Objective To explore the effects of electroacupuncture on hippocampal neuron autophagy and insulin-like growth factor 1 (IGF-1)/phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway in neonatal rats with hypoxic-ischemic brain damage (HIBD).
Methods A total of 108 neonatal rats were randomly divided into sham operation group, model group, IGF-1 group (0.2 mg/kg), electroacupuncture group, electroacupuncture combined with LY294002 group (electroacupuncture combined with 0.3 mg/kg PI3K inhibitor), with 18 rats in each group. HIBD model of neonatal rats was established by ligation of left common carotid artery and hypoxia treatment for 2 hours (the success rate of modeling was 80%). The rats in each group were scored for neurological deficits at being awake after the operation and after electroacupuncture treatment; ELISA was used to detect the content of IGF-1 in brain tissues; hematoxylin-eosin (HE) staining was used to observe the pathological change of brain tissues; transmission electron microscope was used to observe the cell autophagy; immunofluorescence double-labeling method was used to detect the colocalization expression of autophagy markers and neuron-specific nuclear protein (NeuN); western blot method was used to detect the expression of PI3K/Akt pathway and autophagy-related proteins in hippocampusPI3K, phosphorylated PI3K (p-PI3K), Akt, phosphorylated Akt (p-Akt), Beclin-1, microtubule-related protein light chain 3Ⅱ (LC3-Ⅱ), and microtubule-related protein light chain 3Ⅰ (LC3-Ⅰ).
Results Compared with the sham operation group, the neuron damage in the hippocampus of the HIBD model group was aggravated, the neurological deficit score, the Beclin-1 and LC3-Ⅱ/LC3-I expression in the hippocampus were increased, while the IGF-1 content in brain tissues, p-PI3K/PI3K and p-Akt/Akt expression in hippocampus were reduced; compared with the model group, the neuron damage in the IGF-1 group and the electroacupuncture group was alleviated, the neurological deficit score, Beclin-1 and LC3-Ⅱ/LC3-Ⅰ, the number of autophagosomes and the LC3/NeuN co-expressed neurons were decreased or reduced, while the IGF-1 content in brain tissues, p-PI3K/PI3K and p-Akt/Akt expression were increased; the differences mentioned above were statistically significant (P<0.05). LY294002 was able to significantly reduce the level of IGF-1, weaken the activation of the IGF-1/PI3K/Akt pathway of hippocampus and the inhibition of hippocampal neuron autophagy by electroacupuncture.
Conclusion Electroacupuncture may inhibit excessive autophagy of hippocampal neurons by activating the IGF-1/PI3K/Akt pathway, thereby alleviating HIBD in neonatal rats.
DownLoad: