Decreased spasticity of Baishaoluoshi Decoction through the BDNF/TrKB-KCC2 pathway on poststroke spasticity rats

Current evidence of synaptic dysfunction after stroke: Cellular and molecular mechanisms

BACKGROUND

Stroke is an acute cerebrovascular disease in which brain tissue is damaged due to sudden obstruction of blood flow to the brain or the rupture of blood vessels in the brain, which can prompt ischemic or hemorrhagic stroke. After stroke onset, ischemia, hypoxia, infiltration of blood components into the brain parenchyma, and lysed cell fragments, among other factors, invariably increase blood-brain barrier (BBB) permeability, the inflammatory response, and brain edema. These changes lead to neuronal cell death and synaptic dysfunction, the latter of which poses a significant challenge to stroke treatment.

RESULTS

Synaptic dysfunction occurs in various ways after stroke and includes the following: damage to neuronal structures, accumulation of pathologic proteins in the cell body, decreased fluidity and release of synaptic vesicles, disruption of mitochondrial transport in synapses, activation of synaptic phagocytosis by microglia/macrophages and astrocytes, and a reduction in synapse formation.

CONCLUSIONS

This review summarizes the cellular and molecular mechanisms related to synapses and the protective effects of drugs or compounds and rehabilitation therapy on synapses in stroke according to recent research. Such an exploration will help to elucidate the relationship between stroke and synaptic damage and provide new insights into protecting synapses and restoring neurologic function.

Mechanical and signaling responses of unloaded rat soleus muscle to chronically elevated β-myosin activity

It has been reported that muscle functional unloading is accompanied by an increase in motoneuronal excitability despite the elimination of afferent input. Thus, we hypothesized that pharmacological potentiation of spontaneous contractile soleus muscle activity during hindlimb unloading could activate anabolic signaling pathways and prevent the loss of muscle mass and strength. To investigate these aspects and underlying molecular mechanisms, we used β-myosin allosteric effector Omecamtiv Mekarbil (OM). We found that OM partially prevented the loss of isometric strength and intrinsic stiffness of the soleus muscle after two weeks of disuse. Notably, OM was able to attenuate the unloading-induced decrease in the rate of muscle protein synthesis (MPS). At the same time, the use of drug neither prevented the reduction in the markers of translational capacity (18S and 28S rRNA) nor activation of the ubiquitin-proteosomal system, which is evidenced by a decrease in the cross-sectional area of fast and slow muscle fibers. These results suggest that chemically-induced increase in low-intensity spontaneous contractions of the soleus muscle during functional unloading creates prerequisites for protein synthesis. At the same time, it should be assumed that the use of OM is advisable with pharmacological drugs that inhibit the expression of ubiquitin ligases.

Upregulation of MiRNA-149-5p Reduces the Infract Volume in Middle Cerebral Artery Occlusion Rats by Modulating Cation-Chloride Cotransporters Expressions

Background

Brain ischemia often leads to the chloride gradient alternations, which affects volume regulation and neuronal survival. Increase in NKCC1 expression and reduction in KCC2 level under ischemic condition results in inflammation and neuronal death. In this study, we investigated the effect of mimic miRNA and coenzyme Q10 (CoQ10) on the expression of cation-chloride cotransporters (CCCs) (NKCC1 and KCC2) after cerebral ischemia.

Methods

In this study, cerebral ischemia was modeled using the middle cerebral artery occlusion method. Rats were randomly divided into six groups: sham, model, negative control, vehicle, and the first and second treatments. In the Sham group, ischemia was not induced, and no treatment was performed. In the Model group, ischemia induction was performed, and other groups, in addition to ischemia induction, received Scramble miRNA, Ethanol, mimic miRNA-149-5p and CoQ10, respectively. Each group was divided into three subgroups to assess the volume of the tissue damage and neurological deficits scores (NDS) in subgroup 1, brain water content in subgroup 2, level of miRNA-149-5p and CCC expressions in subgroup 3.

Results

Our data suggested that the use of mimic miRNA and Q10 increased the level of miRNA-149 and KCC2 expression and decreased NDS, NKCC1 expression, brain water content, and infract volume.

Conclusion

Findings of this study suggest that the mimic miRNA and Q10 may have neuroprotective effects through reducing infract volume and brain water content and modulating the expression of CCCs after brain ischemia.

microRNA-148a in Exosomes Derived from Bone Marrow Mesenchymal Stem Cells Alleviates Cardiomyocyte Apoptosis in Atrial Fibrillation by Inhibiting SMOC2

Exosomes-related microRNAs (miRNAs) have been considered to be the significant biomarkers contributing to the development of atrial fibrillation (AF). We observed the implicit mechanism of exosomes-miR-148a derived from bone marrow mesenchymal stem cells (BMSCs) in AF. The AF cell and mice models were established firstly. QRT-PCR and Western blot analysis were applied to detect the expression of miR-148a, SPARC-associated modular calcium-binding protein 2 (SMOC2), Bcl-2, Bax, and caspase-3. BMSCs were separated from healthy mice and exosomes were obtained from BMSCs. BMSCs were transfected with mimics and inhibitor, and HL-1 cells were treated with mimics and pcDNA3.1. MTT assay were used to detect cell viability of cells. Flow cytometric analysis and TUNEL analysis were used for detecting cell apoptosis of cells. In our study, exosomes derived from BMSCs inhibited the development of AF, and miR-148a acted a vital role in this segment. SMOC2 was a target gene of miR-148a and promoted apoptosis of HL-1 cells. Additionally, miR-148a mimics decreased cellular apoptosis, eliminated SMOC2 expression, and elevated Bcl-2 expression in AF-treated cells. Collectively, miR-148a overexpressed in BMSC-exosomes restrained cardiomyocytes apoptosis by inhibiting SMOC2.