Effect of Xingnaojing Injection(醒脑静注射液)on Hippocampal N-methyl-D-aspartic Acid Receptors of Focal Cerebral Ischemia in Rats

Objective: To observe and elucidate the neuroprotective effect of Xingnaojing (XNJ) injection on hippocampal N-methyl-D-aspartic acid (NMDA) receptors of focal cerebral ischemia in rats. Methods: Cerebral ischemia was established by occluding the middle cerebral artery with an intraluminal suture technique in rats. Neurological deficit score, infarct volume and quantity of NMDA receptors were estimated in all groups and compared. Results: After being treated with XNJ, the score decreased in the initial 6 hours and infarct volume decreased in 24 hours. And within 24 hours, the quantity of NMDA receptors obviously decreased compared with the model group (P<0. 01) It indicated that XNJ could ameliorate neurological behavior of middle cerebral artery occlusion rats and down-regulate the expression of hippocampal NMDA receptors. Conclusion: The neuroprotective effect of XNJ on focal cerebral ischemia is possibly related to down-regulating the expression of NMDA receptors in rats.

Water-soluble lipopolymer delivery of N-methyl-D-aspartic acid receptor 2B siRNA relieves chronic neuropathic pain in rats

Spinal dorsal horn N-Methyl-D-aspartic acid receptor 2B （NR2B） overexpression plays an important role in the production and maintenance of neuropathic pain. Because small interfering RNA （siRNA） can inhibit NR2B expression, siRNA may provide a novel approach to treat neuropathic pain and possibly nerve injury. However, an efficient and safe vector for NR2B siRNA has not been discovered. This study shows that a water soluble lipopolymer （WSLP） comprised of low molecular weight polyethyleneimine （PEI） and cholesterol can deliver siRNA targeting NR2B for the treatment of neuropathic pain. Results show that intrathecal injection of WSLP/siRNA complexes for 3 days inhibit NR2B gene expression with reductions in mRNA and protein levels by 59% and 54%, respectively, compared with control rats （P 〈 0.01）. Injection of WSLP complexed with scrambled siRNA, or PEI with siRNA did not show this inhibitory effect. Moreover, injection of WSLP/siRNA complexes significantly relieved neuropathic pain at 3, 7, 12, and 21 days, while injection of WSLP with scrambled siRNA or PEI with siRNA did not. These results demonstrate that WSLP can efficiently deliver siRNA targeting NR2B in vivo and relieve neuropathic pain.

Effect of Chronic Noise Exposure on Expression of N-Methyl-D-Aspartic Acid Receptor 2B and Tau Phosphorylation in Hippocampus of Rats

Objective To study the effect of chronic noise exposure on expression of N-methyI-D-aspartic acid receptor 2B （NR2B） and tau phosphorylation in hippocampus of rats. Methods Twenty-four male SD rats were divided in control group and chronic noise exposure group. NR2B expression and tau phosphorylation in hippocampus of rats were detected after chronic noise exposure （100 dB SPL white noise, 4 h/dx30d） and their mechanisms underlying neuronal apoptosis in hippocampus of rats with TUNEL staining. Results The NR2B expression decreased significantly after chronic noise exposure which resulted in tau hyperphosphorylation and neural apoptosis in hippocampus of rats. Immunohistochemistry showed that the tau hyperphosphorylation was most prominent in dentate gyrus （DG） and CA1 region of rat hippocampus. Conclusion The abnormality of neurotransmitter system, especially Glu and NR2B containing NMDA receptor, and tau hyperphosphorylation in hippocampus of rats, may play a role in chronic noise-induced neural apoptosis and cognition impairment.

Subcellular distribution of N-methyl-D-aspartic acid receptor subunit 1 in neural stem cells within subventricular zone of adult rats

The subcellular localization of N-methyI-D-aspartic acid receptor subunit 1 in neural stem cells of the subventricular zone of adult rats was detected using electron microscopy, following immunohistochemistry and immunogold-silver double staining. Results confirmed the presence of neural stem cells in the subventricular zone, which is a key neurogenic region in the central nervous system of adult mammals. The expression of N-methyI-D-aspartic acid receptor subunit 1 was higher than that of nestin and mainly distributed in the cell membrane, cytoplasm, rough endoplasmic reticulum and Golgi complex of neural stem cells.

N-methyl-D-aspartic acid receptor 1 （NMDAR1） aggravates secondary inflammatory damage induced by hemin-NLRP3 pathway after intracerebral hemorrhage

Objective： Inflammation plays a critical role in secondary brain damage after intracerebral hemorrhage （ICH）. However, the mechanisms of inflammatory injury following ICH are still unclear, particularly the involvement of NLRP3 inflammasome, which are crucial to sterile inflammatory responses. In this study, we aim to test the hypothesis that NLRP3 signaling pathway takes a vital position in ICH-induced sec- ondary inflammatory damage and detect the role of N-methyl-D-aspartic acid receptor 1 （NMDARI） in this progress. Methods： ICH was induced in mice by microinjection of heroin into the striatum. The protein levels of NMDAR1, NMDAR1 phosphorylation, NLRP3 and IL-113 were measured by Western blot. The binding of NMDARI to NLRP3 was detected by immunoprecipitation. Results： The expression of NMDARI, NMDAR1 phosphorylation, NLRP3 and IL-I ~ were rapidly increased after ICH. Heroin treatment enhanced NMDAR1 expression and NMDAR1 phosphorylation, as well in cultured microglial cells treated by hemin. Hemin up-regulated NLRP3 and IL-I]3 level, which was reversed by MK801 （NMDAR antagonist） in vitro. Hemin also promoted the binding of NMDAR1 to NLRP3. Conclusion： Our findings suggest that NMDARI plays a pivotal role in hemin-induced NLRP3-mediated inflammatory damage through synergistic activation.

Tongluo Huatan capsule(通络化痰胶囊) improves cognitive function by regulating the endocytosis of N-methyl-D-aspartic acid receptors mediated by clathrin in a rat model of vascular dementia

OBJECTIVE:To explore the neuroprotective mechanisms of Tongluo Huatan capsule(THC)in a rat model of vascular dementia(VD).METHODS:A rat model of VD was established by repeated clamping of bilateral common carotid arteries with the intraperitoneal injection of sodium nitroprusside solution.VD rats were administered THC,memantine hydrochloride,or distilled water daily for 14 d after operation.Learning and memory abilities were assessed using the step-down passive avoidance test,novel object recognition(NOR)test,and Morris water maze(MWM)test.Pathological changes in the hippocampus were observed through hematoxylin and eosin and Nissl staining.The expression levels of clathrin,RAB5 B,andN-methyl-D-aspartic acid receptor 1(NMDAR1)were measured by immunohistochemistry staining,real-time quantitative polymerase chain reaction and Western blot.RESULTS:Rats in VD group showed impaired learning and memory abilities(step-down passive avoidance,NOR,and MWM)and abnormalities in neuronal morphology(light microscopy)in the hippocampus.The m RNA or protein expression levels of clathrin and RAB5 B were decreased,and NMDAR1 was increased in hippocampal tissues(P<0.05).Administration of THC promoted the learning and memory abilities and the morphological structure of hippocampal neurons in VD rats.Besides,THC enhanced m RNA or protein expression levels of clathrin and RAB5 B,and decreased NMDAR1(P<0.05).CONCLUSION:THC may improve cognitive functions by regulating the endocytosis of NMDA receptors mediated by clathrin.

Bile acids inhibit ferroptosis sensitivity through activating farnesoid X receptor in gastric cancer cells

BACKGROUND Gastric cancer(GC)is associated with high mortality rates.Bile acids(BAs)reflux is a well-known risk factor for GC,but the specific mechanism remains unclear.During GC development in both humans and animals,BAs serve as signaling molecules that induce metabolic reprogramming.This confers additional cancer phenotypes,including ferroptosis sensitivity.Ferroptosis is a novel mode of cell death characterized by lipid peroxidation that contributes universally to malignant progression.However,it is not fully defined if BAs can influence GC progression by modulating ferroptosis.AIM To reveal the mechanism of BAs regulation in ferroptosis of GC cells.METHODS In this study,we treated GC cells with various stimuli and evaluated the effect of BAs on the sensitivity to ferroptosis.We used gain and loss of function assays to examine the impacts of farnesoid X receptor(FXR)and BTB and CNC homology 1(BACH1)overexpression and knockdown to obtain further insights into the molecular mechanism involved.RESULTS Our data suggested that BAs could reverse erastin-induced ferroptosis in GC cells.This effect correlated with increased glutathione(GSH)concentrations,a reduced GSH to oxidized GSH ratio,and higher GSH peroxidase 4(GPX4)expression levels.Subsequently,we confirmed that BAs exerted these effects by activating FXR,which markedly increased the expression of GSH synthetase and GPX4.Notably,BACH1 was detected as an essential intermediate molecule in the promotion of GSH synthesis by BAs and FXR.Finally,our results suggested that FXR could significantly promote GC cell proliferation,which may be closely related to its anti-ferroptosis effect.CONCLUSION This study revealed for the first time that BAs could inhibit ferroptosis sensitivity through the FXR-BACH1-GSHGPX4 axis in GC cells.This work provided new insights into the mechanism associated with BA-mediated promotion of GC and may help identify potential therapeutic targets for GC patients with BAs reflux.

Estrogen affects neuropathic pain through upregulating N-methyl-D-aspartate acid receptor 1 expression in the dorsal root ganglion of rats

Estrogen affects the generation and transmission of neuropathic pain,but the specific regulatory mechanism is still unclear.Activation of the N-methyl-D-aspartate acid receptor 1（NMDAR1） plays an important role in the production and maintenance of hyperalgesia and allodynia.The present study was conducted to determine whether a relationship exists between estrogen and NMDAR1 in peripheral nerve pain.A chronic sciatic nerve constriction injury model of chronic neuropathic pain was established in rats.These rats were then subcutaneously injected with 17β-estradiol,the NMDAR1 antagonist D（-）-2-amino-5-phosphonopentanoic acid（AP-5）,or both once daily for 15 days.Compared with injured drug na？ve rats,rats with chronic sciatic nerve injury that were administered estradiol showed a lower paw withdrawal mechanical threshold and a shorter paw withdrawal thermal latency,indicating increased sensitivity to mechanical and thermal pain.Estrogen administration was also associated with increased expression of NMDAR1 immunoreactivity（as assessed by immunohistochemistry） and protein（as determined by western blot assay） in spinal dorsal root ganglia.This 17β-estradiol-induced increase in NMDAR1 expression was blocked by co-administration with AP-5,whereas AP-5 alone did not affect NMDAR1 expression.These results suggest that 17β-estradiol administration significantly reduced mechanical and thermal pain thresholds in rats with chronic constriction of the sciatic nerve,and that the mechanism for this increased sensitivity may be related to the upregulation of NMDAR1 expression in dorsal root ganglia.

Gamma-aminobutyric acid A receptor and N-methyl-D-aspartate receptor subunit expression in rat spiral ganglion neurons

BACKGROUND： Gamma-aminobutyric acid A （GABAA） and N-methyl-D-aspartate （NMDA） receptors are significant receptors in the central nervous system. An understanding of GABAA and NMDA receptor expression in spiral ganglion neurons （SGN） provides information for the functional role of these receptors in the auditory system. OBJECTIVE： To investigate mRNA expression of GABAA receptor （GABAAR） and NMDA receptor （NMDAR） subunits in the rat SGN. DESIGN, TIME AND SETTING： This in vitro, molecular biological study was performed at the Laboratory of Otolaryngology-Head and Neck Surgery, Guangxi Medical University, China from July 2007 to May 2008. MATERIALS： Reverse Transcriptase Kit and Taq DNA polymerase were purchased from Fermentas Burlington, ON, Canada; GABAAR and NMDAR primers were purchased from Shanghai Sangon, Shanghai, China. METHODS： SGN from 3-5 day postnatal Wistar rats was collected for primary cultures, mRNA expression of GABAAR and NMDAR subunits in the SGN was determined by reverse transcription polymerase chain reaction. MAIN OUTCOME MEASURES： Expression levels of GABAAR and NMDAR subunits were determined by quantitative analysis. RESULTS： GABAAR subunits （αl 6, β1 3, and y1 3） and NMDAR subunits （NR1, NR2A, NR2B, NR2C, NR2D, NR3A, and NR3B） were detected in the SGN. In α subunit genes of GABAAR, α1 and α3 expression was similar （P 〉 0.05） and greater than the other subunits. Of the β subunit genes, β1 subunit mRNA levels were greater than β2 and β3. Of the y subunit genes, y2 subunit mRNA levels were greater than y1 and y3. NR1 mRNA expression was the greatest of NMDAR subunits. CONCLUSION： GABAAR subunits （α1 6, β1-3, and y1-3） and NMDAR subunits （NR1, NR2A, NR2B, NR2C, NR2D, NR3A, and NR3B） were expressed in the rat SGN. Through comparison of GABAAR and NMDAR subunit expression, possible GABAAR combinations, as well as highly expressed subunit combinations, were estimated, which provided information for pharmacological and electrophysiological characteristics of GABAAR in the auditory system.

Oleanolic acid improved intestinal immune function by activating and potentiating bile acids receptor signaling in E. coli-challenged piglets

Background Infection with pathogenic bacteria during nonantibiotic breeding is one of the main causes of animal intestinal diseases.Oleanolic acid(OA)is a pentacyclic triterpene that is ubiquitous in plants.Our previous work demonstrated the protective effect of OA on intestinal health,but the underlying molecular mechanisms remain unclear.This study investigated whether dietary supplementation with OA can prevent diarrhea and intestinal immune dysregulation caused by enterotoxigenic Escherichia coli(ETEC)in piglets.The key molecular role of bile acid receptor signaling in this process has also been explored.Results Our results demonstrated that OA supplementation alleviated the disturbance of bile acid metabolism in ETEC-infected piglets(P<0.05).OA supplementation stabilized the composition of the bile acid pool in piglets by regulating the enterohepatic circulation of bile acids and significantly increased the contents of UDCA and CDCA in the ileum and cecum(P<0.05).This may also explain why OA can maintain the stability of the intestinal microbiota structure in ETEC-challenged piglets.In addition,as a natural ligand of bile acid receptors,OA can reduce the severity of intestinal inflammation and enhance the strength of intestinal epithelial cell antimicrobial programs through the bile acid receptors TGR5 and FXR(P<0.05).Specifically,OA inhibited NF-κB-mediated intestinal inflammation by directly activating TGR5 and its downstream c AMP-PKA-CREB signaling pathway(P<0.05).Furthermore,OA enhanced CDCA-mediated MEK-ERK signaling in intestinal epithelial cells by upregulating the expression of FXR(P<0.05),thereby upregulating the expression of endogenous defense molecules in intestinal epithelial cells.Conclusions In conclusion,our findings suggest that OA-mediated regulation of bile acid metabolism plays an important role in the innate immune response,which provides a new diet-based intervention for intestinal diseases caused by pathogenic bacterial infections in piglets.

Effect of propofol on the reactivity of acetylcholinesterase,N-methyl-D-aspartate receptors,and gamma-aminobutyric acid receptors in the hippocampus of aged rats after chronic cerebral ischemia

We induced ischemic brain injury in aging rats to examine the effects of varying doses of propofol on hippocampal activities of acetylcholinesterase, N-methyI-D-aspartate receptors, and y-aminobutyric acid receptors. Propofol exhibited no obvious impact on acetylcholinesterase activity, but directly activated the y-aminobutyric acid receptor. The neuroprotective function of propofol on the hippocampus of aging rats following cerebral ischemic injury may be related to altered activities of y-aminobutyric acid receptors and N-methyI-D-aspartate receptors.

Cognitive dysfunction in schizophrenia patients caused by downregulation of γ-aminobutyric acid receptor subunits

BACKGROUND The expression pattern of gamma aminobutyric acid(GABA)receptor subunits are commonly altered in patients with schizophrenia,which may lead to nerve excitation/inhibition problems,affecting cognition,emotion,and behavior.AIM To explore GABA receptor expression and its relationship with schizophrenia and to provide insights into more effective treatments.METHODS This case-control study enrolled 126 patients with schizophrenia treated at our hospital and 126 healthy volunteers who underwent physical examinations at our hospital during the same period.The expression levels of the GABA receptor subunits were detected using 1H-magnetic resonance spectroscopy.The recognized cognitive battery tool,the MATRICS Consensus Cognitive Battery,was used to evaluate the scores for various dimensions of cognitive function.The correlation between GABA receptor subunit downregulation and schizophrenia was also analyzed.RESULTS Significant differences in GABA receptor subunit levels were found between the case and control groups(P<0.05).A significant difference was also found between the case and control groups in terms of cognitive function measures,including attention/alertness and learning ability(P<0.05).Specifically,as the expression levels of GABRA1(α1 subunit gene),GABRB2(β2 subunit gene),GABRD(δsubunit),and GABRE(εsubunit)decreased,the severity of the patients’condition increased gradually,indicating a positive correlation between the downregulation of these 4 receptor subunits and schizophrenia(P<0.05).However,the expression levels of GABRA5(α5 subunit gene)and GABRA6(α6 subunit gene)showed no significant correlation with schizophrenia(P>0.05).CONCLUSION Downregulation of the GABA receptor subunits is positively correlated with schizophrenia.In other words,when GABA receptor subunits are downregulated in patients,cognitive impairment becomes more severe.

Comparison of three administration modes for establishing a zebrafish seizure model induced by N-Methyl-D-aspartic acid

BACKGROUND Epilepsy is a complex neurological disorder characterized by recurrent,unprovoked seizures resulting from the sudden abnormal discharge of brain neurons.It leads to transient brain dysfunction,manifested by abnormal physical movements and consciousness.It can occur at any age,affecting approximately 65 million worldwide,one third of which are still estimated to suffer from refractory seizures.There is an urgent need for further establishment of seizure models in animals,which provides an approach to model epilepsy and could be used to identify novel anti-epileptic therapeutics in the future.AIM To compare three administration modes for establishing a seizure model caused by N-Methyl-D-aspartic acid(NMDA)in zebrafish.METHODS Three administration routes of NMDA,including immersion,intravitreal injection and intraperitoneal injection,were compared with regard to their effects on inducing seizure-like behaviors in adult zebrafish.We evaluated neurotoxicity by observing behavioral changes in zebrafish and graded those behaviors with a seizure score.In addition,the protective effects of MK-801(Dizocilpine)and natural active constituent resveratrol against NMDA-induced alterations were studied.RESULTS The three NMDA-administration methods triggered different patterns of the epileptic process in adult zebrafish.Seizure scores were increased after increasing NMDA concentration regardless of the mode of administration.However,the curve of immersion continuously rose to a high plateau(after 50 min),while the curves of intravitreal injection and intraperitoneal injection showed a spike in the early stage(10-20 min)followed by a steady decrease in seizure scores.Furthermore,pretreatment with resveratrol and MK-801 significantly delayed seizure onset time and lowered seizure scores.CONCLUSION By comparing the three methods of administration,intravitreal injection of NMDA was the most suitable for establishing an acute epileptic model in zebrafish.Thus,intraperitoneal injection in zebrafish can be applied to simulate diseases such as epilepsy.In addition,NMDA immersion may be an appropriate method to induce persistent seizures.Moreover,MK-801 and resveratrol showed strong anti-epileptic effects;thus,both of them may be clinically valuable treatments for epilepsy.

Targeting harmful effects of non-excitatory amino acids as an alternative therapeutic strategy to reduce ischemic damage

The involvement of the excitatory amino acids glutamate and aspartate in ce rebral ischemia and excitotoxicity is well-documented.Nevertheless,the role of non-excitatory amino acids in brain damage following a stroke or brain trauma remains largely understudied.The release of amino acids by necrotic cells in the ischemic core may contribute to the expansion of the penumbra.Our findings indicated that the reversible loss of field excitato ry postsynaptic potentials caused by transient hypoxia became irreversible when exposed to a mixture of just four non-excitatory amino acids(L-alanine,glycine,L-glutamine,and L-serine)at their plasma concentrations.These amino acids induce swelling in the somas of neurons and astrocytes during hypoxia,along with permanent dendritic damage mediated by N-methyl-D-aspartate receptors.Blocking N-methyl-D-aspartate receptors prevented neuronal damage in the presence of these amino acids during hypoxia.It is likely that astroglial swelling caused by the accumulation of these amino acids via the alanine-serine-cysteine transporter 2 exchanger and system N transporters activates volume-regulated anion channels,leading to the release of excitotoxins and subsequent neuronal damage through N-methyl-D-aspartate receptor activation.Thus,previously unrecognized mechanisms involving non-excitatory amino acids may contribute to the progression and expansion of brain injury in neurological emergencies such as stroke and traumatic brain injury.Understanding these pathways co uld highlight new therapeutic targets to mitigate brain injury.

N-methyl-D-aspartate receptor subunit 1 protein expression in the hippocampus and temporal cortex of kainic acid-induced epilepsy rats

BACKGROUND： The N-methyl-D-aspartate receptor subunit 1 （NMDAR1） contributes to the incidence of epilepsy. However, the relationship between epilepsy-induced brain injury and NMDAR1 remains poorly understood. OBJECTIVE： To investigate changes in NMDAR1 protein expression in the hippocampus and temporal cortex of kainic acid-induced epilepsy rats. DESIGN, TIME AND SETFING： A randomized, controlled, animal experiment was performed at the Department of Physiology and Department of Pathology, Basic Medical College of Jilin University from March 2002 to March 2003. MATERIALS： Rabbit anti-NMDAR1 antibody was purchased from Wuhan Boster Biological Technology, China. METHODS： A total of 80 healthy, male, Wistar rats, aged 22 weeks, were randomly assigned to sham-surgery （n = 10） and model （n = 70） groups. Epilepsy models were established by injecting kainic acid （1μL） into the right amygdala, and rats were sacrificed at 2, 6, 24, 72 hours, and 7, 15, 30 days after surgery, with 10 animals at each time point. The rats in the sham-surgery group were injected with 1μL phosphate buffered saline into the right amygdala. MAIN OUTCOME MEASURES： NMDAR1 protein expression in the hippocampus and temporal cortex at 2, 6, 24, 72 hours and 7, 15, 30 days after epilepsy was detected using immunohistochemistry and flow cytometry analysis. RESULTS： In the sham-surgery group, a few NMDARl-positive cells were distributed in the hippocampus and temporal cortex. In the model group, NMDARl-positive cells were increased in the hippocampus and temporal cortex at 2 hours following kainic acid-induced epilepsy. They were significantly increased at 6 hours, and slightly decreased at 7 days （CA3 region and temporal cortex）, but remained greater than the sham-surgery group. This continued until day 30 （P 〈 0.01 ）. In addition, there were more NMDAR1 positive cells in the hippocampal CA3 and dentate gyrus than the temporal cortex （P 〈 0.01）. CONCLUSION： In epilepsy model rats, NMDAR1 protein expression was upregulated in the hippocampus and temporal cortex, and in particular in the hippocampal CA3 and dentate gyrus. NMDAR1 may participate in epilepsy and the excitation process of the epileptic brain.

Effects of P2Y_1 receptor on glial fibrillary acidic protein and glial cell line-derived neurotrophic factor production of astrocytes under ischemic condition and the related signaling pathways

Objective The present study aimed to explore the role of P2Y1 receptor in glial fibrillary acidic protein （GFAP） production and glial cell line-derived neurotrophic factor （GDNF） secretion of astrocytes under ischemic insult and the related signaling pathways. Methods Using transient right middle cerebral artery occlusion （tMCAO） and oxygen-glucose-serum deprivation for 2 h as the model of ischemic injury in vivo and in vitro, immunofluorescence, quantitative real-time reverse transcription-polymerase chain reaction （RT-PCR）, Western blotting, enzyme linked immunosorbent assay （ELISA） were used to investigate location of P2Y1 receptor and GDNF, the expression of GFAP and GDNF, and the changes of signaling molecules. Results Blockage of P2Y1 receptor with the selective antagonist N^6-methyl-2′-deoxyadenosine 3′,5′-bisphosphate diammonium （MRS2179） reduced GFAP production and increased GDNF production in the antagonist group as compared with simple ischemic group both in vivo and in vitro. Oxygen-glucose-serum deprivation and blockage of P2Y1 receptor caused elevation of phosphorylated Akt and cAMP response element binding protein （CREB）, and reduction of phosphorylated Janus kinase2 （JAK2） and signal transducer and activator of transcription3 （STAT3, Ser727）. After blockage of P2Y1 receptor and deprivation of oxygen-glucose-serum, AG490 （inhibitor of JAK2） reduced phosphorylation of STAT3 （Ser727） as well as expression of GFAP; LY294002, an inhibitor of phosphatidylinositol 3-kinase （PI3-K）, decreased phosphorylation of Akt and CREB; the inhibitor of mitogen-activated protein kinase kinase 1/2 （MEK 1/2） U0126, an important molecule of Ras/extracellular signal- regulated kinase （ERK） signaling pathway, decreased the phosphorylation of JAK2, STAT3 （Ser727）, Akt and CREB. Conclusion These results suggest that P2Y1 receptor plays a role in the production of GFAP and GDNF in astrocytes under transient ischemic condition and the related signaling pathways may be JAK2/STAT3 and PI3-K/Akt/CREB, respectively, and that crosstalk probably exists between them.

Bile acid receptors and nonalcoholic fatty liver disease

With the high prevalence of obesity, diabetes, and otherfeatures of the metabolic syndrome in United States, nonalcoholic fatty liver disease(NAFLD) has inevitably become a very prevalent chronic liver disease and is now emerging as one of the leading indications for liver transplantation. Insulin resistance and derangement of lipid metabolism, accompanied by activation of the pro-inflammatory response and fibrogenesis, are essential pathways in the development of the more clinically significant form of NAFLD, known as nonalcoholic steatohepatitis(NASH). Recent advances in the functional characterization of bile acid receptors, such as farnesoid X receptor(FXR) and transmembrane G protein-coupled receptor(TGR) 5, have provided further insight in the pathophysiology of NASH and have led to the development of potential therapeutic targets for NAFLD and NASH. Beyond maintaining bile acid metabolism, FXR and TGR5 also regulate lipid metabolism, maintain glucose homeostasis, increase energy expenditure, and ameliorate hepatic inflammation. These intriguing features have been exploited to develop bile acid analogues to target pathways in NAFLD and NASH pathogenesis. This review provides a brief overview of the pathogenesis of NAFLD and NASH, and then delves into the biological functions of bile acid receptors, particularly with respect to NASH pathogenesis, with a description of the associated experimental data, and, finally, we discuss the prospects of bile acid analogues in the treatment of NAFLD and NASH.

Dietary saturated fatty acid and polyunsaturated fatty acid oppositely affect hepatic NOD-like receptor protein 3 inflammasome through regulating nuclear factor-kappa B activation

AIM: To investigate the effect of different dietary fatty acids on hepatic inflammasome activation.METHODS: Wild-type C57BL/6 mice were fed either a high-fat diet or polyunsaturated fatty acid (PUFA)-enriched diet. Primary hepatocytes were treated with either saturated fatty acids (SFAs) or PUFAs as well as combined with lipopolysaccharide (LPS). The expression of NOD-like receptor protein 3 (NLRP3) inflammasome, peroxisome proliferator-activated receptor-&#x003b3; and nuclear factor-kappa B (NF-&#x003ba;B) was determined by real-time PCR and Western blot. The activity of Caspase-1 and interleukine-1&#x003b2; production were measured.RESULTS: High-fat diet-induced hepatic steatosis was sufficient to induce and activate hepatic NLRP3 inflammasome. SFA palmitic acid (PA) directly activated NLRP3 inflammasome and increased sensitization to LPS-induced inflammasome activation in hepatocytes. In contrast, PUFA docosahexaenoic acid (DHA) had the potential to inhibit NLRP3 inflammasome expression in hepatocytes and partly abolished LPS-induced NLRP3 inflammasome activation. Furthermore, a high-fat diet increased but PUFA-enriched diet decreased sensitization to LPS-induced hepatic NLRP3 inflammasome activation in vivo. Moreover, PA increased but DHA decreased phosphorylated NF-&#x003ba;B p65 protein expression in hepatocytes.CONCLUSION: Hepatic NLRP3 inflammasome activation played an important role in the development of non-alcoholic fatty liver disease. Dietary SFAs and PUFAs oppositely regulated the activity of NLRP3 inflammasome through direct activation or inhibition of NF-&#x003ba;B.

Effects of ω-3 fatty acids on toll-like receptor 4 and nuclear factor-κB p56 in lungs of rats with severe acute pancreatitis

AIM To determine the effects of ω-3 fatty acids(ω-3FA) on the toll-like receptor 4(TLR4)/nuclear factor κB p56(NF-κBp56) signal pathway in the lungs of rats with severe acute pancreatitis(SAP).METHODS A total of 56 Sprague-Dawley rats were randomly divided into 4 groups: control group, SAP-saline group, SAP-soybean oil group and SAP-ω-3FA group. SAP was induced by the retrograde infusion of sodium taurocholate into the pancreatic duct. The expression of TLR4 and NF-κBp56 in the lungs was evaluated by immunohistochemistry and Western blot analysis. The levels of inflammatory cytokines interleukin-6 and tumor necrosis factor-alpha in the lungs were measured by enzyme-linked immunosorbent assay. RESULTS The expression of TLR4 and NF-κBp56 in lungs and of inflammatory cytokines in serum significantly increased in the SAP group compared with the control group(P < 0.05), but was significantly decreased in the ω-3FA group compared with the soybean oil group at 12 and 24 h(P < 0.05).CONCLUSION During the initial stage of SAP, ω-3FA can efficiently lower the inflammatory response and reduce lung injury by triggering the TLR4/NF-κBp56 signal pathway.

The effect pathway of retinoic acid through regulation of retinoic acid receptor α in gastric cancer cells

AIM To evaluate the role of RARα gone in mediating the growth inhibitory effect of all-trans retinoic acid(ATRA) on gastric cancer cells. METHODS The expression levels of retinoic acid receptors(PARs)in gastric cancer cells were detected by Northern blot.Transient transfection and chlorophenicol acetyl transferase(CAT)assay were used to show the transcriptional activity of β retinoic acid response element (βPARE)and AP-1 activity.Cell growth inhibition was determined by MTT assay and anchorage-independent growth assay,respectively.Stable transfection was performed by the method of Lipofectamine,and the cells were screened by G418. RESULTS ATRA could induce expression level of RARα in MGC80-3,BGC-823 and SGC-7901 cells obviously, resulting in growth inhibition of these cell lines.After sense RARα gone was transfected into MKN-45 cells that expressed rather low level of RARα and could not be induced by ATPA,the cell growth was inhibited by ATPA markedly.In contrast,when antisense RARα gone was transfected into BGC-823 cells,a little inhibitory effect by ATPA was seen,compared with the parallel BGC-823 cells.In transient transfection assay,ATPA effectively induced transcriptional activity of βRARE in MGC80-3, BGC-823,SGC-7902 and MKN/RARα cell lines,but not in MKN-45 and BGC/aRARα cell lines.Similar results were observed in measuring anti-AP-1 activity by ATPA in these cancer cell lines. CONCLUSION ATRA inhibits the growth of gastric cancer cells by up-regulating the level of RARα; RARα is the major mediator of ATRA action in gastric cancer cells;and adequate level of RARα is required for ATRA effect on gastric cancer cells.