Dipotassium N-stearoyltyrosinate ameliorated pathological injuries in triple-transgenic mouse model of Alzheimer's disease.

Recently, anandamide (AEA) analogues have been well recognized for its potent neuroprotective effects in counteracting the deterioration of Alzheimer's disease (AD) brains through multiple pathological processes. In our previous studies, dipotassium N-stearoyltyrosinate (NSTK), an AEA analogue synthesized by our laboratory was reported to exert significant efficacy through multiple interventions. Within this study, the amyloid precursor protein (APP)SWE/presenilin-1 (PS1)M146V/TauP301L mouse (3×Tg-AD) model was used to explore further the neuroprotective effects of NSTK and its underlying mechanisms. NSTK could increase spontaneous locomotor activity in the open field and low anxiety-like behavior in the elevated plus maze, and improve the spatial memory deficits in the Morris water maze. The biochemical analysis suggested that NSTK could decrease Aß42 deposition, abnormal tau aggregation, and the expressions of p-APP Thr668, PS1 and p-tau Ser202/Thr205 in the hippocampus of 3×Tg-AD mice. Consistently, NSTK could reduce the level of malondialdehyde, increase the activity of superoxide dismutase and catalase. Up-regulation of Bcl-2, and down-regulation of BAX, caspase-3 and inflammatory cytokines also occurred in the hippocampus of 3×Tg-AD mice after treatment with NSTK. Thus, NSTK could intervene in multiple pathological processes of AD and would be a drug candidate against AD.

Activation of 5-HT(2C) receptor promotes the expression of neprilysin in U251 human glioma cells.

Abeta accumulation, a hallmark of Alzheimer's disease, promotes the disease progress in multiple facets. Abeta is formed through amyloidogenic cleavage pathway of amyloid precursor protein (APP). Production of Abeta can be decreased via activation of 5-HT2C receptor, which enhances alternative APP non-amyloidogenic cleavage. Besides, as one of the best characterized Aß degrading enzymes, neprilysin (NEP) in AD progress has drawn more and more attention. We investigated whether there exists any connection between 5-HT2C receptor and NEP expression. The mRNA and protein expressions of NEP were increased after treatment of 5-HT2C receptor agonist RO-60-0175 in concentration- and time-dependent manners, and NEP expression was decreased after treatment of 5-HT2C receptor antagonist SB242084 correspondingly. These results suggest that 5-HT2C receptor may inhibit the Abeta formation by promoting NEP expression. The underlying mechanism will be explored in follow-up study and may provide potential target for AD therapy.

RhoC involved in the migration of neural stem/progenitor cells.

Alzheimer's disease (AD) is characterized by deposition of beta-amyloid peptides (Aß) and progressive loss of neurons. Neural stem/progenitor cells (NSPCs) can proliferate and produce immature neurons even in the brain of AD patients. However, Aß42 significantly decreased the expression of RhoC in NSPCs during the co-incubation (P < 0.01). Treating with RhoC siRNA prevented membrane from protrusion and led to a significant reduction in cell migration in responses to SDF-1. Compared with wild-type mice, the numbers of RhoC-immunoreactive cells in hippocampus and cortex were significantly down-regulated in APP/PS1 mice aged 9 months. The results suggest that Aß42 down-regulates the expression of RhoC in NSPCs in vitro and in vivo; down-regulated RhoC expression results in decreased migration of NSPCs.

ß-amyloid42 induces desensitization of CXC chemokine receptor-4 via formyl peptide receptor in neural stem/progenitor cells.

The deposition of ß-amyloid (Aß) plaques and progressive loss of neurons are two main characteristics of Alzheimer's disease (AD). Supplement of neural stem/progenitor cells (NSPCs) is a promising strategy for repair of the neurodegenerative diseases. However, hostile microenvironment of neurodegenerative brain is harmful for the neuroregeneration. Aß(42) promoted the proliferation of NSPCs. Moreover, Aß(42) (10-1000 nM) promoted the migration of NSPCs in a dose-dependent manner. The attraction of NSPCs toward Aß(42) was significantly offset by 10 µM cyclosporin H, a potent and selective formyl peptide receptor antagonist. After incubation with Aß(42) for 9 d, the migration ability of NSPCs was significantly decreased (p<0.05). The expression of formyl peptide receptor (FPR) and CXC chemokine receptor-4 (CXCR4) were significantly decreased in NSPCs. The expression of G protein-coupled receptor kinase 2 (GRK2) was up-regulated on the membrane of NSPCs correspondingly. Our results suggested that Aß(42) decreases the migratory capacity of NSPCs by FPR heterologous desensitization after long time incubation, and GRK2 in NSPCs may be responsible for the damaged migratory capacity.

Nicotine decreases beta-amyloid through regulating BACE1 transcription in SH-EP1-α4ß2 nAChR-APP695 cells.

Alzheimer's disease (AD) is a neurodegenerative disorder that affects the elderly population. Deposition of beta-amyloid (Aß) in the brain is a hallmark of AD pathology. In our previous study, we have constructed a cell line expressing human APP695 (hAPP695) in SH-EP1 cells stably transfected with human nicotinic receptor (nAChR) α4 subunit and ß2 subunit gene. In present study, we found that activation of α4ß2 nAChR by nicotine and epibatidine decreased secreted Aß level in the cell line and hippocampal neurons, but had no effects on full-length APP695 and sAPP-α. Nicotine also decreases BACE1 and PSEN1 expression, as well as ERK1 and NFκB P65 subunit expression in the cell line. Furthermore, BACE1 promoter activity is, but PSEN1 not, decreased by nicotine in the cell line. All the results suggest that activation of α4ß2 nAChR decreases Aß through regulating BACE1 transcription by ERK1-NFκB pathway. Additionally, analysis of BACE1 promoter activity by dual-luciferase reporter assay may be useful for drug screening as a high throughput method.

N-stearoyl-l-Tyrosine inhibits the cell senescence and apoptosis induced by H2O2 in HEK293/Tau cells via the CB2 receptor.

Although considerable energy and money have been spent trying to inhibit Aß production and its related metabolic enzyme activities, there are still no drug treatments available to cure even slow for Alzheimer's disease. Therefore, tau protein has been focused recently as the new target for the treatment of Alzheimer's disease. The transfected human embryonic kidney 293 (HEK 293) cells with or without Tau 411 plasmid were used to evaluate the effect of tau protein on cell viability. H2O2 was added to simulate microenvironment of oxidative stress (OS) during aging. N-stearoyl-l-tyrosine (Nstyr), one of the synthesized N-arachidonoylethanolamide analogues was administrated in HEK293/Tau cells during H2O2 insults. Cellular senescence and tau aberrant modification appeared after tau transfection and aggravated by H2O2 insult which detected by ß-galactosidase staining analysis and western blotting analysis. The level of expression of Bcl-2 and the result of FCAS analysis indicated the appearance of cellular apoptosis. The expression of prosenescence moleculars such as p16-Rb and P53 were induced by tau transfection in HEK293 cells. Both p16-Rb and p53 senescent molecules were inhibited by Nstyr. AM251 (1 µM; an antagonist of CB1 cannabinoid receptor) or AM630 (1 µM; an antagonist of CB2 cannabinoid receptor) was used to offset the anti-senescence effects afforded by NsTyr. The anti-senescence and anti-apoptosis effect of NsTyr was completely abolished by AM630. Meanwhile, transfection of siRNACB2 was used to further confirm the above experimental results and it came out the similar results compared with AM630. Taken together, our results suggest that oxidative stress aggravates cellular senescence and apoptosis in HEK293/Tau, which can be reversed by Nstyr via CB2 receptor.

Panaxynol induces neurite outgrowth in PC12D cells via cAMP- and MAP kinase-dependent mechanisms.

Panaxynol, a polyacetylene ((3R)-heptadeca-1,9-diene-4,6-diyn-3-ol; syn. falcarinol), was isolated from the lipophilic fractions of Panax notoginseng, a Chinese traditional medicinal plant. In the present study, we reported the neurotrophic effects of panaxynol on PC12D cells and mechanism involved in neurite outgrowth of the cells. Panaxynol could morphologically promote neurite outgrowth in PC12D cells, concentration-dependently reduce cell division and up-regulate molecular marker (MAP1B) expression in PC12D cells. Panaxynol induces the elevation of intracellular cAMP in PC12D cells. The neurite outgrowth in PC12D cells induced by panaxynol could be inhibited by the protein kinase A inhibitor RpcAMPS and by MAP kinase kinase 1/2 inhibitor U0126. These observations reveal that panaxynol could induce the differentiation of PC12D cells in a process similar to but distinct from that of NGF and the panaxynol's effects were via cAMP- and MAP kinase-dependent mechanisms.

Neuroprotective effect of the stearic acid against oxidative stress via phosphatidylinositol 3-kinase pathway.

Stearic acid is a long-chain saturated fatty acid consisting of 18 carbon atoms without double bonds. In the present study, we reported the neuroprotective effects and mechanism of stearic acid on cortical or hippocampal slices insulted by oxygen-glucose deprivation, NMDA or hydrogen peroxide (H(2)O(2)) in vitro. Different types of models of brain slice injury in vitro were developed by 10 min of oxygen/glucose deprivation, 0.5 mM NMDA or 2 mM H(2)O(2), respectively. After 30 min of preincubation with stearic acid (3-30 microM), cortical or hippocampal slices were subjected to oxygen-glucose deprivation, NMDA or H(2)O(2). Then the tissue activities were evaluated by using the 2,3,5-triphenyltetrazolium chloride (TTC) method. Population spikes were recorded in randomly selected hippocampal slices. Stearic acid (3-30 microM) dose-dependently protected brain slices from oxygen-glucose deprivation, NMDA and H(2)O(2) insults. Its neuroprotective effect against H(2)O(2) insults can be completely blocked by wortmannin (inhibitor of PI3K) and partially blocked by H7 (inhibitor of PKC) or genistein (inhibitor of TPK). Treatment of cortical or hippocampal slices with 30 microM stearic acid resulted in a significant increase in PI3K activity at 5, 10, 30 and 60 min. These observations reveal that stearic acid can protect cortical or hippocampal slices against injury induced by oxygen-glucose deprivation, NMDA or H(2)O(2), and its neuroprotective effects are via phosphatidylinositol 3-kinase dependent mechanism.

Neuroprotective effects of arachidonic acid against oxidative stress on rat hippocampal slices.

Arachidonic acid (AA), 5,8,11,14-eicosateraenoic acid is abundant, active and necessary in the human body. In the present study, we reported the neuroprotective effects and mechanism of arachidonic acid on hippocampal slices insulted by glutamate, NaN(3) or H(2)O(2)in vitro. Different types of models of brain injury in vitro were developed by 1mM glutamate, 10mM NaN(3) or 2mM H(2)O(2). After 30 min of preincubation with arachidonic acid or linoleic acid, hippocampal slices were subjected to glutamate, NaN(3) or H(2)O(2), then the tissue activities were evaluated by using the 2,3,5-triphenyltetrazolium chloride method. Endogenous antioxidant enzymes activities (SOD, GSH-PX and catalase) in hippocampal slices were evaluated during the course of incubation. MK886 (5 microM; a noncompetitive inhibitor of proliferator-activated receptor [PPAR]alpha), BADGE (bisphenol A diglycidyl ether; 100 microM; an antagonist of PPARgamma) and cycloheximide (CHX; 30 microM; an inhibitor of protein synthesis) were tested for their effects on the neuroprotection afforded by arachidonic acid. Population spikes were recorded in randomly selected hippocapal slices. Arachidonic acid (1-10 microM) dose dependently protected hippocampal slices from glutamate and H(2)O(2) injury (P<0.01), and arachidonic acid (10 microM) can significantly improve the activities of Cu/Zn-SOD in hippocampal slices after 1h incubation. In addition, 10 microM arachidonic acid significantly increased the activity of Mn-SOD and catalase, and decreased the activities of Cu/Zn-SOD to control value after 3h incubation. These secondary changes of SOD during incubation can be reversed by indomethacine (10 microM; a nonspecific cyclooxygenase inhibitor) or AA 861 (20 microM; a 5-lipoxygenase inhibitor). Its neuroprotective effect was completely abolished by BADGE and CHX. These observations reveal that arachidonic acid can defense against oxidative stress by boosting the internal antioxidant system of hippocampal slices. Its neuroprotective effect may be mainly mediated by the activation of PPARgamma and synthesis of new protein in tissue.

The Online Morphology Control and Dynamic Studies on Improving Vitamin B12 Production by Pseudomonas denitrificans with Online Capacitance and Specific Oxygen Consumption Rate.

The relationship between the morphological character of Pseudomonas denitrificans and vitamin B12 synthesis based on real-time capacitance measurement and online specific oxygen consumption rate (Q O2) control was established for enhancing vitamin B12 production. Results demonstrated that the threshold Q O2 value lower than 2.0 mmol/gDCW/l would greatly stimulate the state transfer from the cell number growth phase to the cell elongation phase and promote rapid vitamin B12 biosynthesis, while the vitamin B12 biosynthesis rate could also be inhibited when the rate of cell's length-to-width ratio (ratio-LW) was higher than 10:1. Furthermore, the optimal morphology controlling strategy was achieved based on online Q O2 control, which increases the appropriate active cell numbers at the former phase, and then control the elongation of ratio-LW no more than 10:1 at the vitamin B12 biosynthesis phase. The maximal vitamin B12 production reached 239.7 mg/l at 168 h, which was improved by 14.7 % compared with the control (208 mg/l). This online controlling strategy would be effectively applied for improving industrial vitamin B12 fermentation.

N-Stearoyl-L-Tyrosine Inhibits the Senescence of Neural Stem/Progenitor Cells Induced by Aß 1-42 via the CB2 Receptor.

Alzheimer's disease, one of the neurodegenerative diseases, shows the progressive senescence of neural progenitor/stem cells. N-Stearoyl-L-tyrosine (NsTyr) showed neuroprotective effect against chronic brain ischemia in previous reports. In the present study, we find the antisenescent effects of NsTyr-2K in NSPCs induced by Aß 1-42 in vitro. Cell viability of NSPCs was evaluated by CCK8 assay; SA-ß-gal staining was used to evaluate senescence of NSPCs. CB receptors were detected by immunohistochemistry in NSPCs. AM251 or AM630 was used to offset the anti-senescence effects afforded by NsTyr-2K. The positive rate of SA-ß-gal staining was significantly increased in NSPCs after incubation with Aß 1-42 for 9 days. CB receptors were found on the surface of NSPCs. The expression level of CB1 receptors was significantly decreased in NSPCs after incubation with Aß 1-42. This phenomenon was reversed dose-dependently by NsTyr-2K. NsTyr-2K attenuated Aß 1-42 induced NSPCs senescence dose-dependently, and its antisenescence effect was completely abolished by AM630. Aß 1-42 dose-dependently increased the prosenescence molecules p16 and Rb. Their expression was inhibited by NsTyr-2K dose-dependently and blocked by AM630 in NSPCs. These results suggest that NsTyr-2K can alleviate the senescence of NSPCs induced by Aß 1-42 via CB2 receptor.

Transplanted Neural Stem Cells: Playing a Neuroprotective Role by Ceruloplasmin in the Substantia Nigra of PD Model Rats?

Although mounting evidence suggests that ceruloplasmin (CP) deficiency and iron deposition are pivotal factors responsible for exacerbating demise of dopaminergic neurons in the substantia nigra (SN) of the Parkinsonism and neural stem cells (NSCs) are believed to be excellent candidates for compensating the lost dopaminergic neurons, there are few researches to explore the change of CP expression and of iron deposition in the pathological microenvironment of SN after NSCs transplantation and the ability of grafted NSCs to differentiate directionally into dopaminergic neurons under the changed homeostasis. With substantia nigral stereotaxic technique and NSCs transplantation, we found that tyrosine hydroxylase and CP expression decreased and iron deposition increased in the lesioned SN after 6-OHDA administration compared with control, while tyrosine hydroxylase and CP expression increased and iron deposition decreased after NSCs transplantation compared to 6-OHDA administration alone. Only a small number of embedding NSCs are able to differentiate into dopaminergic neurons. These results suggest that grafted NSCs have an influence on improving the content of CP expression, which may play a neuroprotective role by decreasing iron deposition and ameliorating damage of dopaminergic neurons and possibly underline the iron-related common mechanism of Parkinson's disease and Wilson's disease.

[The influences of propofol on different kinds of brain injuries in rat brain slices].

OBJECTIVE: To investigate the effects of propofol on the three kinds of brain injuries induced by metabolic disorder, neurotoxicity of excitatory amino acid, and oxygen-derived free radicals in rat cerebral cortical and hippocampal slices. METHODS: Slices of rat cerebral cortex and hippocampus were made and incubated in normal artificial cerebrospinal fluid (nACSF). Then the rat cerebral cortical and hippocampal slices were divided into 2 categories: propofol group, the slices in which were co-incubated with 5, 50, or 100 micro mol/L propofol for 3 hours, and 3 experimental injury groups. Each experimental injury group was further subdivided into 3 subgroups including the slices of 4 rats. Two hours after normal incubation the slices were co-incubated with 2,3,5-triphenyltetrazolium chloride (TTC). Formazan, the red crystal product were extracted, and ELISA reader was used to read the absorbance at 490 nm (A(490)) so as to quantitatively evaluate the degree of injury. RESULTS: The values of A(490) of the slices co-incubated with propofol of different concentrations were not significantly different. Compared with those of the control subgroups, the values A490 were significantly decreased in the cerebral cortical and hippocampus slices damaged by OGD, glutamate, and H(2)O(2) injuries (all P < 0.01). The values of A(490) in the subgroups of low and middle concentrations (5 and 50 micro mol/L) of propofol plus OGD or glutamate injury were not significantly different from those of the subgroups of OGD or glutamate injury alone, both in cerebral cortical and hippocampal slices. However, the values of A(490) in the subgroups of high concentration of propofol (100 micro mol/L) plus OGD or glutamate injury was further decreased (P < 0.01). The values of A(490) in the subgroups of low and middle concentrations of propofol plus H(2)O(2) injury were significantly higher than those of the injury subgroup (all P < 0.01), however, however, the values of A490 in the high concentration propofol plus H(2)O(2) injury subgroup were significantly lower than those of the control group (all P < 0.01), even lower than that of the subgroup of H(2)O(2) injury alone. CONCLUSION: Propofol has a neuroprotective effect against hydrogen peroxide injury at low and middle concentrations. Propofol of low and middle concentrations does not improve the decrease of the value of A(490). however, propofol of high concentration augments the oxygen-glucose deprivation and glutamate injuries both in the rat cerebral cortical slices and hippocampal slices.

Optimization of polyhydroxyalkanoates fermentations with on-line capacitance measurement.

The aim of this work was to provide an effective methodology for optimization of the polyhydroxyalkanoates (PHAs) fermentation with Ralstonia eutropha by the on-line capacitance measurement. The present study found the capacitance values could reflect variations of microbial morphology and viability. Furthermore, oxygen uptake rate, specific oxygen uptake rate and specific growth rate were measured in real-time and compared with the capacitance value. In addition, a fed-batch control strategy based on the on-line capacitance measurement was proposed to improve the PHAs production by 22%.

Glycodendrimeric phenylporphyrins as new candidates for retinoblastoma PDT: blood carriers and photodynamic activity in cells.

Photodynamic therapy (PDT) has recently been proposed as a possible indication in the conservative treatment of hereditary retinoblastoma. In order to create photosensitizers with enhanced targeting ability toward retinoblastoma cells, meso-tetraphenylporphyrins bearing one glycodendrimeric moiety have been synthesized. The binding properties to plasma proteins and photodynamic activity of two monodendrimeric porphyrins bearing three mannose units via monoethylene glycol (1) or diethylene glycol (2) linkers have been compared to that of the non-dendrimeric tri-substituted derivative [TPP(p-Deg-O-α-ManOH)(3)]. The dendrimeric structure was found to highly increase the binding affinity to plasma proteins and to modify to some extent plasma distribution. HDL and to a lesser extent LDL have been shown to be the main carriers of dendrimeric and non-dendrimeric compounds. The phototoxicity observed for the two glycodendrimers (1) and (2) (LD(50)=0.5 µM) in Y79 cells is of the same order of magnitude that for TPP(p-Deg-O-α-ManOH)(3) (LD(50)=0.7 µM), with a similar cellular uptake level for (1) and a lower for (2). A serum content increase from 2% to 20% (v/v) in the incubation medium was found to inhibit both cellular uptake and photoactivity of dendrimeric derivatives, whereas those of TPP(p-Deg-O-α-ManOH)(3) remained little affected. Specificities of glycodendrimeric porphyrins, combining a lower cellular uptake together with a higher affinity toward plasma proteins, make these derivatives possible candidates for a vascular targeting PDT.

Overexpression of 5-lipoxygenase increases the neuronal vulnerability of PC12 cells to Aß42.

5-Lipoxygenase (5-LOX), which is believed to be a major source of oxidative stress, participates in somatostatin-receptor transmembrane signaling in the central nervous system. We used the Tet-On inducible expression system in PC12 cells to obtain cell lines with reproducible, stable 5-LOX expression levels to study its function. Cell apoptosis rates induced by Aß(42) were determined using an apo-BrdDU kit. Lipid peroxide, antioxidant enzyme, and caspase-3 activities were evaluated with respective commercial kits. The expression of 5-LOX, bcl-2, and bax were detected by immunoblotting. A subclone of PC18 with Tet-On inducible expression of 5-LOX was selected from PC12 transfectants. Expression of 5-LOX had no significant inhibitory effect on the cell viability of the PC18 clone. In contrast, compared with the control group, the cell viability of clone PC18 was significantly reduced after the induction of 5-LOX during Aß exposure. The differences in cell viability before and after the induction of 5-LOX during Aß insult were significantly offset by AA861. Overexpression of 5-LOX only slightly improved the activities of superoxide dismutase (SOD). The levels of intracellular peroxides, SOD and caspase-3 activity, and Bax expression were significantly upregulated, and the levels of glutathione peroxidase and catalase were downregulated correspondingly in clone PC18 during Aß exposure. These results indicate that constitutive expression of 5-LOX is not detrimental per se, but overexpression of 5-LOX may become problematic during Aß exposure.

Induction of differentiation by panaxydol in human hepatocarcinoma SMMC-7721 cells via cAMP and MAP kinase dependent mechanism.

Panaxydol (PND) is one of the main non-peptidyl small molecules isolated from the lipophilic fractions of Panax notoginseng. The present study was carried out to demonstrate the potential effects of panaxydol on the induction of differentiation of human liver carcinoma cell lines SMMC-7721. Cell viability was evaluated by MTT method and Trypan blue exclusion assay respectively. The changes of morphology were detected by transmission electron microscope. Inhibitors were applied to detect the signaling pathway of differentiation. The level of intracellular cyclic AMP was determined by radioimmunoassay. The expression of p-ERK, Id1, and p21 were determined by Western blot. We found that panaxydol inhibit the proliferation of SMMC-7721 cells and caused the morphology and ultrastructure changes of SMMC-7721. Moreover, panaxydol dose-dependently increased the secretion of albumin and alkaline phosphatase activity, and decreased the secretion of AFP correspondingly. These changes of differentiation markers in SMMC-7721 can be reversed by the protein kinase A inhibitor RpcAMPS and by MAP kinase kinase 1/2 inhibitor U0126 or sorafenib. Intracellular cAMP was elevated by panaxydol in SMMC-7721 cells. Panaxydol dose-dependently decreased the expression of regulatory factors Id1 and increased the protein levels of p21 and p-ERK1/2 correspondingly. It suggested panaxydol might be of value for further exploration as a potential anti-cancer agent via cAMP and MAP kinase-dependent mechanism.

Improved vitamin B(12) production by step-wise reduction of oxygen uptake rate under dissolved oxygen limiting level during fermentation process.

Effects of different oxygen transfer rates (OTR) on the cell growth and vitamin B(12) biosynthesis of Pseudomonas denitrificans were first investigated under dissolved oxygen limiting conditions. The results demonstrated that high OTR accelerated cell growth and initial vitamin B(12) biosynthesis rate, while lower OTR was critical for higher productivity in the late fermentation process. The oxygen uptake rates (OUR) corresponded well with OTR. Based on the metabolic intermediate analysis, a step-wise OUR control strategy was proposed. The strategy was successfully implemented in scale-up to an industrial fermenter (120,000 l). A stable maximum vitamin B(12) production of 208 + or - 2.5 mg/l was achieved, which was increased by 17.3% compared with the control. Furthermore, the glucose consumption coefficient to vitamin B(12) was 34.4% lower than that of the control. An efficient and economical fermentation process based on OUR criterion was established for industrial vitamin B(12) fermentation by P. denitrificans.

Stearic acid protects primary cultured cortical neurons against oxidative stress.

AIM: To observe the effects of stearic acid against oxidative stress in primary cultured cortical neurons. METHODS: Cortical neurons were exposed to glutamate, hydrogen peroxide (H2O2), or NaN3 insult in the presence or absence of stearic acid. Cell viability of cortical neurons was determined by MTT assay and LDH release. Endogenous antioxidant enzymes activity[superoxide dismutases (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT)] and lipid peroxidation in cultured cortical neurons were evaluated using commercial kits. {3-[1(p-chlorobenzyl)- 5-(isopropyl)-3-t-butylthiondol-2-yl]-2,2-dimethylpropanoic acid, Na} [MK886; 5 micromol/L; a noncompetitive inhibitor of proliferator-activated receptor (PPAR) alpha], bisphenol A diglycidyl ether (BADGE; 100 micromol/L; an antagonist of PPAR gamma), and cycloheximide (CHX; 30 micromol/L, an inhibitor of protein synthesis) were tested for their effects on the neuroprotection afforded by stearic acid. Western blotting was used to determine the PPAR gamma protein level in cortical neurons. RESULTS: Stearic acid dose-dependently protected cortical neurons against glutamate or H2O2 injury and increased glutamate uptake in cultured neurons. This protection was concomitant to the inhibition of lipid peroxidation and to the promotion activity of Cu/Zn SOD and CAT in cultured cortical neurons. Its neuroprotective effects were completely blocked by BADGE and CHX. After incubation with H2O2 for 24 h, the expression of the PPAR gamma protein decreased significantly (P<0.05), and the inhibitory effect of H2O2 on the expression of PPAR gamma can be attenuated by stearic acid. CONCLUSION: Stearic acid can protect cortical neurons against oxidative stress by boosting the internal antioxidant enzymes. Its neuroprotective effect may be mainly mediated by the activation of PPAR gamma and new protein synthesis in cortical neurons.

Neuroprotective effects of stearic acid against toxicity of oxygen/glucose deprivation or glutamate on rat cortical or hippocampal slices.

AIM: To observe the effects of stearic acid, a long-chain saturated fatty acid consisting of 18 carbon atoms, on brain (cortical or hippocampal) slices insulted by oxygen-glucose deprivation (OGD), glutamate or sodium azide (NaN3) in vitro. METHODS: The activities of hippocampal slices were monitored by population spikes recorded in the CA1 region. In vitro injury models of brain slice were induced by 10 min of OGD, 1 mmol/L glutamate or 10 mmol/L NaN3. After 30 min of pre-incubation with stearic acid (3-30 micromol/L), brain slices (cortical or hippocampal) were subjected to OGD, glutamate or NaN3, and the tissue activities were evaluated by using the 2,3,5-triphenyltetrazolium chloride method. MK886 [5 mmol/L; a noncompetitive inhibitor of proliferator-activated receptor (PPAR-alpha)] or BADGE (bisphenol A diglycidyl ether; 100 micromol/L; an antagonist of PPAR-gamma) were tested for their effects on the neuroprotection afforded by stearic acid. RESULTS: Viability of brain slices was not changed significantly after direct incubation with stearic acid. OGD, glutamate and NaN3 injury significantly decreased the viability of brain slices. Stearic acid (3-30 micromol/L) dose-dependently protected brain slices from OGD and glutamate injury but not from NaN3 injury, and its neuroprotective effect was completely abolished by BADGE. CONCLUSION: Stearic acid can protect brain slices (cortical or hippocampal) against injury induced by OGD or glutamate. Its neuroprotective effect may be mainly mediated by the activation of PPAR-gamma.