TLR4-mediated hippocampal MMP/TIMP imbalance contributes to the aggravation of perioperative neurocognitive disorder in db/db mice. (November 2020)

• Record Type: Journal Article
• Authors: Zhang, Yang; Liu, Hailin; Chen, Zixuan; Yu, Min; Li, Jiaxin; Dong, Hongquan; Li, Nana; Ding, Xiahao; Ge, Yahe; Liu, Cunming; Ma, Tengfei; Gui, Bo
• Is Part Of: Neurochemistry international. Volume 140(2020)
• Publication Date: 2020-11
• Subjects: Blood-brain barrier -- Db/db mice -- Matrix metalloproteinase -- Perioperative neurocognitive disorders -- Tissue inhibitors of matrix metalloproteinase -- Toll-like receptor 4; ANOVA analysis of variance -- BBB blood-brain barrier -- eHFS electrical high-frequency stimulation -- FCT fear conditioning test -- fEPSPs field excitatory postsynaptic potentials -- IL interleukin -- i.p. intraperitoneal -- LTP long-term potentiation -- MMP matrix metalloproteinase -- PND perioperative neurocognitive disorder -- POD postoperative day -- TEM transmission electron microscopy -- TF tibial fracture -- TIMP tissue inhibitors of matrix metalloproteinase -- TJs tight junctions -- TLR4 Toll-like receptor 4 -- TNF tumor necrosis factor; Neurochemistry -- Periodicals; Neurochemistry -- Periodicals; Neurochimie -- Périodiques; Neurochemistry; Periodicals; 612.804205
• DOI: 10.1016/j.neuint.2020.104818
• Languages: English
• ISSNs: 0197-0186

Abstract

Abstract: Although type 2 diabetes is an important predictor of perioperative neurocognitive disorder (PND), little is currently known about its mechanism of action. Adult male db/db and db/m mice were subjected to four different treatments, including either sham or tibial fracture surgery as well as intraperitoneal injection of vehicle or TAK-242 (the selective inhibitor of TLR4) at 1, 24, and 48 h after surgery. The fear conditioning test was performed to detect cognitive impairment on post-operative day (POD) 3. The hippocampus was collected on POD 1 for western-blots and on POD 3 for western-blots, transmission electron microscopy, and electrophysiological experiments. Toll-like receptor 4 (TLR4) inhibition reversed more profound decline in the freezing behavior of db/db mice on POD 3. The surgery reduced the slope of hippocampal field excitatory postsynaptic potentials, and induced blood-brain barrier (BBB) damage in db/db mice on POD 3. The surgery also increased protein levels of TLR4, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, albumin, matrix metalloproteinase (MMP)-2, and MMP-9, and decreased protein levels of claudin-5, occludin, tissue inhibitor of matrix metalloproteinase (TIMP)-1, and TIMP-2 in the hippocampus of db/db and db/m mice. These changes were all reversed by TAK-242 treatment. At last, compared with those in post-operative db/m mice, the surgery increased protein levels of TLR4, TNF-α, and IL-1β, decreased protein levels of claudin-5 and occludin, and sustained the MMP/TIMP imbalance in the hippocampus of db/db mice on POD 3. Our results suggest that TLR4-mediated aggravated hippocampal MMP/TIMP imbalance, BBB disruption, sustained inflammatory cytokine release, and impairment of long-term potentiation play a key role in tibial fracture surgery-induced persistent PND in db/db mice. Highlights: Tibial fracture surgery caused lower FCT results in db/db mice. TLR4 inhibition reversed surgery-induced lower FCT results in db/db mice. TLR4 inhibition reversed surgery-induced impaired hippocampal LTP in db/db mice. TLR4 inhibition reversed surgery-induced hippocampal BBB disruption in db/db mice. TLR4-mediated MMP/TIMP imbalance induced lower FCT results in db/db mice.