Biomedical subjects

Laia Acarin

Publications and source records attributed to Laia Acarin.

9 recordsLinked to original sources

PubMed2006

Neuroprotection from NMDA excitotoxic lesion by Cu/Zn superoxide dismutase gene delivery to the postnatal rat brain by a modular protein vector.

BACKGROUND: Superoxide mediated oxidative stress is a key neuropathologic mechanism in acute central nervous system injuries. We have analyzed the neuroprotective efficacy of the transient overexpression of antioxidant enzyme Cu/Zn Superoxide dismutase (SOD) after excitotoxic injury to the immature rat brain by using a recently constructed modular protein vector for non-viral gene delivery termed NLSCt. For this purpose, animals were injected with the NLSCt vector carrying the Cu/Zn SOD or the control GFP transgenes 2 hours after intracortical N-methyl-D-aspartate (NMDA) administration, and daily functional evaluation was performed. Moreover, 3 days after, lesion volume, neuronal degeneration and nitrotyrosine immunoreactivity were evaluated. RESULTS: Overexpression of Cu/Zn SOD transgene after NMDA administration showed improved functional outcome and a reduced lesion volume at 3 days post lesion. In secondary degenerative areas, increased neuronal survival as well as decreased numbers of degenerating neurons and nitrotyrosine immunoreactivity was seen. Interestingly, injection of the NLSCt vector carrying the control GFP transgene also displayed a significant neuroprotective effect but less pronounced. CONCLUSION: When the appropriate levels of Cu/Zn SOD are expressed transiently after injury using the non-viral modular protein vector NLSCt a neuroprotective effect is seen. Thus recombinant modular protein vectors may be suitable for in vivo gene therapy, and Cu/Zn SOD should be considered as an interesting therapeutic transgene.

Animals↗

PubMed2006

Antioxidant Cu/Zn SOD: expression in postnatal brain progenitor cells.

Precursor cells have been shown to be affected by oxidative stress, in vivo and vitro, but little is known about the expression of antioxidant mechanisms in neuronal/glial differentiation. We have characterized the expression of Cu/Zn superoxide dismutase (Cu/Zn SOD), one of the main antioxidant proteins involved in the breakdown of superoxide, in the immature rat dorsolateral subventricular zone (SVZ), rostral migratory stream (RMS) and hippocampal subgranular zone (SGZ). Progenitor cells were identified immunohistochemically on cryostat sections by 5'Bromodeoxyuridine (BrdU) incorporation and expressing cells were further characterized using double labeling for progenitor markers. In the SVZ, only a subpopulation of BrdU+ cells, mostly found in the medial SVZ, expressed Cu/Zn SOD. These cells were mostly nestin+ and some were also vimentin+. In contrast, in the lateral SVZ few Cu/Zn SOD+/BrdU+ cells were found. These were primarily nestin+, vimentin-, showed some PSA-NCAM expression, but only a few were NG2+. In the RMS and SGZ virtually all BrdU+ progenitors were Cu/Zn SOD+ and expressed nestin and vimentin. Some RMS cells were also PSA-NCAM+. These findings show a heterogeneous expression of Cu/Zn SOD in restricted cell types in the germinative zones and suggest a role for antioxidant Cu/Zn SOD in progenitor cells of the immature rat brain.

Animals↗

PubMed2005

Cu/Zn superoxide dismutase expression in the postnatal rat brain following an excitotoxic injury.

BACKGROUND: In the nervous system, as in other organs, Cu/Zn superoxide dismutase (Cu/Zn SOD) is a key antioxidant enzyme involved in superoxide detoxification in normal cellular metabolism and after cell injury. Although it has been suggested that immature brain has a different susceptibility to oxidative damage than adult brain, the distribution and cell-specific expression of this enzyme in immature brain and after postnatal brain damage has not been documented. METHODS: In this study, we used immunohistochemistry and western blot to analyze the expression of Cu/Zn SOD in intact immature rat brain and in immature rat brain after an NMDA-induced excitotoxic cortical injury performed at postnatal day 9. Double immunofluorescence labelling was used to identify Cu/Zn SOD-expressing cell populations. RESULTS: In intact immature brain, Cu/Zn SOD enzyme was widely expressed at high levels in neurons mainly located in cortical layers II, III and V, in the sub-plate, in the pyriform cortex, in the hippocampus, and in the hypothalamus. Glial fibrillary acidic protein-positive cells only showed Cu/Zn SOD expression in the glia limitans and in scattered cells of the ventricle walls. No expression was detected in interfascicular oligodendroglia, microglia or endothelial cells. Following excitotoxic damage, neuronal Cu/Zn SOD was rapidly downregulated (over 2-4 hours) at the injection site before neurodegeneration signals and TUNEL staining were observed. Later, from 1 day post-lesion onward, an upregulation of Cu/Zn SOD was found due to increased expression in astroglia. A further increase was observed at 3, 5 and 7 days that corresponded to extensive induction of Cu/Zn SOD in highly reactive astrocytes and in the astroglial scar. CONCLUSION: We show here that, in the intact immature brain, the expression of Cu/Zn SOD was mainly found in neurons. When damage occurs, a strong and very rapid downregulation of this enzyme precedes neuronal degeneration, and is followed by an upregulation of Cu/Zn SOD in astroglial cells.

Journal Article↗

PubMed2005

Proliferation dynamics of germinative zone cells in the intact and excitotoxically lesioned postnatal rat brain.

BACKGROUND: The forebrain subventricular zone (SVZ)-olfactory bulb pathway and hippocampal subgranular zone (SGZ) generate neurons into adulthood in the mammalian brain. Neurogenesis increases after injury to the adult brain, but few studies examine the effect of injury on neural and glial precursors in the postnatal brain. To characterize the spatio-temporal dynamics of cell proliferation in the germinative zones, this study utilized a model of postnatal damage induced by NMDA injection in the right sensorimotor cortex at postnatal day 9. Dividing cell populations were labeled with 5-Bromodeoxyuridine (BrdU) in the intact and damaged postnatal brain. Identity of proliferating cells was determined by double immunolabeling with nestin, GFAP, NeuN and tomato lectin (TL). RESULTS: In the control brain, grouped BrdU+ cells were observed in the Rostral Migratory Stream (RMS), SVZ and SGZ. Maximal proliferation was seen at P12, persisted until P23 and diminished by P49. After injury, a striking reduction in the number of BrdU+ cells was observed in the ipsilateral SVZ from 10 hours (58% decrease) until 14 days post-lesion (88% decrease). In contrast, an increase in grouped BrdU+ cells was seen in the striatum adjacent to the depleted SVZ. Significantly reduced numbers of BrdU+ cells were also seen in the RMS until 3 days post-lesion. No changes were noted in the SGZ. Both in controls and lesioned hemispheres, BrdU+ cells located in the germinal zones were mostly nestin positive and negative for GFAP, NeuN, and TL. In the SVZ area lining the ventricle, BrdU+/nestin+ cells were mainly located between TL+ ependyma and parenchymal GFAP+ astrocytes. After excitotoxicity, a decrease in the number and orientation of GFAP/nestin+ prolongations leaving the SVZ to the cortex, corpus callosum and striatum was noted until 5 days post-lesion. CONCLUSION: Postnatal excitotoxic injury differentially affects proliferating cells in the germinative zones: no change is observed in the dentate gyrus whereas excitotoxicity causes a significant decrease in proliferating cells in the SVZ and RMS. Depletion of BrdU+ cells in the postnatal SVZ and RMS differs from previous studies after adult brain injury and may affect the SVZ-RMS migration and is suggestive of progenitor recruitment to injured areas.

Animals↗

PubMed2005

Astroglial nitration after postnatal excitotoxic damage: correlation with nitric oxide sources, cytoskeletal, apoptotic and antioxidant proteins.

Oxygen free radicals and nitric oxide (NO) participate in the pathogenesis of acute central nervous system (CNS) injury by forming peroxynitrite, which promotes oxidative damage and tyrosine nitration. Neuronal nitration is associated with cell death, but little is known of the characteristics and cell fate of nitrated astrocytes. In this study, we have used a postnatal excitotoxic lesion model (intracortical NMDA injection) and our aims were (i) to evaluate the temporal and spatial pattern of astroglial nitration in correlation with the neuropathological process and the sources of NO; and (ii) to establish, if any, the correlation among astrocyte nitration and other events such as expression of cytoskeletal proteins, antioxidant enzymes, and cell death markers to cope with nitration and/or undergo cell death. Our results show that after postnatal excitotoxic damage two distinct waves of nitration were observed in relation to astrocytes. At 24 h post-lesion, early-nitrated astrocytes were found within the neurodegenerating area, coinciding with the time of maximal cell death. These early-nitrated astrocytes are highly ramified protoplasmic cells, showing diffuse glial fibrillary acidic protein (GFAP) content and expressing inducible NOS. At later time-points, when astrogliosis is morphologically evident, nitrated hypertrophied reactive astrocytes are observed in the penumbra and the neurodegenerated area, displaying increased expression of GFAP and vimentin cytoskeletal proteins and of metallothionein I-II and Cu/Zn superoxide dismutase antioxidant proteins. Moreover, despite revealing activated caspase-3, they do not show TUNEL labeling. In summary, we show that nitrated astrocytes in vivo constitute a subpopulation of highly reactive astrocytes which display high resistance towards oxidative stress induced cell death.

Animals↗

PubMed2002

Expression of inducible nitric oxide synthase and cyclooxygenase-2 after excitotoxic damage to the immature rat brain.

It is well established that after adult brain damage the enzymes cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) play an important role in the inflammatory processes and oxidative stress, which are considered to be the leading factors contributing to delayed cell death. The contribution of these enzymes to postnatal brain damage, however, is poorly understood. In our study, excitotoxic lesions were induced by the injection of N-methyl-D-aspartate in the cortex of postnatal day 9 rats. After different survival times ranging from 4 hr to 7 days post-lesion, brain sections were processed for the immunocytochemical demonstration of COX-2 and iNOS and double labeling with neuronal, glial and neutrophil markers. First and maximal de novo induction of iNOS and COX-2 expression was found at 10 hr post-lesion. Expression of both enzymes started to diminish at 24 hr, reaching basal levels at day 3. iNOS-expressing cells were mainly identified as infiltrated neutrophils as well as highly ramified protoplasmic astrocytes closely associated with blood vessels. Moreover, scattered iNOS-positive neurons were found at the lesion borders. In contrast, COX-2 was mainly observed in reactive microglial cells and neuronal cells. COX-2-positive neurons were found within the degenerating area at 10 hr and at the borders of the lesion later on. This study shows that maximal iNOS and COX-2 expression precedes the period of massive neuronal death observed at 24 hr post-lesion, and may therefore contribute to the evolution of the inflammatory response and the neurodegenerative process after an excitotoxic lesion to the postnatal brain.

Animals↗

PubMed2002

Glial expression of small heat shock proteins following an excitotoxic lesion in the immature rat brain.

Heat shock proteins (HSPs) are chaperones induced under pathological conditions and involved in protein stabilization and cellular protection. In this study, we have evaluated the expression pattern of the glial cell-related HSP27, HSP32, and HSP47 following an excitotoxic lesion in the immature rat brain. Postnatal day 9 rats received an intracortical injection of N-methyl-D-aspartate and tissue was processed immunohistochemically for HSPs and double labeling using astroglial and microglial markers. HSP expression was quantified by image analysis. Excitotoxic damage caused primary cortical degeneration and secondary damage in the corresponding thalamus. In the injured cortex, reactive microglia/macrophages expressed HSP32 from 10 h until 14 days postlesion (PL), showing maximal levels at days 3-5. In parallel, most cortical reactive astrocytes showed expression of HSP47 from 10 h until 14 days PL and a population of them also displayed HSP27 labeling from 1 day PL. In addition, some cortical reactive astrocytes showed a temporary expression of HSP32 at day 1. In general, astroglial HSP expression in the cortex achieved maximal levels at days 3-5 PL. In the damaged thalamus, HSP32 was not significantly induced, but reactive astrocytes expressed HSP47 and some of them also HSP27. Thalamic astroglial HSP induction was transient, peaked at 5 days PL and reached basal levels by day 14. The injury-induced expression of HSP32, HSP27, and HSP47 in glial cells may contribute to glial cell protection and adaptation to damage, therefore playing an important role in the evolution of the glial response and the excitotoxic lesion outcome. HSP32 may provide antioxidant protective mechanisms to microglia/macrophages, whereas HSP47 could contribute to extracellular matrix remodeling and HSP27 may stabilize the astroglial cytoskeleton and participate in astroglial antioxidant mechanisms.

Aging↗

PubMed2002

NF-kappaB and IkappaBalpha expression following traumatic brain injury to the immature rat brain.

NF-kappaB is one of the most important modulators of stress and inflammatory gene expression in the nervous system. In the adult brain, NF-kappaB upregulation has been demonstrated in neurons and glial cells in response to experimental injury and neuropathological disorders, where it has been related to both neurodegenerative and neuroprotective activities. Accordingly, the aim of this study was to evaluate the cellular and temporal patterns of NF-kappaB activation and the expression of its endogenous inhibitor IkappaBalpha following traumatic brain injury (TBI) during the early postnatal weeks, when the brain presents elevated levels of plasticity and neuroprotection. Our results showed that cortical trauma to the 9-day-old rat brain induced a very fast upregulation of NF-kappaB, which was maximal within the first 24 hours after injury. NF-kappaB was mainly observed in neuronal cells of the degenerating cortex as well as in astrocytes located in the corpus callosum adjacent to the injury, where a pulse-like pattern of microglial NF-kappaB activation was also found. In addition, astrocytes of the corpus callosum, and microglial cells to a lower extent, also showed de novo expression of IkappaBalpha within the time of NF-kappaB activation. This study suggests an important role of NF-kappaB activation in the early mechanisms of neuronal death or survival, as well as in the development of the glial and inflammatory responses following traumatic injury to the immature rat brain.

Age Factors↗

PubMed2002

Decrease of proinflammatory molecules correlates with neuroprotective effect of the fluorinated salicylate triflusal after postnatal excitotoxic damage.

BACKGROUND AND PURPOSE: The fluorinated salicylate triflusal has been shown to have a neuroprotective effect after an excitotoxic lesion to the postnatal brain. In this regard, the aim of this study was to elucidate whether neuroprotection was associated with changes in the expression of proinflammatory molecules such as interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), inducible nitric oxide synthase (iNOS), or cyclooxygenase-2 (COX-2), well-known mediators of oxidative stress and inflammation, mechanisms underlying secondary damage occurring after excitotoxic/ischemic brain injury. METHODS: Postnatal day 9 rats received an intracortical injection of N-methyl-D-aspartate followed by oral administration of triflusal (30 mg/kg) 8 hours later. Ten or 24 hours after lesion, animals were killed, and brain sections processed for the immunohistochemical demonstration of IL-1beta, TNF-alpha, iNOS, and COX-2. RESULTS: Besides a reduction in the neurodegenerative area, triflusal strongly decreased iNOS immunolabeling at both survival times analyzed, attenuating iNOS immunoreactivity in astroglial cells and infiltrated neutrophils. Additionally, a moderate reduction in COX-2, IL-1beta, and TNF-alpha was observed. Triflusal decreased neuronal and microglial COX-2 expression at 10 and 24 hours after lesion and microglial and astroglial expression of IL-1beta and TNF-alpha at 24 hours after lesion. TNF-alpha expression in neuronal cells at 10 hours after lesion was, however, maintained. CONCLUSIONS: This study suggests that triflusal neuroprotection is associated with a decrease of iNOS and other inflammatory mediators and therefore may constitute a good therapeutic agent in pathological situations in which regulation of inflammatory genes constitutes a relevant step in the outcome of the neurodegenerative event.

Administration, Oral↗