Neuroprotective effects of electroacupuncture on hypoxic-ischemic encephalopathy in newborn rats are associated with increased expression of GDNF-RET and protein kinase B.

OBJECTIVE: To explore the neuroprotective effects of electroacupuncture (EA) on hypoxic-ischemic encephalopathy (HIE) and to further investigate the role of glial cell line-derived neurotrophic factor (GDNF) family receptor member RET (rearranged during transfection) and its key downstream phosphatidylinositol 3 kinase (PI-3K)/protein kinase B (Akt) pathway in the process. METHODS: A total of 220 seven-day-old SD rats (of either sex, from 22 broods) were randomly divided into two groups, one (30 rats) for sham-surgery group and the other (190 rats) for HIE model group. The HIE model was established using the left common carotid artery ligation method in combination with hypoxic treatment. The successfully established rats were randomly divided into five groups, including control model group, EA group, sham-EA group, antagonist group and antagonist plus electroacupuncture group, with 35 rats in each group. Baihui (GV 20), Dazhui (GV 14), Quchi (LI 11) and Yongquan (KI 1) acupoints were chosen for acupuncture. EA was performed at Baihui and Quchi for 10 min once a day for continuous 1, 3, 7 and 21 days, respectively. The rats were then killed after the operation and injured cerebral cortex was taken for the measurement of neurologic damage by hematoxylin-eosin (HE) staining and the degenerative changes of cortical ultrastructure by transmission electron microscopy. RET mRNA level and Akt protein level were detected by real-time reverse-transcription polymerase chain reaction (RT-PCR) and western blot analysis, respectively. RESULTS: EA could ameliorate neurologic damage of the first somatic sensory area (S1Tr) and alleviate the degenerative changes of ultrastructure of cortical neurons in rats subjected to HIE. And the longer acupuncture treatment lasted, the better its therapeutic effect would be. This was accompanied by gradually increased expression of GDNF family receptor RET at the mRNA level and its downstream signaling Akt at the protein level in the ischemic cortex. CONCLUSION: EA has neuroprotective effects on HIE and could be a potential therapeutic strategy for HIE in the neonate. Activation of RET/Akt signaling pathway might be involved in this process.

[Effect of electroacupuncture on expression of signal transducer and activator of transcription 3 in focal ischemic cerebral tissue in cerebral ischemia rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) intervention on expression of signal transducer and activator of transcription 3 (STAT 3) in the focal ischemic cerebral tissue, so as to study its mechanism underlying improving ischemic stroke. METHODS: A total of 150 SD rats were randomized into sham operation (control) group, cerebral ischemia (CI) model (model) group and EA group which were further randomly divided into 2 hour (2 h), 1 day (1 d), 3 d, 1 week (1 W) and 3 W subgroups (n = 6/subgroup for immunohistochemistry, n = 4/subgroup for Western blot). CI model was established by occlusion of the middle cerebral artery with electro-coagulation method. EA (3 Hz/20 Hz, 2-3 V) was applied to "Baihui" (GV 20) and "Dazhui "(GV 14) for 30 min. The expression of cerebral STAT 3 was detected by immunofluorescence histochemistry and laser-confocal microscopy, and Western blot, separately. RESULTS: Compared with the control group, cerebral STAT 3 immunofluorescence intensity values at the time-points of 2 h, 1 d, 3 d and 1 W, STAT 3 protein expression levels at the time-points of 2 h, 1 d and 3 d in the model group were increased significantly (P < 0.001, P < 0.05). After acupuncture intervention, cerebral STAT 3 immunofluorescence intensity values at the time-points of 1 d, 3 d, 1 W and 3 W, STAT 3 protein expression levels at the time-points of 1 d, 3 d and 3 W in the EA group were down-regulated considerably (P < 0.001, P < 0.01, P < 0.05). No significant differences were found between the control and model groups in STAT 3 immunofluorescence intensity at 3 W, and in STAT 3 protein expression levels at 1 W and 3 W, and between the EA and model groups in STAT 3 immunofluorescence intensity at 2 h, and in STAT 3 protein expression at 2 h, 3 d and 1 W (P > 0.05). CONCLUSION: EA therapy can down-regulate the expression level of STAT 3 protein in the regional ischemic cerebral tissue in cerebral ischemia rats, which may contribute to its efficacy in the treatment of acute and chronic ischemic stroke.