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 microL). Manual acupuncture stimulation was applied to "Baihui" (GV 20) and "Dazhui" (GV 14) once daily for 5 days. Dimethyl Sulfoxide (DMSO, 5 microL, a control solvent) was given to rats of the normal, model and acupuncture groups, and LY294002 (5 microL, 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 checkin 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.