Objective To observe the effect of acupuncture on activities of microglia in traumatic brain injury(TBI)rats.Methods Fifty-four male SD rats were randomly and equally divided into normal control

model and acupuncture groups according to the random number table(n=18 rats in each group).The TBI model was established by using a free fall brain injury striking device after exposing the local cranial bone(to induce the left parietal cerebral contusion).Acupoints"Baihui"(GV20)

"Shuigou"(GV26)

"Fengfu"(GV16)

"Yamen"(GV15)and bilateral"Hegu"(LII4)were stimulated intensively by twirling the filiform needles with force at a range of>360°and a frequency of 160-180 cycles/min for 10 sec in every acupoint

once every5 min during the 15 minutes' needle retaining.The treatment was given once every day for successive 14 days.The rats of the normal and model groups were grabbed and fixed with the same procedure.The behavioral changes were tested using modified neurological severity score(mNSS).The histopathological changes of the injured cerebral cortex tissues were observed by using hematoxylin-eosin(H.E.)staining

and the fluorescence intensity of Iba-1(marker of microglia)positive products in the surrounding tissue of the cerebral focus was displayed by immunofluorescence staining

and the contents of neuron specific enolate(NSE)and neurite outgrowth inhibitor-A(Nogo-A)in serum(indicating a secondary nerve damage)were assayed by ELISA.Results The mNSS scores were significantly increased on day 1

3

7 and 14 in the model group in comparison with the normal group(P<0.01)and considerably decreased at the 4 time-points after acupuncture intervention relevant to the model group(P<0.05

P<0.01).H.E.staining showed that modeling induced pathological changes such as the excursion of cell nucleus

cellular swelling

vacuole-like change

neuron death

karyopyknosis dissolution

and proliferation of fibrous tissue were relatively milder in the acupuncture group.The average fluorescence intensity values of Iba-1-positive products

serum NSE and Nogo-A contents on day3

7 and 14 were significantly higher in the model group than in the normal group(P<0.05

P<0.01)

and notably down-regulated in the acupuncture group than in the model group(P<0.05

P<0.01

except Nogo-A on day 3).Conclusion Acupuncture intervention may accelerate neurological function recovery in TBI rats

which is closely related to its effects in inhibiting the activation of microglia and secondary nerve damage.