The Role of Autophagy and Apoptosis in Neuropathic Pain Formation

Neuropathic pain indicates pain caused by damage to the somatosensory system and is difficult to manage and treat. A new treatment strategy urgently needs to be developed. Both autophagy and apoptosis are critical adaptive mechanisms when neurons encounter stress or damage. Recent studies have shown that, after nerve damage, both autophagic and apoptotic activities in the injured nerve, dorsal root ganglia, and spinal dorsal horn change over time. Many studies have shown that upregulated autophagic activities may help myelin clearance, promote nerve regeneration, and attenuate pain behavior. On the other hand, there is no direct evidence that the inhibition of apoptotic activities in the injured neurons can attenuate pain behavior. Most studies have only shown that agents can simultaneously attenuate pain behavior and inhibit apoptotic activities in the injured dorsal root ganglia. Autophagy and apoptosis can crosstalk with each other through various proteins and proinflammatory cytokine expressions. Proinflammatory cytokines can promote both autophagic/apoptotic activities and neuropathic pain formation, whereas autophagy can inhibit proinflammatory cytokine activities and further attenuate pain behaviors. Thus, agents that can enhance autophagic activities but suppress apoptotic activities on the injured nerve and dorsal root ganglia can treat neuropathic pain. Here, we summarized the evolving changes in apoptotic and autophagic activities in the injured nerve, dorsal root ganglia, spinal cord, and brain after nerve damage. This review may help in further understanding the treatment strategy for neuropathic pain during nerve injury by modulating apoptotic/autophagic activities and proinflammatory cytokines in the nervous system.

Interactions between Autophagy, Proinflammatory Cytokines, and Apoptosis in Neuropathic Pain: Granulocyte Colony Stimulating Factor as a Multipotent Therapy in Rats with Chronic Constriction Injury

Our previous studies have shown that early systemic granulocyte colony-stimulating factor (G-CSF) treatment can attenuate neuropathic pain in rats with chronic constriction injury (CCI) by modulating expression of different proinflammatory cytokines, microRNAs, and proteins. Besides the modulation of inflammatory mediators' expression, previous studies have also reported that G-CSF can modulate autophagic and apoptotic activity. Furthermore, both autophagy and apoptosis play important roles in chronic pain modulation. In this study, we evaluated the temporal interactions of autophagy, and apoptosis in the dorsal root ganglion (DRG) and injured sciatic nerve after G-CSF treatment in CCI rats. We studied the behaviors of CCI rats with or without G-CSF treatment and the various levels of autophagic, proinflammatory, and apoptotic proteins in injured sciatic nerves and DRG neurons at different time points using Western blot analysis and immunohistochemical methods. The results showed that G-CSF treatment upregulated autophagic protein expression in the early phase and suppressed apoptotic protein expression in the late phase after nerve injury. Thus, medication such as G-CSF can modulate autophagy, apoptosis, and different proinflammatory proteins in the injured sciatic nerve and DRG neurons, which have the potential to treat neuropathic pain. However, autophagy-mediated regulation of neuropathic pain is a time-dependent process. An increase in autophagic activity in the early phase before proinflammatory cytokines reach the threshold level to induce neuropathic pain can effectively alleviate further neuropathic pain development.

Bumetanide blocks the acquisition of conditioned fear in adult rats

BACKGROUND AND PURPOSE

Bumetanide has anxiolytic effects in rat models of conditioned fear. As a loop diuretic, bumetanide blocks cation-chloride co-transport and this property may allow bumetanide to act as an anxiolytic by modulating GABAergic synaptic transmission in the CNS. Its potential for the treatment of anxiety disorders deserves further investigation. In this study, we evaluated the possible involvement of the basolateral nucleus of the amygdala in the anxiolytic effect of bumetanide.

EXPERIMENTAL APPROACH

Brain slices were prepared from Wistar rats. extracellular recording, stereotaxic surgery, fear-potentiated startle response, locomotor activity monitoring and Western blotting were applied in this study.

KEY RESULTS

Systemic administration of bumetanide (15.2 mg·kg-1 , i.v.), 30 min prior to fear conditioning, significantly inhibited the acquisition of the fear-potentiated startle response. Phosphorylation of ERK in the basolateral nucleus of amygdala was reduced after bumetanide administration. In addition, suprafusion of bumetanide (5 or 10 μM) attenuated long-term potentiation in the amygdala in a dose-dependent manner. Intra-amygdala infusion of bumetanide, 15 min prior to fear conditioning, also blocked the acquisition of the fear-potentiated startle response. Finally, the possible off-target effect of bumetanide on conditioned fear was excluded by side-by-side control experiments.

CONCLUSIONS AND IMPLICATIONS

These results suggest the basolateral nucleus of amygdala plays a critical role in the anxiolytic effects of bumetanide.

Fragile X Mental Retardation-1 Knockout Zebrafish Shows Precocious Development in Social Behavior

Fragile X syndrome (FXS) is a generally hereditary form of human mental retardation that is caused by triplet repeat expansion (CGG) mutation in fragile X mental retardation 1 (fmr1) gene promoter and that results in the absence of the fragile X mental retardation protein (FMRP) expression. The common symptoms of FXS patients include learning disabilities, anxiety, autistic behaviors, as well as other behavioral abnormalities. Our previous results demonstrated the behavioral abnormalities in fmr1 knockout (KO) zebrafish such as fear memory impairment and autism-like behavior. Here, we studied the functional role of fmr1 gene on the development of social behavior by behavioral experiments, including shoaling behavior, shoaling preference, light/dark test, and novel tank task. Our results demonstrated that precocious development of shoaling behavior is found in fmr1 KO zebrafish without affecting the shoaling preference on conspecific zebrafish. The shoaling behavior appeared after 14 days postfertilization (dpf), and the level of shoaling elevated in fmr1 KO zebrafish. Furthermore, the fmr1 KO zebrafish at 28 dpf expressed higher anxiety level in novel tank task. These results suggest that the change of shoaling behavior in fmr1 KO zebrafish may result from hyperactivity and an increase of anxiety.

Transient receptor potential vanilloid type 4 channels mediate Na-K-Cl-co-transporter-induced brain edema after traumatic brain injury

Na⁺ -K⁺ -2Cl^- co-transporter (NKCC1) plays an important role in traumatic brain injury (TBI)-induced brain edema via the MAPK cascade. The transient receptor potential vanilloid type 4 (TRPV4) channel participates in neurogenic inflammation, pain transmission, and edema. In this study, we investigated the relationship between NKCC1 and TRPV4 and the related signaling pathways in TBI-induced brain edema and neuronal damage. TBI was induced by the calibrated weight-drop device. Adult male Wistar rats were randomly assigned into sham and experimental groups for time-course studies of TRPV4 expression after TBI. Hippocampal TRPV4, NKCC1, MAPK, and PI-3K cascades were analyzed by western blot, and brain edema was also evaluated among the different groups. Expression of hippocampal TRPV4 peaked at 8 h after TBI, and phosphorylation of the MAPK cascade and Akt was significantly elevated. Administration of either the TRPV4 antagonist, RN1734, or NKCC1 antagonist, bumetanide, significantly attenuated TBI-induced brain edema through decreasing the phosphorylation of MEK, ERK, and Akt proteins. Bumetanide injection inhibited TRPV4 expression, which suggests NKCC1 activation is critical to TRPV4 activation. Our results showed that hippocampal NKCC1 activation increased TRPV4 expression after TBI and then induced severe brain edema and neuronal damage through activation of the MAPK cascade and Akt-related signaling pathway.

An early granulocyte colony-stimulating factor treatment attenuates neuropathic pain through activation of mu opioid receptors on the injured nerve

Several studies have shown that the mu opioid receptor (MOR) located in the peripheral nerves can be activated after nerve injury and that it attenuates peripheral nociceptive signals to the spinal dorsal horn. Various cytokines and phosphorylated-p38 (p-p38) activation in the dorsal horn also play an important role in neuropathic pain development. Granulocyte-colony stimulating factor (GCSF) is a growth factor that can stimulate granulocyte formation and has been shown to exert an analgesic effect on neuropathic pain through recruiting opioid-containing leukocytes to the injured nerve. However, the underlying mechanisms are not well understood. Herein, the results of behavior tests in addition to MOR levels in the injured sciatic nerve and the levels of p-p38 and various cytokines in the spinal dorsal horn were studied in vehicle-treated or GCSF-treated chronic constriction injured (CCI) rats at different time points (i.e., 1, 3, and 7 days, respectively) after nerve injury. The results showed that a single early systemic GCSF treatment after nerve injury can up-regulate MORs in the injured nerve, which can decrease peripheral nociceptive signals. Thereafter, those changes suppress the pro-inflammatory cytokine IL-6 but enhance the anti-inflammatory cytokine IL-4, followed by decreases in p-p38 in the dorsal horn, and thus further attenuate neuropathic pain.

Amygdaloid zif268 participated in the D-cycloserine facilitation effect on the extinction of conditioned fear

RATIONALE

The involvement of glutamate in fear extinction is perhaps the most promising in terms of facilitating clinical interventions for posttraumatic stress disorder (PTSD). This study was aimed at elucidating the possible role of zif268 on the D-cycloserine (DCS) facilitation effect on extinction.

OBJECTIVE

We investigated the association between zif268 and the extinction of conditioned fear by using antisense oligodeoxynucleotide (ODN) of zif268 and the fear-potentiated startle paradigm.

METHODS

Male adult Wistar rats were injected DCS (15 mg/kg, IP) 15 min prior to the extinction training, administered with antisense or sense ODN (800 pmol) of zif268 and subjected for fear-potentiated startle paradigm (FPS) and Western blot.

RESULTS

Either context exposure or cue exposure elevated the expression of zif268 in the basolateral nucleus of the amygdala (BLA) (p < 0.05 and p < 0.01, respectively) compared to the control group. Additionally, zif268 expression in BLA was further elevated by the glutamate NMDA receptor agonist DCS administration. Intra-amygdaloid injection of the antisense ODN of zif268 blocked the facilitation effect of DCS on the extinction of conditioned fear. Subsequent control experiments indicated that administration of vehicle or zif268 sense ODN did not alter the facilitation of DCS and that the blockage effect of zif268 antisense ODN was not due to lasting damage to the amygdala.

CONCLUSIONS

Our results suggest that zif268 within the amygdala participates in the DCS facilitation effect on the extinction of conditioned fear.

NKCC1 mediates traumatic brain injury-induced hippocampal neurogenesis through CREB phosphorylation and HIF-1α expression

Traumatic brain injury (TBI) is one of the most prevalent causes of worldwide mortality and morbidity. We previously had evidenced that TBI induced Na-K-2Cl co-transporter (NKCC1) upregulation in hippocampus. Here, we aim to investigate the role of NKCC1 in TBI-induced neurogenesis and the detailed mechanisms. The TBI-associated alternations in the expression of NKCC1, HIF-1α, VEGF, MAPK cascade, and CREB phosphorylation were analyzed by Western blot. TBI-induced neurogenesis was determined by immuno-fluorescence labeling. Chromatin immunoprecipitation was used to elucidate whether HIF-1α would activate VEGF gene after TBI. We found that the level of hippocampal NKCC1 and VEGF began to rise 8 h after TBI, and both of them reached maxima at day 7. Along with the upregulation of NKCC1 and VEGF, MAPK cascade was activated and hippocampal neurogenesis was promoted. Administration of CREB antisense oligonucleotide significantly attenuated the expression of HIF-1α, while HIF-1α antisense oligonucleotide exhibited little effect on the expression of CREB. However, HIF-1α antisense oligonucleotide administration did effectively suppress the expression of VEGF. Our results of the chromosome immunoprecipitation also indicated that HIF-1α could directly act on the VEGF promoter and presumably would elevate the VEGF expression after TBI. All these results have illustrated the correlation between NKCC1 upregulation and TBI-associated neurogenesis. The pathway involves the activation of Raf/MEK/ERK cascade, CREB phosphorylation, and HIF-1α upregulation, and finally leads to the stimulation of VEGF expression and the induction of neurogenesis.

Inhibition of NKCC1 attenuated hippocampal LTP formation and inhibitory avoidance in rat

The loop diuretic bumetanide (Bumex) is thought to have antiepileptic properties via modulate GABAA mediated signaling through their antagonism of cation-chloride cotransporters. Given that loop diuretics may act as antiepileptic drugs that modulate GABAergic signaling, we sought to investigate whether they also affect hippocampal function. The current study was performed to evaluate the possible role of NKCC1 on the hippocampal function. Brain slice extracellular recording, inhibitory avoidance, and western blot were applied in this study. Results showed that hippocampal Long-term potentiation was attenuated by suprafusion of NKCC1 inhibitor bumetanide, in a dose dependent manner. Sequent experiment result showed that Intravenous injection of bumetanide (15.2 mg/kg) 30 min prior to the training session blocked inhibitory avoidance learning significantly. Subsequent control experiment's results excluded the possible non-specific effect of bumetanide on avoidance learning. We also found the phosphorylation of hippocampal MAPK was attenuated after bumetanide administration. These results suggested that hippocampal NKCC1 may via MAPK signaling cascade to possess its function.

Behavioral and synaptic circuit features in a zebrafish model of fragile X syndrome

Fragile X syndrome (FXS) is the most frequent inherited form of human mental retardation. It is characterized by cognitive impairment and physical and behavioral problems and is caused by the silencing of fmr1 transcription and the absence of the fmr1 protein (FMRP). Recently, animal models of FXS have greatly facilitated the investigation of the molecular and cellular mechanisms of this loss-of-function disorder. The present study was aimed to further characterize the role of FMRP in behavior and synaptic function by using fmr1 knockout zebrafish. In adult zebrafish, we found that fmr1 knockout produces the anxiolytic-like responses of increased exploratory behavior in light/dark and open-field tests and avoidance learning impairment. Furthermore, electrophysiological recordings from telencephalic slice preparations of knockout fish displayed markedly reduced long-term potentiation and enhanced long-term depression compared to wild-type fish; however, basal glutamatergic transmission and presynaptic function at the lateral (Dl) and medial (Dm) division of the dorsal telencephalon synapse remained normal. Taken together, our study not only evaluates the mechanism of FRMP but also suggests that zebrafish have valuable potential as a complementary vertebrate model in studying the molecular pathogenesis of human fragile X syndrome.

Electronic structure and characteristics of Fe 3d valence states of Fe(1.01)Se superconductors under pressure probed by x-ray absorption spectroscopy and resonant x-ray emission spectroscopy

The electronic structure and characteristics of Fe 3d valence states of iron-chalcogenide Fe(1.01)Se superconductors under pressure were probed with x-ray absorption spectroscopy and resonant x-ray emission spectroscopy (RXES). The intensity of the pre-edge peak at ~7112.7 eV of the Fe K-edge x-ray absorption spectrum of Fe(1.01)Se decreases for pressure from 0.5 GPa increased to 6.9 GPa. The satellite line Kβ' was reduced in intensity upon applying pressure and became absent for pressure 52 GPa. Fe(1.01)Se shows a small net magnetic moment of Fe(2+), likely arising from strong Fe-Fe spin fluctuations. The 1s3p-RXES spectra of Fe(1.01)Se at pressures 0.5, 6.9, and 52 GPa recorded at the Fe K-edge reveal that unoccupied Fe 3d states exhibit a delocalized character, stemming from hybridization of Fe 3d and 4p orbitals arising from a local distortion around the Fe atom in a tetrahedral site. Application of pressure causes suppression of this on-site Fe 3d-Fe 4p hybridization, and thereby decreases the intensity of the pre-edge feature in the Fe K-edge absorption spectrum of Fe(1.01)Se. Compression enhances spin fluctuations at Fe sites in Fe(1.01)Se and increases the corresponding T(c), through a competition between nearest-neighbor ferromagnetic and next-nearest-neighbor antiferromagnetic superexchange interactions. This result aids our understanding of the physics underlying iron-based superconductors.

Early systemic granulocyte-colony stimulating factor treatment attenuates neuropathic pain after peripheral nerve injury

Recent studies have shown that opioid treatment can reduce pro-inflammatory cytokine production and counteract various neuropathic pain syndromes. Granulocyte colony-stimulating factor (G-CSF) can promote immune cell differentiation by increasing leukocytes (mainly opioid-containing polymorphonuclear (PMN) cells), suggesting a potential beneficial role in treating chronic pain. This study shows the effectiveness of exogenous G-CSF treatment (200 µg/kg) for alleviating thermal hyperalgesia and mechanical allodynia in rats with chronic constriction injury (CCI), during post-operative days 1-25, compared to that of vehicle treatment. G-CSF also increases the recruitment of opioid-containing PMN cells into the injured nerve. After CCI, single administration of G-CSF on days 0, 1, and 2, but not on day 3, relieved thermal hyperalgesia, which indicated that its effect on neuropathic pain had a therapeutic window of 0-48 h after nerve injury. CCI led to an increase in the levels of interleukin-6 (IL-6) mRNA and tumor necrosis factor-α (TNF-α) protein in the dorsal root ganglia (DRG). These high levels of IL-6 mRNA and TNF-α were suppressed by a single administration of G-CSF 48-144 h and 72-144 h after CCI, respectively. Furthermore, G-CSF administered 72-144 h after CCI suppressed the CCI-induced upregulation of microglial activation in the ipsilateral spinal dorsal horn, which is essential for sensing neuropathic pain. Moreover, the opioid receptor antagonist naloxone methiodide (NLXM) reversed G-CSF-induced antinociception 3 days after CCI, suggesting that G-CSF alleviates hyperalgesia via opioid/opioid receptor interactions. These results suggest that an early single systemic injection of G-CSF alleviates neuropathic pain via activation of PMN cell-derived endogenous opioid secretion to activate opioid receptors in the injured nerve, downregulate IL-6 and TNF-α inflammatory cytokines, and attenuate microglial activation in the spinal dorsal horn. This indicates that G-CSF treatment can suppress early inflammation and prevent the subsequent development of neuropathic pain.

Effect of MK-801-induced impairment of inhibitory avoidance learning in zebrafish via inactivation of extracellular signal-regulated kinase (ERK) in telencephalon

N-Methyl-D-aspartate (NMDA) receptors are implicated in a wide range of complex behavioral functions, including cognitive activity. Numerous studies have shown that using the repetitive administration of a noncompetitive NMDA receptor antagonist, MK-801, induces amnesia in rodents. In this study, the effect of a subchronic MK-801 treatment on the cognitive function of zebrafish was evaluated using a novel inhibitory avoidance task. First, we established a new system to investigate the inhibitory avoidance learning of zebrafish where they were trained to refrain from swimming from a shallow compartment to a deep compartment in order to avoid electric shock. Second, we found that blocking NMDA receptors by MK-801 could significantly attenuate the inhibitory avoidance behavior of the zebrafish and alter the telencephalic extracellular signal-regulated kinase (ERK) phosphorylation level 90 min after the inhibitory avoidance training. These results suggest that the formation of long-term emotional memory is possibly mediated by ERK activation in the telencephalon of zebrafish.

Indomethacin protects rats from neuronal damage induced by traumatic brain injury and suppresses hippocampal IL-1β release through the inhibition of Nogo-A expression

BACKGROUND

Nogo-A is a member of the reticulon family of membrane-associated proteins and plays an important role in axonal remodeling. The present study aimed to investigate alterations in Nogo-A expression following traumatic brain injury (TBI)-induced inflammation and neuronal damage.

METHODS

A weight-drop device was used to deliver a standard traumatic impact to rats. Western blot, RT-PCR and ELISA were used to analyze the expression of Nogo-A and IL-1β. Nogo-A antisense, and an irrelevant control oligonucleotide was intracerebroventricularly infused. We also performed H & E staining and luxol fast blue staining to evaluate the neuronal damage and demyelination resulting from TBI and various treatments.

RESULTS

Based on RT-PCR and western blot analyses, the expression of Nogo-A was found to be significantly upregulated in the hippocampus beginning eight hours after TBI. In addition, TBI caused an apparent elevation in IL-1β levels and severe neuronal damage and demyelination in the tested animals. All of the TBI-associated molecular and cellular consequences could be effectively reversed by treating the animals with the anti-inflammatory drug indomethacin. More importantly, the TBI-associated stimulation in the levels of both Nogo-A and IL-1β could be effectively inhibited by a specific Nogo-A antisense oligonucleotide.

CONCLUSIONS

Our findings suggest that the suppression of Nogo-A expression appears to be an early response conferred by indomethacin, which then leads to decreases in the levels of IL-1β and TBI-induced neuron damage.

Stimulation of the lateral division of the dorsal telencephalon induces synaptic plasticity in the medial division of adult zebrafish

In ray-finned fishes, the lateral (Dl) and medial (Dm) division of the dorsal telencephalon are important in learning and memory formation. Tract-tracing studies revealed that neural connections are formed between these regions via afferent Dl fibers projecting to the Dm. However, research analyzing Dl-Dm synaptic transmission is scant. We have used electrophysiological techniques to assess neurotransmission and synaptic plasticity in projections from the Dl to the Dm in zebrafish. We demonstrate that electrical stimulation of the Dl division evoked a negative field potential in the Dm division that could be inhibited by application of the AMPA/kainate receptor antagonist, CNQX (5μM). Pairs of stimuli, when delivered at brief inter-pulse intervals (IPI), elicited paired pulse facilitation (PPF). Long-term potentiation (LTP), induced through the application of three trains of high frequency stimulation (HFS; 100Hz for 1s), lasted for more than 1h and could be inhibited with DL-AP5 (40μM), an N-methyl-d-aspartate (NMDA) receptor antagonist. Our results suggest that the intratelencephalic connection between Dl and Dm may play an important role in the synaptic plasticity of the zebrafish brain. It also provides a new electrophysiological model for studying the neural mechanisms underlying learning and memory in zebrafish.

The novel indole compound SK228 induces apoptosis and FAK/Paxillin disruption in tumor cell lines and inhibits growth of tumor graft in the nude mouse

Drugs in clinical use with indole structure exhibit side effects. Therefore, to search for indole compounds with more efficacy and less side effect for cancer therapy, we developed a novel indole compound SK228 and examined its effects and mechanisms on antitumor growth and invasion inhibition in cell and tumor xenografts in nude mice models. SK228 significantly inhibited growth of different lung and esophageal cancer cell lines at sub-micromolar range, but not normal lung cells. SK228 induced DNA damages mainly by producing reactive oxygen species (ROS) resulting in apoptosis. SK228 treatment increased the release of cytochrome c into the cytosol along with the increased activity of caspase-3 and -9 without affecting caspase-8, whereas these effects were attenuated by ROS inhibitor. The expression levels of BCL-2 family regulators were also affected. Moreover, low-dose SK228 significantly reduced the invasion of cancer cells. The active phosphorylated form of FAK/Paxillin signaling pathway proteins and active form of RhoA were decreased. Moreover, the F-actin cytoskeleton was disrupted after low-dose SK228 treatment. Growth of an A549 tumor cell xenograft was markedly inhibited without significant side effects. SK228-induced apoptosis was confirmed by terminal deoxynucleotidyl transferase dUTP nick end labeling assay and immunohistochemistry of cleaved caspase-3 in tumors from treated mice. Our study provides the first evidence that SK228 exhibits cancer cell-specific cytotoxicity by inducing mitochondria-mediated apoptosis. In addition, SK228 inhibits cancer cell invasion via FAK/Paxillin disruption at noncytotoxic doses. SK228 can be further tested as a pharmaceutical compound for cancer treatment.

Hippocampal neurogenesis after traumatic brain injury is mediated by vascular endothelial growth factor receptor-2 and the Raf/MEK/ERK cascade

Adult neurogenesis occurs in the subgranular zone of the hippocampal dentate gyrus, and can be modulated by physiological and pathological events. We examined the effect of vascular endothelial growth factor (VEGF), and the correlation between VEGF and the Raf/MEK/ERK cascade in neurogenesis after traumatic brain injury (TBI). The expression of VEGF and the phosphorylation level of Raf/MEK/ERK were analyzed by Western blot, and TBI-induced neurogenesis was determined by immunofluorescence labeling and confocal microscopic detection. Hippocampal VEGF began to increase after 12 h, and reached a peak at day 7. Along with the upregulation of VEGF, neurogenesis in the hippocampus also increased. Administration of the VEGF antisense oligodeoxynucleotide, or the VEGF receptor-2 antagonist SU1498 (10 μg, ICV), attenuated the phosphorylation of the MAPK cascade proteins and caused a decrease in neurogenesis in the hippocampus. Similarly, administration of the ERK inhibitor PD98059 (500 ng, ICV) also exhibited a suppressive effect on neurogenesis. Our results indicate that VEGF plays an important role in neurogenesis after TBI, and that the process involves VEGF receptor-2 and the Raf/MEK/ERK cascade.

ATM/ATR and SMAD3 pathways contribute to 3-indole-induced G₁ arrest in cancer cells and xenograft models

BACKGROUND

3-Indole inhibits lung cancer growth by apoptosis. Here, the growth inhibition mechanism besides apoptosis was further characterized.

MATERIALS AND METHODS

The Comet assay was used to examine 3-indole-induced DNA damage. Cell cycle distribution and protein expression were analyzed using flow cytometry, Western blotting and immunohistochemistry in cell and animal models.

RESULTS

3-Indole induced dose-dependent DNA damage, which was reversed by reactive oxygen species (ROS) inhibitor in lung cancer cells. Cell cycle G₁ arrest was observed in the 3-indole-treated cells. DNA damage-responsive proteins involved in the ataxia telangiectasia mutated/ataxia telangiectasia and Rad3-related (ATM/ATR) pathway and G₁ regulation proteins such as p21 and SMA- and MAD-related protein 3 (SMAD3) were induced in the cell models. The altered expression of ATM, ATR, checkpoint kinase 2 (CHK2), and cell division cycle 25 homolog A (CDC25A) were confirmed in xenograft models. Importantly, the 3-indole-induced ATM/ATR and transforming growth factor (TGF)-β/SMAD pathways were attenuated by ROS inhibitor.

CONCLUSION

3-Indole causes DNA damage and triggers ATM/ATR and SMAD3 signaling pathways to arrest lung cancer cells at the G₁-phase.

Neuroprotective effects of resveratrol on MPTP-induced neuron loss mediated by free radical scavenging

Resveratrol is a natural polyphenol and possesses many biological functions such as anti-inflammatory activity and protection against atherosclerosis and myocardial infraction. Parkinson's disease is a common progressive neurodegenerative disease. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is the most useful neurotoxin to induce Parkinsonism. The present study was carried out to elucidate the neuroprotective effect and possible mechanism of resveratrol on MPTP-induced striatal neuron loss. Sixty adult Balb/c mice were divided into four groups: sham operation, MPTP treatment (30 mg/kg, i.p.), MPTP combined with resveratrol administration (20 mg/kg, i.v.), and resveratrol treatment alone. Microdialysis and high-performance liquid chromatography were used to analyze dihydroxybenzoic acid (DHBA) that reflected the hydroxyl radical level. In the present study, we found MPTP chronic administration significantly induced motor coordination impairment in mice. After MPTP administration, the hydroxyl radical levels in substantia nigra were also significantly elevated and animals displayed severe neuronal loss. Resveratrol administration significantly protected mice from MPTP-induced motor coordination impairment, hydroxyl radical overloading, and neuronal loss. Our results demonstrated that resveratrol could elicit neuroprotective effects on MPTP-induced Parkinsonism through free radical scavenging.

Bumetanide administration attenuated traumatic brain injury through IL-1 overexpression

OBJECTIVE

To examine the effects of administration of bumetanide, a specific NKCC1 inhibitor, on traumatic brain injury (TBI)-induced interleukin-1 (IL-1) expression.

METHODS

TBI model was induced by the calibrated weight drop device (450 g in weight, 2.0 m in height) in adult rats based on procedures previously reported. One hundred and sixty Wistar rats were divided into sham-control group and experimental group for time course works of TBI. The expression of IL-1beta brain edema and neuronal damage were determined in these animals after TBI.

RESULTS

We found that both mRNA and protein of IL-1beta were up-regulated in the hippocampus 3-24 hours after TBI. Animals displayed severe brain edema and neuron damage after TBI. Bumetanide (15 mg/kg), a specific Na(+) -K(+) -2Cl(-) cotransporter inhibitor, significantly attenuated the TBI-induced neuronal damage by IL-1beta overexpression. The present study suggests that administration of bumetanide could significantly decreased TBI-induced inflammatory response and neuronal damage.

Glutamate NMDA receptors within the amygdala participate in the modulatory effect of glucocorticoids on extinction of conditioned fear in rats

Recent results show that brain glucocorticoids are involved in the dysregulation of fear memory extinction in post-traumatic stress disorder patients. The present study was aimed to elucidate the possible mechanism of glucocorticoids on the conditioned fear extinction. To achieve these goals, male SD rats, fear-potentiated startle paradigm, and Western blot were used. We found that (1) systemic administration of the synthetic glucocorticoid agonist dexamethasone (DEX) facilitated extinction of conditioned fear in a dose-dependent manner (0.05, 0.1, 0.5, or 1.0 mg/kg, i.p.); (2) systemic administration of the glutamate NMDA receptor antagonist (+/-)-HA966 (6.0 mg/kg, i.p.) and intra-amygdala infusion of the NMDA receptor antagonists MK801 (0.5 ng/side, bilaterally) or D,L-2-amino-5-phosphonovaleric acid (AP5, 2.0 ng/side, bilaterally) blocked the DEX facilitation effect; (3) the corticosteroid synthesis inhibitor metyrapone (25 mg/kg. s.c.) blocked extinction and this was prevented by co-administration of NMDA receptor agonist D-cycloserine (DCS, 5.0 mg/kg, i.p.); (4) co-administration of DEX and DCS in subthreshold doses provided a synergistic facilitation effect on extinction (0.2 and 5 mg/kg, respectively). Control experiments indicated that co-administration of DEX and DCS did not alter the expression of conditioned fear and the effect was not due to lasting damage to the amygdala. These results suggest that glutamate NMDA receptors within the amygdala participate in the modulatory effect of glucocorticoids on extinction.

Extract of Ginkgo biloba EGb761 facilitates extinction of conditioned fear measured by fear-potentiated startle

A standard extract of Ginkgo biloba (EGb761) has been used in the treatment of various common geriatric complaints including vertigo, short-term memory loss, hearing loss, lack of attention, or vigilance. We demonstrated that acute systemic administration of EGb761 facilitated the acquisition of conditioned fear. Many studies suggest the neural mechanism underlies extinction is similar to the acquisition. This raises a possibility that EGb761 may modulate and accelerate the fear extinction process. We tested this possibility by using fear-potentiated startle (FPS) on laboratory rats. Acute systemic injection of EGb761 (10, 20, or 50 mg/kg) 30 min before extinction training facilitated extinction in a dose-dependent manner. Intra-amygdaloid infusion of EGb761 (28 ng/side, bilaterally) 10 min before extinction training also facilitated extinction. Control experiments showed that facilitation effect of EGb761 was not the result of impaired expression of conditioned fear or accelerated forgetting. Rats previously injected with EGb761 showed significant FPS after retraining. Extinction of conditioned fear appeared to result from acute drug effects rather than from toxic action. Systemic administration of EGb761 immediately after extinction training did not facilitate extinction, suggested the EGb761 facilitation effect is contributed to the acquisition phase of extinction learning. Western blot results showed that extinction induced amygdaloid extracellular signal-regulated kinase (ERK1/2) phosphorylation was significantly elevated by EGb761 treatment. Intra-amygdala injection of ERK1/2 inhibitor PD98059 completely blocked the EGb761 effect. Therefore, acute EGb761 administration modulated extinction of conditioned fear by activating ERK1/2.

Vasopressin produces inhibition on phrenic nerve activity and apnea through V(1A) receptors in the area postrema in rats

The area postrema (AP) is the most caudal circumventricular organ in the central nervous system and contains arginine vasopressin (AVP) receptors. To investigate that AVP receptors in the AP might participate in the modulation of respiration, the adult rat was anesthetized with urethane (1.2 g/kg, i.p.), paralyzed, ventilated artificially, and maintained at normocapnia in hyperoxia. The phrenic nerve was separated at C4 level. Phrenic burst was amplified, filtered, integrated, and then stored in the hard disc via the PowerLab system. Three doses of AVP and an AVP V(1A) receptor antagonist, [beta-mercapto-beta,beta-cyclopentamethylenepropionyl1,-O-Me-Tyr2,Arg8]-vasopressin, were microinjected into the AP through a pair of microelectrodes. The moderate and high doses of AVP reduced the PNA to 72% and 45% of the control (P < 0.05), extended the mean TE from 1.4 s before AVP to 4.0 s and 7.6 s, (P < 0.05), and decrease in BP by 26 and 37 mmHg (P < 0.05), respectively. These significant reductions in PNA and BP and elongation of TE were totally abolished by the pre-treatment of the AVP V(1A) receptor antagonist and by application of lidocaine or CoCl2 at the nucleus tractus solitarius (NTS). Moreover, pulmonary inhibition caused by AVP was significantly attenuated by hypercapnia. These results strongly suggest that AVP V(1A) receptors in the AP may participate in the modulation of cardiopulmonary functions through the activation of V(1A) receptors and the pathway connected to the NTS. They may also indicate that a putative vasopressinergic pathway has a projection to the AP to alter the excitability of neurons having AVP V(1A) receptors and results in an inhibition of cardiopulmonary functions via the connection between the AP and NTS.

Dissociation dynamics of positive-ion and negative-ion fragments of gaseous and condensed Si(CH(3))(2)Cl(2) via Si 2p, Cl 2p, and Cl 1s core-level excitations

The state-selective positive-ion and negative-ion dissociation pathways of gaseous and condensed Si(CH(3))(2)Cl(2) following Cl 2p, Cl 1s, and Si 2p core-level excitations have been characterized. The excitations to a specific antibonding state (15a(1) (*) state) of gaseous Si(CH(3))(2)Cl(2) at the Cl 2p, Cl 1s, and Si 2p edges produce significant enhancement of fragment ions. This ion enhancement at specific core-excited states correlates closely with the ion kinetic energy distribution. The results deduced from ion kinetic energy distribution are consistent with results of quantum-chemical calculations on Si(CH(3))(2)Cl(2) using the ADF package. The Cl(-) desorption yields for Si(CH(3))(2)Cl(2)Si(100) at approximately 90 K are notably enhanced at the 15a(1) (*) resonance at both Cl 2p and Si 2p edges. The resonant enhancement of Cl(-) yield occurs through the formation of highly excited states of the adsorbed molecules. These results provide insight into the state-selective ionic fragmentation of molecules via core-level excitation.

Inhibition of the Na+–K+–2Cl−-cotransporter in choroid plexus attenuates traumatic brain injury-induced brain edema and neuronal damage

The present study was aimed to elucidate the possible role of Na+ -K+ -2Cl- -cotransporter (NKCC1) on traumatic brain injury-induced brain edema, cerebral contusion and neuronal death by using traumatic brain injury animal model. Contusion volume was verified by 2,3,5,-triphenyltetrazolium chloride monohydrate staining. NKCC1 mRNA expression was detected by RT-PCR and the protein expression of NKCC1 was measured by Western blot. We found that the expression of NKCC1 RNA and protein were up-regulated in choroid plexus apical membrane from 2 h after traumatic brain injury, peaked at 8 h, and lasted for 24 h. Rats in the experimental group displayed severe brain edema (water content: 81.45 +/- 0.32% compared with 78.38 +/- 0.62% of sham group) and contusion volume significantly increased 8 h after traumatic brain injury (864.14 +/- 28.07 mm3). Administration of the NKCC1 inhibitor bumetanide (15 mg/kg, I.V.) significantly attenuated the contusion volume (464.03 +/- 23.62 mm3) and brain edema (water content: 79.12 +/- 0.28%) after traumatic brain injury. Our study demonstrates that NKCC1 contributes to traumatic brain injury-induced brain edema and neuronal damage.

Systemic and intra-amygdala administration of glucocorticoid agonist and antagonist modulate extinction of conditioned fear

We examined the effect of glucocorticoid agonists on the extinction of conditioned fear in rats by using fear-potentiated startle. Systemic injection of glucocorticoid receptor agonists dexamethasone (DEX) (0.1, 0.5, and 1.0 mg/kg) and intra-amygdala infusion of RU28362 (0.5, 1.0, and 3.0 ng/side) prior to extinction training facilitated extinction of conditioned fear in a dose-dependent manner. Extinction of conditioned fear and circulating corticosterone levels were attenuated by administration of corticosteroid synthesis inhibitor metyrapone (25 mg/kg s.c.) 90 min before extinction training. The facilitation effect of DEX was dependent on repeated presentation of the conditioned stimulus rather than exposure to the experimental context, indicating this effect did not result from impaired expression of conditioned fear or accelerated forgetting. Intra-amygdaloid administration of the glucocorticoid receptor antagonist mifepristone (0.1, 0.2, and 0.5 ng/side, bilaterally) blocked extinction of conditioned fear and the facilitation effect of DEX in a dose-dependent manner. Mifepristone (2 ng/side) did not affect extinction but blocked the facilitating effect of DEX. Systemic administration of DEX after extinction training also facilitated extinction, suggesting that DEX may influence the memory consodilation phase of extinction. The Dose of dexamethsone or metyrapone used here did not influence fear-potentiated startle when administered before testing. Thus, it is unlikely that these drugs influenced extinction by increasing or disrupting CS processing. All results suggested that amygdaloid glucocorticoid receptors were involved in the extinction of conditioned fear.

Extracellular signal-regulated kinase-mediated IL-1-induced cortical neuron damage during traumatic brain injury

Traumatic brain injury (TBI) is one of the most prevalent causes of morbidity and mortality in youth. Interleukin-1 (IL-1) has many roles in the brain in addition to mediating glial inflammatory response; it has also been implicated in neurodegenerative diseases. We demonstrated the signal transduction pathway of IL-1 overproduction-induced cortical neuron loss during TBI. A calibrated weight-drop device (450 g weight and 2m height) was used to induce TBI in adult male Sprague-Dawley rats under general anesthesia (sodium pentobarbital: 40 mg/kg, i.p.). Expression of interleukin-1alpha (IL-1alpha), interleukin-1beta (IL-1beta), extracellular signal-regulated kinase (ERK), Jun, and p-38 were determined by Western blotting and RT-PCR. Neuronal damage was evaluated by microscopic examination. We found both mRNA and proteins of cortical IL-1alpha and IL-1beta increased three hours after TBI. Phosphorylation of ERK significantly increased but there were no significant effects on cortical expression of ERK, Jun and p-38. Administration of ERK inhibitor, PD98059, IL-1alpha antibody and IL-1beta antibody protected animals from TBI-induced neuronal damage. Our results suggest that TBI-induced cortical neuron death was mediated by the IL-1 receptor through ERK phosphorylation.

Effect of Interleukin-1 on Traumatic Brain Injury–Induced Damage to Hippocampal Neurons

Interleukin-1 (IL-1) has many roles in the brain in addition to mediating inflammatory processes in the glia, and has also been implicated in neurodegenerative disease. Traumatic brain injury (TBI) is one of the most prevalent causes of morbidity and mortality in young persons. We conducted a study to assess the effect of IL-1 on the TBI-induced death of hippocampal neurons. After TBI was induced in adult male Sprague-Dawley rats under anesthesia, we evaluated neuronal damage score through microscopic examination and Pulsinelli's grading system. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were used to measure the levels of IL-1alpha and IL- 1beta in brain tissue at different points after the induction of TBI. Over a 4-day period, the specific sites of release of IL-1alpha and IL-1beta in the brain were elucidated by immunocytochemistry with double- labeling. TBI to the hippocampus was followed by disruption of the blood-brain barrier and severe neuronal loss. Levels of IL-1alpha RNA and protein were significantly elevated at 3 h after TBI, peaked at 12 h, and remained elevated for 168 h. IL-1beta RNA and protein expression were also elevated at 3 h after TBI, but remained so only for 48 h. Our findings indicate that the observed TBI-induced increases in IL-1alpha and IL-1beta occur largely through release of these cytokines from neurons and astrocytes, respectively. Intraventricular administration of antibodies to IL-1alpha and IL-1beta before TBI significantly attenuated the TBI-induced loss of hippocampal neurons. These results show that IL-1alpha and IL-1beta play important roles in the TBI-induced loss of hippocampal neurons.

Extract of Ginkgo biloba EGb 761 facilitates fear conditioning measured by fear-potentiated startle

Extract of Ginkgo biloba EGb 761 has been used in the treatment of various common geriatric complaints including vertigo, short-term memory loss, hearing loss, lack of attention, vigilance and cerebral vascular disorder. Recent results suggest that it can serve as a cognitive enhancer and anti-stress buffer. It raises a possibility that EGb 761 may be involved in the fear conditioning. In this study, we used fear-potentiated startle (FPS) to evaluate the possible effects of EGb 761 on the acquisition stage of fear conditioning. Our results showed that administration of EGb 761 30 min prior to the conditioning facilitated acquisition of conditioned fear in a dose dependent manner. No significant differences had been observed in either basal startle response or shock activity. These results indicated that the facilitation effect of EGb 761 was not the result of impaired basal startle response or enhanced pain perception. Subsequent control experiment results indicated that the facilitation effect of EGb 761 on the acquisition was not due to anxiogenic effect or non-specific effect. Our data present the first evidence that EGb 761 can enhance fear memory formation rather than serve as an anti-stress buffer.

Facilitation of conditioned fear extinction by d-cycloserine is mediated by mitogen-activated protein kinase and phosphatidylinositol 3-kinase cascades and requires de novo protein synthesis in basolateral nucleus of amygdala

Recent results showed that either systemic or intra-amygdala administration of d-cycloserine, a partial agonist at the glycine modulatory site on the glutamate N-methyl-d-aspartate receptor facilitates the extinction of conditioned fear. Here we evaluated the role of mitogen-activated protein kinase and phosphatidylinositol 3-kinase in the basolateral nucleus of amygdala on the effect of d-cycloserine. The facilitation effect of d-cycloserine on fear extinction and mitogen-activated protein kinase activation was completely blocked by intra-amygdala administration of mitogen-activated protein kinase inhibitor PD98059 (500 ng/side, bilaterally) or U0-126 (20 microM/side, bilaterally). Furthermore, phosphatidylinositol 3-kinase inhibitor (wortmannin, 5.0 microg/side, bilaterally) infused into the basolateral nucleus of amygdala significantly reduced both facilitation effect of d-cycloserine and phosphatidylinositol 3-kinase activation. Intra-amygdala administration of a transcription inhibitor (actinomycin D, 10 microg dissolved in 1.6 microl vehicle; 0.8 microl per side) and a translation inhibitor (anisomycin, 125 microg dissolved in 1.6 microl vehicle; 0.8 microl per side) completely blocked the facilitation effect of d-cycloserine. Control experiments indicated the blockage by actinomycin D or anisomycin were not due to lasting damage to the basolateral nucleus of amygdala or state dependency. In addition, none of the active drugs used here altered the expression of conditioned fear. These results suggested that phosphatidylinositol 3-kinase and mitogen-activated protein kinase-dependent signaling cascades and new protein synthesis within the basolateral nucleus of amygdala played important roles in the d-cycloserine facilitation of the extinction of conditioned fear.

State selective enhanced production of excited fragments and ionic fragments of gaseous Si(CH3)2Cl2 and solid-state analogs following core-level excitation

State-selective fragmentation dynamics for excited fragments and ionic fragments of gaseous and condensed Si(CH3)2Cl2 following Cl 2p and Si 2p core-level excitations have been characterized. The Cl 2p-->15a1* excitation of Si(CH3)2Cl2 induces significant enhancement of the Cl+ desorption yield in the condensed phase and the Si(CH3)+2 and SiCH+3 yields in the gaseous phase. The core-to-Rydberg excitations at both Si 2p and Cl 2p edges lead to enhanced production of the excited fragments. These complementary results provide deeper insight into the origin of state-selective fragmentation of molecules via core-level excitation.

Genetic testing in spinocerebellar ataxia in Taiwan: expansions of trinucleotide repeats in SCA8 and SCA17 are associated with typical Parkinson's disease

DNA tests in normal subjects and patients with ataxia and Parkinson's disease (PD) were carried out to assess the frequency of spinocerebellar ataxia (SCA) and to document the distribution of SCA mutations underlying ethnic Chinese in Taiwan. MJD/SCA3 (46%) was the most common autosomal dominant SCA in the Taiwanese cohort, followed by SCA6 (18%) and SCA1 (3%). No expansions of SCA types 2, 10, 12, or dentatorubropallidoluysian atrophy (DRPLA) were detected. The clinical phenotypes of these affected SCA patients were very heterogeneous. All of them showed clinical symptoms of cerebellar ataxia, with or without other associated features. The frequencies of large normal alleles are closely associated with the prevalence of SCA1, SCA2, MJD/SCA3, SCA6, and DRPLA among Taiwanese, Japanese, and Caucasians. Interestingly, abnormal expansions of SCA8 and SCA17 genes were detected in patients with PD. The clinical presentation for these patients is typical of idiopathic PD with the following characteristics: late onset of disease, resting tremor in the limbs, rigidity, bradykinesia, and a good response to levodopa. This study appears to be the first report describing the PD phenotype in association with an expanded allele in the TATA-binding protein gene and suggests that SCA8 may also be a cause of typical PD.

Facilitation of conditioned fear extinction by systemic administration or intra-amygdala infusions of D-cycloserine as assessed with fear-potentiated startle in rats

NMDA receptor antagonists block conditioned fear extinction when injected systemically and also when infused directly into the amygdala. Here we evaluate the ability of D-cycloserine (DCS), a partial agonist at the strychnine-insensitive glycine-recognition site on the NMDA receptor complex, to facilitate conditioned fear extinction after systemic administration or intra-amygdala infusions. Rats received 10 pairings of a 3.7 sec light and a 0.4 mA footshock (fear conditioning). Fear-potentiated startle (increased startle in the presence vs the absence of the light) was subsequently measured before and after 30, 60, or 90 presentations of the light without shock (extinction training). Thirty non-reinforced light presentations produced modest extinction, and 60 or 90 presentations produced nearly complete extinction (experiment 1). DCS injections (3.25, 15, or 30 mg/kg) before 30 non-reinforced light exposures dose-dependently enhanced extinction (experiment 2) but did not influence fear-potentiated startle in rats that did not receive extinction training (experiment 3). These effects were blocked by HA-966, an antagonist at the glycine-recognition site (experiment 4). Neither DCS nor HA-966 altered fear-potentiated startle when injected before testing (experiment 5). The effect of systemic administration was mimicked by intra-amygdala DCS (10 microg/side) infusions (experiment 6). These results indicate that treatments that promote NMDA receptor activity after either systemic or intra-amygdala administration promote the extinction of conditioned fear.

A role for the PI-3 kinase signaling pathway in fear conditioning and synaptic plasticity in the amygdala

Western blot analysis of neuronal tissues taken from fear-conditioned rats showed a selective activation of phosphatidylinositol 3-kinase (PI-3 kinase) in the amygdala. PI-3 kinase was also activated in response to long-term potentiation (LTP)-inducing tetanic stimulation. PI-3 kinase inhibitors blocked tetanus-induced LTP as well as PI-3 kinase activation. In parallel, these inhibitors interfered with long-term fear memory while leaving short-term memory intact. Tetanus and forskolin-induced activation of mitogen-activated protein kinase (MAPK) was blocked by PI-3 kinase inhibitors, which also inhibited cAMP response element binding protein (CREB) phosphorylation. These results provide novel evidence of a requirement of PI-3 kinase activation in the amygdala for synaptic plasticity and memory consolidation, and this activation may occur at a point upstream of MAPK activation.

Mitogen-activated protein kinase cascade in the basolateral nucleus of amygdala is involved in extinction of fear-potentiated startle

Previous results indicate that intra-amygdala infusions of NMDA receptor antagonists block the extinction of conditioned fear. Mitogen-activated protein kinase (MAPK) can be activated by NMDA receptor stimulation and is involved in excitatory fear conditioning. Here, we evaluate the role of MAPK within the basolateral amygdala in the extinction of conditioned fear. Rats received 10 light-shock pairings. After 24 hr, fear was assessed by eliciting the acoustic startle reflex in the presence of the conditioned stimulus (CS) (CS-noise trials) and also in its absence (noise-alone trials). Rats subsequently received an intra-amygdala or intrahippocampal infusion of either 20% DMSO or the MAPK inhibitor PD98059 (500 ng/side) followed 10 min later by 30 presentations of the light CS without shock (extinction training). After 24 hr, they were again tested for fear-potentiated startle. PD98059 infusions into the basolateral amygdala but not the hippocampus significantly reduced extinction, which was otherwise evident in DMSO-infused rats. Control experiments indicated that the effect of intra-amygdala PD98059 could not be attributed to lasting damage to the amygdala or to state dependency. These results suggest that a MAPK-dependent signaling cascade within or very near the basolateral amygdala plays an important role in the extinction of conditioned fear.

State-specific enhancement of Cl+ and Cl- desorption for SiCl4 adsorbed on a Si(100) surface following Cl 2 p and Si 2 p core-level excitations

State-specific desorption for SiCl4 adsorbed on a Si(100) surface at approximately 90 K with variable coverage following the Cl 2p and Si 2p core-level excitations has been investigated using synchrotron radiation. The Cl+ yields show a significant enhancement following the Cl 2p-->8a*1 excitation. The Cl- yields are notably enhanced at the 8a*1 resonance at both Cl 2p and Si 2p edges. The enhancement of the Cl- yield occurs through the formation of highly excited states of the adsorbed molecules. These results provide some new dissociation processes from adsorbates on surfaces via core-level excitation.

Protective effects of anti-C5a peptide antibodies in experimental sepsis

We evaluated antibodies to different peptide regions of rat C5a in the sepsis model of cecal ligation and puncture (CLP) for their protective effects in rats. Rabbit polyclonal antibodies were developed to the following peptide regions of rat C5a: amino-terminal region (A), residues 1-16; middle region (M), residues 17-36; and the carboxyl-terminal region (C), residues 58-77. With rat neutrophils, the chemotactic activity of rat C5a was significantly inhibited by antibodies with the following rank order: anti-C > anti-M >> anti-A. In vivo, antibodies to the M and C (but not A) regions of C5a were protective in experimental sepsis, as determined by survival over a 10-day period, in a dose-dependent manner. The relative protective efficacies of anti-C5a preparations (in descending order of efficacy) were anti-C > anti-M >> anti-A. In CLP rats, a delay in infusion of antibodies, which were injected at 6 or 12 h after CLP, still resulted in significant improvement in survival rates. These in vivo and in vitro data suggest that there are optimal targets on C5a for blockade during sepsis and that delayed infusion of anti-C5a antibody until after onset of clinical evidence of sepsis still provides protective effects.

Role of C5a in multiorgan failure during sepsis

In humans with sepsis, the onset of multiorgan failure (MOF), especially involving liver, lungs, and kidneys, is a well known complication that is associated with a high mortality rate. Our previous studies with the cecal ligation/puncture (CLP) model of sepsis in rats have revealed a C5a-induced defect in the respiratory burst of neutrophils. In the current CLP studies, MOF occurred during the first 48 h with development of liver dysfunction and pulmonary dysfunction (falling arterial partial pressure of O(2), rising partial pressure of CO(2)). In this model an early respiratory alkalosis developed, followed by a metabolic acidosis with increased levels of blood lactate. During these events, blood neutrophils lost their chemotactic responsiveness both to C5a and to the bacterial chemotaxin, fMLP. Neutrophil dysfunction was associated with virtually complete loss in binding of C5a, but binding of fMLP remained normal. If CLP animals were treated with anti-C5a, indicators of MOF and lactate acidosis were greatly attenuated. Under the same conditions, C5a binding to blood neutrophils remained intact; in tandem, in vitro chemotactic responses to C5a and fMLP were retained. These data suggest that, in the CLP model of sepsis, treatment with anti-C5a prevents development of MOF and the accompanying onset of blood neutrophil dysfunction. This may explain the protective effects of anti-C5a in the CLP model of sepsis.

Quantitative measurement on three-dimensional computed tomography: an experimental validation using phantom objects

BACKGROUND

The use of 3-dimensional computed tomography (CT) imaging has been applied to the craniofacial region as well as to many other parts of the human body. Quantitative measurements have frequently been performed on the 3-dimensional images. However, critical validation of the measurement has been insufficient in the literature. This study was designed to evaluate the errors of the 3-dimensional measurements.

METHODS

Four phantom objects, a cube, a sphere, a cylinder, and a life-size adult skull model, were scanned using standard CT acquisition protocol. The data were transferred, reformatted, and displayed on an IBM-compatible personal computer running AnalyzePC 2.5 software. Linear, area, and volume measurements were obtained using one of the two methods. The first was physical measurement of the phantom objects using a caliper for linear measurement and mathematical calculations for area and volume measurements. The second was done by computer measurement on 3-dimensional images using the AnalyzePC 2.5 program. Each measurement was performed twice. The differences were compared between the repeated measurements and between the two methods.

RESULTS

The images were displayed according to standard 3-dimensional CT protocol. The differences between the measurements were insignificant and ranged from 0.00 to 2.57%.

CONCLUSION

This study validated the accuracy of the quantitative measurements on 3-dimensional CT images.

Promotion of forskolin-induced long-term potentiation of synaptic transmission by caffeine in area CA1 of the rat hippocampus

Caffeine which is present in soft drinks has been shown to increase alertness and allays drowsiness and fatigue. The aim of this study is to investigate whether caffeine could produce a long-term effect on the synaptic transmission using extracellular recording technique in the hippocampal slices. Bath application of caffeine (100 microM) reversibly increased the slope of field excitatory postsynaptic potential (fEPSP). Forskolin (25 microM) by its own did not affect the fEPSP significantly. However, in the presence of caffeine, forskolin induced a long-term potentiation (LTP) of fEPSP. Enprofylline which has been shown to exhibit some actions like caffeine but with a low adenosine antagonistic potency did not affect the normal synaptic transmission or the effect of forskolin at a lower concentration (10 microM). However, when the concentrations were increased to 20 and 50 microM, enprofylline significantly enhanced the fEPSP slope and promoted forskolin-induced LTP. The parallel increase of fEPSP and promotion of LTP observed with enprofylline suggests that adenosine A1 antagonism is the primary mechanism behind caffeine's effect. This hypothesis was further strengthened by the finding that promotion of forskolin-induced LTP was mimicked by the non-xanthine adenosine antagonist 9-chloro-2-(furyl)[1,2,4]triazolo [1,5-c]quinazolin-5-amine (CGS 15943). The promotion of forskolin-induced LTP provides a cellular basis behind caffeine's increase in capacity for sustained intellectual performance.

Involvement of mitogen-activated protein kinase in hippocampal long-term potentiation

Mitogen-activated protein kinase (MAPK) cascade classically is thought to be involved in cellular transformation, including proliferation and differentiation. Recent behavioral studies suggest that MAPK may also have a role in learning and memory. Long-term potentiation (LTP), a candidate mechanism for learning and memory, has at least two distinct temporal phases: an early phase (E-LTP) which lasts for 1-2 h and a late phase (L-LTP) which can persist >/=3 h. Here, we report that PD 098059, a selective inhibitor of MAPK cascade, attenuates L-LTP induced by bath application of forskolin without affecting basal synaptic transmission. This effect was mimicked by direct injection of animals with MAPK antisense oligonucleotide into the hippocampal CA1 region. MAPK activity measured by using a synthetic peptide corresponding to the sequence surrounding the major site of phosphorylation of the myelin-basic protein by MAPK was enhanced by forskolin. The same antisense treatment also completely inhibited the increased MAPK activity. These results demonstrate an involvement of MAPK in the induction of L-LTP in the hippocampal CA1 neurons.

Masking of forskolin-induced long-term potentiation by adenosine accumulation in area CA1 of the rat hippocampus

At hippocampal Schaffer collateral-CA1 synapses, activation of beta-adrenergic receptors and adenylyl cyclase increases transmitter release. However, this effect is transient, which is in contrast to that seen at mossy fiber-CA3 synapses, where activation of cyclic-AMP-dependent protein kinase results in long-lasting facilitation of transmitter release, a phenomenon known as a presynaptic form of long-term potentiation. The present study was aimed at investigating whether forskolin, an adenylyl cyclase activator, could produce long-term effects at the Schaffer collateral-CA1 synapses using extracellular recording techniques. As has been reported previously, forskolin persistently increased the amplitude of evoked population spikes without having a long-term effect on the field excitatory postsynaptic potentials. However, under the conditions where adenosine A1 receptors are inhibited, cyclic-AMP metabolism is disrupted or the transport of cyclic-AMP is blocked, forskolin induces long-term potentiation. Forskolin-induced potentiation is associated with a decrease in paired-pulse facilitation and is blocked by the cyclic-AMP-dependent protein kinase inhibitor Rp-adenosine-3',5'-cyclic monophosphorothioate. Activation of N-methyl-D-aspartate receptors is not required for forskolin-induced long-term potentiation, because pretreatment of slices with the N-methyl-D-aspartate receptor antagonist D-2-amino-5-phosphonovalerate did not prevent forskolin-induced potentiation. These results suggest that blockade of adenosine A1 receptors unmasks forskolin-induced long-term potentiation, and activation of cyclic-AMP-dependent protein kinase induces a form of long-term potentiation which is different from that induced by tetanic stimulation.

Endogenous serotonin inhibits epileptiform activity in rat hippocampal CA1 neurons via 5-hydroxytryptamine1A receptor activation

The modulatory effects of endogenous serotonin on the synaptic transmission and epileptiform activity were studied in the rat hippocampus with the use of extracellular and intracellular recording techniques. Field excitatory postsynaptic potential was reversibly depressed by serotonin in a concentration-dependent manner. Intracellular recordings revealed that serotonin-mediated synaptic depression was unaffected by extracellular Ba2+ or intracellular application of Cs+ while the postsynaptic hyperpolarizing effect was completely blocked. Epileptiform activity induced by picrotoxin (50 microM), a GABA(A) receptor antagonist, was also dose-dependently suppressed by serotonin. The antiepileptic effect was mimicked by 5-hydroxytryptamine1A agonist and was blocked by 5-hydroxytryptamine1A antagonists. 5-Hydroxytryptamine2 antagonist had no effect on the modulation. Similarly, fluoxetine, a selective serotonin re-uptake blocker, potently inhibited the epileptiform activity and this effect was blocked by 5-hydroxytryptamine1A receptor antagonist. Depletion of endogenous serotonin by pretreating the slices with p-chloroamphetamine completely prevented the antiepileptic action of fluoxetine, without modifying the action of serotonin in the same cells. These results suggest that the antiepileptic action of fluoxetine is due to an enhancement of endogenous serotonin which in turn is mediated by 5-hydroxytryptamine1A receptor. Endogenous serotonin transmission in the hippocampus is therefore capable of limiting the development and propagation of seizure activity.

Heat shock protein expression protects against death following exposure to heatstroke in rats

Rats 0, 16, or 48 h after heat shock (42 degrees C core temperature for 15 min) or chemical stress (5 mg/kg sodium arsenite, i.p.) were exposed to a high ambient temperature (43 degrees C) to induce heatstroke onset. The moment in which the mean arterial pressure and cerebral blood flow began to decrease from their peak values was taken as the onset of heatstroke. Prior heat shock or chemical stress conferred significant protection against heatstroke-induced arterial hypotension, cerebral ischemia, cerebral neuronal damage and death, and correlated with expression of HSP72 in brain, heart, liver and kidney at 16 h. However, at 48 h, when HSP72 expression returned to basal values, the above responses that occurred after the onset of heatstroke of two groups (0 h group VS 48 h group) were indistinguishable. The data suggest that HSP72 presence increases survival in rat heatstroke by attenuating arterial hypotension, cerebral ischemia and neuronal damage.

Population cell differentiation of Serratia marcescens on agar surface and in broth culture

The bacterium Serratia marcescens shows population surface migration (swarming) phenomenum on an LB swarming plate, and differentiated cells can be observed at the swarming front. How the cell population differentiates during swarming on the agar surface is not known, neither is it clear whether cells with differentiated characteristics can be observed in broth culture. To monitor the population cell differentiation in a highly sensitive way without cell destruction, experiments were designed using bacterial luciferase genes luxAB as the reporter genes to allow direct monitoring of the differentiating cells through bioluminescence. An isogenic S. marcescens strain was constructed with luxAB under the control of the promoter of flagellin gene hag (phag::luxAB). Patterns of cell differentiation were monitored either by direct X-ray film exposure and/or by Autolumat luminometer detection. Results show that population cell differentiation on the agar surface occurs first in a temporal and then spatial way during colonial growth. It was also found that cells harvested from both the spreading agar plate and broth culture showed differentiation patterns similar to those from swarming cells, suggesting that the agar surface culture may not be essential for the formation of differentiated cells.

Inhibition of synaptic transmission and epileptiform activity in central neurones by fluspirilene

1. Recent studies have shown that fluspirilene, a dopamine D2 receptor antagonist which is a long-acting neuroleptic useful in the maintenance therapy of schizophrenic patients, also displays Ca2+ channel blocking activity. In the present study, we have investigated the effect of fluspirilene on synaptic transmission and epileptiform activity induced in slices of hippocampus and amygdala. 2. Fluspirilene reversibly suppressed the field excitatory postsynaptic potential (f-e.p.s.p) in a concentration-dependent manner in the area CA1 of the hippocampus without affecting the size and shape of fibre volley. Fluspirilene also inhibited the intracellularly recorded e.p.s.p. in amygdala neurones without affecting the resting membrane potential or neuronal input resistance. 3. Fluspirilene increased the ratio of paired-pulse facilitation suggesting a presynaptic mode of action. 4. Epileptiform activity induced in the disinhibited slices was suppessed by fluspirilene in a concentration-dependent manner. This antiepileptic effect was occluded in slices pretreated with the adenosine A1 receptor agonist, N6-cyclopentyladenosine (CPA). 5. It is concluded that fluspirilene-induced synaptic inhibition is probably due to a reduction in presynaptic Ca2+ currents. In clinical trials, the low incidence of seizures provoked by fluspirilene might be related to its intrinsic ability to inhibit synaptic transmission and epileptiform activity.

Effect of glucose concentration on swimming motility in enterobacteria

Since the observation that glucose prevents the synthesis of flagella in Escherichia coli was first reported in 1967, many studies have addressed the underlying mechanism. Currently, it is thought that an increase in glucose concentration decreases the intracellular CRP/cAMP concentration. This leads to an inhibitory effect on the expression of the flhD operon, the master operon for flagella synthesis. In our study on defining factors influencing the cell differentiation of Serratia marcescens, glucose catabolite repression of hag expression and swimming/swarming motility was not observed. Further experiments using a simple swimming motility assay extended this observation to other members of Enterobacteriaceae. Although the underlying mechanism is still uncharacterised, our results suggest that glucose catabolite repression of swimming motility may not be a common phenomenon in Enterobacteriaceae.

Subspecies typing of Vibrio parahaemolyticus by pulsed-field gel electrophoresis

Vibrio parahaemolyticus is one of the most important food-borne pathogens in Taiwan, Japan, and other costal regions. We report on the development of a pulsed-field gel electrophoresis (PFGE) method for the molecular typing of this pathogen. Genomic DNA was digested with SfiI, and the fragments were resolved on 1% agarose with a contour-clamped homogeneous electric field apparatus set at 190 V and a pulse time of 3 to 80 s. A total of 130 selected isolates obtained from outbreaks during 1993 and 1994 on Taiwan were also characterized by this PFGE method. These isolates were grouped into 14 PFGE types which consisted on one to six patterns, and a total of 39 patterns were identified. Most of these domestic clinical isolates could be clustered into several major types (types A, B, C, and G). These major types showed relatively low degrees of similarity to several foreign strains and other domestic but environmental strains. Strain CCRC12863, which originated from Japan, was close to the group consisting of F, G, and H PFGE types, suggesting a clonal relationship between this Japanese strain and other domestic isolates.