Expression of c-fos and hsp70 mRNA after traumatic brain injury in transgenic mice overexpressing CuZn-superoxide dismutase

Pediococcus acidilactici CCFM6432 mitigates chronic stress-induced anxiety and gut microbial abnormalities

The discovery of psychobiotics has improved the therapeutic choices available for clinical mental disorders and shows promise for regulating mental health in people by combining the properties of food and medicine. A Pediococcus acidilactici strain CCFM6432 was previously isolated and its mood-regulating effect was investigated in this study. Viable bacteria were given to chronically stressed mice for five weeks, and then the behavioral, neurobiological, and gut microbial changes were determined. CCFM6432 significantly reduced stress-induced anxiety-like behaviors, mitigated hypothalamic-pituitary-adrenal (HPA) axis hyperactivity, and reversed the abnormal expression of hippocampal phosphorylated CREB and the c-Fos protein. In particular, CCFM6432 improved the gut microbial composition by inhibiting the over-proliferated pathogenic bacteria (e.g., Escherichia-shigella) and promoting beneficial bacteria growth (e.g., Bifidobacterium). Lactic acid, rather than bacteriocin, was further confirmed as the key compound that determined the antimicrobial activity of CCFM6432. Collectively, these results first proved the psychobiotic potential of the Pediococcus acidilactici strain. Ingestion of CCFM6432, or fermented food containing it, may facilitate mental health management in daily life, especially during the COVID-19 pandemic.

Mitochondrial functions in astrocytes: neuroprotective implications from oxidative damage by rotenone

Mitochondria are critical for cell survival and normal development, as they provide energy to the cell, buffer intracellular calcium, and regulate apoptosis. They are also major targets of oxidative stress, which causes bioenergetics failure in astrocytes through the activation of different mechanisms and production of oxidative molecules. This review provides an insightful overview of the recent discoveries and strategies for mitochondrial protection in astrocytes. We also discuss the importance of rotenone as an experimental approach for assessing oxidative stress in the brain and delineate some molecular strategies that enhance mitochondrial function in astrocytes as a promising strategy against brain damage.

Astrocytic-neuronal crosstalk: implications for neuroprotection from brain injury

The older neurocentric view of the central nervous system (CNS) has changed radically with the growing understanding of the many essential functions of astrocytes. Advances in our understanding of astrocytes include new observations about their structure, organization, function and supportive actions to other cells. Although the contribution of astrocytes to the process of brain injury has not been clearly defined, it is thought that their ability to provide support to neurons after cerebral damage is critical. Astrocytes play a fundamental role in the pathogenesis of brain injury-associated neuronal death, and this secondary injury is primarily a consequence of the failure of astrocytes to support the essential metabolic needs of neurons. These needs include K+ buffering, glutamate clearance, brain antioxidant defense, close metabolic coupling with neurons, and the modulation of neuronal excitability. In this review, we will focus on astrocytic activities that can both protect and endanger neurons, and discuss how manipulating these functions provides a novel and important strategy to enhance neuronal survival and improve the outcome following brain injury.

CuZn-SOD deficiency, rather than overexpression, is associated with enhanced recovery and attenuated activation of NF-kappaB after brain trauma in mice

Superoxide-dismutases (SOD) catalyze O2- conversion to hydrogen peroxide (H2O2) and with other antioxidant enzymes and low molecular weight antioxidants (LMWA) constitute endogenous defense mechanisms. We first assessed the effects of SOD1 levels on outcome after closed head injury (CHI) and later, based on these results, the effects of SOD1 deficiency on cellular redox homeostasis. Superoxide-dismutase 1-deficient (SOD1-/-) and -overexpressing (transgenic (Tg)) mice and matched wild-type (WT) controls were subjected to CHI and outcome (neurobehavioral and memory functions) was assessed during 14 days. Brain edema, LMWA, and SOD2 activity were measured along with histopathological analysis. Transactivation of nuclear factor-kappa B (NF-kappaB) was evaluated by electromobility shift assay. Mortality, motor, and cognitive outcome of Tg and WT mice were comparable. Mortality and edema were similar in SOD1-/- and WT mice, yet, unexpectedly, SOD1-/- displayed better neurobehavioral recovery (P<0.05) at 14 days after CHI. Basal LMWA were higher in the cortex and liver of SOD1-/- mice (P<0.05) and similar to WT in the cerebellum. Five minutes after CHI, cortical LMWA decreased only in SOD1-/- mice. One week after CHI, SOD2 activity decreased fourfold in WT cortex (P<0.001), but was preserved in the SOD1-/-. Constitutive NF-kappaB transactivation was comparably low in SOD1-/- and WT; however, CHI induced a robust NF-kappaB activation that was absent in SOD1-/- cortices (P<0.005 versus WT). At the same time, immunohistochemical analysis of brain sections revealed that astrogliosis and neurodegeneration were of lesser severity in SOD1-/- mice. We suggest that SOD1 deficiency impairs H2O2-mediated activation of NF-kappaB, decreasing death-promoting signals, and leading to better outcome.

Inhibition of aquaporin-4 expression in astrocytes by RNAi determines alteration in cell morphology, growth, and water transport and induces changes in ischemia-related genes

Recent studies indicate a key role of aquaporin (AQP) 4 in astrocyte swelling and brain edema and suggest that AQP4 inhibition may be a new therapeutic way for reducing cerebral water accumulation. To understand the physiological role of AQP4-mediated astroglial swelling, we used 21-nucleotide small interfering RNA duplexes (siRNA) to specifically suppress AQP4 expression in astrocyte primary cultures. Semiquantitative RT-PCR experiments and Western blot analysis showed that AQP4 silencing determined a progressive and parallel reduction in AQP4 mRNA and protein. AQP4 gene suppression determined the appearance of a new morphological cell phenotype associated with a strong reduction in cell growth. Water transport measurements showed that the rate of shrinkage of AQP4 knockdown astrocytes was one-half of that of controls. Finally, cDNA microarray analysis revealed that the gene expression pattern perturbed by AQP4 gene silencing concerned ischemia-related genes, such as GLUT1 and hexokinase. Taken together, these results indicate that 1) AQP4 seems to be the major factor responsible for the fast water transport of cultured astrocytes; 2) as in skeletal muscle, AQP4 is a protein involved in cell plasticity; 3) AQP4 alteration may be a primary factor in ischemia-induced cerebral edema; and 4) RNA interference could be a new potent tool for studying AQP pathophysiology in those organs and tissues where they are expressed.

Fos protein expression following acute administration of diethyldithiocarbamate in rats

Dithiocarbamates are compounds commonly used in medicine and in agriculture and their prolonged use is known to result in neurotoxicity. Whether this response may be related to early gene expression has not been investigated. We have addressed this issue by mapping Fos expression in rats acutely injected with diethyldithiocarbamate (DDTC) and correlating these data to neural damage in the hippocampus as determined by pyknotic nuclei count. In comparison to saline injected rats, DDTC treatment induced a marked Fos expression in most brain regions at 1 and 3 h. In the hippocampus, a high Fos expression was followed by a variable number of pyknotic nuclei at 6 h, depending on the subregion. The data suggest that, in this model of neurotoxicity, c-fos induction does not reflect a cell commitment to die or survive, but rather a cell response to the DDTC-induced oxidative disorder.

Glutamine and its relationship with intracellular redox status, oxidative stress and cell proliferation/death

Glutamine is a multifaceted amino acid used for hepatic urea synthesis, renal ammoniagenesis, gluconeogenesis in both liver and kidney, and as a major respiratory fuel for many cells. Decreased glutamine concentrations are found during catabolic stress and are related to susceptibility to infections. Besides, glutamine is not only an important energy source in mitochondria, but is also a precursor of the brain neurotransmitter glutamate, which is likewise used for biosynthesis of the cellular antioxidant glutathione. Reactive oxygen species, such as superoxide anions and hydrogen peroxide, function as intracellular second messengers activating, among others, apoptosis, whereas glutamine is an apoptosis suppressor. In fact, it could contribute to block apoptosis induced by exogenous agents or by intracellular stimuli. In conclusion, this article shows evidences for the important role of glutamine in the regulation of the cellular redox balance, including brain oxidative metabolism, apoptosis and tumour cell proliferation.

Depolarization induces insulin-like growth factor binding protein-2 expression in vivo via NMDA receptor stimulation

The effect of depolarization and N-methyl-D-aspartate (NMDA) receptor blockade on insulin-like growth factor-I (IGF-I), IGF binding protein-2 (IGFBP-2) and IGFBP-4 expression was analysed in vivo. Depolarization was induced in adult rat brains by applying 3 M KCl to the exposed cortex for 10 min. A subgroup of animals also received daily injections of MK-801. Four days after KCl exposure, the brains were analysed by in situ hybridization, immunohistochemistry and TUNEL. A significant upregulation of IGFBP-2 mRNA and protein was detected in astrocytes after KCl exposure This upregulation was reduced by MK-801 treatment. No alterations in IGF-I or IGFBP-4 mRNA levels were noted. We did not detect TUNEL positive cells, morphological signs of necrosis or apoptosis, or neuronal loss in the depolarized zone. Taken together, these findings indicate that upregulation of IGFBP-2 by depolarization is mediated by NMDA receptors, and, as no neuronal damage was detected, astrocytic NMDA receptors may be responsible for this upregulation.

The expression and changes of heat shock protein 70, MDA and haemorheology in rat cortex after diffuse axonal injury with secondary insults

In the present study the role of heat shock protein 70 (HSP70) expression, changes of malonyldialdehyde (MDA) in rat cortex and haemorheology with time after diffuse axonal injury (DAI) only and DAI with secondary insults (SI) were studied. The rat DAI and DAI with SI model were made according to our previous work and animals were divided into a control and another five injury groups with time after injury. Immunohistochemical assay was used to detect the neuronal expression of HSP70 at 0.5h, 3h, 12h, 24h, 72h after DAI or DAI with SI. In the meantime, the high (etah ) and low whole blood viscosity (etaL ), haematocrit (HCT) and RBC aggregation index (AI = etaL/etah ) were also detected and calculated. MDA in the homogenised brain tissue was assayed by thiobarbituric acid (TBA) reaction. The results showed that HSP70 positive neurons were not detected at 30 minutes, but the number of HSP70 positive neurons begin to increase obviously at 3 hours, reach a peak at 24 hours (P< 0.01), and decrease at 72 hours (P= 0.05) after brain injury. The trend of expression of HSP70 was alike for both DAI only or DAI with SI. Meanwhile, MDA, etah, etaL, HCT and AI changes showed the same tendency. Compared with DAI only group, MDA and blood viscosity indexes in DAI with SI were significantly higher at respective time points (P< 0.01). It is concluded that HSP70 expression, MDA and haemorheology indices increased after brain injury and brain injury with SI. Free radicals and haemorheological changes play an important role in the aggravation of brain damage and HSP70 expression upregulation.

Cell death after exposure to subarachnoid hemolysate correlates inversely with expression of CuZn-superoxide dismutase

BACKGROUND AND PURPOSE

Subarachnoid hemolysate (SAH) has been associated with oxidative brain injury, cell death, and apoptosis. We hypothesized that over-expression of CuZn-superoxide dismutase (CuZn-SOD) would protect against injury after SAH, whereas reduction of its expression would exacerbate injury.

METHODS

Saline (n=16) or hemolysate (n=50) was injected into transgenic mice overexpressing CuZn-SOD (SOD1-Tg), CuZn-SOD heterozygous knockout mutants (SOD1+/-), and wild-type littermates (Wt). Mice were killed at 24 hours. Stress gene induction was evaluated by immunocytochemistry and Western blotting for hemeoxygenase-1 and heat shock protein 70. Apoptosis was evaluated by 3'-OH nick end-labeling and DNA gel electrophoresis. Cell death was quantified through histological assessment after cresyl violet staining.

RESULTS

Histological assessment demonstrated neocortical cell death in regions adjacent to the blood injection. Overall cell death was reduced 43% in SOD1-Tg mutants (n=6) compared with Wt littermates (n=6; P<0.02). In contrast, cell death was increased >40% in SOD1+/- mutants (n=6; P<0.05). Both hemeoxygenase-1 and heat shock protein 70 were induced after SAH. Apoptosis was also present after SAH, as evidenced by 3'-OH end-labeling and DNA laddering. However, the degree of stress gene induction and apoptosis did not vary between Wt, SOD1-Tg, and SOD1+/- mice.

CONCLUSIONS

The extent of CuZn-SOD expression in the cytosol correlates with cell death after exposure to SAH in a manner separate from apoptosis. Overexpression of CuZn-SOD may potentially be an avenue for therapeutic intervention.

Free radical pathways in CNS injury

Free radicals are highly reactive molecules implicated in the pathology of traumatic brain injury and cerebral ischemia, through a mechanism known as oxidative stress. After brain injury, reactive oxygen and reactive nitrogen species may be generated through several different cellular pathways, including calcium activation of phospholipases, nitric oxide synthase, xanthine oxidase, the Fenton and Haber-Weiss reactions, by inflammatory cells. If cellular defense systems are weakened, increased production of free radicals will lead to oxidation of lipids, proteins, and nucleic acids, which may alter cellular function in a critical way. The study of each of these pathways may be complex and laborious since free radicals are extremely short-lived. Recently, genetic manipulation of wild-type animals has yielded species that over- or under-express genes such as, copper-zinc superoxide dismutase, manganese superoxide dismutase, nitric oxide synthase, and the Bcl-2 protein. The introduction of the species has improved the understanding of oxidative stress. We conclude here that substantial experimental data links oxidative stress with other pathogenic mechanisms such as excitotoxicity, calcium overload, mitochondrial cytochrome c release, caspase activation, and apoptosis in central nervous system (CNS) trauma and ischemia, and that utilization of genetically manipulated animals offers a unique possibility to elucidate the role of free radicals in CNS injury in a molecular fashion.

Spreading depression-induced expression of c-fos and cyclooxygenase-2 in transgenic mice that overexpress human copper/zinc-superoxide dismutase

Spreading depression (SD) is a wave of sustained depolarization challenging the energy metabolism of cells without causing irreversible damage. SD is a major mechanism of gene induction that takes place in cortical injury, including ischemia. We studied the role of oxygen radicals in SD-induced c-fos and cyclooxygenase-2 (COX-2) induction using transgenic (Tg) mice that overexpress copper/zinc-superoxide dismutase (SOD1). The frequency, amplitude and duration of SD waves were similar in the Tg mice and wild-type littermates. c-fos and COX-2 mRNAs were strongly induced 1 and 4 h after SD. The induction of both genes was slightly but significantly less at 4 h in the Tg mice. The results indicate that even a mild, noninjurious metabolic stimulation increases the concentration of oxygen radicals to the level that contributes to gene expression.

The use of transgenic and mutant mice to study oxygen free radical metabolism

To distinguish the role of Mn superoxide dismutase (MnSOD) from that of cytoplasmic CuZn superoxide dismutase (CuZnSOD), the mouse MnSOD gene (Sod2) was inactivated by homologous recombination. Sod2 -/- mice on a CD1 (outbred) genetic background die within the first 10 days of life (mean, 5.4 days) with a complex phenotype that includes dilated cardiomyopathy, accumulation of lipid in liver and skeletal muscle, metabolic acidosis and ketosis, and a severe reduction in succinate dehydrogenase (complex II) and aconitase (a TCA cycle enzyme) activities in the heart and, to a lesser extent, in other organs. These findings indicate that MnSOD is required to maintain the integrity of mitochondrial enzymes susceptible to direct inactivation by superoxide. On the other hand, Lebovitz et al. reported an independently derived MnSod null mouse (Sod2tmlLeb) on a mixed C57BL/6 and 129Sv background with a different phenotype. Because a difference in genetic background is the most likely explanation for the phenotypic differences, the two mutant lines were crossed into different genetic backgrounds for further analyses. To study the phenotype of Sod2tmlLeb mice CD1 background, the Sod2tmlLeb mice were crossed to CD1 for two generations before the -/+ mice were intercrossed to generate -/- mice. The life span distribution of CD1 < Sod2-/- > Leb was shifted to the left, indicating a shortened life span on the CD1 background. Furthermore, the CD1 < Sod2-/- > Leb mice develop metabolic acidosis at an early stage as was observed with CD1 < Sod2-/- > Cje. When Sod2tmlCje was placed on C57BL/6J (B6) background, the -/- mice were found to die either during midgestation or within the first 4 days after birth. However, when the B6 < Sod2 -/+ > Cje were crossed with DBA/2J (D2) for the generation of B6D2F2 < Sod2-/- > Cje mice, an entirely different phenotype, similar to that described by Lebovitz et al., was observed. The F2 Sod -/- mice were able to survive up to 18 days, and the animals that lived for more than 15 days displayed neurological abnormalities including ataxia and seizures. Their hearts were not as severely affected as were those of the CD1 mice, and neurological degeneration rather than heart defect appears to be the cause of death.

Oxidative stress and gene regulation

Reactive oxygen species are produced by all aerobic cells and are widely believed to play a pivotal role in aging as well as a number of degenerative diseases. The consequences of the generation of oxidants in cells does not appear to be limited to promotion of deleterious effects. Alterations in oxidative metabolism have long been known to occur during differentiation and development. Experimental perturbations in cellular redox state have been shown to exert a strong impact on these processes. The discovery of specific genes and pathways affected by oxidants led to the hypothesis that reactive oxygen species serve as subcellular messengers in gene regulatory and signal transduction pathways. Additionally, antioxidants can activate numerous genes and pathways. The burgeoning growth in the number of pathways shown to be dependent on oxidation or antioxidation has accelerated during the last decade. In the discussion presented here, we provide a tabular summary of many of the redox effects on gene expression and signaling pathways that are currently known to exist.

Pulsatile shear stress leads to DNA fragmentation in human SH-SY5Y neuroblastoma cell line

1. Using an in vitro model of shear stress-induced cell injury we demonstrate that application of shear to differentiated human SH-SY5Y cells leads to cell death characterized by DNA fragmentation. Controlled shear stress was applied to cells via a modified cone and plate viscometer. 2. We show that pulsatile shear stress leads to DNA fragmentation, as determined via flow cytometry of fluorescein-12-dUTP nick-end labelled cells, in 45 +/- 4 % of cells. No lactate dehydrogenase (LDH) release was observed immediately after injury; however, 24 h after injury significant LDH release was observed. 3. Nitric oxide production by cells subjected to pulsatile shear increased two- to threefold over that in unsheared control cells. 4. Inhibition of protein synthesis, nitric oxide production, Ca2+ entry into cells, and pertussis toxin-sensitive G protein activation attenuated the shear stress-induced cell injury. 5. Our results show for the first time that application of pulsatile shear stress to a neuron-like cell in vitro leads to nitric oxide-dependent cell death.

Expression of c-fos, junB, c-jun, MKP-1 and hsp72 following traumatic neocortical lesions in rats--relation to spreading depression

The effects of a traumatic neocortical lesion on c-fos, junB, c-jun, MKP-1 and hsp72 expression were examined by in situ hybridization and immunocytochemistry 1-6 h following transcranial cold injury. The direct current potential was recorded in the injury-remote cortex to evaluate the role of transient direct current shifts, i.e. spreading depressions, in gene expression. In 14 out of 21 injured rats, spreading depression-like depolarizations of the direct current potential were noticed, which were accompanied by a transient decrease in electroencephalographic activity and increase in laser Doppler flow. In seven injured animals, no spontaneous spreading depressions were seen. In animals without spreading depressions, only a short-lasting response of c-fos, junB, c-jun and MKP-1 messenger RNAs as well as c-Fos protein was bilaterally found in the piriform cortex, and--with ipsilateral dominance--the dentate gyrus and hippocampal CA3/4 fields at 1 h after lesioning. In injured animals with spreading depressions however, a strong elevation was seen in layers II-IV and VI of the injury-remote ipsilateral cerebral cortex, which persisted over as long as 6 h. Messenger RNA levels for c-fos, junB and MKP-1 were closely related to the time interval between the last depolarization and the end of experiment. Levels were highest shortly after transient direct current shifts, and decreased thereafter mono-exponentially with half-lives of 48, 75 and 58 min for c-fos, junB and MKP-1 messenger RNAs, respectively. In 6 h animals with spreading depressions, hsp72 messenger RNA was slightly elevated in layer II of the injury-remote cortex, but heat shock protein 72 was not increased. The present results demonstrate that spreading depression is the most prominent factor influencing the trauma-related gene response in the lesion-remote cortical tissue.

Attenuated c-fos mRNA induction after middle cerebral artery occlusion in CREB knockout mice does not modulate focal ischemic injury

To elucidate the mechanism of ischemia-induced signal transduction in vivo, we investigated the effect of the targeted disruption of the alpha and delta isoforms of the cAMP-responsive element-binding protein (CREB) on c-fos and heatshock protein (hsp) 72 gene induction. Permanent focal ischemia was induced by occlusion of the middle cerebral artery of the CREB mutant mice (CREB(-/-), n = 5) and the wild-type mice (n = 6). Three hours after onset of ischemia, the neurologic score was assessed and pictorial measurements of ATP and cerebral protein synthesis (CPS) were carried out to differentiate between the ischemic core (where ATP is depleted), the ischemic penumbra (where ATP is preserved but CPS is inhibited), and the intact tissue (where both ATP and CPS are preserved). There were no significant differences in neurologic score or in ATP, pH, and CPS between the two groups, suggesting that the sensitivity of both strains to ischemia is the same. Targeted disruption of the CREB gene significantly attenuated c-fos gene induction in the periischemic ipsilateral hemisphere but had no effect on either c-fos or hsp72 mRNA expression in the penumbra. The observations demonstrate that CREB expression, despite its differential effect on c-fos, does not modulate acute focal ischemic injury.

Inducible and constitutive transcription factors in the mammalian nervous system: control of gene expression by Jun, Fos and Krox, and CREB/ATF proteins

This article reviews findings up to the end of 1997 about the inducible transcription factors (ITFs) c-Jun, JunB, JunD, c-Fos, FosB, Fra-1, Fra-2, Krox-20 (Egr-2) and Krox-24 (NGFI-A, Egr-1, Zif268); and the constitutive transcription factors (CTFs) CREB, CREM, ATF-2 and SRF as they pertain to gene expression in the mammalian nervous system. In the first part we consider basic facts about the expression and activity of these transcription factors: the organization of the encoding genes and their promoters, the second messenger cascades converging on their regulatory promoter sites, the control of their transcription, the binding to dimeric partners and to specific DNA sequences, their trans-activation potential, and their posttranslational modifications. In the second part we describe the expression and possible roles of these transcription factors in neural tissue: in the quiescent brain, during pre- and postnatal development, following sensory stimulation, nerve transection (axotomy), neurodegeneration and apoptosis, hypoxia-ischemia, generalized and limbic seizures, long-term potentiation and learning, drug dependence and withdrawal, and following stimulation by neurotransmitters, hormones and neurotrophins. We also describe their expression and possible roles in glial cells. Finally, we discuss the relevance of their expression for nervous system functioning under normal and patho-physiological conditions.

Oxidative stress and superoxide dismutase in development, aging and gene regulation

Free radicals and other reactive oxygen species are produced in the metabolic pathways of aerobic cells and affect a number of biological processes. Oxidation reactions have been postulated to play a role in aging, a number of degenerative diseases, differentiation and development as well as serving as subcellular messengers in gene regulatory and signal transduction pathways. The discovery of the activity of superoxide dismutase is a seminal work in free radical biology, because it established that free radicals were generated by cells and because it made removal of a specific free radical substance possible for the first time, which greatly accelerated research in this area. In this review, the role of reactive oxygen in aging, amyotrophic lateral sclerosis (a neurodegenerative disease), development, differentiation, and signal transduction are discussed. Emphasis is also given to the role of superoxide dismutases in these phenomena.

Histological markers of neuronal, axonal and astrocytic changes after lateral rigid impact traumatic brain injury

The model of lateral, rigid impact traumatic brain injury is widely used but remains relatively poorly characterized by comparison with fluid percussion injury models. Thus, whilst the gross morphological changes that occur over the short- and long-term post-injury have been described, more subtle measures of neuronal injury and activation, and markers of axonal and glial reactions have not been investigated, complicating interpretation of data from this model. To address this issue, a variety of neurohistological markers were examined in adult male rats which had been subjected to open brain, lateral rigid impact injury. A piston device was unilaterally driven 3.0 mm into the somatosensory cortex at a speed of 3.2 m/s. Neuronal activation evidenced by Fos-like immunoreactivity showed a complex pattern at 3 h after injury which appeared to be related both to proximity to the impact site and cortical efferent connectivity. At 24 h after injury, acid fuchsin staining demonstrated dying neurons in the margin of the injury and in ipsilateral hippocampus and dorsal thalamus. Injured cells identified by heat-shock protein immunoreactivity showed a similar distribution. Axonal injury demonstrated with 68 kDa neurofilament immunoreactivity was more widely distributed. Less axonal damage was found with increasing distance from the injury site. At 7 days post-injury, glial fibrillary acidic protein immunoreactive astrocytes were prolific in the ipsilateral thalamus, hippocampus and striatum and throughout the injured cortex. In general, controlled, lateral rigid impact injury provides a more focused injury than is seen with lateral fluid percussion which may have implications for the behavioral deficits seen in this injury model.

Effects of neuroprotective dose of fructose-1,6-bisphosphate on hypoxia-induced expression of c-fos and hsp70 mRNA in neonatal rat cerebrocortical slices

In situ hybridization (ISH) measurements of c-fos and hsp70 expression were made in brain slice studies of hypoxia, with or without fructose-1,6-bisphosphate (FBP) pretreatment. Each experiment used eighty 350 microns thick cerebrocortical slices, obtained from twenty 7-day old rats. Thirty minute periods of hypoxia were followed by 8 h of hyperoxic perfusion. Slices were removed at eight predetermined times, and processed for ISH and immunohistochemistry. In three of six hypoxia experiments, slices were pretreated for 60 min with 2 mM FBP, a condition known to maintain ATP level in brain slices during hypoxia. In three other hypoxia experiments slices received no pretreatment. In two control experiments slices were perfused for 11.5 h without hypoxia. In control experiments, hsp70 mRNA was barely detectable in slices at all times, although moderate c-fos mRNA expression occurred at 1 h after decapitation. Hypoxia produced a modest but statistically significant increase in c-fos mRNA and hsp70 mRNA induction 4 h following reoxygenation. At all times after hypoxia, FBP pretreatment reduced expression of c-fos and hsp70 mRNA. The absence of hsp70 mRNA in control slices suggests that intracellular protein denaturation was minimal in this preparation. In slices made hypoxic, the decrease in c-fos and hsp70 mRNA caused by FBP pretreatment suggests ameliorated progression towards injury. Immunohistochemistry showed no HSP70 protein at any time following hypoxia, with or without FBP pretreatment, presumably due to delayed HSP70 protein synthesis, or to a block in translation, as observed in vivo in other studies.

DNA fragmentation and Prolonged expression of c-fos, c-jun, and hsp70 in kainic acid-induced neuronal cell death in transgenic mice overexpressing human CuZn-superoxide dismutase

Kainic acid (KA) neurotoxicity was examined in transgenic (Tg) mice overexpressing human CuZn-superoxide dismutase (SOD-1). The doses of KA required to produce seizures, the severity of the seizures, and the regions damaged were similar in SOD-1 Tg and non-transgenic wild-type mice. Intraperitoneal KA injection induced seizure-related neuronal damage in the CA3 and CA1 regions of the hippocampus and in other regions of the brain in both SOD-1 Tg and wild-type mice. These damaged neurons were labeled with the terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling (TUNEL) technique up to 72 h, although no significant difference in the number of TUNEL-positive neurons was observed between SOD-1 Tg and wild-type mice. In situ hybridization showed that c-fos, c-jun, and hsp70 genes were expressed in the hippocampus, cortex, and other regions of the brain after KA treatment. The expression of these genes was maximal 1 to 4 h following KA treatment but persisted longer in the hippocampus and other regions in SOD-1 Tg compared with wild-type mice; however, cell death in the hippocampus, assessed using cresyl violet staining, was similar in SOD-1 Tg and wild-type mice. The data show that superoxide radicals modulate both immediate early gene and heat shock gene expression after KA-induced seizures. The prolonged expression of c-fos, c-jun, and hsp70 in SOD-1 Tg compared with wild-type mice may indicate that hippocampal neurons survive longer in SOD-1 Tg than in wild-type animals; however, cell death as well as the seizure threshold, seizure severity and the pattern of regional vulnerability were not affected substantially by increased levels of SOD in the brain.