The Effects Of Apelin-13 On Stress-induced Recognition Memory Deficits And Abnormal Of SGK1-GR Pathway In Rats

[Background] Our previous study has been reported that apelin-13 improves acute forced swim-induced novel object recognition memory deficits via phosphatidylinositol 3-kinase(PI3K)signaling pathway in rats.However,the downstream molecule mechanism remains unknown.Serum and glucocorticoid induced kinase 1(SGK1)and glucocorticoid receptor(GR)are downstream molecules of PI3 K signaling pathway.Besides,SGK1-GR pathway regulates learning and memory function via multiple ways.Our research is based on the model of repetitive footshock stress(RFS),and we detect the effects of apelin-13 on RFS-induced recognition memory deficits and abnormal of SGK1-GR signaling pathway.[Method] We establisehed the cognitive memory impairment rat model by RFS;we observed the effects of apelin-13 treatment to novel object location(NOL)and novel object recognition(NOR)task in RFS-induced rats;we observed the effects of apelin-13 treatment on mRNA expression of SGK1 and GR in hippocampus,hypothalamus and media prefrontal cortex(mPFC)in RFS-induced rats by RT-qPCR;we observed the effects of apelin-13 treatment on phosphorylation level of SGK1 at Ser422 and GR at Ser211,the total protein level of SGK1 and GR,the nuclear translocation of GR in hippocampus,hypothalamus and mPFC in RFS-induced rats by Western Blot.[Result] Apelin-13 treatment improved NOL and NOR memory task impairments induced by RFS;apelin-13 treatment reversed upregulated mRNA expression of SGK1 induced by RFS in hippocampus and hypothalamus in rats;apelin-13 treatment reversed upregulated phospho-level of SGK1 at Ser422 and total protein level of SGK1 induced by RFS in hippocampus,hypothalamus and mPFC in rats;apelin-13 treatment reversed upregulated mRNA expression of GR induced by RFS in mPFC in rats;apelin-13 treatment reversed upregulated phospho-level of GR at Ser211 induced by RFS in hippocampus and hypothalamus in rats;apelin-13 treatment reversed upregulated total protein level of GR induced by RFS in hippocampus in rats;apelin-13 treatment reversed upregulated nuclear thranslocation of GR induced by RFS in hypothalamus and mPFC in rats.[Conclusion] Apelin-13 improves RFS-induced recognition memory deficits in rats,the mechanism nay be related to the regulation effects of apelin-13 on SGK1-GR signaling pathway.