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Oxygen resuscitation exacerbates hypoxic ischemic outcomes in rat cortex
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Poster Session 2 Abstracts 3 June 2008 / Int. J. Devl Neuroscience 26 (2008) 867–892
[P2.03] Oxygen resuscitation exacerbates hypoxic ischemic outcomes in rat cortex C.B.R. Reilly, H.C.R. Rea *, M.B.G. Gill, D.C.F. Ferrari University of Texas Medical Branch, USA *Corresponding author. Keywords: Hypoxia-ischemia; Hyperoxia; Inflammation; Cyclooxygenase 2
Using a P7 rat model of hypoxic-ischemic (HI) brain injury we have shown that exposure to hypoxia and hyperoxia (HHI) results in generation of reactive oxygen species, inflammation and cell death—all risk factors for subsequent deficits in neuronal development and function. Hyperoxia increases oxidative stress that can trigger inflammatory cascades, neutrophil activation, and brain microvascular injury. Our experiments utilize a modified version of the Rice–Vanucci model of perinatal hypoxia-ischemia in Wistar rat pups that undergo exposure to 100% oxygen. By using T2weighted magnetic resonance imaging we documented enhanced cortical lesions in HHI animals. Electrochemical monitoring showed bursts of superoxide during 100% oxygen resuscitation. Western blot analyses showed increased cell death measured by cleaved caspase 3 and cytosolic oligonucleosomes, and augmented IL-1 signalling above and beyond levels reported for HI alone. Multiplex antibody cytokine assay demonstrates a spectrum of pro-inflammatory cytokines elevated at 24 h post injury. Consistent with the observed increases in oxidative stress components in the HI rat pups resuscitated with 100% oxygen, there was an increase in COX-2 levels likely to account in part for the increase in oxidative stress. In 80% of preterm infants, the common view is that the benefits of oxygen therapy outweigh the risks. We have shown deficits in attention, motor, visual-motor, and executive processing skills in preterm infants otherwise considered ‘‘healthy,’’ but these are not apparent before entry into formal learning settings [Smith et al., 2008. Int. J. Dev. Neurosci. 26 (1): 125–131]. Few clinical studies have attempted to target improving outcomes in this large preterm population. These deficits may be accounted for by inflammation caused by the use of 100% oxygen resuscitation. Our long-term goal is to guide clinical trials of oxygen resuscitation by exploring its consequences in the P7 rat model of HI and developing novel interventions that will enhance benefits while decreasing inflammatory consequences. doi: 10.1016/j.ijdevneu.2008.09.128 [P2.04] Autism-like behaviors in BTBR T+tf/J mice are not attributable to early maternal environment or corpus callosum absence M. Yang *, A. Clarke, V. Zhodzishsky, J. Crawley National Institute of Mental Health, USA *Corresponding author. Keywords: Autism etiology; Corpus callosum agenesis; Social behaviors; BTBR T+tf/ J mice
Autism is a neurodevelopmental disorder of complex etiology. Both genetic and environmental factors have been implicated. BTBR T+tf/J (BTBR) is an inbred strain of mice that displays social deficits and repetitive behaviors analogous to the first and third defining symptoms of autism, representing a promising mouse model for autism. In searching for the causes of the autism-like phenotypes in BTBR, we tested possible hypotheses: (1) early postnatal maternal environment, and (2) the complete absence of a corpus callosum (CC), in the BTBR brain.
To test the maternal hypothesis, entire litters of pups were cross-fostered to either a dam of the same strain or one of the opposite strain, within 24 h after birth. Offspring were tested for juvenile play at postnatal day 21 (PND21), for sociability and selfgrooming between 8 and 11 weeks. Results indicate that crossfostering had no effect on play behaviors in juveniles of, and did not affect sociability and self-grooming in adults. To test the acallosal hypothesis, we lesioned the CC in the commonly used C57BL/6J (B6) strain, and also evaluated LP/J, a strain with a normal CC that is genetically closest to BTBR. CC lesion at PND 7 did not affect sociability nor elevate self-grooming in B6. LP/J resembled BTBR in displaying juvenile play deficits and repetitive self-grooming. These findings rule out the CC absence as the necessary or sufficient condition for the autistic-like phenotypes in BTBR. Our findings support a genetic basis for the autism-like phenotypes in BTBR, rather than early maternal care or CC reduction per se. The CC absence in BTBR may represent one of many subtle abnormalities in the development of brain pathways. Genes whose mutations underlie such subtle disruptions are likely to contribute to the aberrant behavioral phenotypes in the BTBR mouse model of autism. Supported by the NIMH Intramural Research Program. doi: 10.1016/j.ijdevneu.2008.09.129 [P2.05] Region-restricted origins of astrocytes in the developing spinal cord H.-H. Tsai 1,*, L.C. Foo 2, B.A. Barres 2, W.D. Richardson 3, D.H. Rowitch 1 1
UCSF, USA Stanford University, USA 3 University College London, UK *Corresponding author. 2
Keywords: Astrocyte origin; Spinal cord; Olig2; Lineage tracing
There are three major cell types in the central nervous system, and they are neurons, oligodendrocytes, and astrocytes. Astrocytes are glial cells responsible for diverse functions, such as modulating synaptic functions and providing trophic support for neurons and other glia. Astrocytes are generally considered to be homogeneous. However, the developmental origins of astrocytes are not well established, and it is unclear whether diverse functions exerted by astrocytes correspond to astrocyte molecular and cellular heterogeneity. In order to elucidate the in vivo origin(s) of astrocytes in the developing mouse spinal cord and to gain insights into astrocyte heterogeneity, we used a series of mouse lines expressing Cre proteins under specific neuroepithelial markers representing several progenitor domains along the dorsal–ventral axis of the spinal cord. By crossing those mice to conditional green fluorescent protein (GFP) reporter lines, progeny from specific domains are permanently marked by Cre. The marked GFP + cells are quantitatively analyzed for their lineage identities to be neurons, oligodendrocytes, or (1) fibrous astrocytes or (2) protoplasmic astrocytes at postnatal stages (P1 to P28). We found that the most dorsal domain in the spinal cord, represented by Math-1, does not contribute to astrogenesis. Whereas about 20% of marked cells generated from the more ventral domain, represented by Ngn3, are astrocytes. Among the labeled cells from the Olig2 domain, only about 2–3% of the cells are astrocytes at P7.
Poster Session 2 Abstracts 3 June 2008 / Int. J. Devl Neuroscience 26 (2008) 867–892
[P2.03] Oxygen resuscitation exacerbates hypoxic ischemic outcomes in rat cortex C.B.R. Reilly, H.C.R. Rea *, M.B.G. Gill, D.C.F. Ferrari University of Texas Medical Branch, USA *Corresponding author. Keywords: Hypoxia-ischemia; Hyperoxia; Inflammation; Cyclooxygenase 2
Using a P7 rat model of hypoxic-ischemic (HI) brain injury we have shown that exposure to hypoxia and hyperoxia (HHI) results in generation of reactive oxygen species, inflammation and cell death—all risk factors for subsequent deficits in neuronal development and function. Hyperoxia increases oxidative stress that can trigger inflammatory cascades, neutrophil activation, and brain microvascular injury. Our experiments utilize a modified version of the Rice–Vanucci model of perinatal hypoxia-ischemia in Wistar rat pups that undergo exposure to 100% oxygen. By using T2weighted magnetic resonance imaging we documented enhanced cortical lesions in HHI animals. Electrochemical monitoring showed bursts of superoxide during 100% oxygen resuscitation. Western blot analyses showed increased cell death measured by cleaved caspase 3 and cytosolic oligonucleosomes, and augmented IL-1 signalling above and beyond levels reported for HI alone. Multiplex antibody cytokine assay demonstrates a spectrum of pro-inflammatory cytokines elevated at 24 h post injury. Consistent with the observed increases in oxidative stress components in the HI rat pups resuscitated with 100% oxygen, there was an increase in COX-2 levels likely to account in part for the increase in oxidative stress. In 80% of preterm infants, the common view is that the benefits of oxygen therapy outweigh the risks. We have shown deficits in attention, motor, visual-motor, and executive processing skills in preterm infants otherwise considered ‘‘healthy,’’ but these are not apparent before entry into formal learning settings [Smith et al., 2008. Int. J. Dev. Neurosci. 26 (1): 125–131]. Few clinical studies have attempted to target improving outcomes in this large preterm population. These deficits may be accounted for by inflammation caused by the use of 100% oxygen resuscitation. Our long-term goal is to guide clinical trials of oxygen resuscitation by exploring its consequences in the P7 rat model of HI and developing novel interventions that will enhance benefits while decreasing inflammatory consequences. doi: 10.1016/j.ijdevneu.2008.09.128 [P2.04] Autism-like behaviors in BTBR T+tf/J mice are not attributable to early maternal environment or corpus callosum absence M. Yang *, A. Clarke, V. Zhodzishsky, J. Crawley National Institute of Mental Health, USA *Corresponding author. Keywords: Autism etiology; Corpus callosum agenesis; Social behaviors; BTBR T+tf/ J mice
Autism is a neurodevelopmental disorder of complex etiology. Both genetic and environmental factors have been implicated. BTBR T+tf/J (BTBR) is an inbred strain of mice that displays social deficits and repetitive behaviors analogous to the first and third defining symptoms of autism, representing a promising mouse model for autism. In searching for the causes of the autism-like phenotypes in BTBR, we tested possible hypotheses: (1) early postnatal maternal environment, and (2) the complete absence of a corpus callosum (CC), in the BTBR brain.
To test the maternal hypothesis, entire litters of pups were cross-fostered to either a dam of the same strain or one of the opposite strain, within 24 h after birth. Offspring were tested for juvenile play at postnatal day 21 (PND21), for sociability and selfgrooming between 8 and 11 weeks. Results indicate that crossfostering had no effect on play behaviors in juveniles of, and did not affect sociability and self-grooming in adults. To test the acallosal hypothesis, we lesioned the CC in the commonly used C57BL/6J (B6) strain, and also evaluated LP/J, a strain with a normal CC that is genetically closest to BTBR. CC lesion at PND 7 did not affect sociability nor elevate self-grooming in B6. LP/J resembled BTBR in displaying juvenile play deficits and repetitive self-grooming. These findings rule out the CC absence as the necessary or sufficient condition for the autistic-like phenotypes in BTBR. Our findings support a genetic basis for the autism-like phenotypes in BTBR, rather than early maternal care or CC reduction per se. The CC absence in BTBR may represent one of many subtle abnormalities in the development of brain pathways. Genes whose mutations underlie such subtle disruptions are likely to contribute to the aberrant behavioral phenotypes in the BTBR mouse model of autism. Supported by the NIMH Intramural Research Program. doi: 10.1016/j.ijdevneu.2008.09.129 [P2.05] Region-restricted origins of astrocytes in the developing spinal cord H.-H. Tsai 1,*, L.C. Foo 2, B.A. Barres 2, W.D. Richardson 3, D.H. Rowitch 1 1
UCSF, USA Stanford University, USA 3 University College London, UK *Corresponding author. 2
Keywords: Astrocyte origin; Spinal cord; Olig2; Lineage tracing
There are three major cell types in the central nervous system, and they are neurons, oligodendrocytes, and astrocytes. Astrocytes are glial cells responsible for diverse functions, such as modulating synaptic functions and providing trophic support for neurons and other glia. Astrocytes are generally considered to be homogeneous. However, the developmental origins of astrocytes are not well established, and it is unclear whether diverse functions exerted by astrocytes correspond to astrocyte molecular and cellular heterogeneity. In order to elucidate the in vivo origin(s) of astrocytes in the developing mouse spinal cord and to gain insights into astrocyte heterogeneity, we used a series of mouse lines expressing Cre proteins under specific neuroepithelial markers representing several progenitor domains along the dorsal–ventral axis of the spinal cord. By crossing those mice to conditional green fluorescent protein (GFP) reporter lines, progeny from specific domains are permanently marked by Cre. The marked GFP + cells are quantitatively analyzed for their lineage identities to be neurons, oligodendrocytes, or (1) fibrous astrocytes or (2) protoplasmic astrocytes at postnatal stages (P1 to P28). We found that the most dorsal domain in the spinal cord, represented by Math-1, does not contribute to astrogenesis. Whereas about 20% of marked cells generated from the more ventral domain, represented by Ngn3, are astrocytes. Among the labeled cells from the Olig2 domain, only about 2–3% of the cells are astrocytes at P7.