[Effect of "Huayu Tongluo" moxibustion on expressions of oligodendrocyte-related proteins and myelin ultrastructure in the corpus callosum in rats with vascular dementia].

Abstract

Objectives: 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.

Methods: 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.

Results: 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).

Conclusions: "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.