Combined treatment with valproic acid and estrogen has neuroprotective effects in ovariectomized mice with Alzheimer's disease.

Postmenopausal women with Alzheimer's disease (AD) exhibit dramatically reduced sensitivity to estrogen replacement therapy, which is though to be related to an estrogen receptor (ER)α/ERß ratio imbalance arising from a significantly decreased level of ERs of the brain. The aim of our study was to investigate whether valproic acid (VPA) can enhance the beneficial effects of estrogen on cognitive function through restoration of ERα and ERß expression in the brain. We removed the ovaries of female APP/PS1 mice to simulate the low estrogen levels present in postmenopausal women and then administered VPA (30 mg/kg, intraperitoneal injection, once daily), 17ß-estradiol (E2) (2.4 µg, intraperitoneal injection, once daily), liquiritigenin (LG) (50 µg/kg, intragastric infusion, once daily), VPA + E2, or VPA + LG for 4 successive weeks. Compared with treatment with a single drug, treatment with VPA + E2 or VPA + LG significantly increased the level of glycogen synthase kinase 3ß, increased the expression of estrogen receptor α, reduced the expression of small ubiquitin-like modifiers, and increased the level of estrogen receptor ß. This resulted in enhanced sensitivity to estrogen therapy, reduced amyloid ß aggregation, reduced abnormal phosphorylation of the tau protein, reduced neuronal loss, increased dendritic spine and postsynaptic density, and significantly alleviated memory loss and learning impairment in mice. This study was approved by the Chongqing Medical University Animal Protection and Ethics Committee, China on March 6, 2013.

Dihydromyricetin inhibits microglial activation and neuroinflammation by suppressing NLRP3 inflammasome activation in APP/PS1 transgenic mice.

BACKGROUND: Activated microglia-mediated inflammation plays a key role in the pathogenesis of Alzheimer's disease (AD). In addition, chronic activation of NLRP3 inflammasomes triggered by amyloid ß peptide (Aß) in microglia contributes to persistent neuroinflammation. Here, the primary goal was to assess whether Dihydromyricetin (DHM), a plant flavonoid compound, is effective therapies for AD; it is crucial to know whether DHM will affect microglial activation and neuroinflammation in APP/PS1 transgenic mice. METHODS: After DHM was intraperitoneally injected in APP/PS1 double-transgenic mice, we assessed the effect of DHM on microglial activation, the expression of NLRP3 inflammasome components, and the production of inflammatory cytokine IL-1ß by immunofluorescence and Western blot. To determine whether DHM play roles in the Aß production and deposition, amyloid ß protein precursor (APP) and ß-site APP cleaving enzyme1 (BACE1), as well as neprilysin (NEP), were detected by Western blot. Finally, behavior was tested by Morris Water Maze to illustrate whether DHM treatment has a significantly positive effect on ameliorating the memory and cognition deficits in AD. RESULTS: Dihydromyricetin treatment significantly ameliorated memory and cognition deficits and decreased the number of activated microglia in the hippocampus and cortex of APP/PS1 mice. In addition, APP/PS1 mice show reduced activation of NLRP3 inflammasomes and reduced expression of NLRP3 inflammasome components. Furthermore, DHM could promote clearance of Aß, a trigger for NLRP3 inflammasome activation, by increasing levels of NEP and shift microglial conversion to the M2-specific agrinase-1-positive cell phenotype, which enhances microglial clearance of Aß and its aggregates but not production of Aß. CONCLUSION: Taken together, our findings suggest that DHM prevents progression of AD-like pathology through inhibition of NLRP3 inflammasome-based microglia-mediated neuroinflammation and may be a promising therapeutic drug for treating AD.

Valproic Acid Modifies Synaptic Structure and Accelerates Neurite Outgrowth Via the Glycogen Synthase Kinase-3ß Signaling Pathway in an Alzheimer's Disease Model.

AIM: Tau hyperphosphorylation and amyloid ß-peptide overproduction, caused by altered localization or abnormal activation of glycogen synthase kinase-3ß (GSK-3ß), is a pathogenic mechanism in Alzheimer's disease (AD). Valproic acid (VPA) attenuates senile plaques and neuronal loss. Here, we confirmed that VPA treatment improved spatial memory in amyloid precursor protein (APP)/presenilin 1 (PS 1) double-transgenic mice and investigated the effect of VPA on synaptic structure and neurite outgrowth. METHODS: We used ultrastructural analysis, immunocytochemistry, immunofluorescence staining, and Western blot analysis to assess the effect of VPA treatment in mice. RESULTS: VPA treatment thickened the postsynaptic density, increased the number of presynaptic vesicles, and upregulated the expression of synaptic markers PSD-95 and GAP43. VPA increased neurite length of hippocampal neurons in vivo and in vitro. In VPA-treated AD mouse brain, inactivated GSK-3ß (pSer9-GSK-3ß) was markedly increased, while hyperphosphorylation of tau at Ser396 and Ser262 was decreased; total tau levels remained similar. VPA treatment notably improved pSer133-cAMP response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) levels, which are associated with synaptic function and neurite outgrowth. CONCLUSION: VPA improves behavioral deficits in AD, modifies synaptic structure, and accelerates neurite outgrowth, by inhibiting the activity of GSK-3ß, decreasing hyperphosphorylated tau, enhancing CREB and BDNF expression.

[The expressions of HSP 70 mRNA and c-fos mRNA in the skeletal muscle and cardiac muscle of rabbits by electrocuted].

OBJECTIVE: To study the changes of HSP 70 mRNA and c-fos mRNA expression and to find a method to differentiate antemortem from postmortem electrocution. METHODS: Fifteen New Zealand rabbits were randomly divided into three groups, the antemortem electrocution group, the postmortem electrocution group, and the control group. Each group consists of five rabbits. The levels of HSP 70 mRNA and c-fos mRNA in skeletal muscle and cardiac muscle were examined with quantitative fluorescent RT-PCR. RESULTS: The levels of HSP 70 mRNA and c-fos mRNA in the antemortem electrocution group increased significantly (P<0.05), compared with that of the postmortem electrocution group. CONCLUSION: The changes of HSP 70 mRNA and c-fos mRNA expression in skeletal muscle and cardiac muscle can be used as an indicator to distinguish antemortem from postmortem electrocution.

[Apoptosis and caspase-12 expression in progressive compressive spinal cord injury: experiment with rats].

OBJECTIVE: To investigate the apoptosis and caspase-12 expression in progressive compression of spinal cord (PCSC). METHODS: 120 adult Wistar rats were randomly divided into 2 equal groups, experimental group, undergoing operation so as to establish PCSC models, and control group, undergoing sham operation. 1, 3, 7, 14, 21, and 28 days after the operation, 5 rats from each group were anesthetized with their spinal cords taken out. TUNNEL method was used to observe the apoptosis of the neurons in the compressed segments. Another 5 rats from each group at different time points were anesthetized with their spinal cords as well. Immunohistochemistry was used to detect the mRNA expression of caspase-12 in the compressed segments. Western blotting was used to detect the protein expression of caspase-12. RESULTS: The apoptotic rates of neurons and gliocytes 1, 3, 7, 14, 21, and 28 days after were 12.5% +/- 2.3%, 13.0% +/- 3.6%, 17.2% +/- 4.3%, 29.4% +/- 4.4%, 36.1% +/- 6.5%, and 2.3% +/- 7.9% respectively, with significant differences among the values 14, 21, and 28 days and those at other time points after the operation (all P < 0.05). Immunohistochemistry showed that the number of caspase-12 positive neurons increased since 1 day after, and became remarkably high 14, 21, and 28 days after with significant differences among different time points (all P < 0.05). Western blotting showed that the protein expression of caspase-12 was low 1, 3, and 7 days after, and peaked 14 days after, and then gradually decreased, however, the expression levels 21 and 28 days after were still significantly higher then those 1, 3, and 7 days after (all P < 0.05). CONCLUSION: Caspase-12 is involved in the apoptosis of neurons in PCSC.

[Changes in noradrenergic neurons in the rat spinal cord after brain injury].

OBJECTIVE: To investigate the impact of experimental brain injury on the noradrenergic (NA) neurons in the spinal cord, in order to explore possible mechanism of the changes in NA neuron expression. METHODS: Seventy healthy Wistar rats were randomly divided into two groups: normal group (n=10), brain injury (BI) group (n=60). The animals in BI group were subjected to BI with the modified Feeney's method. The spinal cords of rats were harvested at 3, 6, 12, 24, 48 and 72 hours after the injury, respectively. Immunohistochemistry (IHC) and reverse transcriptase-polymerase chain reaction (RT-PCR) were used to assess the changes in dopamine-beta-hydroxylase (DBH) expression. RESULTS: IHC showed a small number of DBH-positive neurons distributed in anterior horn of the cervical and lumbar enlargements in control group; a larger number of dark-stained noradrenergic neurons were found in anterior horn, and also in posterior and lateral horns of spinal cord in brain injury group at different time points after injury, as compared with control group (P<0.05 or P<0.01). RT-PCR showed that the expression of DBH mRNA in brain injury group was significantly higher than that in control group at different time points after injury (P<0.05 or P<0.01). CONCLUSION: A significant increase of NA neurons in spinal cord of brain injury group suggests that more NA is synthesized by the neurons, which is necessary to meet the demand of the organism under the stress condition, suggesting that NA plays a very important role in the course of brain injury.

[Expression of PDGF-B after fluid percussion brain injury in rats].

OBJECTIVE: To elucidate the changes of PDGF-B chain in the brain injured by fluid percussion. METHODS: The expression of PDGF-B protein was studied by immunohistochemistry and the results were assessed by image analysis system. RESULTS: Enhanced expression of PDGF-B protein induced by fluid percussion injury was seen at 1 h, and its marked up-regulation was noted at 4-7 days, and then the expression became decreased but it remained above the control levels till 14 days after injury. CONCLUSION: Fluid percussion brain injury induced expression of PDGF-B. The regular change pattern of PDGF-B level in time course seems to be of value in estimating the age of brain injury.

[A study on the expression of Snap-25 mRNA in rat poisoned by tetramine].

OBJECTIVE: This study sought to reveal the relationship between Snap-25 and tetramine poisoning in order to approach the mechanism of tetramine poisoning. METHODS: The levels of Snap-25 mRNA in the brain tissues of poisoned SD rats were detected by RT-PCR method. RESULTS: After 1 hour of intoxication, the expression level of Snap-25 mRNA did not change in the rat brain. It increased at day 1 and reached its peak at day 3. The expression level of Snap-25 mRNA begain to descend at day 5, but it was still higher than that in the rat brain tissue of control group. CONCLUSION: In this study the expression of Snap-25 of rat poisoned by tetramine was not markedly increased in the early stage of poisoning, indicating that the symptoms of rat poisoned by tetramine are not induced by the changes of the Snap-25 level. The mechanism of high expression in Snap-25 mRNA probably involves the negative feedback of the body, which may increase the releasing of neurohumor and hence mitigate the symptoms of poisoning.