"Huayu Tongluo" moxibustion improves learning-memory ability and promotes myelin regeneration by regulating Sonic Hedgehog signaling pathway in vascular dementia rats

Abstract

To investigate the effect of "Huayu Tongluo" (resolving blood stagnation to dredge meridian-collaterals) moxibustion on remyelination and Sonic Hedgehog (Shh) signaling pathway in the corpus callosum of vascular dementia (VD) rats, so as to explore its mechanisms underlying improvement of VD. Male Wistar rats were randomized into sham-operation, model, medication and moxibustion groups, with 12 rats in each group.The VD model was established by bilateral common carotid artery occlusion. Moxibustion was applied to "Shenting"(GV24), "Baihui"(GV20) and "Dazhui"(GV14) for 20 min once a day, 7 d as a treatment course, for 3 courses, with one day's rest between every two courses. Rats of the medication group were treated by gavage of 10 mg/kg of chloromastine solution once a day, and the course of treatment was the same as that of the moxibustion group. The rat's learning-memory ability was assessed by Morris water maze test (escape latency). The neurological deficits were evaluated by using Longa's scale.The mRNA and protein expressions of Shh and Gli1 in the corpus callosum were measured by quantitative real-time fluorescence PCR and Western blot, separately. The ultrastructure of the myelin sheath and myelinated axons was observed under transmission electron microscopy (TCM). Compared with the sham-operation group, the neurologic score and escape latency were significantly increased and prolonged (P<0.01), and the mRNA and protein expression levels of Shh and Gli1 and the number of myelinated axons were obviously decreased in the model group (P<0.01). In comparison with the model group, the escape latency was apparently shortened (P<0.05), while the mRNA and protein expression levels of Shh and Gli1 as well as the number of myelinated axons were strikingly increased in both moxibustion and medication groups (P<0.01). Results of TCM showed that in the model group, the arrangement of myelin coil structures was sparse and fuzzy, and some structures were bulged and disbanded. The oligodendrocytes were irregular, and the number of myelin sheath was rare. These situations were relatively milder in both moxibustion and medication groups. "Huayu Tongluo" moxibustion can promote the differentiation and maturation of oligodendrocyte precursor cells after cerebral ischemia by regulating the expressions of Shh and Gli1 in Shh signaling pathway, thus promoting the regeneration of cerebral white matter myelin sheaths in VD rats, which may contribute to improving learning-memory ability.