MXYF has potential neuroprotective activities by the regulation of apoptotic pathway, MXYF is a promising agent in treatment of stroke.

A Homogeneous Polysaccharide from Fructus Schisandra chinensis (Turz.) Baill Induces Mitochondrial Apoptosis through the Hsp90/AKT Signalling Pathway in HepG2 Cells

According to the potential anti-hepatoma therapeutic effect of Schisandra chinensis polysaccharides presented in previous studies, a bioactive constituent, homogeneous Schisandra chinensis polysaccharide-0-1 (SCP-0-1), molecular weight (M_W) circa 69.980 kDa, was isolated and purified. We assessed the efficacy of SCP-0-1 against human hepatocellular liver carcinoma (HepG2) cells to investigate the effects of its antitumour activity and molecular mechanisms. Anticancer activity was evaluated using microscopy, 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyltetrazolium bromide (MTT) assay, Hoechst 33258 staining, acridine orange (AO) staining, flow cytometry (FCM), and cell-cycle analysis. SCP-0-1 inhibited the HepG2 cells’ growth via inducing apoptosis and second gap/mitosis (G2/M) arrest dose-dependently, with a half maximal inhibitory concentration (IC₅₀) value of 479.63 µg/mL. Western blotting of key proteins revealed the apoptotic and autophagic potential of SCP-0-1. Besides, SCP-0-1 upregulated Bcl-2 Associated X Protein (Bax) and downregulated B-cell leukemia/lymphoma 2 (Bcl-2) in the HepG2 cells. The expression of caspase-3, -8, and -9; poly (ADP-ribose) polymerase (PARP); cytochrome c (Cyt C); tumor protein 53 (p53); survivin; sequestosome 1 (p62); microtubule-associated protein 1 light chain-3B (LC3B); mitogen-activated protein kinase p38 (p38); extracellular regulated protein kinases (ERK); c-Jun N-terminal kinase (JNK); protein kinase B (AKT); and heat shock protein 90 (Hsp90) were evaluated using Western blotting. Our findings demonstrate a novel mechanism through which SCP-0-1 exerts its antiproliferative activity and induces mitochondrial apoptosis rather than autophagy. The induction of mitochondrial apoptosis was attributed to the inhibition of the Hsp90/AKT signalling pathway in an extracellular signal-regulated kinase-independent manner. The results also provide initial evidence on a molecular basis that SCP-0-1 can be used as an anti-hepatocellular carcinoma therapeutic agent in the future.

Glycerol-3-phosphate acyltransferase-1 upregulation by O-GlcNAcylation of Sp1 protects against hypoxia-induced mouse embryonic stem cell apoptosis via mTOR activation

Oxygen signaling is critical for stem cell regulation, and oxidative stress-induced stem cell apoptosis decreases the efficiency of stem cell therapy. Hypoxia activates O-linked β-N-acetyl glucosaminylation (O-GlcNAcylation) of stem cells, which contributes to regulation of cellular metabolism, as well as cell fate. Our study investigated the role of O-GlcNAcylation via glucosamine in the protection of hypoxia-induced apoptosis of mouse embryonic stem cells (mESCs). Hypoxia increased mESCs apoptosis in a time-dependent manner. Moreover, hypoxia also slightly increased the O-GlcNAc level. Glucosamine treatment further enhanced the O-GlcNAc level and prevented hypoxia-induced mESC apoptosis, which was suppressed by O-GlcNAc transferase inhibitors. In addition, hypoxia regulated several lipid metabolic enzymes, whereas glucosamine increased expression of glycerol-3-phosphate acyltransferase-1 (GPAT1), a lipid metabolic enzyme producing lysophosphatidic acid (LPA). In addition, glucosamine-increased O-GlcNAcylation of Sp1, which subsequently leads to Sp1 nuclear translocation and GPAT1 expression. Silencing of GPAT1 by gpat1 siRNA transfection reduced glucosamine-mediated anti-apoptosis in mESCs and reduced mammalian target of rapamycin (mTOR) phosphorylation. Indeed, LPA prevented mESCs from undergoing hypoxia-induced apoptosis and increased phosphorylation of mTOR and its substrates (S6K1 and 4EBP1). Moreover, mTOR inactivation by rapamycin (mTOR inhibitor) increased pro-apoptotic proteins expressions and mESC apoptosis. Furthermore, transplantation of non-targeting siRNA and glucosamine-treated mESCs increased cell survival and inhibited flap necrosis in mouse skin flap model. Conversely, silencing of GPAT1 expression reversed those glucosamine effects. In conclusion, enhancing O-GlcNAcylation of Sp1 by glucosamine stimulates GPAT1 expression, which leads to inhibition of hypoxia-induced mESC apoptosis via mTOR activation.

Statins Trigger Mitochondrial Reactive Oxygen Species-Induced Apoptosis in Glycolytic Skeletal Muscle

AIMS

Although statins are the most widely used cholesterol-lowering agents, they are associated with a variety of muscle complaints. The goal of this study was to characterize the effects of statins on the mitochondrial apoptosis pathway induced by mitochondrial oxidative stress in skeletal muscle using human muscle biopsies as well as in vivo and in vitro models.

RESULTS

Statins increased mitochondrial H2O2 production, the Bax/Bcl-2 ratio, and TUNEL staining in deltoid biopsies of patients with statin-associated myopathy. Furthermore, atorvastatin treatment for 2 weeks at 10 mg/kg/day in rats increased H2O2 accumulation and mRNA levels and immunostaining of the Bax/Bcl-2 ratio, as well as TUNEL staining and caspase 3 cleavage in glycolytic (plantaris) skeletal muscle, but not in oxidative (soleus) skeletal muscle, which has a high antioxidative capacity. Atorvastatin also decreased the GSH/GSSG ratio, but only in glycolytic skeletal muscle. Cotreatment with the antioxidant, quercetin, at 25 mg/kg/day abolished these effects in plantaris. An in vitro study with L6 myoblasts directly demonstrated the link between mitochondrial oxidative stress following atorvastatin exposure and activation of the mitochondrial apoptosis signaling pathway.

INNOVATION

Treatment with atorvastatin is associated with mitochondrial oxidative stress, which activates apoptosis and contributes to myopathy. Glycolytic muscles are more sensitive to atorvastatin than oxidative muscles, which may be due to the higher antioxidative capacity in oxidative muscles.

CONCLUSION

There is a link between statin-induced mitochondrial oxidative stress and activation of the mitochondrial apoptosis signaling pathway in glycolytic skeletal muscle, which may be associated with statin-associated myopathy.

Differential regulation of apoptosis in slow and fast twitch muscles of aged female F344BN rats

Age-related muscle atrophy is characterized by decreases in muscle mass and is thought be mediated, at least in part, by increases in myocyte apoptosis. Recent data has demonstrated that the degree of muscle loss with aging may differ between males and females while other work has suggested that apoptosis as indicated by DNA fragmentation may be regulated differently in fast- and slow-twitch muscles. Herein, we investigate how aging affects the regulation of muscle apoptosis in the fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus muscles of young (6-month), aged (26-month), and very aged (30-month) female Fischer 344/NNiaHSD × Brown Norway/BiNia (F344BN) rats. Tissue sections were stained with hydroethidium for ROS and protein extract was subjected to immunoblotting for assessing apoptotic markers. Our data suggest that decreases in muscle mass were associated with increased DNA fragmentation (TUNEL positive) and increases in reactive oxygen species (ROS) as determined by hydroethidium staining in both the EDL and soleus. Similar to our previous work using aged male animals, we observed that the time course and magnitude of changes in Bax, Bcl-2, caspase-3, caspase-9, and cleavage of α-fodrin protein were regulated differently between muscles. These data suggest that aging in the female F344BN rat is associated with decreases in muscle mass, elevations in ROS level, increased muscle cell DNA fragmentation, and alterations in cell membrane integrity and that apoptotic mechanisms may differ between fiber types.

Evaluation of neuronal apoptosis precursors in an experimental model of acute normovolemic hemodilution

Background

The effects of acute anemia on neuronal cells and the safe limits of hematocrit are not well established. The objective of this study was to evaluate neuronal pro- and anti-apoptotic Bax and Bcl-x proteins, caspase-3 and -9 activity, and DNA fragmentation after acute normovolemic hemodilution (ANH).

Methods

Twenty-four pigs were anesthetized and randomized into 4 groups: Sham, ANH to 15% hematocrit (ANH15%), ANH to 10% hematocrit (ANH10%) and hypoxia (Hx). ANH was achieved by simultaneous blood withdrawal and hydroxyethyl starch infusion. Hx consisted of ventilation with a 6% inspired oxygen fraction for 60 minutes. Bax and Bcl-x proteins as well as DNA fragmentation were evaluated in cortical nuclear and mitochondrial fractions. Caspase-3 and -9 activity was evaluated in the cortical mitochondrial and hippocampal cytosolic fractions. The data were compared using analysis of variance followed by Tukey’s test (P<0.05).

Results

No changes were observed in Bax protein expression after hemodilution in the ANH15% and ANH10% groups compared to the Sham group. Bax expression in the Hx group was increased in the nuclear and mitochondrial fractions compared to all other groups. No significant difference was observed in Bcl-x expression. Caspase-3 and -9 activity in the cytosolic and mitochondrial fractions was different in the Hx group compared to all other groups. No statistical significance in DNA fragmentation was found among the Sham, ANH15% or ANH10% groups.

Conclusion

ANH to 10 and 15% hematocrit did not induce alterations in apoptosis precursors, suggesting that cerebral oxygenation was preserved during these anemic states.

Differential effect of intrauterine hypoxia on caspase 3 and DNA fragmentation in fetal guinea pig hearts and brains

The aim of this study is to quantify the effect of intrauterine hypoxia (HPX) and the role of nitric oxide (NO) on the apoptotic enzyme, caspase 3, and DNA fragmentation in fetal heart and brain. Hypoxia and NO are important regulators of apoptosis, although this has been little studied in the fetal organs. We investigated the effect of intrauterine HPX on apoptosis and the role of NO in both fetal hearts and brains. Pregnant guinea pigs were exposed to room temperature (N = 14) or 10.5% O₂ (N = 12) for 14 days prior to term (term = 65 days) and administered water or L-N6-(1-iminoethyl)-lysine (LNIL), an inducible nitric oxide synthase (iNOS) inhibitor, for 10 days. Fetal hearts and brains were excised from anesthetized near-term fetuses for study. Chronic HPX decreased pro- and active caspase 3, caspase 3 activity, and DNA fragmentation levels in fetal hearts compared with normoxic controls. L-N6-(1-iminoethyl)-lysine prevented the HPX-induced decrease in caspase 3 activity but did not alter DNA fragmentation levels. In contrast, chronic HPX increased both apoptotic indices in fetal brains, which were inhibited by LNIL. Thus, the effect of HPX on apoptosis differs between fetal organs, and NO may play an important role in modulating these effects.

Gastric cancer cell lines AGS before and after CD40 signal activating

The aim of this study was to investigate the molecular mechanisms underlying the antitumour effects of CD40L through analysing the change of genes expression profile in AGS using Affymetrix Gene Chip. Human gastric carcinoma AGS cells were first incubated with 2 μg/ml sCD40L or equal volume of medium (control) in F12 medium. RNA was isolated from AGS and were reverse transcribed, labeled with digoxigenin-11-dUTP, and then hybridized with Clontech Atlas mouse cDNA expression arrays for comparison. Performing clustering analysis, we found that 7 detected genes were down-regulated and 38 were upregulated as the sCD40L acted on AGS. To further verify the results of gene chip screening, Gene Database was searched, finding that the most significantly up-regulated genes were Gadd45a, c-Jun and Bcl-2, and the most significantly down-regulated genes were Cyclin D1, CDC6, TNFR10B, c-IAP2 and ORC5L. Based upon these findings, the signalling pathways that possibly mediate CD40-induced apoptosis are proposed.

A maternal diet supplemented with creatine from mid-pregnancy protects the newborn spiny mouse brain from birth hypoxia

The creatine-phosphocreatine shuttle is essential for the maintenance of cellular ATP, particularly under hypoxic conditions when respiration may become anaerobic. Using a model of intrapartum hypoxia in the precocial spiny mouse (Acomys cahirinus), the present study assessed the potential for maternal creatine supplementation during pregnancy to protect the developing brain from the effects of birth hypoxia. On day 38 of gestation (term is 39 days), the pregnant uterus was isolated and placed in a saline bath for 7.5 min, inducing global hypoxia. The pups were then removed, resuscitated, and cross-fostered to a nursing dam. Control offspring were delivered by caesarean section and recovered immediately after release from the uterus. At 24 h after birth hypoxia, the brains of offspring from dams fed a normal diet showed significant increases in lipid peroxidation as measured by the amount of malondialdehyde. In the cortical subplate, thalamus and piriform cortex there were significant increases in cellular expression of the pro-apoptotic protein BAX, cytoplasmic cytochrome c and caspase-3. When pregnant dams were fed the creatine supplemented diet, the increase in malondialdehyde, BAX, cytochrome c and caspase 3 were almost completely prevented, such that they were not different from control (caesarean-delivered) neonates. This study provides evidence that the neuroprotective capacity of creatine in the hypoxic perinatal brain involves abrogation of lipid peroxidation and apoptosis, possibly through the maintenance of mitochondrial function. Further investigation into these mechanisms of protection, and the long-term development and behavioural outcomes of such neonates is warranted.

Single-prolonged stress induces apoptosis by activating cytochrome C/caspase-9 pathway in a rat model of post-traumatic stress disorder

The purpose of this study was to provide a novel insight into the mechanism of how amygdala might participate in PTSD by investigating the changes of cytochrome c oxidase (COX), caspase-9, and caspase-3 in the amygdala of single-prolonged stress (SPS) rats. A total of 80 healthy, male Wistar rats were selected for this study. The models of post-traumatic stress disorder (PTSD) were created by SPS, which is an established animal model for PTSD. The change of COX was detected by light microscope and transmission electron microscopy (TEM). The expression of caspase-9 and caspase-3 in the basolateral amygdala was examined by immunofluorescence and reverse transcription-polymerase chain reaction (RT-PCR). SPS exposure resulted in a significant change of COX in the SPS model groups compared with the normal control group. Evaluation by enzymohistochemistry indicated translocation of COX from mitochondria to cytoplasm. The expression of both caspase-9 and caspase-3 significantly increased 1 day after SPS stimulation, then gradually increased and peaked at SPS 7d. This findings suggest changes of COX, caspase-9, and caspase-3 in the amygdala of SPS rats, which may play important roles in the pathogenesis of PTSD.

Mitochondrial death effectors: relevance to sarcopenia and disuse muscle atrophy

Accelerated apoptosis in skeletal muscle is increasingly recognized as a potential mechanism contributing to the development of sarcopenia of aging and disuse muscle atrophy. Given their central role in the regulation of apoptosis, mitochondria are regarded as key players in the pathogenesis of myocyte loss during aging and other atrophying conditions. Oxidative damage to mitochondrial constituents, impaired respiration and altered mitochondrial turnover have been proposed as potential triggering events for mitochondrial apoptotic signaling. In addition, iron accumulation within mitochondria may enhance the susceptibility to apoptosis during the development of sarcopenia and possibly acute muscle atrophy, likely through exacerbation of oxidative stress. Mitochondria can induce myocyte apoptosis via both caspase-dependent and independent pathways, although the apoptogenic mediators involved may be different depending on age, muscle type and specific atrophying conditions. Despite the considerable advances made, additional research is necessary to establish a definite causal link between apoptotic signaling and the development of sarcopenia and acute atrophy. Furthermore, a translational effort is required to determine the role played by apoptosis in the pathogenesis of sarcopenia and disuse-induced muscle loss in human subjects.

Mild hypothermia alone or in combination with anesthetic post-conditioning reduces expression of inflammatory cytokines in the cerebral cortex of pigs after cardiopulmonary resuscitation

Introduction

Hypothermia improves survival and neurological recovery after cardiac arrest. Pro-inflammatory cytokines have been implicated in focal cerebral ischemia/reperfusion injury. It is unknown whether cardiac arrest also triggers the release of cerebral inflammatory molecules, and whether therapeutic hypothermia alters this inflammatory response. This study sought to examine whether hypothermia or the combination of hypothermia with anesthetic post-conditioning with sevoflurane affect cerebral inflammatory response after cardiopulmonary resuscitation.

Methods

Thirty pigs (28 to 34 kg) were subjected to cardiac arrest following temporary coronary artery occlusion. After seven minutes of ventricular fibrillation and two minutes of basic life support, advanced cardiac life support was started according to the current American Heart Association guidelines. Return of spontaneous circulation was achieved in 21 animals who were randomized to either normothermia at 38°C, hypothermia at 33°C or hypothermia at 33°C combined with sevoflurane (each group: n = 7) for 24 hours. The effects of hypothermia and the combination of hypothermia with sevoflurane on cerebral inflammatory response after cardiopulmonary resuscitation were studied using tissue samples from the cerebral cortex of pigs euthanized after 24 hours and employing quantitative RT-PCR and ELISA techniques.

Results

Global cerebral ischemia following resuscitation resulted in significant upregulation of cerebral tissue inflammatory cytokine mRNA expression (mean ± SD; interleukin (IL)-1β 8.7 ± 4.0, IL-6 4.3 ± 2.6, IL-10 2.5 ± 1.6, tumor necrosis factor (TNF)α 2.8 ± 1.8, intercellular adhesion molecule-1 (ICAM-1) 4.0 ± 1.9-fold compared with sham control) and IL-1β protein concentration (1.9 ± 0.6-fold compared with sham control). Hypothermia was associated with a significant (P < 0.05 versus normothermia) reduction in cerebral inflammatory cytokine mRNA expression (IL-1β 1.7 ± 1.0, IL-6 2.2 ± 1.1, IL-10 0.8 ± 0.4, TNFα 1.1 ± 0.6, ICAM-1 1.9 ± 0.7-fold compared with sham control). These results were also confirmed for IL-1β on protein level. Experimental settings employing hypothermia in combination with sevoflurane showed that the volatile anesthetic did not confer additional anti-inflammatory effects compared with hypothermia alone.

Conclusions

Mild therapeutic hypothermia resulted in decreased expression of typical cerebral inflammatory mediators after cardiopulmonary resuscitation. This may confer, at least in part, neuroprotection following global cerebral ischemia and resuscitation.

Antioxidant therapy and neuroprotection in the newborn

Injury to the perinatal brain is a leading cause of childhood mortality and lifelong disability. Despite recent improvements in neonatal care, no effective treatment for perinatal brain lesions is available. The newborn, especially if preterm, is highly prone to oxidative stress (OS) and to the toxic effect of free radicals (FRs). At birth, the newborn is exposed to a relatively hyperoxic environment caused by an increased oxygen bioavailability with greatly enhanced generation of FRs. Additional sources (e.g., inflammation, hypoxia, ischemia, glutamate and free iron release) occur, magnifying OS. In the preterm baby, the perinatal transition is accompanied by the immaturity of the antioxidant systems and the reduced ability to induce efficient homeostatic mechanisms designed to control overproduction of cell-damaging FRs. Improved understanding of the pathophysiological mechanism involved in perinatal brain lesions helps to identify potential targets for neuroprotective interventions, and the knowledge of these mechanisms has enabled scientists to develop new therapeutic strategies that have confirmed their neuroprotective effects in animal studies. Considering the growing role of OS in preterm newborn morbidity in respect to the higher risk of FR damage in these babies, erythropoietin, allopurinol, melatonin and hypothermia demonstrate great promise as potential neuroprotectans. This article provides an overview of the pathogenesis of FR-mediated diseases of the newborn and the antioxidant strategies now tested in order to reduce OS and its damaging effects.

Nuclear mechanisms of hypoxic cerebral injury in the newborn: the role of caspases

Our laboratory has been actively engaged in investigating mechanisms of activation of initiator caspase-9 during hypoxia in the developing newborn and fetal brains. The present review has been organized as follows: (a) the effect of hypoxia on the expression and activation of caspase-3, -8, and -9 in the newborn brain; (b) the role of nitric oxide in caspase-9, and caspase-3 activation during hypoxia in the newborn brain; (c) the role of nuclear Ca(2+)-influx in caspase-9 and caspase-3 activation during hypoxia in the newborn brain; (d) the effect of caspase-9 inhibition during hypoxia on preventing downstream events including caspase-3 activation. The results of our research investigations presented in (b), (c), and (d) elucidate mechanisms of caspase activation during hypoxia in the newborn brain. These studies provide the fundamental framework for developing neuroprotective strategies in the hypoxic newborn.

Age-related activation of mitochondrial caspase-independent apoptotic signaling in rat gastrocnemius muscle

Mitochondria-mediated apoptosis represents a central process driving age-related muscle loss. However, the temporal relation between mitochondrial apoptotic signaling and sarcopenia as well as the regulation of release of pro-apoptotic factors from the mitochondria has not been elucidated. In this study, we investigated mitochondrial apoptotic signaling in skeletal muscle of rats across a wide age range. We also investigated whether mitochondrial-driven apoptosis was accompanied by changes in the expression of Bcl-2 proteins and components of the mitochondrial permeability transition pore (mPTP). Analyses were performed on gastrocnemius muscle of 8-, 18-, 29- and 37-month-old male Fischer344 x Brown Norway rats (9 per group). Muscle weight declined progressively with advancing age, concomitant with increased apoptotic DNA fragmentation. Cytosolic and nuclear levels of apoptosis inducing factor (AIF) and endonuclease G (EndoG) increased in old and senescent animals. In contrast, cytosolic levels of cytochrome c were unchanged with age. Mitochondrial Bcl-2, Bax and Bid increased dramatically in 37-month-old rats, with no changes in the Bax/Bcl-2 ratio in any of the age groups. Finally, expression of cyclophilin D (CyPD) was enhanced at very old age. Our findings indicate that the mitochondrial caspase-independent apoptotic pathway may play a more prominent role in skeletal muscle loss than caspase-mediated apoptosis.

Perinatal hypoxia induces subsequent retinal degeneration in the offspring of ovoviviparous fish, Xiphophorous maculates

OBJECTIVE

This experiment evaluated the perinatal hypoxic effect on the retina of offspring of the ovoviviparous fish.

ANIMAL STUDIED

The ovoviviparous fish Xiphophorous maculates was used for the experiment.

PROCEDURE

The mothers were kept in a hypoxic environment of 3.5% oxygen for 6 h, starting 30 h before hatching. Subsequently, the retinae of the offspring were fixed, sectioned at 6 microm and evaluated microscopically from the age of 1 to 35 days.

RESULTS

Degeneration of the outer nuclear layer of the retina was noted on the 3rd day and severe retinal degeneration was observed on the 35th day. Immunocytochemistry confirmed apoptosis by TUNEL reaction. There was no difference in neovascularization, as revealed by vascular endothelial growth factor, between controls (group 1) and hypoxic fish (group 2).

CONCLUSIONS

Perinatal hypoxia could have long-lasting effects on the central nervous system in some species.

Nitric oxide generation is associated with an unbalance of protein tyrosine phosphatases during liver transplantation

Organ dysfunction secondary to ischemia-reperfusion (I/R) injury still represents a major problem in liver transplantation. Apoptosis has been observed in hepatocytes and sinusoidal endothelial cell, following I/R injury and it has been postulated as a contributing factor in ischemia-reperfusion graft dysfunction, involving a complex series of events, as changes of protein tyrosine-kinase phosphorylation. We evaluated hepatic purine metabolites, protein tyrosine phosphatases (PTPs), nitrate plus nitrite levels (NOx), caspase-3 (C-3) activity and DNA fragmentation in the time course of twelve pig orthotopic liver transplantation. Biopsies were taken before explantation (t0), after cold ischemic storage (t1) and 30 min from reperfusion (t2). During the ischemic period we observed a reduction of high energy phosphates and an increase of purine bases; PTP activity was largely increased. At t2 high energy phosphates showed a tendency to increase with respect to t1, with a partial restoration of phosphorylation potential, measured as ATP/ADT ratio. PTP activity was significantly reduced, with a concomitant increase of NOx production and C-3 activity; in a considerable number of cases we observed a sustained DNA fragmentation. We speculate that NOx production could be related to nitrosative stress, which in turn leads to dynamic alteration in PTP balance and cell signalling, regulating the activity of a number of proteins implicated in apoptotic cell death. These findings could be of interest in new potential strategy to prevent and treat I/R injury.