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MiR-199a modulates autophagy and inflammation in rats with cerebral infarction via regulating mTOR expression
1Department of Internal Medicine, Wuhan Hospital of Traditional Chinese Medicine, Wuhan, China. 349033774@qq.com.
Objective:
The aim of this study was to investigate the roles of micro ribonucleic acid (miR)-199a in rats with cerebral infarction by regulating mammalian target of rapamycin (mTOR).
Materials And Methods:
A total of 36 Sprague-Dawley rats were randomly assigned into three groups, including: sham group (n=12), model group (n=12) and miR-199a mimics group (n=12). In sham group internal and external carotid arteries were exposed. The ischemia-reperfusion model was successfully established using suture embolization in the other two groups. After modeling, rats in sham group and model group were intraperitoneally injected with normal saline. However, rats in miR-199a mimics group were injected with miR-199a mimics. Following intervention for 3 d, sampling was conducted. Neurological deficit was evaluated in rats based on the Zea-Longa scoring system. Hematoxylin-eosin (HE) staining was performed to observe neuronal morphology. The expression of mTOR was detected using immunohistochemistry, and the relative expression level of tau protein was determined via Western blotting (WB). Besides, the messenger RNA (mRNA) expressions of mTOR and tau were detected by quantitative Polymerase Chain Reaction (qPCR). Finally, inflammatory factor content was measured through enzyme-linked immunosorbent assay (ELISA).
Results:
Model group and miR-199a mimics group exhibited a substantially higher Zea-Longa score than sham group (p<0.05). Compared with model group, the Zea-Longa score rose prominently in miR-199a mimics group (p<0.05). According to the results of HE staining, the structure of neurons in sham group was clear and intact, while the structure of neurons in model group was disordered. Meanwhile, neuronal morphology in miR-199a mimics group was significantly worse than that in model group (p<0.05). Immunohistochemistry results demonstrated that the positive expression level of mTOR was considerably upregulated in both model group and miR-199a mimics group in comparison with sham group (p<0.05). Moreover, its positive expression level in miR-199a mimics group was markedly higher that in model group (p<0.05). Based on the results of WB, model and miR-199a mimics groups exhibited a remarkably higher relative expression level of tau protein than sham group (p<0.05). However, the relative expression level of tau protein in miR-199a mimics group was prominently higher than that in model group (p<0.05). QPCR results manifested that the relative mRNA expression levels of mTOR and tau in model group and miR-199a mimics group were dramatically higher than those in sham group (p<0.05). Compared with those in model group, the relative mRNA expression levels of mTOR and tau increased significantly in miR-199a mimics group (p<0.05). ELISA results revealed that model group and miR-199a mimics group had prominently higher content of inflammatory factors than sham group (p<0.05). In addition, content of inflammatory factors in miR-199a mimics group was considerably higher than that in model group (p<0.05).
Conclusions:
MiR-199a modulates mTOR expression to exert important regulatory effects on the autophagy and inflammation in rats with cerebral infarction.
Insights
Micro ribonucleic acid (miR)-199a exacerbates cerebral infarction in rats by upregulating mammalian target of rapamycin (mTOR) and increasing inflammation. This suggests miR-199a may be a therapeutic target for stroke treatment.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Cerebral infarction, a major cause of disability, involves complex molecular mechanisms.
- Micro ribonucleic acid (miR)-199a and mammalian target of rapamycin (mTOR) signaling are implicated in various cellular processes relevant to brain injury.
Purpose of the Study:
- To investigate the role of miR-199a in a rat model of cerebral infarction.
- To explore the regulatory relationship between miR-199a and mTOR in this context.
Main Methods:
- Establishment of a cerebral infarction model in Sprague-Dawley rats.
- Administration of miR-199a mimics to assess its effects.
- Evaluation of neurological deficits, neuronal morphology, and expression of mTOR and tau protein.
- Measurement of inflammatory factors using techniques including HE staining, immunohistochemistry, Western blotting, qPCR, and ELISA.
Main Results:
- miR-199a mimics significantly worsened neurological deficits and neuronal damage compared to the model group.
- Upregulation of mTOR and tau protein expression was observed in both model and miR-199a mimics groups, with further increases in the mimics group.
- Elevated levels of inflammatory factors were detected in both model and miR-199a mimics groups, with a more pronounced increase in the mimics group.
Conclusions:
- miR-199a plays a detrimental role in cerebral infarction by modulating mTOR expression.
- The findings suggest miR-199a influences autophagy and inflammation, contributing to the severity of cerebral infarction.
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