Effect of dexmedetomidine on TLR4/MyD88/NF-κB signaling pathway in hippocampus of mice with cognitive impairment after traumatic brain injury
10.3760/cma.j.cn131073-20250201-00813
- VernacularTitle:右美托咪定对TBI后认知功能障碍小鼠海马TLR4/MyD88/NF-κB信号通路的影响
- Author:
Gege LYU
1
;
Yudong SHAN
;
Caoyuan MA
;
Ruichao LI
;
Limin ZHANG
;
Wei ZHANG
Author Information
1. 郑州大学第一附属医院麻醉科，郑州 450052
- Publication Type:Journal Article
- Keywords:
Dexmedetomidine;
Craniocerebral trauma;
Cognitive dysfunction;
Toll-like receptor 4;
Myeloid differentiation factor 88;
NF-kappa B;
Hippocampus
- From:
Chinese Journal of Anesthesiology
2025;45(8):992-997
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To evaluate the effect of dexmedetomidine on Toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/nuclear factor κB (NF-κB) signaling pathway in the hippocampus of mice with cognitive impairment after traumatic brain injury (TBI).Methods:Sixty specific pathogen-free healthy adult wild-type C57BL/6 mice, aged 21-23 months, weighing 28-34 g, were divided into 5 groups ( n=12 each) by a random number table method: sham operation + vehicle group (SV group), sham operation + dexmedetomidine group (SD group), TBI + vehicle group (TV group), TBI + dexmedetomidine group (TD group) and TBI + TLR4 inhibitor TAK-242 group (TT group). The modified Feeney free fall epidural impact method was used to establish a mild TBI model. At 30 min before model preparation, dexmedetomidine 25 μg/kg was intraperitoneally injected in SD group and TD group, TAK-242 10 mg/kg was intraperitoneally injected in TT group, and the equal volume of normal saline was intraperitoneally injected in SV group and TV group. Neurological severity scores (NSSs) were used to evaluate the neurological function at 1, 7 and 14 days after developing the model. The novel object recognition test (recognition index) and fear conditioning test (the percentage of freezing time related to context and sound) were used to evaluate the cognitive function of mice at 16 days after developing the model. The number and morphology of hippocampal neurons (NeuN-positive cells) and activated microglia (ionized calcium-binding adaptor molecule 1[IBA1]-positive cells) were measured by immunofluorescent staining. The expression of interleukin-1beta (IL-1β), IL-6, tumor necrosis factor-alpha (TNF-α), TLR4, MyD88 and nuclear factor kappa B (NF-κB) was detected by Western blot. Results:Compared with SV group, the NSS was significantly increased, the recognition index was decreased, the percentage of freezing time related to context and sound was decreased, the number of NeuN-positive cells was decreased, the number of IBA1-positive cells was increased and the cell body area was enlarged, the total branch length and intersection points were decreased, and the expression of TLR4, MyD88, NF-κB, IL-1β, IL-6 and TNF-α was up-regulated in TV group ( P<0.05). Compared with TV group, the NSS was significantly decreased, the recognition index was increased, the percentage of freezing time related to context and sound was increased, the number of NeuN-positive cells was increased, the number of IBA1-positive cells was decreased and the cell body area was reduced, the total branch length and intersection points were increased, and the expression of TLR4, MyD88, NF-κB, IL-1β, IL-6 and TNF-α was down-regulated in TD group and TT group ( P<0.05). There was no statistically significant difference in the aforementioned parameters between TD group and TT group ( P>0.05). Conclusions:The mechanism by which dexmedetomidine mitigates TBI-induced cognitive impairment may be related to inhibition of the hippocampal TLR4/MyD88/NF-κB signaling pathway and reduction of neuroinflammatory responses in mice.
