Expression of gap junction genes connexin 32,connexin 43 and their proteins in hepatocellular carcinoma and normal liver tissues

AIM To investigate the significance andmechanism of cx32 mRNA,cx43 mRNA and theirproteins in hepatocarcinogenesis.METHODS Sixty-one cases of HCC and 14cases of normal liver tissues were detected byimmunohistochemical and in situ hybridization(ISH)methods.RESULTS In HCC grades Ⅰ,Ⅱ,Ⅲ and normalliver tissues,the positive rates of Cx32 proteinwere 55.6%,42.1%,18.2% and 92.9%,respectively.The detection rates of Cx43 proteinwere 44.4%,26.3%,12.1% and 78.6%,respectively.There was significant difference inCx32 and Cx43 protein between HCC and normalliver tissues(P【0.01).ISH the positive rates ofcx32 mRNA shown by ISH in HCC grades Ⅰ,Ⅱ,Ⅲ and normal liver tissues were 88.9%,84.2%,87.9% and 92.9%,respectively.Those of cx43mRNA were 77.8%,78.6%,78.8% and 85.7%,respectively.There was no statistical differencein the positive rates of cx32 mRNA and cx43mRNA between HCC and normal liver tissue(P】0.05).CONCLUSION The aberrant location of Cx32and Cx43 proteins could be responsible forprogression of hepatocarcinogenesis,and thedefect of cx genes in post-translationalprocessing might be the possible mechanism.

Cisplatin-induced premature senescence with concomitant reduction of gap junctions in human fibroblasts

To examine the role of gap junctions in cell senescence,the changes of gap junctions in cisplatin-induced premature senescence of primary cultured fibroblasts were studied and compared with the replicative senescent human fibroblasts.Dye transfer assay for gap junction function and immunofluorescent staining for connexin 43 protein distribution were done respectively. Furthermore,cytofluorimetry and DAPI fluorescence staining were performed for cell cycle and apoptosis analysis. p53 gene expression level was detected with indirect immunofluorescence. We found that cisplatin (10 mM) treatment could block cell growth cycle at G1 and induced premature senescence. The premature senescence changes included high frequency of apoptosis,elevation of p53 expression,loss of membranous gap junctions and reduction of dye-transfer capacity. These changes were comparable to the changes of replicative senescence of human fibroblasts. It was also concluded that cisplatin could induce premature senescence concomitant with inhibition of gap junctions in the fibroblasts. Loss of functional gap junctions from the cell membrane may account for the reduced intercellular communication in the premature senescent fibroblasts. The cell system we used may provide a model useful for the study of the gap junction thus promoting agents against premature senescence.

Altered Expression of Connexin-43 and Impaired Capacity of Gap Junctional Intercellular Communication in Prostate Cancer Cells

Connexin-43 (Cx43) expression in prostate cancer (PCa) cells and the potency of gap junctional intercellular communication (GJIC) in the cells were investigated, with an attempt to elu- cidate the reason why the so-called 'bystander effect' mediated by thymidine kinase (TK) suicide gene therapy on PCa cells is not of significance and to explore the role of GJIC in PCa carcinogenesis. mRNA and protein expression of Cx43 in a PCa cell line PC-3m was detected by re- verse-transcription polymerase chain reaction (RT-PCR) and strapt-avidin-biotin-enzyme complex (SABC) immunohistochemical staining, and inherent GJIC of PC-3m cells was assayed by scrape-loading and dye transfer (SLDT) assay. The expression of Cx43 in human normal and malig- nant prostate tissues was determined by SABC immunohistochemistry as well. It was found that Cx43 mRNA and protein expression in PC-3m cells was slightly reduced as compared with positive controls and the location of Cx43 protein was aberrant in cytoplasm rather than on membrane. As- sessment of paraffin sections demonstrated that the expression of Cx43 protein in PCa cells was ab- normally located and markedly diminished as compared with normal prostatic epithelial ones, dis- playing a negative correlation to the pathological grade (χ2=4.025, P<0.05). Additionally, capacity of inherent GJIC in PC-3m cells was disrupted, which was semi-quantified as (+) or (-). It was indi- cated that both down-regulated expression of Cx43 mRNA and aberrant location of Cx43 protein par- ticipated in the mechanisms leading to deficient GJIC in PC-3m cells. Lack of efficient GJIC is a molecular event, which may contribute not only to limited extent of 'bystander effect', but also to initiation and progression of prostatic neoplasm.

Improvement of cardiac function and reversal of gap junction remodeling by Neuregulin-1β in volume-overloaded rats with heart failure

Objective We performed experiments using Neuregulin-1β （NRG-1β） treatment to determine a mechanism for the protective role derived from its beneficial effects by remodeling gap junctions （GJs） during heart failure （HF）. Methods Rat models of I-IF were established by aortocaval fistula. Forty-eight rats were divided randomly into the HF （HF, n = 16）, NRG-1β trealanent （NRG, n = 16）, and sham operation （S, n = 16） group. The rats in the NRG group were administered NRG-1β （10 μg/kg per day） for 7 days via the tail vein, whereas the other groups were injected with the same doses of saline, Twelve weeks after operation, Connexin 43 （Cx43） expression in single myocytes obtained from the left ventricle was determined by immunocytochemistry. Total protein was extracted from frozen left ventricular tissues for immunoblotting assay, and the ultrastmcture of myocytes was observed by transmission electron microscopy. Results Compared with the HF group, the cardiac fimction of rats in the NRG group was markedly improved, irregular distribution and deceased Cx43 expression were relieved. The ultrastmcture of myocytes was seriously damaged in HF rats, and NRG-1β reduced these pathological damages. Conclusions Short-term NRG-1β treatment can rescue pump failure in experimental models of volume overload-induced HF, which is related to the recovery of GJs structure and the improvement of Cx43 expression.

The gap junction blocker carbenoxolone enhances propofol and sevoflurane-induced loss of consciousness

General anesthetics induce loss of consciousness by inhibiting ascending arousal pathways, and they interfere with gap junction electrical coupling. The present study aimed to determine whether inhibition of gap junction-mediated signaling could influence general anesthetic-induced loss of consciousness. The general anesthetics sevoflurane and propofol were used. Intracerebroventricular administration of carbenoxolone, a gap junction blocker, significantly decreased the time to loss of the righting reflex （P 0.05）, but prolonged the time to recovery of the reflex （P 0.05）. Moreover, intracerebroventricular administration of carbenoxolone increased the sensitivity to sevoflurane, with a leftward shift of the loss of righting reflex dose-response curve, and decreased the 50% effective concentration of sevoflurane. These results suggest that the gap junction blocker carbenoxolone enhances propofol and sevoflurane-mediated general anesthesia.

THE EFFECT OF ALL-TRANS RETINOIC ACID ON GAP JUNCTIONAL INTERCELLULARCOMMUNICATION AND CONNEXIN 43 GENE EXPRESSION IN GLIOMA CELLS

To illuminate the regulating effect of all trans retinoic acid (ATRA ) on gap junctional intercellular communication (GJIC) and connexin 43 (Cx43) ge ne expression in glioma cells, which is tissue and organ specific. Method. Rat C6 glioma cells were exposed to ATRA at a concentration of 1, 10, 10 0 μmol/L respectively, and the GJIC function of the cells was examined with scr ape loading dye transfer assay 24 hours, 48 hours and 72 hours after ATRA treat ment. The effect of ATRA on Cx43 gene expression was measured with semiquantitat ive reverse transcription polymerase chain reaction (RT PCR) 24 hours after ATR A exposure. Results. The GJIC function of C6 glioma cells was significantly increased by ATR A at each concentration applied. The dye passed 4 to 5 rows of cells from the sc raping edge in ATRA treated cells, but only 1 or 2 rows in the control. The augm ent effect was observed 24 hours after each concentration ATRA treatment, and la sted till 72 hours after treatment with 1μmol/L and 10μmol/L ATRA. Forty eigh t hours after exposed to 100μmol/L ATRA, the enhancement of GJIC was less obvi ous. There was no significant increase induced by ATRA on the transcription of C x43 gene, as demonstrated by semiquantitative RT PCR. Conclusion. ATRA turned out to be a potent enhancer on GJIC function in C6 gliom a cells, and the enhancement effect was most probable at post transcriptional l evel.

Do the expressions of gap junction gene connexin messenger RNA in noncancerous liver remnants of patients with hepatocellular carcinoma correlate with postoperative recurrences?

AIM: To investigate whether the changes of gap junction gene connexin messenger RNA in the noncancerous liver tissue of patients with hepatocellular carcinoma (HCC) could play a significant role in its postresection recurrence.METHODS: Seventy-nine consecutive patients having undergone curative resection for HCC entered this study.Using a reverse-transcription polymerase chain reaction (RT-PCR)-based assay, connexin (Cx) 26, connexin (Cx)32 and connexin (Cx) 43 mRNAs were determined prospectively in noncancerous liver tissues from these 79 patients and in the liver tissues from 15 controls. The correlations between connexin mRNA expression and the clinicopathological variables and outcomes (tumor recurrence and recurrence related mortality) were studied.RESULTS: Compared with liver tissues of control patients,the expression of Cx 32 mRNA in noncancerous liver tissues was significantly lower (mean: 0.715 vscontrol 1.225,P＜0.01), whereas the decreased Cx 26 mRNA (mean:0.700 vs of control 1.205,P＞0.05) and increased Cx 43 mRNA (mean: 0.241 vscontrol 0.100, P＞0.05) had no statistical significance. We defined the value of Cx 32 mRNA or Cx 26mRNA below 0.800 as a lower value. By multivariate analysis for noncancerous livers, a lower value of Cx 32 mRNA correlated significantly with a risk of HCC recurrence and recurrence-related mortality. The lower value of Cx 26 mRNA did not correlate with recurrence and mortality. The increased value of Cx43 mRNA also did not correlate with postoperative recurrence and recurrence-related mortality. By multivariate analysis, other significant predictors of HCC recurrence included vascular permeation, cellular dedifferentiation, and less encaps-ulation. The other significant parameter of recurrence related mortality was vascular permeation.CONCLUSION: The decreased expression of Cx 32 mRNA in noncancerous liver tissues plays a significant role in the prediction of postoperative recurrence of HCC.

Up-Regulation of the Gap Junction Intercellular Communication by Tea Polyphenol in the Human Metastatie Lung Carcinoma Cell Line

Our previous study has proven that tea polyphenol has a role in lung neoplasms. The present communication was to investage the anti-proliferation effect of tea polyphenol on the PG cells, which was a high metastatic human lung carcinoma cell line, by 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-diphenytetrazoliumromide (MTT) cell viability assay, and to study the change of intracellular calcium concentration, connexin43 (Cx43) expression, gap junctional intercellular communication (GJIC) and cell cycle distribution after the tea polyphenol treatment by laser scanning confocal microscopy and flow cytometry. The results showed that 1) tea polyphenol could kill the PG cells in a dose-depent manner via inhibiting the PG cell proliferation and blocking the PG cell cycle progression staying in G0/G1 phase and not transfering in S and G2/M phases to reduce the PG cell proliferation index;2) the increases of intracellular calcium concentration, GJIC and Cx43 expression were related with the tea polyphenol doses. The data suggested that tea polyphenol could inhibit the growth of PG cells, which mechanism was associated with the up-regulation of GJIC.

Energy gap suppression and excess current in TI2Ba2CaCu208 intrinsic Josephson junctions

Intrinsic Josephson junctions in misaligned T12Ba2CaCu208 thin film were fabricated on LaA103 substrate. The temperature dependence of the critical current is investigated around liquid nitrogen temperature. In the current voltage characteristic, large voltage jump and lack of resistive branch are observed, which shows good consistency with the intrinsic Josephson junctions. By analyzing the large gap voltage in the curve, great suppression of the energy gap is found. Through discussing the temperature dependence of the gap voltage in liquid nitrogen temperature, it is shown that this phenomenon can be caused by the non-equilibrium quasiparticle injection. The temperature influence on the excess current also confirms the non-equilibrium effect.

Connexin therapeutics:blocking connexin hemichannel pores is distinct from blocking pannexin channels or gap junctions

Compounds that block the function of connexin and pannexin protein channels have been suggested to be valuable therapeutics for a range of diseases.Some of these compounds are now in clinical trials,but for many of them,the literature is inconclusive about the molecular effect on the tissue,despite evidence of functional recovery.Blocking the different channel types has distinct physiological and pathological implications and this review describes current knowledge of connexin and pannexin protein channels,their function as channels and possible mechanisms of the channel block effect for the latest therapeutic compounds.We summarize the evidence implicating pannexins and connexins in disease,considering their homeostatic versus pathological roles,their contribution to excesive ATP release linked to disease onset and progression.

Quantitative Structure-activity Relationship Studies on the Antioxidant Activity and Gap Junctional Communication of Carotenoids

The antioxidant and gap junctional communication（GJC） activities of carotenoids are known to be the two main anticancer mechanisms.Quantitative structure-activity relationship（QSAR） models of the two activities were developed using stepwise regression and multilayer perceptron neural network based on the calculated descriptors of quantum chemistry.The results showed that the significant molecular descriptor related to the antioxidant activity of carotenoids was the HOMO-LUMO energy gap（EHL） and the molecular descriptor related to the GJC was the lowest unoccupied molecular orbital energy（ELUMO）.The two models of antioxidant activity both showed good predictive power,but the predictive power of the neural network QSAR model of antioxidant activity was better.In addition,the two GJC models have similar,moderate predictive power.The possible mechanisms of antioxidant activity and GJC of carotenoids were discussed.

Influence of a Semiconductor Gap’s Energy on the Electrical Parameters of a Parallel Vertical Junction Photocell

The present work is a theoretical study on a parallel vertical junction solar cell under a multi-spectral illumination in static regime. The density of the minority charge carriers was determined based on the diffusion equation. Photocurrent and photovoltage are deducted from such density. All these parameters are studied taking into account the influence of the gap energy (Eg).

Pharmacological Effects of Statins Related to Gap Junction Modulation

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, or “statins”, are widely using cholesterol-lowering drugs with pleiotropic pharmacological effects. In this review, we summarized the pharmacological effects of statins related to gap junction modulation. The main function of cellular gap junctions, which are composed of trans-membrane proteins named connexins (Cxs), is to mediate direct cell-to-cell communication through material exchange. Statins could rectify the disturbed expression, distribution, or phosphorylation of Cxs and thus modify the functions of gap junctions in a variety of tissues like the aorta, cardiomyocytes, or tumors. The effects of statins on Cxs and gap junctions were associated with their pharmacological activities against atherosclerosis, arrhythmias, and tumors. Despite some evidences suggested that the anti-inflammatory or HMG-CoA reductase inhibiting effects of statins may contribute in part to the modulation of Cxs and gap junctions, the detailed underlying mechanisms are largely unrevealed and merit further investigation. In addition, it is likely that the modulating effects of statins on gap junctions may also contribute to their pharmacological activities against some diabetic complications. Future studies of these issues will help to provide scientific evidences for the appropriate clinical application of statins.

Effect of Apigenin on Gap Junctional Intercellular Communication in Human Tenon's Capsule Fibroblasts

Purpose:To investigate the effect of apigenin on gap junctional intercellular communication (GJIC) in human Tenon's capsule fibroblasts (HTFs) and its underlying mechanism. Methods:After a 48 h treatment of cultured HTFs with apigenin.(80 μmol/L),the GJIC was detected by a scrape-loading/dye transfer technique with Lucifer yellow dye and rhodamine (Rh) dextran. The coupling index represents a quantification of GJIC where a high coupling index is associated with a greater number of cells demonstrating cell-cell communication through gap junction channels.The changes in connexin 43 (Cx43) distribution and the expression of Cx43 at the protein and mRNA levels were statistically compared between the two groups by means of immunocytochemistry, western blotting,and real-time polymerase chain reaction (PCR). Results:The functioning of GJIC in the HTFs was significantly enhanced after 48 hours by apigenin treatment when compared with the control cells. In the apigenin group, the intercellular dye transfer grade was above 9, while this value was only grade 3-4 in the control group. The coupling index was significantly increased up to 9.205±0.3621 in the apigenin group,compared with 5.1775 ±0.3177 in the control group (F=279.581, P=0.000). The expression of Cx43 at the protein and mRNA levels was significantly up-regulated in the apigenin group compared with the control group. Conclusion:Apigenin can significantly enhance the function of GJIC in HTFs by up-regulating the expression of Cx43 at both the protein and mRNA levels,suggesting that the enhancement of GJIC in HTFs by apigenin probably acts as an important mechanism underlying the inhibitory effect of apigenin on HTF proliferation.

Oligodendrocytes in Mouse Corpus Callosum are Coupled Via Gap Junction Channels Formed by Connexin47 and Connexin32

已有的超微结构研究显示,白质中的少突胶质细胞和星形胶质细胞之间存在缝隙连接,但少突胶质细胞之间不存在缝隙连接,虽然体外培养的少突胶质细胞可形成功能性缝隙连接。本文研究新生小鼠胼胝体急性脑片中的少突胶质细胞的功能性连接。以全细胞膜片钳技术用生物胞素(一种可渗透的缝隙连接示踪剂)标记少突胶质细胞。平均61个细胞为链霉亲和素-Cy3标记的生物胞素阳性。约77%的连结细胞表达少突胶质细胞标志蛋白CNPase阳性染色,9%表达星形胶质细胞标志蛋白GFAP阳性,14%为CNPase和GFAP阴性。后者的大部分表达Olig2和一些NG2(少突胶质细胞前体细胞的标志物)。少突胶质细胞表达Cx47、Cx32和Cx29,星形胶质细胞表达Cx43和Cx30。在Cx47敲除小鼠中,连结细胞的数量减少80%。单独删除Cx32或Cx29并不能显著减少连结细胞的数量,但Cx32/Cx47双缺陷小鼠中没有观察到相互连结的细胞。Cx47敲除完全消除了少突胶质细胞与星形胶质细胞间的耦联。在Cx43敲除动物中,少突胶质细胞-星形胶质细胞间连接仍然存在,但与少突胶质细胞前体细胞间的耦联没有被观察到。在Cx43/Cx30双敲除小鼠中,少突胶质细胞-星形胶质细胞连接几乎不存在。解开连结的少突胶质细胞显示为较高的膜输入电阻。本文认为,白质中的少突胶质细胞依靠Cx47和Cx32的表达形成功能性的合胞体,而星形胶质蛋白缝隙连接蛋白的表达能提升此网络的大小。

Gap junction communication involved in brain protection following focal ischemia and reperfusion in rats

BACKGROUND： Studies have suggested that gap junctions not only modulate the fate of the neocortex, but are also involved in maintaining homeostasis in the mature brain. However, the neuroprotective effects of gap junction communication following brain ischemic injury remain poorly understood. OBJECTIVE： To investigate the neuroprotective effects and possible mechanisms of gap junction communication following focal ischemia and reperfusion. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the School of Basic Medical Sciences of Lanzhou University between June 2007 and May 2008. MATERIALS： Rabbit polyclonal anti-connexin 43 （Cx43） and gap junction blocking agent octanol were purchased from Sigma, USA; mouse monoclonal anti-rat glial fibrillary acidic protein （GFAP） was provided by Santa Cruz, USA; mouse monoclonal anti-rat CD11 b was produced by Abcam, England. METHODS： A total of 52 adult, male, Sprague Dawley rats were randomly assigned to three groups： sham-operated （n = 12）, vehicle control （n = 20）, and octanol-treated （n = 20）. Brain ischemia and reperfusion were induced by transient middle cerebral artery occlusion （MCAO） in vehicle control and octanol-treated groups, while no MCAO was administered to the sham-operated group. In the octanol-treated group, 5 mmol/kg octanol was dissolved in dimethyl sulfoxide （0.005% v/v） and was intraperitoneally injected 30 minutes prior to ischemic onset. Sham-operated and vehicle groups received equivalent volumes of dimethyl sulfoxide. MAIN OUTCOME MEASURES： Infarct volumes in ipsilateral striatum after MCAO were measured using cresyl violet dye; GFAP, CD11 b, and Cx43 expression in the ipsilateral striatum following MCAO were detected by immunohistochemistry; Western blot analysis was employed to determine Cx43 and GFAP expression. RESULTS： At 1 and 3 days following MCAO and reperfusion, ipsilateral striatum infarct volumes in the octanol group were significantly greater than in the vehicle group （P 〈 0.05）. There was no infarction in the sham-operated group. Cx43 and GFAP expression in the ipsilateral striatum of the octanol group was remarkably decreased compared with the vehicle group （P 〈 0.05）, and expression in the sham-operated group was less than in the other two groups （P 〈 0.05）. In the octanol-treated group, CD11 b expression was significantly increased compared with the vehicle group （P 〈 0.05）, and there were less CD11 b-immunoreactive cells in the sham-operated group compared with the other two groups （P 〈 0.05）. CONCLUSION： The pretreatment of blocking gap junction aggravated brain injury following MCAO. These results were possibly due to reduced astrocyte proliferation and activation, as well as reduced inflammatory response via activated microglia.

Gap junctions enhance the antiproliferative effect by transfer of microRNAs in glioma cells

OBJECTIVE To investigate the permeability of gap junction composed of connexin 43(Cx43)for micro RNAs(mi RNAs)and the impact of gap junction-mediated transfer of mi RNAs in glioma U87 cells.METHODS Co-culture assay demonstrated the transmission of miR NAs through gap junction channel into adjacent cells.U87 cells were labeled with green fluorescein protein(GFP)as receivers and cells were transfected mi RNAs as donors.Receiver cells and donor cells were mixed together in a ratio of 1∶1.After 12 h co-culture,cells were separated using a BD influx flow cytometer based on the GFP labeled.Quantitative real-time polymerase chain reaction(q RT-PCR)was applied detect to the expressions of miR NAs and Cx43 mR NA.Western blotting was performed to detect the protein expressions of Cx43 and GFP in U87 cells.CCK-8 assay is used to detect cell growth.RESULTS Co-culture assays demonstrated mi R-34a could transfer between U87 cells.The role of the contact independent could also transfer of miR-34a.Gap junctions inhibitor(CBX and 18-α-GA)showed lower miR-34a expression than co-culture group,whereas gap junctions enhancer(RA and Galanglin)enhanced miR-34a expression.Knockdown of Cx43 could significantly decrease the transferring of miR-34a between U87 cells.Different length of miR NAs(miR-1827,miR-144,miR-203a and miR-1183)were similar to the expression of miR-34a between U87 cells.Additionally,we demonstrated that gap junctions mediate the effect of antiproliferation mediated by mi R-34a in U87 cells.The functional inhibition of gap junctions using either si RNA or inhibition eliminated the miR-34a mediated antiproliferation,whereas the enhancement of gap junctions treatment augmented this mi R34a-mediated antiproliferation.CONCLUSION Our study demonstrates that gap junction composed of Cx43-mediated transfer mi RNAs in different length of nucleotides and gap junction-mediated transfer of mi R-34a enhance the antiproliferative effect in glioma U87 cells.

Gap junctions enhance the antiproliferative effect of microrna-34a in glioma cells

OBJECTIVE To investigate the effect of gap junctions on the anti-tumor function induced by mi R-34a in glioma U87 cells.METHODS 1.Transfection(miR-34a mimics were transfected into glioma cells to upregulate their expression);2.Co-culture assay(U87cells were transfected with mi R-34a co-cultured with U87 cells that was transfected PCMV-eG FP plasmid);3.Flow cytometry analysis(select the e GFP labed U87 cells);4.RNA isolation and real-time PCR;5.CCK-8 assay;6.Western blotting.RESULTS Mi R-34a mimics transfered between the U87 cells.Parachute assay showed that GJ inhibition(CBX and 18-α-GA)can decrease mi R-34a expression than co-culture group.RA and galanglin enhanced mi R-34a expression than co-culture group.Mi R-34a relative expression reduced after co-culture,while gap junctions composed of Cx43 were down-regulated by sh RNA.Transfected with mi R-34a mimics reduced the survival of U87 cells in a dose-dependent manner.To more specifically establish the role of GJIC in mi R-34a induced growth inhibition of U87 cells,si RNA was used to knockdown the expression of Cx43,the dominant connexin expressed in U87 cells.CCK-8 assay showed that siR NAs have no effect on cell growth,but they could aggravate the growth inhibition of miR-34a to U87 cels.CONCLUSION Gap junctions enhance the antiproliferative effect of miR NA-34a in glioma cells.

Mechanical allodynia and affective behavior are improved by INI-0602,a gap junction hemichannel inhibitor,in a rat model of neuropathic pain induced by sciatic nerve injury

OBJECTIVE To investigated the effects of INI-0602 on nociceptive reflex,depression-associated andanxiety-related behaviors caused by neuropathic pain in sciatic nerve injury rats.METHODS Male rat were subjected to sciatic nerve injury(SNI)or sham surgery.Rat received daily treatment with INI-0602 intrathecally,at a dose of 0.25μg/10μL.The response frequency to mechanical allodynia in animals was measured with von Frey hairs on day 1,3,5,7,14,21.Rats were evaluated in the forced swimming test(FST)test,tail suspension test(TST),sucrose preference test(SPT)for depression-like behavior.We performed open field test(OFT)and elevated plus-maze test(EPM)to evaluate anxiety-associated behaviors.Besides,we investigated the alterations of NMDA receptor and the brain-derived neurotrophic factor(BDNF)and also the expression of connexin43 and connexin32,structure protein of gap junction channel,on the protein level and the number of activated astrocyte showed by immunohistochemical.RESULTS The SNI procedure produced mechanical allodynia and accompanied with depressive-like and anxiety-like behavior.Treatment with INI-0602 produced a significant analgesic effect in SNI rats at day 7(model+NS:11.017±1.506 g;model+INI-0602:31.157±1.532 g,P<0.01),and still obviously on the 21th day(31.067±1.787,P<0.01).INI-0602 could also improve the performance of sciatic nerve injury rats among program behavior tests related to depression and anxiety.In parallel with relief of pain,the alterations of NMDA receptor and the brain-derived neurotrophic factor(BDNF),involved in central sensitization and synaptic plasticity,were investigated.INI-0602 not only could inhibited spared nerve injury induced up-regulated of NR2B and phosphorylation NR2B in early and late neuropathic pain(early phase:Nr2b:2.897±0.228,P<0.01;p-Nr2b:2.984±0.236,P<0.01;late phase:Nr2b:2.594±0.187,P<0.01;p-Nr2b:3.124±0.330,P<0.01),but also could inhibit the increased of BDNF in the early(model+NS:3.637±0.381,model+INI-0602:1.148±0.372,P<0.01)and upregulate the BDNF in late stage(model+NS:0.438±0.103,model+INI-0602:1.222±0.092,P<0.01).Meanwhile,INI-0602 significantly decreased the expression of connexin43 and connexin32,structure protein of gap junction channel,on the protein level and the number of activated astrocyte showed by immunohistochemical.CONCLUSION INI-0602 blocked behavioral changes induced by neuropathic pain,suggesting that it might be a promising pharmacological approach of painemotion diseases.

The synchronization of FitzHugh-Nagumo neuron network coupled by gap junction

It is well known that the strong coupling can synchronize a network of nonlinear oscillators. Synchronization provides the basis of the remarkable computational performance of the brain. In this paper the FitzHugh-Nagumo neuron network is constructed. The dependence of the synchronization on the coupling strength, the noise intensity and the size of the neuron network has been discussed. The results indicate that the coupling among neurons works to improve the synchronization, and noise increases the neuron random dynamics and the local fluctuations; the larger the size of network, the worse the synchronization. The dependence of the synchronization on the strength of the electric synapse coupling and chemical synapse coupling has also been discussed, which proves that electric synapse coupling can enhance the synchronization of the neuron network largely.