Clemastine Ameliorates Perioperative Neurocognitive Disorder in Aged Mice Caused by Anesthesia and Surgery

Abstract

Perioperative neurocognitive disorder (PND) leads to progressive deterioration of cognitive function, especially in aged patients. Demyelination is closely associated with cognitive dysfunction. However, the relationship between PND and demyelination remains unclear. Here we showed that demyelination was related to the pathogenesis of PND. Clemastine, an antihistamine with potency in remyelination, was predicted to have a potential therapeutic effect on PND by next-generation sequencing and bioinformatics in our previous study. In the present study, it was given at 10 mg/kg per day for 2 weeks to evaluate the effects on PND in aged mice. We found that clemastine ameliorated PND and reduced the expression levels of inflammatory factors such as tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β). Further investigation suggested clemastine increased the expression of oligodendrocyte transcription factor 2 (OLIG2) and myelin basic protein (MBP) to enhance remyelination by inhibiting the overactivation of the WNT/β-catenin pathway. At the same time, the expression of post-synaptic density protein 95 (PSD95, or DLG4), brain-derived neurotrophic factor (BDNF), synaptosomal-associated protein 25 (SNAP25) and neuronal nuclei (NEUN) were also improved. Our results suggested that clemastine might be a therapy for PND caused by anesthetic and surgical factors in aged patients.

Keywords: clemastine; neuroinflammation; perioperative neurocognitive disorder; remyelination; synaptic plasticity; wnt/β-catenin signaling.

FIGURE 1

Diagram of timeline of experimental procedures.

FIGURE 2

Anesthesia and surgery-induced cognitive impairments were ameliorated by clemastine treatment. (A) Total distance in the open field test among four groups. (B) Time spent in the center of open field test among four groups. (C) Context test in the fear conditioning test among four groups. (D) Tone test in the fear conditioning test among four groups. (E) Performance during the training phase of the Barnes maze. (F, G) Performance during the testing phase of Barnes maze. (H, I) Representative movement traces on day 1 and day 8 of the Barnes maze test phase. The data are presented as mean ± S.D. (n = 20 mice per group). ^* p < 0.05 compared with the CON group. ***p < 0.005 compared with the CON group. ****p < 0.001 compared with the CON group. ^# p < 0.05 compared with the PND group. ^#### p < 0.001 compared with the PND group. ^∨ p < 0.05 compared with the CON + CLE group. ^∨∨ p < 0.01 compared with the CON + CLE group. ^∨∨∨∨ p < 0.001 compared with the CON + CLE group. ^&&&& p < 0.001 compared with the day 1 in CON group. ^@@@@ p < 0.001 compared with the day 1 in CON + CLE group. ^$ p < 0.05 compared with the first day in PND group. ^{^} p < 0.05 compared with the first day in PND + CLE group.

FIGURE 3

Effects of clemastine on expression levels of inflammatory cytokines in hippocampus of aged mice after anesthesia and surgery. (A) Relative mRNA expressions of TNF-α and IL-1β, normalized to that of the GAPDH internal control. (B) Representative western blot images of TNF-α and IL-1β. (C) Relative protein expressions of TNF-α and IL-1β, normalized to that of the β-tubulin internal control. The data are presented as mean ± S.D. (n = 10 mice per group). ^* p < 0.05 compared with the CON group. ***p < 0.005 compared with the CON group. ****p < 0.001 compared with the CON group. ^# p < 0.05 compared with the PND group. ^### p < 0.005 compared with the PND group. ^#### p < 0.001 compared with the PND group.

FIGURE 4

Effects of clemastine on expression levels of WNT/β-catenin signaling pathway. (A) The differential expression of WNT10B was labeled in our previous sequencing results. (B) Relative mRNA expressions of WNT10B and β-catenin, normalized to that of the GAPDH internal control. (C) Representative western blot images of WNT10B and β-catenin. (D) Relative protein expressions of WNT10B and β-catenin, normalized to that of the β-tubulin internal control. The data are presented as mean ± S.D. (n = 10 mice per group). ***p < 0.005 compared with the CON group. ****p < 0.001 compared with the CON group. ^# p < 0.05 compared with the PND group. ^## p < 0.01 compared with the PND group. ^### p < 0.005 compared with the PND group. ^#### p < 0.001 compared with the PND group.

FIGURE 5

Effects of clemastine on expression levels of OLIG2 and MBP in hippocampus of aged mice after anesthesia and surgery. (A) Relative mRNA expressions of OLIG2 and MBP, normalized to that of the GAPDH internal control. (B) Representative western blot images of OLIG2 and MBP. (C) Relative protein expressions of OLIG2 and MBP, normalized to that of the β-tubulin internal control. The data are presented as mean ± S.D. (n = 10 mice per group). ^* p < 0.05 compared with the CON group. ****p < 0.001 compared with the CON group. ^### p < 0.005 compared with the PND group. ^#### p < 0.001 compared with the PND group.

FIGURE 6

Effects of clemastine on expression levels of synaptic plasticity-related proteins in hippocampus of aged mice after anesthesia and surgery. (A) Co-expression relationship of MBP, PSD95 (or DLG4), BDNF and SNAP25 from the STRING database. (B) Relative mRNA expressions of PSD95, BDNF and SNAP25, normalized to that of the GAPDH internal control. (C) Representative western blot images of synaptic plasticity-related proteins. (D) Relative protein expressions of PSD95, BDNF and SNAP25, normalized to that of the β-tubulin internal control. The data are presented as mean ± S.D. (n = 10 mice per group). ^* p < 0.05 compared with the CON group. **p < 0.01 compared with the CON group. ***p < 0.005 compared with the CON group. ****p < 0.001 compared with the CON group. ^# p < 0.05 compared with the PND group. ^## p < 0.01 compared with the PND group. ^### p < 0.005 compared with the PND group. ^#### p < 0.001 compared with the PND group.

FIGURE 7

Immunofluorescence analysis detected MBP and NEUN protein levels in hippocampal dentate gyrus (scale bar = 50 µm). (A) Representative images of MBP and NEUN in the dentate gyrus. (B) Mean fluorescence density of MBP in the dentate gyrus. (C) Mean fluorescence density of NEUN in the dentate gyrus. The data are presented as mean ± S.D. (n = 10 mice per group). ****p < 0.001 compared with the CON group. ^## p < 0.01 compared with the PND group. ^#### p < 0.001 compared with the PND group.