Effect of "Huayu Tongluo" moxibustion on expressions of oligodendrocyte-related proteins and myelin ultrastructure in the corpus callosum in rats with vascular dementia
To observe the effect of "Huayu Tongluo"(blood stasis-removing and meridian-collateral dredging) moxibustion on oligodendrocyte-related protein expression and myelin ultrastructure in the corpus callosum tissue of rats with vascular dementia (VD), so as to explore its mechanism underlying improvement of VD. Male SD rats were randomly divided into model group, "Huayu Tongluo" moxibustion group and non-acupoint moxibustion group, with 42 rats in each group. According to the treatment time, the rats were further divided into 1 course (7 d) group (n=12), 2 courses (14 d) group (n=12) and 4 courses (28 d) group (n=18), and the other 18 rats were used as the sham operation group. The VD model was established by using modified 2-vessel occlusion (VO) method. The rats in the "Huayu Tongluo" moxibustion group were treated with suspended moxibustion of "Baihui"(GV20), "Dazhui"(GV14) and "Shenting"(GV24) for 20 min, once a day for 7 d, 14 d or 28 d, respectively. The rats of the non-acupoint moxibustion group were treated with suspended moxibustion at the three locations 2, 3 and 5 cm away from the tail, and the course of treatment was the same as that of "Huayu Tongluo" moxibustion group. Morris water maze test was used to assess the rats' learning-memory ability. A transmission electron microscopy was used to observe the ultrastructure of myelin sheath and the number of myelinated nerve axons, and to calculate the g-ratio (axon diameter/(axon diameter + myelin sheath thickness)) of the myelin sheath thickness. Western blot and immunofluorescence staining were used to separately detect the expressions and fluorescence intensities of oligodendrocyte markers 2', 3'-cyclic nucleotide-3'-phosphodiesterase (CNPase), oligodendrocyte transcription factor 2 (Olig2) and myelin oligodendrocyte glycoprotein (MOG) in the corpus callosum of each group. Compared with the sham operation group, the model group showed prolonged escape latency (P<0.01) and reduced number of platform quadrant crossings (P<0.01) in the 1, 2 and 4 courses of treatment, significantly decreased number of myelinated nerve axons in the corpus callosum (P<0.01), increased g-ratio value of axonal myelin (P<0.01), and decreased relative fluorescence intensities and expression levels of CNPase, Olig2, and MOG proteins in the 1, 2 and 4 courses of intervention (P<0.01). Compared with the model group, the "Huayu Tongluo" moxibustion group showed shortened escape latency (P<0.01) and increased number of platform quadrant crossing after 2 and 4 courses of intervention (P<0.01), significantly increased number of myelinated nerve axons (P<0.01), decreased g-ratio value of axonal myelin, and significantly elevated relative fluorescence intensities and protein expression levels of CNPase, Olig2, and MOG in all the different courses of intervention (P<0.01, P<0.05);and the non-acupoint moxibustion group had an increase in the immunofluorescence intensities of CNPase and MOG, and the expression of CNPase protein in the 4 courses of intervention (P<0.05). Comparison between the two treatment groups showed that the effect of "Huayu Tongluo" moxibustion was significantly superior to that of non-acupoint moxibustion in lowering the g-ratio of axonal myelin (P<0.05), and in up-regulating the number of myelinated nerve axons, and the immunofluorescence intensities and protein expressions of CNPase, Olig2 and MOG in the 3 different courses of intervention (P<0.01, P<0.05). "Huayu Tongluo" moxibustion can improve the learning-memory ability of VD rats, which may be related to its functions in promoting the proliferation and differentiation of oligodendrocyte precursor cells into mature oligodendrocytes, and up-regulating the protein expressions of CNPase, Olig2 and MOG in the corpus callosum. The therapeutic effect was the best in the 4 courses of intervention.
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