Rehabilitation training inhibits neuronal apoptosis by down-regulation of TLR4/MyD88 signaling pathway in mice with cerebral ischemic stroke

Abstract

Objective: To investigate the role of rehabilitation training and TLR4/MyD88 signaling pathway on neuronal apoptosis in mice with cerebral ischemic stroke.

Methods: Mice were randomized into six groups, which were normal group (healthy mice, n=20), control group (sham surgery, n=20), model group (middle cerebral artery occlusion (MCAO) model, n=20), training (MCAO model, continuous rehabilitation training for 4 weeks, n=20), TAK-242 group (MCAO model, TL R4 inhibitor TAK-242, n=20), and TAK-242 + Training group (MCAO model, TLR4 inhibitor TAK-242 + rehabilitation training, n=20).

Results: Neurobehavioral assessment was performed, and cerebral infarction area of mice was detected by triphenyl tetrazolium chloride staining. Compared with the normal group, no significant differences in all indicators were found in the control group (all P>0.05), while the other groups had higher neurological function scores, cerebral infarction area, neuronal apoptosis rate, increased expressions of TLR4, MyD88, Bax, NF-κB, TNF-α, Caspase-3, IL-1βA and decreased mRNA and protein expressions of Bcl-2 (all P<0.05).

Conclusion: Rehabilitation training can effectively reduce the apoptosis of hippocampal neurons in mice with ischemic stroke by inhibiting the TLR4/MyD88 signaling pathway.

Keywords: TLR4/MyD88 signaling pathway; apoptosis; hippocampal neuron; ischemic stroke; rehabilitation training.

Figure 1

Neurobehavioral assessment outcome. Compared with the normal group, ^*P<0.05; compared with the control group, ^#P<0.05; compared with the model group, ^&P<0.05; compared with the TAK-242 group, ^$P<0.05; compared with the Training group, ^@P<0.05.

Figure 2

Cerebral infarction area in each group. A: TTC-stained sections; B: Cerebral infarction area. Compared with the normal group, ^*P<0.05; compared with the control group, ^#P<0.05; compared with the model group, ^&P<0.05; compared with the TAK-242 group, ^$P<0.05; compared with the Training group, ^@P<0.05.

Figure 3

Expressions of TLR4, MyD88, NF-κB, TNF-α and IL-1β mRNAs in the TLR4/MyD88 signaling pathway detected by qRT-PCR. Compared with the normal group, ^*P<0.05; compared with the control group, ^#P<0.05; compared with the model group, ^&P<0.05; compared with the TAK-242 group, ^$P<0.05; compared with the Training group, ^@P<0.05. TLR: toll-like receptor.

Figure 4

Protein expressions of TLR4, MyD88, NF-κB, TNF-α, and IL-1β in TLR4/MyD88 signaling pathway detected by Western blot. A: Protein bands; B: Protein expressions. Compared with the normal group, ^*P<0.05; compared with the control group, ^#P<0.05; compared with the model group, ^&P<0.05; compared with the TAK-242 group, ^$P<0.05; compared with the Training group, ^@P<0.05. TLR, toll-like receptor.

Figure 5

Hippocampal neuronal apoptosis detected by flow cytometry. A: Flow cytometry image; B: Hippocampal neuronal apoptosis rate. Compared with the normal group, ^*P<0.05; compared with the control group, ^#P<0.05; compared with the model group, ^&P<0.05; compared with the TAK-242 group, ^$P<0.05; compared with the Training group, ^@P<0.05.

Figure 6

Expressions of Bcl-2, Bax, and Caspase-3 mRNAs detected by qRT-PCR. Compared with the normal group, ^*P<0.05; compared with the control group, ^#P<0.05; compared with the model group, ^&P<0.05; compared with the TAK-242 group, ^$P<0.05; compared with the Training group, ^@P<0.05.

Figure 7

Protein expressions of Bcl-2, Bax, and Caspase-3 detected by Western blot. A: Protein bands; B: Protein expressions. Compared with the normal group, ^*P<0.05; compared with the control group, ^#P<0.05; compared with the model group, ^&P<0.05; compared with the TAK-242 group, ^$P<0.05; compared with the Training group, ^@P<0.05.