Effect of moxibustion on learning-memory ability and expression of hippocampal inflammatory factors and microtubule associated proteins in vascular dementia rats

Abstract

To observe the effect of moxibustion on learning-memory ability and expression of hippocampal inflammatory factors and microtubule-associated protein doublecortin (DCX, a marker of neuronal regeneration) in vascular dementia (VD) rats, so as to explore its mechanisms underlying improvement of VD. SD rats were randomly divided into normal control, sham operation, VD model, moxibustion and medication groups (n=15 rats in each group). The VD model was established by repeated occlusion of the bilateral common carotid arteries and reperfusion. Moxibustion was applied to "Guanyuan" (CV4), "Mingmen" (GV4) and "Dazhui"(GV14) for 15 min, once a day, 6 days a week for 4 weeks. Rats of the medication group were treated by gavage of Nimodipine (2mg·kg-1·d-1) 3 times daily for 4 weeks. Morris water maze test was used to detect the average escape latency of location navigation tasks for assessing the rats' learning-memory ability. H.E. staining was used to detect histopathological changes of the hippocampus tissue. The number of DCX-positive neurons (DCX/NeuN co-expression) in the dentate gyrus (DG) region of hippocampus was counted under microscope after immunofluorescence double staining, the immunoactivity of hippocampal DCX detected by using immunohistochemistry stain and the expression of DCX, TNF-α, IL-1β, MPO, NF-κB p65 and IL-6 proteins in the hippocampus tissue detected using Western blot. Following modeling, the average escape latency was significantly longer in the model group than in the normal control and sham operation groups (P<0.01), and notably shorter in both the moxibustion and medication groups than in the model group after the treatment (P<0.01, P<0.05). The number of DCX-positive neurons, and the expression levels of DCX, TNF-α, IL-1β, MPO, NF-κB p65 and IL-6 proteins in the hippocampus were significantly increased in the model group in comparison with the normal control and sham operation groups (P<0.01, P<0.05). After the interventions and in comparison with the model group, the number of DCX-positive neurons and the expression level of DCX were further up-regulated in both moxibustion and medication groups (P<0.01), while the expression levels of hippocampal TNF-α, IL-1β, MPO, NF-κB p65 and IL-6 proteins were considerably down-regulated in the moxibustion and medication groups (P<0.01). The effect of moxibustion was weaker than that of medication in down-regulating the expression of TNF-α,MPO, NF-κB p65, IL-6 and IL-1β, and in up-regulating DCX-positive neuron number and DCX expression (P<0.05, P<0.01). H.E. staining showed loose arrangement of neurons (with vague neuronal membrane in some cells), uneven organelle chromatin, disappearance of partial nucleolus, necrocytosis, and infiltration of small number of lymphocytes after modeling, which was relatively milder in both moxibustion and medication groups. Moxibustion can improve learning-memory ability in VD rats, which may be related to its effect in down-regulating the expression of inflammatory factors and up-regulating the expression of DCX to promote neuronal repair and regeneration.