| ObjectiveThis study was conducted to investigate the effects of(-)-epigallocatechin-3-gallate(EGCG)on the behavioral performances of rats with restraint stress,and to explore EGCG's modulation on some related signaling transduction pathways in the central nervous system,such as protein kinase C(PKC),extracellular signal-regulated kinase(ERK1/2),phosphatidylinositol 3-kinase(PI3K)/serine/threonine kinase(AKT),janus kinase-signal transducer and activator of transcription(JAK-STAT).So this research will clarify the related molecular mechanisms of EGCG to improve neural injuries induced by stress.MethodsForty healthy male Wistar rats were randomly assigned to four groups as follows:normal control(CT)group,stress control(ST)group,stress group with green tea polyphenols modulation(GST)and stress group with EGCG modulation(EST).The stress model was established by restraint.GTPs and EGCG were given to experimental animals by intragastric administration at a dose of 500mg/kg·bw·d.The changes of behaviors were examined by open-field test and step-through test.The contents of cortisol and neurotransmitters in plasma were detected by radio immun-oassay(RIA)and enzyme linked immunosorbentassay(ELISA)respectively.The ex-pressions and phosphorylation levels of signaling proteins in hippocampus and cortex were examined by Western blot.And the mRNA levels of signaling proteins in hippo-campus and cortex were detected by real-time fluorescent quantitative PCR.Results1.Compared with CT group,the latency of ST group in open-field test was prolonged and the crossing frequency was reduced apparently(P<0.05).These changes in GST group and EST group were statistically improved in contrast to ST group(P<0.05).The results of step-through test showed that the latency of ST group was decreased and the shock frequency was increased in contrast to CT group(P<0.05).There were remarkable differences in GST group and EST group in contrast to ST group.The content of plasma cortisol in ST group was increased obviously(P<0.05)and the plasma cortisol levels in GST and EST groups were decreased than that of ST group.In addition,plasma levels of serotonin and dopamine decreased significantly in ST group(P<0.05),and their levels in GST and EST rats were notably increased in contrast to ST group(P<0.05).And there is a relationship between animals' behaviors and plasma contents of cortisol and neurotransmitters.2.The expressions of PKC,ERK1/2,AKT and STAT3 in cerebrum had no significant differences among the four groups.Compared with CT group,the expres-sions of p-PKC,p-ERK1/2,p-AKT and p-STAT3 in the hippocampus of ST group were decreased significantly(P<0.05).And their levels in in the hippocampus of GST and EST groups were increased obviously in contrast to ST group(P<0.05).Compared with CT group,the levels of p-ERK1/2 and p-STAT3 in cortex of ST group were lowered remarkably(P<0.05).And the corresponding changes in GST and EST groups were increased in contrast to ST group.There were no significant diffremces of p-PKC and p-AKT in cortex among the four groups.3.The changes of mRNA expressions of the four signaling proteins were similar to their phosphorylation levels.In hippocampus,the mRNA levels of PKC,ERK1/2,AKT and STAT3 in ST group were downregulated compared with CT group(P<0.05).And their expressions in GST and EST group were increased significantly in contrast to ST group(P<0.05).In cortex,only the expressions of ERK1/2 mRNA and STAT3 mRNA were lowered in ST group.And their levels in GST and EST groups were increased obviously compared with ST group(P<0.05).Conclusion1.Restraint stress could impair body's behavioral performances and moderate EGCG modulationcould could improve these changes induced by stress.2.EGCG may play an important role in modulating the related signaling proteins in central nervous system,such as PKC,ERK1/2,AKT,STAT3 and so on.The results indicated the protective effects of EGCG on neural injury induced by stress may involved with its regulation on some related signaling transduction pathways. |
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