Upregulation of Spinal MDGA1 in Rats After Nerve Injury Alters Interactions Between Neuroligin-2 and Postsynaptic Scaffolding Proteins and Increases GluR1 Subunit Surface Delivery in the Spinal Cord Dorsal Horn.

Previous studies suggested that postsynaptic neuroligin-2 may shift from inhibitory toward excitatory function under pathological pain conditions. We hypothesize that nerve injury may increase the expression of spinal MAM-domain GPI-anchored molecule 1 (MDGA1), which can bind to neuroligin-2 and thereby, alter its interactions with postsynaptic scaffolding proteins and increase spinal excitatory synaptic transmission, leading to neuropathic pain. Western blot, immunofluorescence staining, and co-immunoprecipitation studies were conducted to examine the critical role of MDGA1 in the lumbar spinal cord dorsal horn in rats after spinal nerve ligation (SNL). Small interfering ribonucleic acids (siRNAs) targeting MDGA1 were used to examine the functional roles of MDGA1 in neuropathic pain. Protein levels of MDGA1 in the ipsilateral dorsal horn were significantly upregulated at day 7 post-SNL, as compared to that in naïve or sham rats. The increased levels of GluR1 in the synaptosomal membrane fraction of the ipsilateral dorsal horn tissues at day 7 post-SNL was normalized to near sham level by pretreatment with intrathecal MDGA1 siRNA2308, but not scrambled siRNA or vehicle. Notably, knocking down MDGA1 with siRNAs reduced the mechanical and thermal pain hypersensitivities, and inhibited the increased excitatory synaptic interaction between neuroligin-2 with PSD-95, and prevented the decreased inhibitory postsynaptic interactions between neuroligin-2 and Gephyrin. Our findings suggest that SNL upregulated MDGA1 expression in the dorsal horn, which contributes to the pain hypersensitivity through increasing the net excitatory interaction mediated by neuroligin-2 and surface delivery of GluR1 subunit in dorsal horn neurons.

Sevoflurane induces neurotoxic effects on developing neurons through the WNK1/NKCC1/Ca2+ /Drp-1 signalling pathway.

Children repeatedly exposed to anaesthesia have a high risk of cognitive impairment, but the mechanism of its regulation in this context is unknown. The objective of this study was to investigate the possible toxic mechanism of sevoflurane through the WNK1/NKCC1/Ca2+ /Drp-1 signalling pathway. The hippocampal neuronal HT22 cell line was used in this study. The intervention group was treated with the WNK1 inhibitor WNK-463, CaN inhibitor FK506 and Drp-1 inhibitor Mdivi-1 respectively in the medium for 30 min before sevoflurane anaesthesia. The sevofluane group and all intervention group treated with 4.1% sevoflurane for 6 h. Compared with the control group, sevoflurane treatment decreased cell viability and increased cellular apoptosis. Our study found that WNK-463, FK506 and Mdivi-1 can all alleviate the sevoflurane-induced reduction in cell viability, decrease the cell apoptosis. In addition, WNK-463 pretreatment could inhibit the increase of WNK1 kinase and NKCC1 protein concentration caused by sevoflurane. Further, sevoflurane anaesthesia causes intracellular calcium overload, increases the expression of CaN and induces the dephosphorylation of Drp-1 protein at ser637, while CaN inhibitor FK506 pretreatment could reduce the dephosphorylation of Drp-1. Therefore, the WNK1/NKCC1/Ca2+ /Drp-1 signalling pathway plays an important role in sevoflurane-related neurotoxicity. Reducing intracellular calcium influx may be one of the important mechanism to ameliorate sevoflurane toxicity.

Morphine pretreatment protects against cerebral ischemic injury via a cPKCγ-mediated anti-apoptosis pathway.

It has been reported that morphine pretreatment (MP) can exert neuroprotective effects, and that protein kinase C (PKC) participates in the initiation and development of ischemic/hypoxic preconditioning in the brain. However, it remains unknown whether PKC is involved in MP-induced neuroprotection. The aim of the present study, which included in vivo and in vitro experiments, was to determine whether the conventional γ isoform of PKC (cPKCγ) was involved in the protective effects of MP against cerebral ischemic injury. The present study included an in vivo experiment using a mouse model of middle cerebral artery occlusion and an in vitro experiment using neuroblastoma N2a cells with oxygen-glucose deprivation (OGD). Furthermore, a cPKCγ antagonist, Go6983, was used to determine the involvement of cPKCγ in the protective effects of MP against cerebral ischemic injury. In the in vivo experiment, neurological deficits, ischemic infarct volume, neural cell damage, apoptosis and caspase-3 activation were evaluated. In the in vitro experiment, flow cytometry was used to determine the activation of caspase-3 in N2a cells with OGD. It was found that MP protected against cerebral ischemic injury. However, intracerebroventricular injection of the cPKCγ antagonist before MP attenuated the neuroprotective effect of MP and increased the activation of cleaved caspase-3. These findings suggested that MP may provide protection against cerebral ischemic injury via a cPKCγ-mediated anti-apoptosis pathway.

[Changes in microglia number and Iba1 expression level in the prefrontal cortex of type 1 diabetic mice].

The aim of the present study was to observe the activation of microglia in the prefrontal cortex of type 1 diabetes mellitus (T1DM) mice, and the expression of the marker genes of the disease-associated microglia (DAM) associated with neurodegenerative diseases. Sixty healthy adult male C57BL/6J mice were randomly divided into two groups, normal control (CON) group and T1DM group. Streptozocin (STZ) was injected intraperitoneally to induce T1DM mice. The spatial learning and memory function of mice was detected by Morris water maze at the 8th week after the successful model establishment. The number and activation of microglia in the prefrontal cortex of mice were detected by immunofluorescence staining and Western blot. Changes in the mRNA level of several DAM molecular markers were detected by RT-FQ-PCR. The results showed that, compared with CON mice, the fasting blood glucose of T1DM mice increased significantly, while the body weight of T1DM mice decreased remarkably (P < 0.05). The escape latency of water maze in T1DM mice was longer than that in CON mice (P < 0.05). Compared with CON group, the Iba1 protein expression and the number of microglia in prefrontal cortex of T1DM group increased significantly (P < 0.05). In addition, the mRNA levels of several DAM markers in prefrontal cortex of T1DM group were increased significantly (P < 0.05). These results suggest that the microglia are activated and transformed to DAM type in the prefrontal cortex of T1DM mice.

An EZ-Diffusion Model Analysis of Attentional Ability in Patients With Retinal Pigmentosa.

Retinitis pigmentosa (RP) is characterized by visual acuity decrease and visual field loss. However, the impact of visual field loss on the cognitive performance of RP patients remains unknown. In the present study, in order to understand whether and how RP affects spatial processing and attentional function, one spatial processing task and three attentional tasks were conducted on RP patients and healthy controls. In addition, an EZ-diffusion model was performed for further data analysis with four parameters, mean decision time, non-decision time, drift rate, and boundary separation. It was found that in the spatial processing task, compared with the control group, the RP group exhibited a slower response speed in large and medium visual eccentricities, and slower drift rate for the large stimulus, which is strongly verified by the significant linear correlation between the visual field eccentricity with both reaction time (p = 0.047) and non-decision time (p = 0.043) in RP patients. In the attentional orienting task and the attentional switching task, RP exerted a reduction of speed and an increase of non-decision time on every condition, with a decrease of drift rate in the orienting task and boundary separation in the switching task. In addition, the switching cost for large stimulus was observed in the control group but not in the RP group. The stop-signal task demonstrated similar inhibition function between the two groups. These findings implied that RP exerted the impairment of spatial cognition correlated with the visual field eccentricity, mainly in the peripheral visual field. Moreover, specific to the peripheral visual field, RP patients had deficits in the attentional orienting and flexibility but not in the attentional inhibition.

Effects of methamphetamine abuse on spatial cognitive function.

Methamphetamine (MA) abuse has been rising rapidly over the past decade, however, its impact in spatial cognitive function remains unknown. To understand its effect on visuospatial ability and spatial orientation ability, 40 MA users and 40 non-MA users conducted the Simple Reaction Task (Task 1), the Spatial Orientation Task (Task 2), and the Mental Rotation Task (Task 3), respectively. There was no significant difference in either accuracy or reaction time (RT) between 2 groups in Task 1. During Task 2, in comparison with non-MA users, MA users performed poorer on RT, but not in accuracy for foot and hand stimuli. In addition, both non-MA and MA users responded much more quickly to upward stimuli than downward stimuli on vertical surface, however, only non-MA users exhibited leftward visual field advantage in horizontal orientation processing. As for Task 3, MA users exhibited poorer performance and more errors than their healthy counterparts. For each group, linear relationship was revealed between RT and orientation angle, whereas MA abuse led to longer intercept for all stimuli involved. Our findings suggested that MA abuse may lead to a general deficit in the visuospatial ability and the spatial orientation ability with more serious impact in the former.

Sevoflurane neurotoxicity in neonatal rats is related to an increase in the GABAA R α1/GABAA R α2 ratio.

Exposure of neonatal rat to sevoflurane leads to neurodegeneration and deficits of spatial learning and memory in adulthood. However, the underlying mechanisms remain unclear. The type A γ-aminobutyric acid receptor (GABAA R) is a target receptor for sevoflurane. The present study intends to investigate the changes in GABAA R α1/α2 expression and its relationship with the neurotoxicity effect due to sevoflurane in neonatal rats. After a dose-response curve was constructed to determine minimum alveolar concentration (MAC) and safety was guaranteed in our 7-day-old neonatal rat pup mode, we conducted two studies among the following groups: (A) the control group; (B) the sham anesthesia group; and (C) the sevoflurane anesthesia group and all three groups were treated in the same way as the model. First, poly(ADP-ribose) polymerase-1 protein (PARP-1) expression was determined in the different brain areas at 6 hr after anesthesia. Second, the expression of PARP-1 and GABAA R α1/GABAA R α2 in the hippocampus area was tested by Western blotting at 6 hr, 24 hr, and 72 hr after anesthesia in all three groups. After 4 hr, with 0.8 MAC (2.1%) sevoflurane anesthesia, the PARP-1 expression was significantly higher in the hippocampus than the other brain areas (p < .05). Compared with Groups A and B, the expression of PARP-1 in the hippocampus of Group C significantly increased at 6 hr after sevoflurane exposure (216% ± 15%, p < .05), and the ratio of the α1/α2 subunit of GABAA R surged at 6 hr (126% ± 6%), 24 hr (127% ± 8%), and 72 hr (183% ± 22%) after sevoflurane exposure in the hippocampus (p < .05). Our study showed that sevoflurane exposure of 0.8 MAC (2.1%)/4 hr was a suitable model for 7-day-old rats. And the exposure to sevoflurane could induce the apoptosis of neurons in the early stage, which may be related to the transmission from GABAA R α2 to GABAA R α1.

[The Relationship Between GSK-3 and Mental Disorders].

Glycogen synthase kinase 3 ( GSK-3) is a constitutive serine/threonine kinase, which plays a important role in many essential physiological activities, and regulates cellular processes including metabolism, development and apoptosis through a number of signaling pathways such as Wnt/ß-catenin. Numbers of studies claimed that abnormal regulation of GSK-3 may activate several differential cells, pathways and loops, and bring out the mental disorder, including bipolar disorder, depression, anxiety, schizophrenia and so on. Inhibiting GSK-3 plays an important role in therapy for mental diseases. This review summed up the mechanism of how GSK-3 does work in mental diseases at home and abroad recent years, and hoping to provide basis for clinical treatment.

The PD-1/B7-H1 pathway modulates the natural killer cells versus mouse glioma stem cells.

PURPOSE: Glioblastoma multiforme (GBM) is the most malignant primary type of brain tumor in adults. There has been increased focus on the immunotherapies to treat GBM patients, the therapeutic value of natural killer (NK) cells is still unknown. Programmed death-1 (PD-1) is a major immunological checkpoint that can negatively regulate the T-cell-mediated immune response. We tested the combination of the inhibiting the PD-1/B7H1 pathway with a NK-cell mediated immune response in an orthotopic mouse model of GBM. METHODS AND MATERIALS: Mouse glioma stem cells (GL261GSCs) and mouse NK cells were isolated and identified. A lactate dehydrogenase (LDH) assay was perfomed to detect the cytotoxicity of NK cells against GL261GSCs. GL261GSCs were intracranially implanted into mice, and the mice were stratified into 3 treatment groups: 1) control, 2) NK cells treatment, and 3) PD-1 inhibited NK cells treatment group. Overall survival was quantified, and animal magnetic resonance imaging (MRI) was performed to determine tumor growth. The brains were harvested after the mice were euthanized, and immunohistochemistry against CD45 and PCNA was performed. RESULTS: The mouse NK cells were identified as 90% CD3- NK1.1+CD335+ by flow cytometric analysis. In the LDH assay, the ratios of the damaged GL261GSCs, with the E:T ratios of 2.5:1, 5:1, and 10:1, were as follows: 1) non-inhibited group: 7.42%, 11.31%, and 15.1%, 2) B7H1 inhibited group: 14.75%, 18.25% and 29.1%, 3) PD-1 inhibited group: 15.53%, 19.21% and 29.93%, 4) double inhibited group: 33.24%, 42.86% and 54.91%. In the in vivo experiments, the mice in the PD-1 inhibited NK cells treatment group and IL-2-stimulated-NK cells treatment group displayed a slowest tumor growth (F = 308.5, P<0.01) and a slower tumor growth compared with control group (F = 118.9, P<0.01), respectively. The median survival of the mice in the three groups were as follows: 1) conrol group: 29 days, 2) NK cells treatment group: 35 days (P = 0.0012), 3) PD-1 inhibited NK cells treatment group: 44 days (P = 0.0024). Immunologic data of PCNA-positive cell ratios and CD45-positive cell ratios of the tumor specimens in the three groups were as follows: 1) control group: 65.72% (PCNA) and 0.92% (CD45), 2) NK treatment group: 27.66% (PCNA) and 13.46% (CD45), and 3) PD-1 inhibited NK cells treatment group: 13.66% (PCNA) and 23.66% (CD45) (P<0.001). CONCLUSION: The results demonstrated that blockade of PD-1/B7H1 pathway could promote mouse NK cells to kill the GL261GSCs, and the PD-1-inhibited NK cells could be a feasible immune therapeutic approach against GBM.

Overactivation of corticotropin-releasing factor receptor type 1 and aquaporin-4 by hypoxia induces cerebral edema.

Cerebral edema is a potentially life-threatening illness, but knowledge of its underlying mechanisms is limited. Here we report that hypobaric hypoxia induces rat cerebral edema and neuronal apoptosis and increases the expression of corticotrophin releasing factor (CRF), CRF receptor type 1 (CRFR1), aquaporin-4 (AQP4), and endothelin-1 (ET-1) in the cortex. These effects, except for the increased expression of CRF itself, could all be blocked by pretreatment with an antagonist of the CRF receptor CRFR1. We also show that, in cultured primary astrocytes: (i) both CRFR1 and AQP4 are expressed; (ii) exogenous CRF, acting through CRFR1, triggers signaling of cAMP/PKA, intracellular Ca(2+), and PKCε; and (iii) the up-regulated cAMP/PKA signaling contributes to the phosphorylation and expression of AQP4 to enhance water influx into astrocytes and produces an up-regulation of ET-1 expression. Finally, using CHO cells transfected with CRFR1(+) and AQP4(+), we show that transfected CRFR1(+) contributes to edema via transfected AQP4(+). In conclusion, hypoxia triggers cortical release of CRF, which acts on CRFR1 to trigger signaling of cAMP/PKA in cortical astrocytes, leading to activation of AQP4 and cerebral edema.

[Effects of cPKCßII/γ membrane translocation ischemic/hypoxic tolerance induced by morphine postconditioning in hippocampal slices].

OBJECTIVE: To determine whether or not morphine postconditioning can induce ischemic/hypoxic tolerance in neurons subjected to reperfusion injury after oxygen-glucose deprivation (OGD). METHODS: Hippocampal slices of 400 µm thickness were prepared from healthy adult male BALB/c mice. The slices were incubated in oxygen-saturated ACSF without or with calcium, then were subjected to OGD for 20 min. After recovery, the samples were immersed in oxygenated artificial fluid for 2 hours in the presence or absence of morphine postconditioning at 3 µmol/L during the first 5 - 60 min. The assessment of slices injury was performed by a determination of the intensity of slice stain incubated with TTC (2% 2, 3, 5-triphenyltetrazolium chloride) and the leakage rate of LDH also evaluated. At the designated periods during incubation, some slices were immersed into liquid nitrogen for a later analysis of Western blot. The frozen slices were homogenized, sonicated and centrifuged to separate soluble and particulate proteins. 10% SDS-PAGE Western blot was used to identify the changes of membrane-specific translocation of cPKCßII/γ. RESULTS: After reperfusion, the cell survival significantly decreased with the elongation of OGD (51.4%). The release rate of LDH (184.05%) significantly increased simultaneously. In hippocampal slices postconditioned with morphine for 20 - 60 min, the release rate of LDH (136%, 142%, 144%) significantly decreased as compared with the group OGD. In the hippocampal slices postconditioned with morphine for 10 - 30 min, the cell survival rate (64.9%, 69.9%, 63.5%) significantly increased as compared with reperfusion alone. cPKCγ of particulate fraction increased versus the control. And there was a corresponding decrease of cytosolic fraction. Morphine postconditioning significantly inhibited the cPKCγ isoform-specific membrane translocation. It declined from 136% in the group OGD to 123%, 118%, 114% in the group morphine 20 - 60 min. cPKCßII membrane translocation had no change. CONCLUSION: Morphine postconditioning can induce ischemic tolerance in nerons. The protective mechanism may be through inhibiting the cPKCγ isoform-specific membrane translocation.

[Brain mechanisms of male sexual function].

In this paper, we reviewed the brain imaging studies of male sexual function in recent years from three aspects: the brain mechanism of normal sexual function, the brain mechanism of sexual dysfunction, and the mechanism of drug therapy for sexual dysfunction. Studies show that the development stages of male sexual activities, such as the excitement phase, plateau phase and orgasm phase, are controlled by different neural networks. The mesodiencephalic transition zone may play an important role in the start up of male ejaculation. There are significant differences between sexual dysfunction males and normal males in activation patterns of the brain in sexual arousal. The medial orbitofrontal cortex and inferior frontal gyrus in the abnormal activation pattern are correlated with sexual dysfunction males in sexual arousal. Serum testosterone and morphine are commonly used drugs for male sexual dysfunction, whose mechanisms are to alter the activating levels of the medial orbitofrontal cortex, insula, claustrum and inferior temporal gyrus.

[Modelling of cerebral hyper-perfusion after chronic forebrain ischemia in rats].

OBJECTIVE: To establish the cerebral hyper-perfusion model after chronic forebrain ischemia in rats. METHODS: A total of 72 male rats were equally randomized into 2 modeling groups. The ligation of bilateral common carotid artery could induce chronic forebrain ischemia. And 36 rats were randomly grouped by ischemia duration: control group (n = 9), sham group (n = 9), 2-week ischemia group (n = 9) and 4-week ischemia group (n = 9). The blood flow in frontal lobe was measured at pre- and post-ligation. The neurological score and cerebral infarction area were also compared among the groups. The cerebral reperfusion was concurrently undertaken with an infusion dose of phenylephedrine at 4 µg×kg(-1)×min(-1) via tail vein to produce cerebrally hyperperfused blood flow rate over 200% of baseline following chronic ischemia. According to cerebral hyper-perfusion duration, 36 rats were randomly assigned into 4 groups: control group (n = 9), saline infusion group (n = 9), 30-minute cerebral hyper-perfusion group (n = 9) and 2-hour cerebral hyper-perfusion group (n = 9). The blood flow in frontal lobe was measured before and after cerebral hyper-perfusion. The neurological score, blood-brain barrier permeability and dry-wet weight ratio of brain also were compared among the groups. RESULTS: The forebrain blood flow decreased by 67% ± 2% after the ligation of bilateral common carotid artery. There was significant difference between cerebral hyper-perfusion and saline infusion groups (P < 0.01). No statistic difference was observed in neurological score and cerebral infarction area between 2-week ischemia and control groups. But it was obvious between 4-week ischemia and control groups. The permeability in blood-brain barrier of rats significantly increased in 2-hour hyper-perfusion group (P < 0.05). CONCLUSION: The 2-hour duration of cerebral hyper-perfusion following a 2-week ligation of bilateral common carotid artery may establish a reliable cerebral hyper-perfusion model in rats.

[Effect of repetitive hypoxia on MMP-2/9 expression and activation in murine brain].

AIM: To explore the changes of MMP-2/9 protein expression and excitation in brain of repetitive hypoxic mice. METHODS: The biochemistry techniques of SDS-PAGE, Western bolt and Gel Goc Image Analysis System were applied to determine the level of MMP-2 and MMP-9 expression and activation in cortex and hippocampus of mice. The animals were randomly divided into 5 groups: the normal control group (H0), acute hypoxic (H1, hypoxic exposure once), repetitive hypoxic groups (H2-H4, repetitive hypoxia for 2-4 runs respectively). RESULTS: (1) The MMP- 2 expression level was increased first then decreased in hippocampus and the significant decrease was found in H4 group (P < 0.05, n=6), but no significant changes among the 5 groups in cortex. In addition, no activated form of 66 kD MMP-2 had been detected both in hippocampus and cortex. (2) Along with the development of brain hypoxic preconditioning, the level MMP-9 protein expression also increased first then decreased gradually in hippocampus, and the significant changes were found both in H1 and H4 groups (P < 0.05, n=7 for each group). The same trace of changes was also found in the activation of MMP-9 (include 82 and 78 kD forms) in hippocampus, and the significance both in H1 and H4 (P < 0.05, n=7 for each group) were detected. However, there was not any significant change in the level of MMP-9 protein expression or activation to be found in cortex. CONCLUSION: These results suggested that MMP-2 and MMP-9 might play certain role in the development of cerebral hypoxic preconditioning, the different changes of MMP-2/9 protein expression and activation both in cortex and hippocampus might be involved in their selective vulnerability to hypoxia.

[Hypoxic preconditioning increases cPKCgamma membrane translocation in murine brain].

Cerebral hypoxic preconditioning (CHP), which was induced by repetitive sub-lethal hypoxic insult, is an endogenous protection of neuron against subsequent severe hypoxic injury. Although a number of possible induction pathways have been investigated, such as neuroactive cytokines, activation of glutamate receptors, the ATP-sensitive potassium channel, nitric oxide and oxidative stress, the exact mechanism underlying CHP-induced protection remains unclear. It is interesting that all the above-mentioned mechanisms are involved in the activation of protein kinases C (PKC). Recently we reported that the level of PKCs membrane translocation was significantly increased in the brain of hypoxic preconditioned mice. In order to explore the role of conventional protein kinases C (cPKC) in the development of cerebral hypoxic preconditioning, biochemical techniques of SDS-PAGE and Western bolt were applied to observe the effects of repetitive hypoxic exposure (H1-H4) on the level of cPKCalpha and gamma membrane translocation in the cortex and hippocampus of mice. Experiments were carried out in accordance with the National Institutes of Health guide for the care and use of laboratory animals. The hypoxic preconditioned mice model was adapted with minor modification from our previous report. In brief, healthy adult BALB/C mice weighing 18-20 g of either sex were randomly divided into 5 groups: control group (H0), hypoxic control group (H1, hypoxic exposure once ), hypoxic preconditioned group (H2-H4, repetitive hypoxic exposure for 2-4 times respectively). The first sign of gasping breath was taken as the end of each hypoxic exposure, and then the mice were kept in normal control condition for a 30-min interval to recover before the following hypoxic insult. We found that the level of cPKCgamma membrane translocation was increased significantly (*P<0.05, n=6) with the increase of the hypoxic exposure times in both hippocampus (H0: 100% vs H1 approximately H4: 119.2%+/-7.0% *, 139.3% +/-7.4%*, 134.2% +/-8.95%*, 184.0% +/-10.8%*) and cortex (H0: 100% vs H1-H4: 129.7% +/-13.8%, 143.3% +/-13.9%*, 204.0% +/-12.1%*, 229.5% +/-14.6%*) of mice. But there were no significant changes in cPKCalpha membrane translocation in cortex and hippocampi of hypoxic preconditioned mice. These results suggest that cPKCgamma plays an important role in the development of cerebral hypoxic preconditioning. The changes in some other forms of novel and atypical PKCs are still under investigation.

[Hypoxic preconditioning increase nPKCepsilon membrane translocation in the brain of mice].

AIM: To explore the role of novel protein kinases C (nPKCs) in the development of cerebral hypoxic preconditioning. METHODS: By using the mice model of hypoxic preconditioning, which was established before in our lab, the biochemistry techniques of SDS-PAGE and Western blot were applied to observe the effects of repetitive hypoxic exposure (H0-H4) on nPKCs (nPKCepsilon, delta, eta, mu and theta) membrane translocation in hippocampus and cortex. RESULTS: nPKCepsilon membrane translocation was increased in response to the hypoxic exposure times in the hippocampus (H0: 41.6% +/- 1.4% vs. H1-H4: 46.9% +/- 4.5%, 52.7% +/- 3.9%, 58.8% +/- 2.7% and 61.3% +/- 3.7%) and cortex (H0: 38.4% +/- 4.5% vs. 42.4% +/- 5.0%, 48.7% +/- 6.5%, 55.3% +/- 8.9% and 61.2% +/- 10.2%) of mice, and there were statistic significances among H2, H3 and H4 in hippocampus, and H3 and H4 in cortex respectively (P < 0.01). But for nPKCdelta, eta, mu and theta membrane translocation, there were no any significant changes in hippocampus and cortex of hypoxic preconditioned mice. CONCLUSION: nPKCepsilon may play an important role in the development of cerebral hypoxic preconditioning, but it need more evidence to prove.

[Neurogranin: a brain-specific protein].

Neurogranin (Ng) is a newly discovered brain-specific protein composed of 78 amino acid residues, which mainly located postsynaptically in the cerebral cortex, hippocampus and olfactory bulb in adult human or animals. As a member of calpacitin family, Ng is a protein kinase C (PKC) substrate and calmodulin (CaM) reservoir. In the physiological conditions, Ng forms a complex with CaM, and its CaM-binding affinity was modulated by phosphorylation, oxidation and glutathiolation under the activation of PKC or oxidant stress, which may be involved in the regulation of CaM and CaM-activated proteins, such as CaM-dependent nitric oxide synthase (NOS), CaM-dependent protein kinase II (CaMKII) and CaM-dependent adenylate cyclase (AC). Since most of CaM-activated proteins were involved in long-term potentiation (LTP) and long-term depression (LTD), and the timing pattern of Ng gene expression and protein synthesis are coincidence with synaptogenesis and development, it is suggested that Ng may play an important role in learning, memory and neuroplasticity. In addition, it was found that the changes of Ng expression might associate with certain cerebral pathophysiologic disorders, such as hypothyroidism, sleep-deprivation, brain aging and cerebral hypoxic preconditioning.