Uric Acid Protects against Focal Cerebral Ischemia/Reperfusion-Induced Oxidative Stress via Activating Nrf2 and Regulating Neurotrophic Factor Expression.

The aim of this study was to investigate whether uric acid (UA) might exert neuroprotection via activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway and regulating neurotrophic factors in the cerebral cortices after transient focal cerebral ischemia/reperfusion (FCI/R) in rats. UA was intravenously injected through the tail vein (16 mg/kg) 30 min after the onset of reperfusion in rats subjected to middle cerebral artery occlusion for 2 h. Neurological deficit score was performed to analyze neurological function at 24 h after reperfusion. Terminal deoxynucleotidyl transferase-mediated dNTP nick end labeling (TUNEL) staining and hematoxylin and eosin (HE) staining were used to detect histological injury of the cerebral cortex. Malondialdehyde (MDA), the carbonyl groups, and 8-hydroxyl-2'-deoxyguanosine (8-OHdG) levels were employed to evaluate oxidative stress. Nrf2 and its downstream antioxidant protein, heme oxygenase- (HO-) 1,were detected by western blot. Nrf2 DNA-binding activity was observed using an ELISA-based measurement. Expressions of BDNF and NGF were analyzed by immunohistochemistry. Our results showed that UA treatment significantly suppressed FCI/R-induced oxidative stress, accompanied by attenuating neuronal damage, which subsequently decreased the infarct volume and neurological deficit. Further, the treatment of UA activated Nrf2 signaling pathway and upregulated BDNF and NGF expression levels. Interestingly, the aforementioned effects of UA were markedly inhibited by administration of brusatol, an inhibitor of Nrf2. Taken together, the antioxidant and neuroprotective effects afforded by UA treatment involved the modulation of Nrf2-mediated oxidative stress and regulation of BDNF and NGF expression levels. Thus, UA treatment could be of interest to prevent FCI/R injury.

5-HMF attenuates striatum oxidative damage via Nrf2/ARE signaling pathway following transient global cerebral ischemia.

Recent studies have shown 5-hydroxymethyl-2-furfural (5-HMF) has favorable biological effects, and its neuroprotection in a variety of neurological diseases has been noted. Our previous study showed that treatment of 5-HMF led to protection against permanent global cerebral ischemia. However, the underlying mechanisms in cerebral ischemic injury are not fully understood. This study was conducted to investigate the neuroprotective effect of 5-HMF and elucidate the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway mechanism in the striatum after transient global cerebral ischemia. C57BL/6 mice were subjected to bilateral common carotid artery occlusion for 20 min and sacrificed 24 h after reperfusion. 5-HMF (12 mg/kg) or an equal volume of vehicle was intraperitoneally injected 30 min before ischemia and 5 min after the onset of reperfusion. At 24 h after reperfusion, neurological function was evaluated by neurological disability status scale, locomotor activity test and inclined beam walking test. Histological injury of the striatum was observed by cresyl violet staining and terminal deoxynucleotidyl transferase (TdT)-mediated dNTP nick end labeling (TUNEL) staining. Oxidative stress was evaluated by the carbonyl groups introduced into proteins, and malondialdehyde (MDA) levels. An enzyme-linked immunosorbent assay (ELISA)-based measurement was used to detect Nrf2 DNA binding activity. Nrf2 and its downstream ARE pathway protein expression such as heme oxygenase-1, NAD (P)H:quinone oxidoreductase 1, glutamate-cysteine ligase catalytic subunit and glutamate-cysteine ligase modulatory subunit were detected by western blot. Our results showed that 5-HMF treatment significantly ameliorated neurological deficits, reduced brain water content, attenuated striatum neuronal damage, decreased the carbonyl groups and MDA levels, and activated Nrf2/ARE signaling pathway. Taken together, these results demonstrated that 5-HMF exerted significant antioxidant and neuroprotective effects following transient cerebral ischemia, possibly through the activation of the Nrf2/ARE signaling pathway.

Dietary cholesterol alters memory and synaptic structural plasticity in young rat brain.

Cholesterol plays an important role in synaptic plasticity, learning and memory. To better explore how dietary cholesterol contributes to learning and memory and the related changes in synaptic structural plasticity, rats were categorized into a regular diet (RD) group and a cholesterol-enriched diet (CD) group, and were fed with respective diet for 2 months. Dietary cholesterol impacts on learning and memory, hippocampal synaptic ultrastructure, expression levels of postsynaptic density-95 (PSD-95), synaptophysin (SYP) and cannabinoid receptor type 1 (CB1R) were investigated. We found CD rats had better performances in learning and memory using Morris water maze and object recognition test than RD rats. The memory improvement was accompanied with alterations of synaptic ultrastructure in the CA1 area of the hippocampus evaluated by electron microscopy, enhanced immunoreactivity of SYP, a presynaptic marker in hippocampus detected by immunocytochemistry, as well as increased levels of PSD-95, SYP and decreased level of CB1R in brains of CD rats determined by Western blot. Taken together, the results suggest that the improvement of learning and memory abilities of the young adult rats induced by dietary cholesterol may be linked with changes in synaptic structural plasticity in the brain.

Cornel iridoid glycoside inhibits inflammation and apoptosis in brains of rats with focal cerebral ischemia.

The capacity of cornel iridoid glycoside (CIG) to suppress the manifestations of ischemic stroke was investigated. CIG was administered to rats by the intragastric route once daily for 7 days. Focal cerebral ischemia was induced by 2 h of middle cerebral artery occlusion followed by 24 h of reperfusion. In non-treated rats large infarct areas were observed within 24 h of reperfusion. Examination of the ischemic cerebral cortex revealed microglia and astrocyte activation, increased interleukin-1beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) concentrations, increased DNA fragmentation in the ischemia penumbra, elevated Bax expression, increased caspase-3 cleavage, and decreased Bcl-2 expression. Pretreatment with CIG decreased the infarct area, DNA fragmentation, IL-1beta and TNF-alpha concentrations, microglia and astrocyte activation, Bax expression, and caspase-3 cleavage while increasing Bcl-2 expression. CIG exerts anti-neuroinflammatory and anti-apoptotic effects which should prove beneficial for prevention or treatment of stroke.

[Effects of epimedium flavonoids on synapse related protein in brains of dementia transgenic mice].

OBJECTIVE: To investigate changes of synapse related protein, such as synaptophysin (SYP) and postsynaptic dense material 95 (PSD-95), in brains of 10 months old transgenic mice, and the effects of Epimedium flavonoids (EF) on expression of SYP and PSD-95 in brain of 10 months old of APP transgenic mice. METHODS: The mice of drug treated group were administered intragastrically by EF (at low doses of 0.03 and high dose of 0.1 g.kg(-1).d(-1)) from 4 to 10 months old. The mice of normal group and negative transgene group were administered of distilled water by the same way. The expression of SYP in CA1, CA3, and dentate gyrus (DG) areas of hippocampus and cortex, and PSD-95 in hippocampus and cortex were detected by immunohistochemistry and Western blot respectively. RESULTS: Compared to negative transgenic mice, the expression of SYP in cortex was decreased by 51.3% (P < 0.01). The IOD value of SYP immuno-reactivity cell in CA1, CA3 and DG areas of hippocampus in 10 months old transgenic mice were significantly decreased (the suppression rates were 59.1%, 57.7% and 56.5% in CA1, CA3 and DG respectively, all P < 0.01). The expression of PSD-95 in cortex decreased by 36.4% (P < 0.01). The count of PSD-95 immuno-reactivity cell in CA1 area of hippocampus decreased with the suppression rate of 18.5% (P < 0.05). After being administered intragastrically by EF for 6 months, the expression of SYP in cortex of EF low doses and high dose group mice increased by 40.0% (P < 0.05) and 106.4% (P < 0.01) respectively in comparison with that of the control group. The IOD value of SYP immuno-reactivity cell in hippocampal CA1, CA3 and DG areas of EF low and high dose group mice were all significantly increased (all P < 0.01). The expression of PSD-95 in cortex of EF low and high dose group mice increased by 57.3% (P < 0.05) and 84.3% (P < 0.01) respectively when compare to the control group. The count of PSD-95 immuno-reactivity cell in CA1 area of hippocampus of mice in EF high dose group increased by 22.5% (P < 0.05). CONCLUSION: Epimedium flavonoids could protect the synaptic structure and function by promoting the expression of synaptophysin and postsynaptic dense material 95, which suggest that Epimedium Flavonoids may have a promising application prospect in improving the synaptic impairment of AD.

[Evaluation of tongue manifestation of blood stasis syndrome and its relationship with blood rheological disorder in a rat model of transient brain ischemia].

OBJECTIVE: To study the tongue tissue blood oxygen saturation measurement for evaluating tongue manifestation of blood stasis syndrome, and to explore its correlation with blood rheological disorder in a rat model of acute transient brain ischemia. METHODS: Twenty-eight SD rats were randomly divided into sham-operated group and ischemia group. Middle cerebral artery occlusion was induced by thread in rats of the ischemia group. Tongue tissue blood oxygen saturation, neurological severity score and the changes of blood viscosity, red blood cell deformity, thrombin time and fibrinogen in the rats were measured after 24-hour reperfusion. RESULTS: Blood viscosity and the content of fibrinogen in the ischemia group were significantly higher than those in the sham-operated group. Red blood cell deformity, thrombin time and tongue tissue blood oxygen saturation in the ischemia group were decreased as compared with the sham-operated group. There was a positive correlation between red blood cell deformity and tongue tissue blood oxygen saturation. CONCLUSION: Tongue tissue blood oxygen saturation is a good measurement for evaluating blood stasis in a rat model of focal cerebral ischemia, and this model can be used as a rat model of stroke with blood stasis syndrome.