Protective effects of the salt-induced kinase inhibitor HG-9-91-01 on sepsis-associated cognitive dysfunction in mice and the underlying mechanisms
10.11817/j.issn.1672-7347.2023.230208
- VernacularTitle:盐诱导激酶抑制剂HG-9-91-01对小鼠脓毒症相关认知功能障碍的保护作用及其机制
- Author:
Xueqin WANG
1
;
Shuang WANG
;
Yanhui CUI
Author Information
1. 中南大学基础医学院人体解剖学与神经生物学系,长沙 410013;长沙医学院神经变性病基础与临床湖南省普通高等学校重点实验室,长沙 410219
- Keywords:
sepsis;
cognitive dysfunction;
salt-inducible kinase;
cAMP response element-binding protein-regulated transcription coactivator 1;
insulin-like growth factor 1;
HG-9-91-01;
neuroinflammation;
synaptic plasticity
- From:
Journal of Central South University(Medical Sciences)
2023;48(12):1793-1803
- CountryChina
- Language:Chinese
-
Abstract:
Objective:Sepsis-associated cognitive dysfunction is a common complication in patients with sepsis and lack of effective treatment.Its pathological mechanisms remain unclear.Salt-induced kinase(SIK)is an important molecule in the regulation of metabolism,immunity,and inflammatory response.It is associated with the development of many neurological diseases.This study aims to investigate the expression of SIK in the hippocampus of septic mice,and to evaluate the role and mechanism of the SIK inhibitor HG-9-91-01 in sepsis-associated cognitive dysfunction. Methods:Firstly,C57BL/6 mice were randomly divided into a control group(Con group)and a sepsis model group[lipopolysaccharide(LPS)group].The model group was injected intraperitoneally with LPS at a dose of 8 mg/kg and the Con group was injected with an equal volume of normal saline.Hippocampal tissues were harvested at 1,3,and 6 days after injection and the expressions of SIK1,SIK2,and SIK3 were detected by real-time fluorescence quantitative PCR(qPCR)and Western blotting.Secondly,C57BL/6 mice were randomly divided into a Con group,a LPS group,and a SIK inhibitor group(HG group).The LPS and HG groups were injected with LPS to establish a sepsis model;in the HG group,HG-9-91-01(10 mg/kg)was injected intraperitoneally at 3-6 days after LPS injection,and the LPS group was injected with the same volume of vehicle.Cognitive function was assessed at 7-11 days after LPS injection using the Morris water maze(MWM).Hippocampal tissues were harvested after the behavioral tests,and the mRNA levels of inflammatory factors and microglial markers were assessed by qPCR.The protein levels of inducible nitric oxide synthase(iNOS),CD68,ionized calcium binding adaptor molecule 1(Iba-1),N-methyl-D-aspartate(NMDA)receptor(NR)subunit,cAMP response element-binding protein(CREB)-regulated transcription coactivator 1(CRTC1),and insulin-like growth factor 1(IGF-1)were detected by Western blotting.Immunohistochemistry(IHC)was used to detect the expression of Iba-1 positive cells in the CA1,CA3 and dentate gyrus(DG)of the hippocampus,followed by Sholl analysis. Results:Compared with the Con group,the mRNA and protein levels of SIK1,SIK2,and SIK3 in the hippocampus were increased in the LPS group(all P<0.05).Compared with the Con group,mice in the LPS group had a significantly longer escape latency,a lower percentage of target quadrant dwell time and a reduced locomotor speed(all P<0.05);the HG group had a decreased escape latency and an increased percentage of time spent in the target quadrant in comparison with the LPS group(both P<0.05).The mRNA levels of inflammatory factors[tumor necrosis factor-α(TNF-α),interleukin-1β(IL-1β),interleukin-6(IL-6)],and the M1-type microglial markers iNOS and CD68 in the hippocampus of the LPS group were increased in comparison with the Con group,while the M2-type microglial markers CD206 and arginase-1(Arg-1)were decreased.Compared with the LPS group,the mRNA levels of TNF-α,IL-1β,IL-6,and iNOS were downregulated,while the levels of CD206 and Arg-1 were upregulated in the HG group(all P<0.05).The protein levels of iNOS,CD68,and Iba-1 in the hippocampus of the LPS group were increased in comparison with the Con group,but they were downregulated in the HG group in comparison with the LPS group(all P<0.05).The number of Iba-1 positive cells in CA1,CA3,and DG of the hippocampus was increased in the LPS group in comparison with the Con group,but they were decreased in the HG group in comparison with the LPS group(all P<0.05).Sholl analysis showed that the number of intersections at all radii between 8-38 μm from the microglial soma was decreased in the LPS group in comparison with the Con group(all P<0.05).Compared with the LPS group,the number of intersections at all radii between 14-20 μm was significantly increased in the HG group(all P<0.05).The protein levels of NR subunit NR1,NR2A,NR2B,and IGF-1 were downregulated in the hippocampus of the LPS group in comparison with the Con group,while the expression of phosphorylated CRTC1(p-CRTC1)was increased.Compared with the LPS group,the levels of NR1,NR2A,NR2B,and IGF-1 were upregulated,while p-CRTC1 was downregulated in the HG group(all P<0.05). Conclusion:SIK expression is upregulated in the hippocampus of septic mice.The SIK inhibitor HG-9-91-01 ameliorates sepsis-associated cognitive dysfunction in mice,and the mechanism may involve in the activation of the CRTC1/IGF-1 pathway,inhibition of neuroinflammation,and enhancement of synaptic plasticity.
