Objective To observe the effect of moxibustion preconditioning on learning-memory ability

Toll like receptor 4(TLR4)/nuclear factor-kappa B(NF-κB) signal pathway related proteins and microglia in rats with Alzheimer's disease(AD)

so as to explore its possible mechanisms underlying improvement of AD. Methods Male SD rats were randomly divided into normal

sham operation

AD model and pre-moxibustion groups

with 9 rats in each group. Moxibustion was applied to “Baihui”(GV20)

“Shenshu”(BL23) and “Zusanli”(ST36) for 15 min

once daily

6 days as a course of treatment for 3 courses. At the end of moxibustion

the AD model was established by injection of Aβ_(25-35) aggregation solution into the bilateral hippocampus. The sham operation group was only injected with the same amount of 0.9% Nacl solution. The spatial learning-memory ability of rats was detected by Morris water maze test

the ultrastructure of hippocampal neurons was observed by transmission electron microscope(TEM). The histopathological changes of hippocampus tissue were observed by HE staining

and the protein expression levels of TLR4 and NF-κB p65 in the hippocampus detected by Western blot

and the positive expressions of Iba-1

CD80 and CD206 in the hippocampal CA1 region were detected by immunofluorescence labeling. The contents of inflammatory factors IL-1β

TNF-α and IL-10 in the hippocampus were measured by ELISA.Results Compared with the sham operation group

the escape latency was significantly increased(P<0.01)

and the number of platform quadrant crossing times was decreased(P<0.01) in the model group. In comparison with the model group

the increased escape latency and the decreased platform quadrant crossing times were reversed in the pre-moxibustion group(P<0.01). TEM and light microscope observation showed loose arrangement of cells

enlarged cell space

degeneration

swelling and deformation of hippocampal neurons

rupture of membranes of a large number of cells

reduction of mitochondria

dilation of endoplasmic reticulum

and matrix vacuoles

uneven distribution of organelles and cytoplasm

and being difficult in distinguishing the nuclear cytoplasm in the model group

which was relatively milder in the pre-moxibustion group. The expression levels of hippocampal NF-κB p65 and TLR4

the mean immunofluorescence density of Iba-1 and CD80

as well as the contents of IL-1β and TNF-α in hippocampal CA1 region were significantly increased in the model group than those in the sham operation group(P<0.01)

and obviously decreased in the pre-moxibustion group than those in the model group(P<0.05

P<0.01). Whereas the expression of CD206 and the content of IL-10 were evidently decreased in the model group than those in the sham operation group(P<0.01)

and strikingly increased in the pre-moxibustion group than those in the model group(P<0.01). No significant differences were found between the sham operation group and the normal group in all the indexes mention above(P >0.05).Conclusion Pre-moxibustion at GV20

BL23 and ST36 can improve learning-memory ability in AD rats

which may be associated with its functions in promoting the polarization of microglia from M1 to M2 and reducing the neuroinflammatory response by way of TLR4/NF-κB signaling pathway.