OBJECTIVE: To observe the effects of "olfactory three needles" on cognition, learning and memory abilities, as well as hippocampal microglia (MG) phagocytic activity in vascular dementia (VD) rats, and explore the mechanisms of acupuncture in regulating MG activation and improving remyelination, so as to ameliorate VD. METHODS: Among 38 SD rats meeting experimental requirements, 9 rats were randomly assigned to a sham-operation group, and the remaining rats underwent permanent bilateral common carotid artery ligation to establish VD model. Eighteen successfully modeled rats were randomly divided into a model group and an electroacupuncture (EA) group, with 9 rats in each one. In the EA group, EA was performed at "olfactory three needles" ("Yintang" [GV24⁺] and bilateral "Yingxiang" [LI20]), at disperse-dense wave, the frequency of 2 Hz/15 Hz and the current intensity of 1 mA, for 15 min per intervention, once daily. One course was composed of 7 days, and 2 courses were required, with the interval of 2 days. The novel object recognition test was employed to assess the cognition of rats, and the Morris water maze was adopted to observe learning and memory abilities. Luxol fast blue (LFB) staining was performed to evaluate myelin sheath loss in the hippocampus, the Western blot was used to detect the protein expression of triggering receptor expressed on myeloid cells-2 (TREM2) and proteolipid protein (PLP) in the hippocampus; and the immunofluorescence staining was used to detect the positive expression of PLP, sex determining region Y-box 10 (SOX10), ionized calcium binding adaptor molecule 1 (Iba1)⁺ TREM2⁺ and Iba1⁺ lysosome-associated membrane protein 1 (LAMP1)⁺ in the hippocampus. RESULTS: Compared with the sham-operation group, the rats in the model group exhibited the prolonged escape latency on day 3 and 4 (P<0.05, P<0.01), the increase of the total distance traveling (P<0.01) and the decrease of the recognition index (RI) and platform crossing frequency (P<0.01). Compared with the model group, the rats in the EA group showed the shortened escape latency on day 3 and 4 (P<0.05), the decrease of total distance traveling (P<0.01) and the increase of RI and platform crossing frequency (P<0.05, P<0.01). When compared with the sham-operation group, the rats of the model group presented uneven staining, sparse arrangement of myelin sheath fibers, unclear contours, and prominent vacuole-like changes in the hippocampal CA1 region. When compared with the model group, the EA group showed more dense staining, the increase of myelin sheath fibers with more orderly alignment, and fewer vacuolar changes in the hippocampal CA1 region. Compared with the sham-operation group, the model group exhibited the increase of TREM2 protein expression and the decrease of PLP protein expression in the hippocampus (P<0.01), whereas the EA group showed the up-regulation of TREM2 and PLP protein expression when compared with the model group (P<0.01, P<0.05). The positive expression of the hippocampal PLP, SOX10, and Iba1⁺LAMP1⁺ in the model group was reduced in comparison with the sham-operation group (P<0.05, P<0.01), and the positive expression of Iba1⁺ TREM2⁺ was elevated (P<0.05). In the EA group, the positive expression of PLP, SOX10, Iba1⁺TREM2⁺, and Iba1⁺ LAMP1⁺ was higher compared with that in the model group (P<0.05, P<0.01). CONCLUSION "Olfactory three needles" can improve the learning and memory, and cognitive functions of VD rats, and its mechanism may be associated with the up-regulation of TREM2 and LAMP1 to adjust MG phagocytic activity and intracellular degradation, and promote remyelination.
Animals ; Dementia, Vascular/metabolism* ; Rats ; Rats, Sprague-Dawley ; Microglia/metabolism* ; Male ; Acupuncture Therapy/instrumentation* ; Acupuncture Points ; Humans ; Remyelination ; Memory ; Hippocampus/cytology* ; Cognition ; Electroacupuncture ; Needles

Demyelination and remyelination play key roles in spinal cord injury (SCI), affecting the recovery of motor and sensory functions. Research in rodent models is extensive, but the study of these processes in non-human primates is limited. Therefore, our goal was to thoroughly study the histological features of demyelination and remyelination after contusion injury of the cervical spinal cord in Macaca fascicularis. In a previous study, we created an SCI model in M. fascicularis by controlling the contusion displacement. We used Eriochrome Cyanine staining, immunohistochemical analysis, and toluidine blue staining to evaluate demyelination and remyelination. The results showed demyelination ipsilateral to the injury epicenter both rostrally and caudally, the former mainly impacting sensory pathways, while the latter primarily affected motor pathways. Toluidine blue staining showed myelin loss and axonal distension at the injury site. Schwann cell-derived myelin sheaths were only found at the center, while thinner myelin sheaths from oligodendrocytes were seen at the center and surrounding areas. Our study showed that long-lasting demyelination occurs in the spinal cord of M. fascicularis after SCI, with oligodendrocytes and Schwann cells playing a significant role in myelin sheath formation at the injury site.
Animals ; Spinal Cord Injuries/physiopathology* ; Demyelinating Diseases/etiology* ; Remyelination/physiology* ; Macaca fascicularis ; Disease Models, Animal ; Myelin Sheath/pathology* ; Oligodendroglia/pathology* ; Schwann Cells/pathology* ; Female ; Spinal Cord/pathology* ; Axons/pathology*

Multiple sclerosis(MS) shows the pathological characteristics of "inflammatory injury of white matter" and "myelin repair disability" in the central nervous system(CNS). It is very essential for MS treatment and reduction of disease burden to strengthen repair, improve function, and reduce disability. Accordingly, different from the simple immunosuppression, we believe that key to strengthening remyelination and maintaining the "damage-repair" homeostasis of tissue is to change the current one-way immunosuppression strategy and achieve the "moderate pro-inflammation-effective inflammation removal" homeostasis. Traditional Chinese medicine shows huge potential in this strategy. Through literature research, this study summarized the research on remyelination, discussed the "mode-rate pro-inflammation-effective inflammation removal" homeostasis and the "damage-repair" homeostasis based on microglia, and summed up the key links in remyelination in MS. This review is expected to lay a theoretical basis for improving the function of MS patients and guide the application of traditional Chinese medicine.
Humans ; Multiple Sclerosis/pathology* ; Remyelination/physiology* ; Myelin Sheath/pathology* ; Inflammation/drug therapy* ; Homeostasis

Insufficient remyelination due to impaired oligodendrocyte precursor cell (OPC) differentiation and maturation is strongly associated with irreversible white matter injury (WMI) and neurological deficits. We analyzed whole transcriptome expression to elucidate the potential role and underlying mechanism of action of lipocalin-2 (LCN2) in OPC differentiation and WMI and identified the receptor SCL22A17 and downstream transcription factor early growth response protein 1 (EGR1) as the key signals contributing to LCN2-mediated insufficient OPC remyelination. In LCN-knockdown and OPC EGR1 conditional-knockout mice, we discovered enhanced OPC differentiation in developing and injured white matter (WM); consistent with this, the specific inactivation of LCN2/SCl22A17/EGR1 signaling promoted remyelination and neurological recovery in both atypical, acute WMI due to subarachnoid hemorrhage and typical, chronic WMI due to multiple sclerosis. This potentially represents a novel strategy to enhance differentiation and remyelination in patients with white matter injury.
Mice ; Animals ; Remyelination/physiology* ; Oligodendrocyte Precursor Cells/metabolism* ; White Matter ; Subarachnoid Hemorrhage/metabolism* ; Lipocalin-2/metabolism* ; Early Growth Response Protein 1/metabolism* ; Oligodendroglia/metabolism* ; Mice, Knockout ; Cell Differentiation/physiology* ; Brain Injuries/metabolism*

The exacerbation of progressive multiple sclerosis (MS) is closely associated with obstruction of the differentiation of oligodendrocyte progenitor cells (OPCs). To discover novel therapeutic compounds for enhancing remyelination by endogenous OPCs, we screened for myelin basic protein expression using cultured rat OPCs and a library of small-molecule compounds. One of the most effective drugs was pinocembrin, which remarkably promoted OPC differentiation and maturation without affecting cell proliferation and survival. Based on these in vitro effects, we further assessed the therapeutic effects of pinocembrin in animal models of demyelinating diseases. We demonstrated that pinocembrin significantly ameliorated the progression of experimental autoimmune encephalomyelitis (EAE) and enhanced the repair of demyelination in lysolectin-induced lesions. Further studies indicated that pinocembrin increased the phosphorylation level of mammalian target of rapamycin (mTOR). Taken together, our results demonstrated that pinocembrin promotes OPC differentiation and remyelination through the phosphorylated mTOR pathway, and suggest a novel therapeutic prospect for this natural flavonoid product in treating demyelinating diseases.
Animals ; Cell Differentiation ; Flavanones ; Mice ; Mice, Inbred C57BL ; Myelin Sheath/metabolism* ; Oligodendroglia/metabolism* ; Rats ; Remyelination ; Signal Transduction ; TOR Serine-Threonine Kinases/metabolism*

The obstacle to successful remyelination in demyelinating diseases, such as multiple sclerosis, mainly lies in the inability of oligodendrocyte precursor cells (OPCs) to differentiate, since OPCs and oligodendrocyte-lineage cells that are unable to fully differentiate are found in the areas of demyelination. Thus, promoting the differentiation of OPCs is vital for the treatment of demyelinating diseases. Shikimic acid (SA) is mainly derived from star anise, and is reported to have anti-influenza, anti-oxidation, and anti-tumor effects. In the present study, we found that SA significantly promoted the differentiation of cultured rat OPCs without affecting their proliferation and apoptosis. In mice, SA exerted therapeutic effects on experimental autoimmune encephalomyelitis (EAE), such as alleviating clinical EAE scores, inhibiting inflammation, and reducing demyelination in the CNS. SA also promoted the differentiation of OPCs as well as their remyelination after lysolecithin-induced demyelination. Furthermore, we showed that the promotion effect of SA on OPC differentiation was associated with the up-regulation of phosphorylated mTOR. Taken together, our results demonstrated that SA could act as a potential drug candidate for the treatment of demyelinating diseases.
Animals ; Apoptosis ; drug effects ; Cell Differentiation ; drug effects ; Cell Proliferation ; drug effects ; Cells, Cultured ; Demyelinating Diseases ; prevention & control ; Encephalitis ; prevention & control ; Encephalomyelitis, Autoimmune, Experimental ; prevention & control ; Female ; Mice, Inbred C57BL ; Myelin Basic Protein ; metabolism ; Neuroprotective Agents ; administration & dosage ; Oligodendrocyte Precursor Cells ; drug effects ; metabolism ; Rats ; Remyelination ; drug effects ; Shikimic Acid ; administration & dosage ; TOR Serine-Threonine Kinases ; metabolism

The differentiation and maturation of oligodendrocyte precursor cells (OPCs) is essential for myelination and remyelination in the CNS. The failure of OPCs to achieve terminal differentiation in demyelinating lesions often results in unsuccessful remyelination in a variety of human demyelinating diseases. However, the molecular mechanisms controlling OPC differentiation under pathological conditions remain largely unknown. Myt1L (myelin transcription factor 1-like), mainly expressed in neurons, has been associated with intellectual disability, schizophrenia, and depression. In the present study, we found that Myt1L was expressed in oligodendrocyte lineage cells during myelination and remyelination. The expression level of Myt1L in neuron/glia antigen 2-positive (NG2) OPCs was significantly higher than that in mature CC1 oligodendrocytes. In primary cultured OPCs, overexpression of Myt1L promoted, while knockdown inhibited OPC differentiation. Moreover, Myt1L was potently involved in promoting remyelination after lysolecithin-induced demyelination in vivo. ChIP assays showed that Myt1L bound to the promoter of Olig1 and transcriptionally regulated Olig1 expression. Taken together, our findings demonstrate that Myt1L is an essential regulator of OPC differentiation, thereby supporting Myt1L as a potential therapeutic target for demyelinating diseases.
Animals ; Cell Differentiation ; physiology ; Demyelinating Diseases ; chemically induced ; Lysophosphatidylcholines ; toxicity ; Mice ; Mice, Inbred C57BL ; Nerve Tissue Proteins ; metabolism ; Oligodendrocyte Precursor Cells ; cytology ; metabolism ; Oligodendroglia ; cytology ; metabolism ; Remyelination ; physiology ; Transcription Factors ; metabolism