Objective To observe the protective effect of acupuncture stimulation on pyramidal cells in hippocampal CA 1 and CA 3 regions and to analyze the involvement of phosphatidy linositol-3-kinase(PI 3 K) /protein kinase B(PKB or Akt)signaling pathway in the acupuncture effect in epilepsy rats.Methods A total of 120 SD rats were randomly divided into normal control group

model group

LY 294002(a specific antagonist for PI 3 K/Akt signaling) group

acupuncture+LY 294002 group and acupuncture group(n=24 in each group

12 for H.E.staining

and 12 for electron microscope observation).Epilepsy model was established by intraperitoneal injection of pentylenetetrazol(PTZ

5 μL).Manual acupuncture stimulation was applied to "Baihui"(GV 20) and "Dazhui"(GV 14) once daily for 5 days.Dimethyl Sulfoxide(DMSO

5 μL

a control solvent) was given to rats of the normal

model and acupuncture groups

and LY 294002(5 μL

dissolved in DMSO) given to rats of the LY 294002 and acupuncture+LY 294002 groups by lateral ventricular injection.Four hours and 24 h after modeling

the hippocampus tissues were sampled for observing pathological changes of CA 1 and CA 3 regions after H.E.staining under light microscope and for checking ultrastructural changes of the pyramidal cells under transmission electron microscope.Results In comparison with the normal control group

the numbers of pyramidal cells of hippocampal CA 3 region in the model group were decreased significantly 4 h and 24 h after epileptic seizure(P<0.01).While compared to the model group

the pyramidal cells of hippocampal CA 3 region in the acupuncture group were increased considerably in the number at both 4 h and 24 h after seizure(P<0.01).No significant differences were found between the LY 294002 and model groups

and between the acupuncture+ LY 294002 and model groups in the numbers of pyramidal cells at 4 h and 24 h after seizure(P>0.05).Findings of the light microscope and electron microscope showed that the injury severity of pyramidal cells of hippocampal CA 1 and CA 3 regions was moderate 4 h after epileptic seizure and even worse 24 h after seizure in the model group

LY 294002 group and acupuncture+LY 294002 group

but relatively lighter in the acupuncture group.These results suggested an elimination of the acupuncture effect after blocking the PI 3 K/Akt signaling pathway by lateral ventricular injection of LY 294002 in epilepsy rats.Conclusion Acupuncture intervention has a protective effect on pyramidal cells of hippocampal CA 1 and CA 3 regions in epilepsy rats

which is associated with the normal function of intracellular PI 3 K/Akt signaling pathway.