Apoptotic Neuronal Cell Death Research Articles

Effect of licorice (Glycyrrhiza uralensis fisch) on amyloid-β-induced neurotoxicity in PC12 cells

Alzheimer’s disease is characterized by neuronal loss and the presence of extracellular senile plaques whose major constituent is amyloid-β peptide (Aβ). In this study, we investigated the effects of a water extract of licorice (Glycyrrhiza uralensis F.) (GWE) on Aβ25-35-induced apoptosis in PC12 cells. Exposure to Aβ25-35-induced apoptosis, such as decreased mitochondrial transmembrane potential, increased lipid peroxide formation, decreased antiapoptotic bcl-2 and poly(ADP-ribose) polymerase, and elevated proapoptotic bax, and caspase-3. However, treatment of GWE effectively decreased cell deaths evoked by Aβ25-35. This result suggests that GWE exerts protective effect against apoptotic neuronal cell death induced by Aβ fragments.

Near-Infrared Fluorescence Imaging of Apoptotic Neuronal Cell Death in a Live Animal Model of Prion Disease

Apoptotic cell death via activation of the caspase family of cysteine proteases is a common feature of many neurodegenerative diseases including Creutzfeldt-Jakob disease. Molecular imaging of cysteine protease activities at the preclinical stage may provide valuable mechanistic information about pathophysiological pathways involved in disease evolution and in response to therapy. In this study, we report synthesis and characterization of a near-infrared (NIR) fluorescent contrast agent capable of noninvasively imaging neuronal apoptosis in vivo, by conjugating a NIR cyanine dye to Val-Ala-Asp-fluoromethylketone (VAD-fmk), a general inhibitor of active caspases. Following intravenous administration of the NIR-VAD-fmk contrast agent, in vivo fluorescence reflectance imaging identified significantly higher levels of active caspases in the brain of mice with advanced but preclinical prion disease, when compared with healthy controls. The contrast agent and related analogues will enable the longitudinal study of disease progression and therapy in animal models of many neurodegenerative conditions.

Role of Cytoskeleton Proteins in the Morphological Changes During Apoptotic Cell Death of Cerebellar Granule Neurons

Cytoskeleton proteins are substrates for proteases and further apoptotic death. We evaluated the participation of cytoskeleton in morphological changes during cell death induced by two apoptotic conditions, potassium deprivation (K5) and staurosporine, in cerebellar granule neurons (CGC). We found that K5 induced somatic damage, but neurites were relatively preserved, which corresponded to the reorganization of actin and α-tubulin in neurites. Staurosporine (STS) induced an early alteration of neurites with reorganization of cytoskeleton proteins in somas. Caspase inhibitor ZVAD totally inhibited STS-induced α-tubulin reorganization and partially blocked STS-induced actin reorganization. α-tubulin and actin reorganization induced by K5 was affected by ZVAD. Calpain inhibitor (IC1) did not affect α-tubulin or actin reorganization induced by STS, K5 or ionomycin. Neither ZVAD, nor IC1 changed α-tubulin or actin levels upon K5 treatment. STS increased α-tubulin and actin levels, but neither ZVAD nor IC1 changed α-tubulin levels upon STS treatment. In contrast, ZVAD reduced the STS-induced increase of actin. These results suggest that CGC cytoskeleton proteins undergo a differential expression and reorganization depending on the apoptotic condition.

Inhibition of the Rho/ROCK pathway prevents neuronal degeneration in vitro and in vivo following methylmercury exposure

Methylmercury (MeHg) is an environmental neurotoxicant which induces neuropathological changes in both the central nervous and peripheral sensory nervous systems. Our recent study demonstrated that down-regulation of Ras-related C3 botulinum toxin substrate 1 (Rac1), which is known to promote neuritic extension, preceded MeHg-induced damage in cultured cortical neurons, suggesting that MeHg-mediated axonal degeneration is due to the disturbance of neuritic extension. Therefore we hypothesized that MeHg-induced axonal degeneration might be caused by neuritic extension/retraction incoordination. This idea brought our attention to the Ras homolog gene (Rho)/Rho-associated coiled coil-forming protein kinase (ROCK) pathway because it has been known to be associated with the development of axon and apoptotic neuronal cell death. Here we show that inhibition of the Rho/ROCK pathway prevents MeHg-intoxication both in vitro and in vivo. A Rho inhibitor, C3 toxin, and 2 ROCK inhibitors, Fasudil and Y-27632, significantly protected against MeHg-induced axonal degeneration and apoptotic neuronal cell death in cultured cortical neuronal cells exposed to 100 nM MeHg for 3 days. Furthermore, Fasudil partially prevented the loss of large pale neurons in dorsal root ganglia, axonal degeneration in dorsal spinal root nerves, and vacuolar degeneration in the dorsal columns of the spinal cord in MeHg-intoxicated model rats (20 ppm MeHg in drinking water for 28 days). Hind limb crossing sign, a characteristic MeHg-intoxicated sign, was significantly suppressed in this model. The results suggest that inhibition of the Rho/ROCK pathway rescues MeHg-mediated neuritic extension/retraction incoordination and is effective for the prevention of MeHg-induced axonal degeneration and apoptotic neuronal cell death.

Reactive oxygen species and the brain in sleep apnea

Rodents exposed to intermittent hypoxia (IH), a model of obstructive sleep apnea (OSA), manifest impaired learning and memory and somnolence. Increased levels of reactive oxygen species (ROS), oxidative tissue damage, and apoptotic neuronal cell death are associated with the presence of IH-induced CNS dysfunction. Furthermore, treatment with antioxidants or overexpression of antioxidant enzymes is neuroprotective during IH. These findings mimic clinical cases of OSA and suggest that ROS may play a key causal role in OSA-induced neuropathology. Controlled production of ROS occurs in multiple subcellular compartments of normal cells and de-regulation of such processes may result in excessive ROS production. The mitochondrial electron transport chain, especially complexes I and III, and the NADPH oxidase in the cellular membrane are the two main sources of ROS in brain cells, although other systems, including xanthine oxidase, phospholipase A2, lipoxygenase, cyclooxygenase, and cytochrome P450, may all play a role. The initial evidence for NADPH oxidase and mitochondrial involvement in IH-induced ROS production and neuronal injury unquestionably warrants future research efforts.

Cancer incidence in a trial of an antiapoptotic agent for Parkinson's disease

We performed a placebo-controlled trial of CEP-1347, an inhibitor of neuronal apoptotic cell death, in patients with early Parkinson's disease (PD) to determine whether long-term therapy would slow disability progression. This also provided an opportunity to monitor cancer incidence in a large cohort of PD patients followed prospectively including periods before and after patients developed disability requiring dopaminergic therapy. This was a multicenter study of 806 patients with early PD, without disability requiring dopaminergic therapy, assigned randomly to placebo or one of three doses of CEP-1347. Patients were monitored for an average of 1.8 years (1,467 patient-years) with routine cancer screening evaluations and annual skin examinations by a dermatologist. There was no significant excess of cancers among patients taking CEP-1347 compared with placebo for any cancer type (all P > 0.1). Nonmelanoma skin cancers were the most common cancer type observed. The incidence of melanomas was 20.9 times that predicted in the general population. Most melanomas occurred in patients who had never taken dopaminergic therapy. We found no evidence that CEP-1347 affected cancer incidence within 2 years of follow-up. Melanoma occurrence in our PD patients was greater than predicted compared with the general population and was unrelated to dopaminergic therapy. Clinical surveillance of PD patients for melanoma may be warranted.

Caspase-3 activation is required for reovirus-induced encephalitisin vivo

Reovirus infection of neonatal mice provides a classic experimental system for understanding the molecular pathogenesis of central nervous system (CNS) viral infection. CNS tissue injury, caused by many human neurotropic viruses, including herpes viruses and West Nile virus, is associated with caspase-dependent apoptotic neuronal cell death. We have previously shown that reovirus-induced CNS tissue injury results from apoptosis and is associated with activation of both death-receptor and mitochondrial apoptotic pathways culminating in the activation of the downstream effector caspase, caspase-3. In order to directly investigate the role of caspase-3 in virus-induced neuronal death and CNS tissue injury during encephalitis, we have compared the pathogenesis of reovirus CNS infection in mice lacking the caspase-3 gene (caspase-3 (-/-)) to syngeneic wild-type mice. Prior studies of antiapoptotic treatments for reovirus-infected mice have indicated that protection from reovirus-induced neuronal injury can occur without altering the viral titer in the brains of infected mice. We now show that reovirus infection of caspase-3 (-/-) mice was associated with dramatic reduction in severity of CNS tissue injury, decreased viral antigen and titer in the brain, and enhanced survival of infected mice. Following intracerebral inoculation, the authors also show that virus spread from the brain to the eyes in reovirus-infected caspase-3 (-/-) mice, indicating that viral spread was intact in these mice. Examination of brains of long-term survivors of reovirus infection among caspase-3 (-/-) mice showed that these mice eventually clear their CNS viral infection, and do not manifest residual or delayed CNS tissue injury.

Therapeutic strategies to avoid long-term adverse outcomes of neonatal antiepileptic drug exposure.

Antiepileptic drugs (AEDs) such as phenobarbital, phenytoin, and valproic acid, when given in therapeutic doses to neonatal rats, cause pronounced neuronal apoptotic cell death. This effect is especially pronounced in the striatum and cortex during the second postnatal week, a period corresponding to the "brain growth spurt" (third trimester of gestation and early infancy) in humans. Of particular concern is the fact that phenobarbital is the most frequently used therapy for neonatal epilepsy. If AED-induced neuronal cell death leads to long-term functional impairment, then it becomes crucial to find therapies that avoid this neurotoxicity in the sensitive period. Herein we examine short- and long-term functional effects following exposure of neonatal rat pups to phenobarbital; the functions tested include striatal gamma-aminobutyric acid (GABA)ergic synaptic responses and reflex development in pups, and fear conditioning, emotionality, and sensory-motor gating in adults. In all cases, phenobarbital exposure during the second postnatal week was sufficient to cause significant impairment. In contrast, adult animals exposed as pups to lamotrigine (given in a dose that does not cause apoptotic neuronal death) were not impaired on the tasks we examined. Our data suggest that treatments devoid of proapoptotic actions may be promising therapies for avoiding adverse outcomes after neonatal exposure. In addition, our findings identify early exposure to certain AEDs as an important potential risk factor contributing to psychiatric and neurologic abnormalities later in life.

Inhibition of Apoptotic Cell Death by Ghrelin Improves Functional Recovery after Spinal Cord Injury

Spinal cord injury (SCI) induces massive cell death, leading to permanent neurological disability. No satisfactory treatment is currently available. Ghrelin, a gastric hormone, is known to stimulate GH release from the hypothalamus and pituitary gland. Here, we report that ghrelin administration improves functional recovery after SCI in part by inhibiting apoptosis of neurons and oligodendrocytes. Ghrelin was not detected in normal, uninjured spinal cords, but spinal cord neurons and oligodendrocytes expressed the ghrelin receptor. Ghrelin significantly inhibited apoptotic cell death of neurons and oligodendrocytes, release of mitochondrial cytochrome c, and activation of caspase-3 after moderate contusion SCI. Ghrelin also significantly increased the level of phosphorylated ERK but decreased the level of phosphorylated p38MAPK. In addition, ghrelin increased the level of ERK-dependent brain-derived neurotrophic factor expression and decreased the level of pronerve growth factor expression. Furthermore, the neuroprotective effects of ghrelin were mediated through the ghrelin receptor. Finally, ghrelin significantly improved functional recovery and reduced the size of the lesion volume and the loss of axons and myelin after injury. These results suggest that ghrelin may represent a potential therapeutic agent after acute SCI in humans.

Acupuncture-mediated inhibition of inflammation facilitates significant functional recovery after spinal cord injury

Here, we first demonstrated the neuroprotective effect of acupuncture after SCI. Acupuncture applied at two specific acupoints, Shuigou (GV26) and Yanglingquan (GB34) significantly alleviated apoptotic cell death of neurons and oligodendrocytes, thereby leading to improved functional recovery after SCI. Acupuncture also inhibited caspase-3 activation and reduced the size of lesion cavity and extent of loss of axons. We also found that the activation of both p38 mitogen-activated protein kinase and resident microglia after injury are significantly attenuated by acupuncture. In addition, acupuncture significantly reduced the expression or activation of pro-nerve growth factor, proinflammatory factors such as tumor necrosis factor-α, interleukin-1β, interleukin-6, nitric oxide synthase, cycloxygenase-2, and matrix metalloprotease-9 after SCI. Thus, our results suggest that the neuroprotection by acupuncture may be partly mediated via inhibition of inflammation and microglial activation after SCI and acupuncture can be used as a potential therapeutic tool for treating acute spinal injury in human.

Aprotinin Confers Neuroprotection by Reducing Apoptotic Cell Death

Aprotinin has been used in pediatric cardiac surgery for its antiinflammatory and hemostatic benefits. We have reported that aprotinin has a direct cellular neuroprotective effect through reduction of excitotoxicity. The purpose of this study was to investigate whether aprotinin is neuroprotective against apoptotic cell death. Near-pure neuronal cultures containing <5% astrocytes were obtained from fetal mice. Serum deprivation was initiated at 7 days by transferring the cultures, which are dependent on serum for survival, into growth medium lacking serum for 24 h. Neuronal cell death was assessed by phase-contrast cell counting after staining with 0.4% trypan blue dye. Aprotinin at a clinically relevant concentration of 100 KIU.mL(-1) significantly reduced apoptotic neuronal cell death from 84.4% to 51.8%. This result suggests that aprotinin has the potential to reduce brain injury resulting from apoptotic cell death induced by an ischemic insult. Additional studies are needed to evaluate the potential of aprotinin to reduce neurological injury in patients at high risk of cerebral injury, including those undergoing circulatory arrest.

Different pathways lead to mitochondrial fragmentation during apoptotic and excitotoxic cell death in primary neurons

Mitochondrial fragmentation is recognized to be an important event during the onset of apoptosis. In this current study, we have used single cell imaging to investigate the role of the mitochondrial fission protein DRP-1 on mitochondrial morphology and mitochondrial fragmentation in primary hippocampal neurons undergoing necrotic or apoptotic cell death. Treatment of neurons with 500 nM staurosporine (apoptosis) or 30 μM glutamate (l-Glu; excitotoxic necrosis) produced a fragmentation and condensation of mitochondria, which although occurred over markedly different time frames appeared broadly similar in appearance. In neurons exposed to an apoptotic stimuli, inhibiting DRP-1 activity using overexpression of the dominant negative DRP-1(K38A) slowed the rate of mitochondrial fragmentation and decreased total cell death when compared to overexpression of wild-type DRP-1. In contrast, responses to l-Glu appeared DRP-1 independent. Similarly, alterations in the fission/fusion state of the mitochondrial network did not alter mitochondrial Ca(2+) uptake or the ability of l-Glu to stimulate excitotoxic Ca(2+) overload. Finally, apoptosis-induced mitochondrial fragmentation was observed concurrent with recruitment of Bax to the mitochondrial membrane. In contrast, during glutamate excitotoxicity, Bax remained in the cytosolic compartment. We conclude that different pathways lead to the appearance of fragmented mitochondria during necrotic and apoptotic neuronal cell death.

THE RATIONALE FOR NEUROPROTECTION IN EPILEPSY: STEPS FORWARD FOR NEW THERAPEUTIC AND PREVENTIVE STRATEGIES

The growing number of research in epilepsy provides evidences regarding the progressive neuronal damage which occur as a result of recurrent brief seizures as well as prolonged seizures. Advances in understanding the neurobiology of epilepsy indicate that initial seizure injury triggers a sequence of adaptive molecular and cellular mechanisms that interact in a highly complex manner. These changes evolve over a period of time (up to years) and involve gene alteration, channel dysfunction, impaired inhibitory/excitatory balance tipped towards excitation, mitochondrial embarrassment, homeostatic alteration of cell essential elements and exhaustion of endogenous protective mechanisms. This results in long-lasting functional and structural neurobiological reorganization at different levels that contribute to neuronal hyperexcitability, excitotoxicity, apoptotic and necrotic cell death, gliosis, persistent epileptogenesis and spontaneous seizures later in life. Importantly, seizure is only one aspect of epilepsy, however, behavioral and cognitive deficits which occur as a result of seizures or its treatment can be more detrimental to an individual's overall function. The perspectives of beneficial neuroprotection in epilepsy aim not only to improve seizure control, but also to promote compensatory processes in repairing, modifying or blocking the active changes triggered by the initial injury. Recent evidences indicate that the current AEDs have some neuroprotective potentials. However, their limited capabilities against broader range of neurotoxic insults, differential effect on the brain during various stages of development and undesirable adverse effects, trigger the inspiration of new strategies. Speculative targets may include free radical scavengers/antioxidants, modifiers of mitochondrial dysfunction, antiapoptotics, immunomodulators, hormonotherapy and neurotrophic factors. For all, assessments of therapeutic time window, long-term neuroprotective potentials and adverse consequences are mandatory.

Mitochondrial dysfunction and oxidative stress in seizure-induced neuronal cell death.

Epilepsy is considered one of the most common neurological disorders worldwide. The burst firing associated with prolonged epileptic discharges could lead to a large number of changes and cascades of events at the cellular level. From its role as the cellular powerhouse, the mitochondrion is emerging as a key participant in cell death because of its association with an ever-growing list of apoptosis-related proteins. Prolonged seizures may result in the mitochondrial dysfunction and increased production of reactive oxygen species and nitric oxide (NO) precede neuronal cell death and cause subsequent epileptogenesis. Emerging evidences also showed that intrinsic mitochondrial apoptotic pathway may contribute to the neuropathology of human epilepsy, particularly in the hippocampus. Subsequent laboratory studies in the animal model of status epilepticus provide credence to the notion that activation of nuclear factor-κB upregulates NO synthase (NOS) II gene expression with temporal correlation of NOS II derived NO-, superoxide anion- and peroxynitrite-dependent reduction in mitochondrial Complex I activity, leading to apoptotic neuronal cell death in the hippocampus. These results will broaden our understanding on the intimate link between mitochondrial function, oxidative stress and mitochondria-dependent apoptotic signaling triggered by epileptic seizures. It will open a new vista in the development of more effective neuroprotective strategies against seizure-induced brain damage by modification of bioenergetic failure in the mitochondria and in the design of novel treatment perspectives for therapy-resistant forms of epilepsy.

Transcriptional upregulation of nitric oxide synthase II by nuclear factor‐κB promotes apoptotic neuronal cell death in the hippocampus following experimental status epilepticus

Whereas status epilepticus, or the condition of continuous epileptic seizures, produces a characteristic pattern of preferential neuronal cell loss in the hippocampus, the underlying mechanism is still unsettled. Based on an experimental model of temporal lobe status epilepticus, we demonstrated previously that prolonged seizures prompted an overproduction of nitric oxide (NO) by upregulation of NO synthase II (NOS II) in the hippocampal CA3 subfield, followed by the activation of mitochondrial apoptotic signaling cascade. Using the same animal model, the present study evaluated the hypothesis that transcriptional upregulation of NOS II gene by nuclear factor-kappaB (NF-kappaB) promotes apoptotic neuronal cell death in the hippocampus following status epilepticus. In Sprague-Dawley rats, significantly augmented nucleus-bound translocation of NF-kappaB p50 and p65 subunits and DNA binding activity of NF-kappaB were observed in hippocampal CA3 neurons as early as 30 min after elicitation of sustained seizure activity by microinjection of kainic acid into the CA3 subfield, followed by a progressive elevation that peaked at 90 min. In addition, application bilaterally into the hippocampal CA3 subfield of a selective NF-kappaB inhibitor, pyrrolidine dithiocarbamate or double-stranded kappaB decoy DNA significantly antagonized the activated NOS II-peroxynitrite signaling cascade (3 hr) and the associated manifestations of apoptotic cell death (7 days) in the hippocampus. We conclude that activation of NF-kappaB in hippocampal CA3 neurons upregulates NOS II gene expression following experimental temporal lobe status epilepticus, leading to apoptotic neuronal cell death in the hippocampus.

Evidence of altered DNA integrity in the brain regions of suicidal victims of Bipolar Depression

Deoxyribonucleic acid (DNA) integrity plays a significant role in cell function. There are limited studies with regard to the role of DNA damage in bipolar affective disorder (BP). In the present study, we have assessed DNA integrity, conformation, and stability in the brain region of bipolar depression (BD) patients (n=10) compared to age-matched controls (n=8). Genomic DNA was isolated from 10 postmortem BD patients’ brain regions (frontal cortex, Pons, medulla, thalamus, cerebellum, hypothalamus, Parietal, temporal, occipital lobe, and hippocampus) and from the age-matched control subjects. DNA from the frontal cortex, pons, medulla, and thalamus showed significantly higher number of strand breaks in BD (P<0.01) compared to the age-matched controls. However, DNA from the hippocampus region was intact and did not show any strand breaks. The stability studies also indicated that the melting temperature and ethidium bromide binding pattern were altered in the DNA of BD patients’ brain regions, except in the hippocampus. The conformation studies showed B-A or secondary B-DNA conformation (instead of the normal B-DNA) in BD patients’ brain regions, with the exception of the hippocampus. The levels of redox metals such as Copper (Cu) and Iron (Fe) were significantly elevated in the brain regions of the sufferers of BD, while the Zinc (Zn) level was decreased. In the hippocampus, there was no change in the Fe or Cu levels, whereas, the Zn level was elevated. There was a clear correlation between Cu and Fe levels versus strand breaks in the brain regions of the BD. To date, as far as we are aware, this is a new comprehensive database on stability and conformations of DNA in different brain regions of patients affected with BD. The biological significance of these findings is discussed here.

Baicalein protects HT22 murine hippocampal neuronal cells against endoplasmic reticulum stress-induced apoptosis through inhibition of reactive oxygen species production and CHOP induction

Baicalein is one of the major flavonoids in Scutellaria baicalensis Georgi and possesses various effects, including cytoprotection and anti-inflammation. Because endoplasmic reticulum (ER) stress has been implicated in neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and cerebral ischemia, we investigated the effects of baicalein on apoptotic death of HT22 mouse hippocampal neuronal cells induced by thapsigargin (TG) and brefeldin A (BFA), two representative ER stress inducers. Apoptosis, reactive oxygen species (ROS) production, and mitochondrial membrane potential (MMP) were measured by flow cytometry. Expression level and phosphorylation status of ER stress-associated proteins and activation and cleavage of apoptosis-associated proteins were analyzed by Western blot. Baicalein reduced TG- and BFA-induced apoptosis of HT22 cells and activation and cleavage of apoptosis-associated proteins, such as caspase-12 and -3 and poly(ADP-ribose) polymerase. Baicalein also reduced the TG- and BFA-induced expression of ER stress-associated proteins, including C/EBP homologous protein (CHOP) and glucose-regulated protein 78, the cleavage of X-box binding protein-1 and activating transcription factor 6α, and the phosphorylation of eukaryotic initiation factor-2α and mitogen-activated protein kinases, such as p38, JNK, and ERK. Knock-down of CHOP expression by siRNA transfection and specific inhibitors of p38 (SB203580), JNK (SP600125), and ERK (PD98059) as well as anti-oxidant (N-acetylcysteine) reduced TG- or BFA-induced cell death. Baicalein also reduced TG- and BFA-induced ROS accumulation and MMP reduction. Taken together, these results suggest that baicalein could protect HT22 neuronal cells against ER stress-induced apoptosis by reducing CHOP induction as well as ROS accumulation and mitochondrial damage.

Bark Constituents from Mushroom-detoxifiedRhus vernicifluaSuppress Kainic Acid-induced Neuronal Cell Death in Mouse Hippocampus

Urushinol, a plant allergen, has significantly restricted the medical application of Rhus verniciflua, although it has been reported to possess a wide variety of biological activities such as anti-inflammatory, antioxidant, and anti-cancer actions. To reduce the urushinol content while maintaining the beneficial biological activities, mushroom-mediated fermentation of Rhus verniciflua was carried out and this method resulted in significantly attenuated allergenicity [1]. In the present study, to examine the neuroprotective properties of mushroom-fermented stem bark of Rhus verniciflua, two constituents were isolated from mushroom-fermented bark and their neuroprotective properties were examined in a mouse model of kainic acid (KA)-induced excitotoxicity. KA resulted in significant apoptotic neuronal cell death in the CA3 region of mouse hippocampus. However, seven daily administrations of RVH-1 or RVH-2 prior to KA injection significantly attenuated KA-induced pyramidal neuronal cell death in the CA3 region. Furthermore, pretreatment with RVH-1 and RVH-2 also suppressed KA-induced microglial activation in the mouse hippocampus. The present study demonstrates that RVH-1 and RVH-2 isolated from Rhus verniciflua and detoxified using mushroom species possess neuroprotective properties against KA-induced excitotoxicity. This leads to the possibility that detoxified Rhus verniciflua can be a valuable asset in herbal medicine.

Distinct Time Courses of Secondary Brain Damage in the Hippocampus Following Brain Concussion and Contusion in Rats

Secondary brain damage (SBD) is caused by apoptosis after traumatic brain injury that is classified into concussion and contusion. Brain concussion is temporary unconsciousness or confusion caused by a blow on the head without pathological changes, and contusion is a brain injury with hemorrhage and broad extravasations. In this study, we investigated the time-dependent changes of apoptosis in hippocampus after brain concussion and contusion using rat models. We generated the concussion by dropping a plumb on the dura from a height of 3.5 cm and the contusion by cauterizing the cerebral cortex. SBD was evaluated in the hippocampus by histopathological analyses and measuring caspase-3 activity that induces apoptotic neuronal cell death. The frequency of abnormal neuronal cells with vacuolation or nuclear condensation, or those with DNA fragmentation was remarkably increased at 1 hr after concussion (about 30% for each abnormality) from the pre-injury level (0%) and reached the highest level (about 50% for each) by 48 hrs, whereas the frequency of abnormal neuronal cells was increased at 1 hr after contusion (about 10%) and reached the highest level (about 40%) by 48 hrs. In parallel, caspase-3 activity was increased sevenfold in the hippocampus at 1 hr after concussion and returned to the pre-injury level by 48 hrs, whereas after contusion, caspase-3 activity was continuously increased to the highest level at 48 hrs (fivefold). Thus, anti-apoptotic-cell-death treatment to prevent SBD must be performed by 1 hr after concussion and at latest by 48 hrs after contusion.

P2.018 Recapitulation of neurodegenerative disease and apoptotic neuronal cell death caused by 26S proteasome dysfunction

P2.018 Recapitulation of neurodegenerative disease and apoptotic neuronal cell death caused by 26S proteasome dysfunction