Objective

2

To explore the mechanism of electroacupuncture (EA) at ＂Fengchi＂ (GB 20) and ＂Sishencong＂ (EX-HN 1) on learning and memory impairment in vascular dementia (VD) rats by observing the influences on the N-methyl-D-aspartate receptor (NMDAR)/cyclic adenosine monophosphate response element-binding protein (CREB)/brain-derived neurotrophic factor (BDNF) signaling pathway and the excitotoxicity induced by hippocampal calciumoverload.

Methods

2

Thirty-two male SD rats of SPF grade were selected and randomized into a normal group (6 rats)

a sham-operation group (6 rats) and an operation group (20 rats). VD model was established with the modified Pulsinelli's four-vessel occlusion (4-VO) method. Twelve rats after successfully modeled were assigned randomly into a model group and an EA group

6 rats in each one. In the EA group

EA was delivered at bilateral ＂Fengchi＂ (GB 20) and ＂Sishencong＂ (EX-HN 1)

with the continuous wave

the frequency of 2 Hz and the electric current of 1 mA. Stimulation intensity was adjusted depending on the slightly trembling of rat head. EA was given once daily

30 min each time; and EA intervention was delivered for 21 days continuously. Using Morris water maze test

the learning and memory function was assessed. The neuronal morphology in the hippocampal CA1 was observed with HE staini

ng; the level of glutamate (GLU) in serum and hippocampal tissue

as well as the activity of calcium pump (Ca

2+

-ATP) in the hippocampus were detected using colorimetric method. The protein expression of NMDAR

calmodulin-dependent protein kinase Ⅱ (CaMKⅡ)

phosphorylated calmodulin-dependent protein kinase Ⅱ (p-CaMKⅡ)

phosphorylated cyclic phosphoradenosine effector element binding proteins (p-CREB)

CREB

and BDNF in the hippocampal CA1 was detected using immunohistochemistry. The protein expression of NMDAR

CREB

p-CREB and BDNF in the hippocampal tissue was detected using Western blot method.

Results

2

Compared to the sham-operation group

in the model group

the escape latency was prolonged and the platform crossing times of rats were reduced (

P

<

0.01)

the hippocampal neuron structure was damaged to different degrees

the structure in hippocampal CA1 was loosened

the arrangement disorganized

with clear grid-like structure; the neuronal morphology was irregular

pyknosis and even dissolution occurred

glial cells increased

blood capillary was dilated and the inflammatory cells were infiltrated and scattered. The level of GLU in the serum and hippocampal tissue and the protein expression of hippocampal NMDAR were elevated (

P

<

0.01)

the activity of Ca

2+

-ATP and the protein expression of CaMKⅡ

p-CaMKⅡ

CREB

p-CREB and BDNF were reduced (

P

<

0.01

P

<

0.05); and the ratio of p-CaMKⅡ/CaMKⅡ and that of p-CREB/CREB were dropped (

P

<

0.05). In comparison with the model group

in the EA group

the escape latency was shortened and the platform crossing times of rats rose (

P

<

0.01)

the arrangement was improved in the hippocampal CA1

the neuronal morphology was intact

the nucleoli were clear relatively and the pyknosis or dissolution were attenuated

the numbers of glial cells reduced relatively

the dilation of blood capillary was alleviated. The lev

el of GLU in the serum and hippocampal tissue and the protein expression of NMDAR were reduced in the hippocampal tissue (

P

<

0.01)

the activity of Ca

2+

-ATP and the protein expression of CaMKⅡ

p-CaMKⅡ

CREB

p-CREB and BDNF were elevated (

P

<

0.05

P

<

0.01); and the ratio of p-CaMKⅡ/CaMKⅡ and that of p-CREB/CREB increased (

P

<

0.05).

Conclusion

2

EA at ＂Fengchi＂ (GB 20) and ＂Sishencong＂ (EX-HN 1) can attenuate learning and memory impairment in VD rats

which may be obtained by reducing GLU level in hippocampal tissue

inhibiting hippocampal excitotoxicity

mediating protein expression related to the NMDAR/CREB/BDNF signaling pathway

and maintaining neuronal survival and growth.