Apoptotic Neurodegeneration Research Articles

Taurine protects cerebellar neurons of the external granular layer against ethanol-induced apoptosis in 7-day-old mice

Acute alcohol administration is harmful especially for the developing nervous system, where it induces massive apoptotic neurodegeneration leading to alcohol-related disorders of newborn infants. Neuroprotection against ethanol-induced apoptosis may save neurons and reduce the consequences of maternal alcohol consumption. Previously we have shown that taurine protects immature cerebellar neurons in the internal granular layer of cerebellum from ethanol-induced apoptosis. Now we describe a similar protective action for taurine in the external layer of cerebellum of 7-day-old mice. The mice were divided into three groups: ethanol-treated, ethanol + taurine-treated and controls. Ethanol (20% solution) was administered subcutaneously at a total dose of 5 g/kg (2.5 g/kg at time 0 h and 2.5 g/kg at 2 h) to the ethanol and ethanol + taurine groups. The ethanol + taurine group also received subcutaneously two injections of taurine (1 g/kg each, 1 h before the first dose of ethanol and 1 h after the second dose of ethanol). To verify apoptosis, immunostaining for activated caspase-3 and TUNEL staining were made in the mid-sagittal sections containing lobules I-X of the cerebellar vermis at 8 h after the first ethanol injection. Ethanol induced apoptosis in the cerebellar external granular layer. Taurine treatment significantly reduced the number of activated caspase-3-immunoreactive and TUNEL-positive cells. Taurine has thus a neuroprotective antiapoptotic action in the external granular layer of the cerebellum, preserving a number of neurons from ethanol-induced apoptosis.

N-Methyl-d-aspartate Receptor Mechanosensitivity Is Governed by C Terminus of NR2B Subunit

N-methyl-D-aspartate receptors (NMDARs), critical mediators of both physiologic and pathologic neurological signaling, have previously been shown to be sensitive to mechanical stretch through the loss of its native Mg(2+) block. However, the regulation of this mechanosensitivity has yet to be further explored. Furthermore, as it has become apparent that NMDAR-mediated signaling is dependent on specific NMDAR subtypes, as governed by the identity of the NR2 subunit, a crucial unanswered question is the role of subunit composition in observed NMDAR mechanosensitivity. Here, we used a recombinant system to assess the mechanosensitivity of specific subtypes and demonstrate that the mechanosensitive property is uniquely governed by the NR2B subunit. NR1/NR2B NMDARs displayed significant stretch sensitivity, whereas NR1/NR2A NMDARs did not respond to stretch. Furthermore, NR2B mechanosensitivity was regulated by PKC activity, because PKC inhibition reduced stretch responses in transfected HEK 293 cells and primary cortical neurons. Finally, using NR2B point mutations, we identified a PKC phosphorylation site, Ser-1323 on NR2B, as a unique critical regulator of stretch sensitivity. These data suggest that the selective mechanosensitivity of NR2B can significantly impact neuronal response to traumatic brain injury and illustrate that the mechanical tone of the neuron can be dynamically regulated by PKC activity.

Ketamine-induced Neuroapoptosis in the Fetal and Neonatal Rhesus Macaque Brain

Exposure of rhesus macaque fetuses for 24 h or neonates for 9 h to ketamine anesthesia causes neuroapoptosis in the developing brain. The current study clarifies the minimum exposure required for and the extent and spatial distribution of ketamine-induced neuroapoptosis in rhesus fetuses and neonates. Ketamine was administered by IV infusion for 5 h to postnatal day 6 rhesus neonates or to pregnant rhesus females at 120 days' gestation (full term = 165 days). Three hours later, fetuses were delivered by cesarean section, and the fetal and neonatal brains were studied for evidence of apoptotic neurodegeneration, as determined by activated caspase-3 staining. Both the fetal (n = 3) and neonatal (n = 4) ketamine-exposed brains had a significant increase in apoptotic profiles compared with drug-naive controls (fetal n = 4; neonatal n = 5). Loss of neurons attributable to ketamine exposure was 2.2 times greater in fetuses than in neonates. The pattern of neurodegeneration in fetuses was different from that in neonates, and all subjects exposed at either age had a pattern characteristic for that age. The developing rhesus macaque brain is sensitive to the apoptogenic action of ketamine at both a fetal and neonatal age, and exposure duration of 5 h is sufficient to induce a significant neuroapoptosis response at either age. The pattern of neurodegeneration induced by ketamine in fetuses was different from that in neonates, and loss of neurons attributable to ketamine exposure was 2.2 times greater in the fetal than neonatal brains.

NP1 Regulates Neuronal Activity-Dependent Accumulation of BAX in Mitochondria and Mitochondrial Dynamics

In cultured cerebellar granule neurons, low neuronal activity triggers the intrinsic program of apoptosis, which requires protein synthesis-dependent BAX translocation to mitochondria, a process that may underlie neuronal damage in neurodegeneration. However, the mechanisms that link neuronal activity with the induction of the mitochondrial program of apoptosis remain unclear. Neuronal pentraxin 1 (NP1) is a pro-apoptotic protein induced by low neuronal activity that is increased in damaged neurites in Alzheimer's disease-affected brains. Here we report that NP1 facilitates the accumulation of BAX in mitochondria and regulates mitochondrial dynamics during apoptosis in rat and mouse cerebellar granule neurons in culture. Reduction of neuronal activity increases NP1 protein levels in mitochondria and contributes to mitochondrial fragmentation in a Bax-dependent manner. In addition, NP1 is involved in mitochondrial transport in healthy neurons. These results show that NP1 is targeted to mitochondria acting upstream of BAX and uncover a novel function for NP1 in the regulation of mitochondrial dynamics and trafficking during apoptotic neurodegeneration.

Neuroprotection with metformin and thymoquinone against ethanol-induced apoptotic neurodegeneration in prenatal rat cortical neurons

BackgroundExposure to ethanol during early development triggers severe neuronal death by activating multiple stress pathways and causes neurological disorders, such as fetal alcohol effects or fetal alcohol syndrome. This study investigated the effect of ethanol on intracellular events that predispose developing neurons for apoptosis via calcium-mediated signaling. Although the underlying molecular mechanisms of ethanol neurotoxicity are not completely determined, mitochondrial dysfunction, altered calcium homeostasis and apoptosis-related proteins have been implicated in ethanol neurotoxicity. The present study was designed to evaluate the neuroprotective mechanisms of metformin (Met) and thymoquinone (TQ) during ethanol toxicity in rat prenatal cortical neurons at gestational day (GD) 17.5.ResultsWe found that Met and TQ, separately and synergistically, increased cell viability after ethanol (100 mM) exposure for 12 hours and attenuated the elevation of cytosolic free calcium [Ca2+]c. Furthermore, Met and TQ maintained normal physiological mitochondrial transmembrane potential (ΔψM), which is typically lowered by ethanol exposure. Increased cytosolic free [Ca2+]c and lowered mitochondrial transmembrane potential after ethanol exposure significantly decreased the expression of a key anti-apoptotic protein (Bcl-2), increased expression of Bax, and stimulated the release of cytochrome-c from mitochondria. Met and TQ treatment inhibited the apoptotic cascade by increasing Bcl-2 expression. These compounds also repressed the activation of caspase-9 and caspase-3 and reduced the cleavage of PARP-1. Morphological conformation of cell death was assessed by TUNEL, Fluoro-Jade-B, and PI staining. These staining methods demonstrated more cell death after ethanol treatment, while Met, TQ or Met plus TQ prevented ethanol-induced apoptotic cell death.ConclusionThese findings suggested that Met and TQ are strong protective agents against ethanol-induced neuronal apoptosis in primary rat cortical neurons. The collective data demonstrated that Met and TQ have the potential to ameliorate ethanol neurotoxicity and revealed a possible protective target mechanism for the damaging effects of ethanol during early brain development.

Hypoxia inducible factor‐1α is involved in the neurodegeneration induced by isoflurane in the brain of neonatal rats

More and more data show isoflurane, a commonly used volatile anesthetic has dual effects on neuron fate. However, the underlying mechanisms that can explain the apparent paradox are poorly understood. Hypoxia inducible factor (HIF)-1α, a transcription factor, has been found regulating both prosurvival and prodeath pathways in the CNS. Previously, we found that isoflurane can activate HIF-1α under normoxic conditions in vitro and HIF-1α has been found to be involved in the pre-conditioning effect of isoflurane in various organs. Here, we investigated whether HIF-1α is a contributing factor in the neurodegenration in rodent primary cultured neurons and in developing rat brain. Isoflurane dose-dependently induced apoptotic neurodegeneration in neonatal rats as assessed by S100β, cleaved caspase 3 and poly-(ADP-ribose) polymerase (PARP), respectively. Notably, isoflurane up-regulates HIF-1α protein levels in vivo and in vitro during induction of neurodegeneration. Likewise, isoflurane resulted in a significant elevation of cytosonic calcium levels in neuron cultures. Furthermore, knockdown of HIF-1α expression in cultured neurons attenuated isoflurane-induced neurotoxicity. Finally, Morris water maze (MWM) test showed neonatal exposure to isoflurane impaired juvenile learning and memory ability in rats. These findings indicate that HIF-1α is involved in the neurodegeneration induced by isoflurane in the brain of neonatal rats, suggesting HIF-1α may be a candidate for the dual effects of isoflurane on neuron fate.

Propylene glycol produces excessive apoptosis in the developing mouse brain, alone and in combination with phenobarbital

Propylene glycol (PG) is a common solvent used in medical preparations. It is generally recognized as safe at regulated concentrations; however, its apoptotic potential is unknown. PG triggered widespread apoptotic neurodegeneration with the greatest damage at postnatal day 7 (P7). Significant apoptosis was observed at doses as low as 2 ml/kg. These findings have implications for the safety of drug preparations used in pediatric medicine. The anticonvulsant phenobarbital (PB), which alone produces apoptosis in the immature central nervous system (CNS) is prepared in 68% PG and 10% ethanol (EtOH). We assessed whether PG contributes to the neurotoxic potential of PB. The agents (both at subtoxic doses) produce significantly more apoptosis when used in combination. In conclusion, finding an alternative non-apoptotic solvent that can be used as a substitute for PG may be beneficial to patients. C57BL/6 mice (P4-30) were exposed to PG to examine whether PG could produce apoptosis in the developing CNS.

Protective Function of Nicotinamide Against Ketamine-induced Apoptotic Neurodegeneration in the Infant Rat Brain

During development, anesthetics activate neuroapoptosis and produce damage in the central nervous system that leads to several types of neurological disorders. A single dose of ketamine (40mg/kg) during synaptogenesis in a 7-day-old rat brain activated the apoptotic cascade and caused extensive neuronal cell death in the forebrain. In this study, we investigated the protective effect of nicotinamide against ketamine-induced apoptotic neurodegeneration. After 4h, neuronal cell death induced by ketamine was associated with the induction of Bax, release of cytochrome c into the cytosol, and activation of caspase-3. One single dose of 1mg/g nicotinamide was administered to a developing rat and was found to inhibit ketamine-induced neuroapoptosis by downregulating Bax, inhibiting cytochrome c release from mitochondria into cytosol, and inhibiting the expression of activated caspase-3. TUNEL and immunohistochemical analyses showed that ketamine-induced cell death occurred through apoptosis and that it was inhibited by nicotinamide. Fluoro-Jade-B staining demonstrated an increased number of dead cells in the cortex and thalamus after ketamine treatment; treatment with nicotinamide reduced the number of dead cells in these brain regions. Our findings suggest that nicotinamide attenuated ketamine-induced neuronal cell loss in the developing rat brain and is a promising therapeutic and neuroprotective agent for the treatment of neurodevelopmental disorders.

Nicotinamide inhibits alkylating agent-induced apoptotic neurodegeneration in the developing rat brain.

BackgroundExposure to the chemotherapeutic alkylating agent thiotepa during brain development leads to neurological complications arising from neurodegeneration and irreversible damage to the developing central nerve system (CNS). Administration of single dose of thiotepa in 7-d postnatal (P7) rat triggers activation of apoptotic cascade and widespread neuronal death. The present study was aimed to elucidate whether nicotinamide may prevent thiotepa-induced neurodegeneration in the developing rat brain.Methodology/Principal FindingsNeuronal cell death induced by thiotepa was associated with the induction of Bax, release of cytochrome-c from mitochondria into the cytosol, activation of caspase-3 and cleavage of poly (ADP-ribose) polymerase (PARP-1). Post-treatment of developing rats with nicotinamide suppressed thiotepa-induced upregulation of Bax, reduced cytochrome-c release into the cytosol and reduced expression of activated caspase-3 and cleavage of PARP-1. Cresyl violet staining showed numerous dead cells in the cortex hippocampus and thalamus; post-treatment with nicotinamide reduced the number of dead cells in these brain regions. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL) and immunohistochemical analysis of caspase-3 show that thiotepa-induced cell death is apoptotic and that it is inhibited by nicotinamide treatment.ConclusionNicotinamide (Nic) treatment with thiotepa significantly improved neuronal survival and alleviated neuronal cell death in the developing rat. These data demonstrate that nicotinamide shows promise as a therapeutic and neuroprotective agent for the treatment of neurodegenerative disorders in newborns and infants.

Cognitive and Behavioral Outcomes After Early Exposure to Anesthesia and Surgery

Annually, millions of children are exposed to anesthetic agents that cause apoptotic neurodegeneration in immature animals. To explore the possible significance of these findings in children, we investigated the association between exposure to anesthesia and subsequent (1) learning disabilities (LDs), (2) receipt of an individualized education program for an emotional/behavior disorder (IEP-EBD), and (3) scores of group-administered achievement tests. This was a matched cohort study in which children (N = 8548) born between January 1, 1976, and December 31, 1982, in Rochester, Minnesota, were the source of cases and controls. Those exposed to anesthesia (n = 350) before the age of 2 were matched to unexposed controls (n = 700) on the basis of known risk factors for LDs. Multivariable analysis adjusted for the burden of illness, and outcomes including LDs, receipt of an IEP-EBD, and the results of group-administered tests of cognition and achievement were outcomes. Exposure to multiple, but not single, anesthetic/surgery significantly increased the risk of developing LDs (hazard ratio: 2.12 [95% confidence interval: 1.26-3.54]), even when accounting for health status. A similar pattern was observed for decrements in group-administered tests of achievement and cognition. However, exposure did not affect the rate of children receiving an individualized education program. Repeated exposure to anesthesia and surgery before the age of 2 was a significant independent risk factor for the later development of LDs but not the need for educational interventions related to emotion/behavior. We cannot exclude the possibility that multiple exposures to anesthesia/surgery at an early age may adversely affect human neurodevelopment with lasting consequence.

General Anesthesia Causes Long-term Impairment of Mitochondrial Morphogenesis and Synaptic Transmission in Developing Rat Brain.

Clinically used general anesthetics, alone or in combination, are damaging to the developing mammalian brain. In addition to causing widespread apoptotic neurodegeneration in vulnerable brain regions, exposure to general anesthesia at the peak of synaptogenesis causes learning and memory deficiencies later in life. In vivo rodent studies have suggested that activation of the intrinsic (mitochondria-dependent) apoptotic pathway is the earliest warning sign of neuronal damage, suggesting that a disturbance in mitochondrial integrity and function could be the earliest triggering events. Because proper and timely mitochondrial morphogenesis is critical for brain development, the authors examined the long-term effects of a commonly used anesthesia combination (isoflurane, nitrous oxide, and midazolam) on the regional distribution, ultrastructural properties, and electron transport chain function of mitochondria, as well as synaptic neurotransmission, in the subiculum of rat pups. This anesthesia, administered at the peak of synaptogenesis, causes protracted injury to mitochondria, including significant enlargement of mitochondria (more than 30%, P < 0.05), impairment of their structural integrity, an approximately 28% increase in their complex IV activity (P < 0.05), and a twofold decrease in their regional distribution in presynaptic neuronal profiles (P < 0.05), where their presence is important for the normal development and functioning of synapses. Consequently, the authors showed that impaired mitochondrial morphogenesis is accompanied by heightened autophagic activity, decrease in mitochondrial density (approximately 27%, P < 0.05), and long-lasting disturbances in inhibitory synaptic neurotransmission. The interrelation of these phenomena remains to be established. Developing mitochondria are exquisitely vulnerable to general anesthesia and may be important early target of anesthesia-induced developmental neurodegeneration.

Chronic exposure of gestation rat to sevoflurane impairs offspring brain development

Recently it was demonstrated that the exposure of the developing brain during the period of synaptogenesis to drugs that block NMDA glutamate receptors can trigger widespread apoptotic neurodegeneration. Sevoflurane is a new inhalation anesthetic agent commonly used in the clinic. Here we address whether sevoflurane could induce neurotoxicity in the developing brain. Sevoflurane was administered to rats before pregnancy and pregnant rats on embryonic days E6, E10, E14, and E18 1MAC for 6 h, and we employed histopathological, immunochemistry, semiquantitative RT-PCR, and Western blot to investigate the effect of the exposure of pregestation and gestation rats to sevoflurane on the offspring brain development. The results showed that the exposure of gestation but not pregestation rats to sevoflurane-induced extensive apoptotic neurodegeneration in the hippocampus of offspring at P0, P7, and P14, accompanied by altered expression of casepase-3, GAP-43, nNOS, NMDAR1, NMDAR2A, and NMDAR2B. Furthermore, upregulation of PKCα and p-JNK and downregulation of p-ERK and FOS protein levels were observed in the hippocampus of offspring at P0, P7, and P14 from rats exposed to sevoflurane at gestation, but not pregestation. In summary, our data suggest that sevoflurane induces developmental neurotoxicity in rats and this may be attributed to the upregulation of PKCα and p-JNK and downregulation of p-ERK and FOS protein in the hippocampus.

Protective effect of pyruvate against ethanol-induced apoptotic neurodegeneration in the developing rat brain

Exposure to alcohol during the early stages of brain development can lead to neurological disorders in the CNS. Apoptotic neurodegeneration due to ethanol exposure is a main feature of alcoholism. Exposure of developing animals to alcohol (during the growth spurt period in particular) elicits apoptotic neuronal death and causes fetal alcohol effects (FAE) or fetal alcohol syndrome (FAS). A single episode of ethanol intoxication (at 5g/kg) in a seven-day-old developing rat can activate the apoptotic cascade, leading to widespread neuronal death in the brain. In the present study, we investigated the potential protective effect of pyruvate against ethanol-induced neuroapoptosis. After 4h, a single dose of ethanol induced upregulation of Bax, release of mitochondrial cytochrome-c into the cytosol, activation of caspase-3 and cleavage of poly (ADP-ribose) polymerase (PARP-1), all of which promote apoptosis. These effects were all reversed by co-treatment with pyruvate at a well-tolerated dosage (1000mg/kg). Histopathology performed at 24 and 48h with Fluoro-Jade-B and cresyl violet stains showed that pyruvate significantly reduced the number of dead cells in the cerebral cortex, hippocampus and thalamus. Immunohistochemical analysis at 24h confirmed that ethanol-induced cell death is both apoptotic and inhibited by pyruvate. These findings suggest that pyruvate treatment attenuates ethanol-induced neuronal cell loss in the developing rat brain and holds promise as a safe therapeutic and neuroprotective agent in the treatment of neurodegenerative disorders in newborns and infants.

Local and Regional Network Function in Behaviorally Relevant Cortical Circuits of Adult Mice Following Postnatal Alcohol Exposure

Ethanol consumption during pregnancy can lead to fetal alcohol spectrum disorder (FASD), which consists of the complete spectrum of developmental deficits including neurological dysfunction. FASD is associated with a variety of neurobehavioral disturbances dependent on the age and duration of exposure. Ethanol exposure in neonatal rodents can also induce widespread apoptotic neurodegeneration and long-lasting behavioral abnormalities similar to FASD. The developmental stage of neonatal rodent brains that are at the peak of synaptogenesis is equivalent to the third trimester of human gestation. Male and female C57BL/6By mice were injected with ethanol (20%, 2.5 g/kg, 2 s.c. injections) or an equal volume of saline (controls) on postnatal day 7 (P7). Animals were allowed to mature and at 3 months were tested on an olfactory habituation task known to be dependent on piriform cortex function, a hippocampal-dependent object place memory task, and used for electrophysiological testing of spontaneous and odor-evoked local field potential (LFP) activity in the olfactory bulb, piriform cortex, and dorsal hippocampus. P7 ethanol induced widespread cell death within 1 day of exposure, with highest levels in the neocortex, intermediate levels in the dorsal hippocampus, and relatively low levels in the primary olfactory system. No impairment of odor investigation or odor habituation was detected in P7 ethanol-exposed 3-month-old mice compared to saline controls. However, hippocampal-dependent object place memory was significantly impaired in the P7 ethanol-treated adult mice. Odor-evoked LFP activity was enhanced throughout the olfacto-hippocampal pathway, primarily within the theta frequency band, although the hippocampus also showed elevated evoked delta frequency activity. In addition, functional coherence between the piriform cortex and olfactory bulb and between the piriform cortex and dorsal hippocampus was enhanced in the beta frequency range in P7 ethanol-treated adult mice compared to controls. P7 ethanol induces an immediate wave of regionally selective cell death followed by long-lasting changes in local circuit and regional network function that are accompanied by changes in neurobehavioral performance. The results suggest that both the activity of local neural circuits within a brain region and the flow of information between brain regions can be modified by early alcohol exposure, which may contribute to long-lasting behavioral abnormalities known to rely on those circuits.

Alcohol-induced neuronal death in central extended amygdala and pyriform cortex during the postnatal period of the rat

Mothers who consume alcohol during pregnancy may cause a neurotoxic syndrome defined as fetal alcohol spectrum disorder (FASD) in their offspring. This disorder is characterized by reduction in brain size, cognitive deficits and emotional/social disturbances. These alterations are thought to be caused by an alcohol-induced increase in apoptosis during neurodevelopment. Little is known about neuroapoptosis in the central extended amygdala and the pyriform cortex, which are key structures in emotional/social behaviors. The goal of this study was to determine the vulnerability of neuroapoptotic alcohol effects in those areas. Rats were administered alcohol (2.5 g/kg s.c. at 0 and 2 h) or saline on postnatal day (PND) 7, 15 and 20. The Amino-cupric-silver technique was used to evaluate neurodegeneration and immunohistochemistry to detect activated caspases 3–8 and 9 at 2 h, 4, 6, 8, 12 and 24 h after drug administration. We measured blood alcohol levels each hour, from 2 to 8 h post second administration of alcohol in each of the ages studied. Results showed alcohol induced apoptotic neurodegeneration in the central extended amygdala on PND 7 and 15, and pyriform cortex on PND 7, 15 and 20. These structures showed activation of caspase 3 and 9 but not of caspase 8 suggesting that alcohol-induced apoptosis could occur by the intrinsic pathway. The pharmacokinetic differences between ages did not associate with the neurodegeneration age dependence. In conclusion, these limbic areas are damaged by alcohol, and each one has their own window of vulnerability during the postnatal period. The possible implications in emotional/social features in FASD are discussed.

Low-level lead exposure triggers neuronal apoptosis in the developing mouse brain

While the toxic effects of lead have been recognized for millennia, it has remained a significant public health concern due to its continued use and toxicological potential. Of particular interest is the increased susceptibility of young children to the toxic effects of lead. Although the exact mechanism(s) for lead toxicity is currently not well understood, research has established that it can be a potent NMDA antagonist. Previous research has established that exposure to NMDA antagonists during the brain growth spurt period (first 2weeks of life in mice) can produce apoptotic neurodegeneration throughout the brain. Based on this information, the ability of lead exposure (two injections of 350mg/kg lead 4h apart) to produce apoptosis in the neonatal mouse brain was assessed histologically 8–24h after treatment using activated caspase-3 immunohistochemistry, De Olmos silver technique, Nissl staining, and electron microscopy. Lead exposure produced significant neurodegeneration in the caudate/putamen, hippocampus, subiculum, and superficial and deep cortical layers of the frontal cortical regions. Further ultrastructural examination revealed cellular profiles consistent with apoptotic cell death. Statistical results showed that lead exposure significantly increased apoptotic neurodegeneration above that seen in normal controls in animals treated at postnatal day 7, but not on day 14. The results of this study may provide a basis for further elucidation of mechanisms through which the immature nervous system may be particularly susceptible to lead exposure.

Academic Performance in Adolescence after Inguinal Hernia Repair in Infancy

Although animal studies have indicated that general anesthetics may result in widespread apoptotic neurodegeneration and neurocognitive impairment in the developing brain, results from human studies are scarce. We investigated the association between exposure to surgery and anesthesia for inguinal hernia repair in infancy and subsequent academic performance. Using Danish birth cohorts from 1986-1990, we compared the academic performance of all children who had undergone inguinal hernia repair in infancy to a randomly selected, age-matched 5% population sample. Primary analysis compared average test scores at ninth grade adjusting for sex, birth weight, and paternal and maternal age and education. Secondary analysis compared the proportions of children not attaining test scores between the two groups. From 1986-1990 in Denmark, 2,689 children underwent inguinal hernia repair in infancy. A randomly selected, age-matched 5% population sample consists of 14,575 individuals. Although the exposure group performed worse than the control group (average score 0.26 lower; 95% CI, 0.21-0.31), after adjusting for known confounders, no statistically significant difference (-0.04; 95% CI, -0.09 to 0.01) between the exposure and control groups could be demonstrated. However, the odds ratio for test score nonattainment associated with inguinal hernia repair was 1.18 (95% CI, 1.04-1.35). Excluding from analyses children with other congenital malformations, the difference in mean test scores remained nearly unchanged (0.05; 95% CI, 0.00-0.11). In addition, the increased proportion of test score nonattainment within the exposure group was attenuated (odds ratio = 1.13; 95% CI, 0.98-1.31). In the ethnically and socioeconomically homogeneous Danish population, we found no evidence that a single, relatively brief anesthetic exposure in connection with hernia repair in infancy reduced academic performance at age 15 or 16 yr after adjusting for known confounding factors. However, the higher test score nonattainment rate among the hernia group could suggest that a subgroup of these children are developmentally disadvantaged compared with the background population.

Valproic acid induces apoptosis in differentiating hippocampal neurons by the release of tumor necrosis factor-α from activated astrocytes

Human studies of neurodevelopment suggest that children exposed in utero to certain antiepileptic drugs (AEDs) suffer a variety of brain-behavior sequelae, such as neural tube defects, developmental delays, cognitive deficits, etc. Valproic acid (VPA), a commonly used AED, has greater risk for these side effects compared with other AEDs. However, the detailed molecular mechanisms underlying this developmental neurotoxicity of VPA is unclear despite previous research demonstrating that VPA could induce widespread apoptotic neurodegeneration in developing brains of animal models. This study characterizes the role of astrocytes in VPA-induced neurodegeneration. In developing brains, we evaluated the developmental neurotoxicity of VPA on differentiating neurons and astrocytes from neural progenitor cells cultured from the hippocampus of human fetuses. Exposure of a neuron-enriched culture to VPA at 250μM or 500μM did not cause neuronal apoptosis, but at 1mM and 7 days exposure, a slight increase in the percentage of apoptotic cells was observed. In contrast, VPA at 250μM to 1mM, selectively induced neuronal apoptosis in a neuron–astrocyte mixed cell culture model. The VPA-treated astrocytes showed morphological changes, and the level of tumor necrosis factor-α (TNF-α) was elevated in the supernatant. Both neuronal apoptosis and TNF-α release from astrocytes increased with concentration and exposure time to VPA, suggesting a synergism between the two cell types. Treatment of the neuron–astrocyte mixed culture exposed to VPA with TNF-α antibody partly prevented neuronal apoptosis, while the addition of exogenous TNF-α induced apoptosis in both cultures. Moreover, this pro-apoptotic effect was specific to VPA, as another AED, valpromide, failed to mimic this pro-apoptotic effect, nor did an inhibitor of histone deacetylase (iHDAC), sodium butyrate (NaB). We report a novel finding that astrocytes participate in VPA induced neurodegeneration by releasing TNF-α.

Resveratrol prevents alcohol-induced cognitive deficits and brain damage by blocking inflammatory signaling and cell death cascade in neonatal rat brain

Human prenatal ethanol exposure that occurs during a period of increased synaptogenesis known as the 'brain growth spurt' has been associated with significant impairments in attention, learning and memory. Recent studies have shown that administration of ethanol to infant rats during the synaptogenesis period (first 2 weeks after birth) triggers extensive apoptotic neurodegeneration throughout many regions of the developing brain and results in cognitive dysfunctions as the animal matures. The present study was designed with an aim to investigate the effect of resveratrol, a polyphenolic phytoalexin (trans-3,5,4-trihydroxy stilbene) present in red wine on alcohol-induced cognitive deficits and neuronal apoptosis in rat pups postnatally exposed to ethanol. Pups were administered ethanol (5 g/kg, 12% v/v) by intragastric intubation on postnatal days 7, 8, and 9. Ethanol-exposed pups showed impaired memory performance in both Morris water maze elevated plus maze task recorded by using computer tracking with EthoVision software. Behavioral deficit in ethanol-exposed pups was associated with enhanced acetylcholinesterase activity, increased oxidative-nitrosative stress, cytokine (TNF-α, IL-1β and TGF-β), nuclear factor kappa beta and caspase 3 levels in both cerebral cortex and hippocampus. Chronic treatment with resveratrol (10 and 20 mg/kg) significantly attenuated all the behavioral, biochemical and molecular changes in different brain regions of ethanol administered pups. The major finding of the study is that resveratrol blocks activation of nuclear factor kappa beta pathway and apoptotic signaling and prevents cognitive deficits in rats postnatally exposed to ethanol.

Research progress in the effects of general anesthetics on the apoptosis of developing neurons of mammalian brain

It was observed that general anesthetics, such as Ketamin, midazolam, N2O, Diprivan and isoflurane, could trigger the apoptotic neurodegeneration in developing neurons of brain through blocking of NMDAR and/or overactivation of GABAR.The apoptosis is closely associated with the following factors: duration of medication, drug dose, coadministration with other drugs,age of mouse. It is comfirmed by neuroethology tests that the apoptosis will exert lasting influence on learning and memory in the future. Key words: Apoptosis; Ethanol; GABAA receptors; NMDA receptors