Effects Of Acupuncture On Expression Profile Of Genes Of Neurotrophic Factors And Receptors In Cerebral Cortex Of Neonatal Rats After Hypoxic-ischemic Injury

Background Hypoxic-ischemic encephalopathy(HIE) is one of the most severe diseases in the neonate. It usually causes neonatal death or severe neural dysfunction such as amentia, epilepsy, cerebral palsy and so on, which greatly damage the health and life quality of neonates. However, there is no effective treatment to this frequent occurring disease in western medicine until nowadays, while acupuncture has been proved to be effective in the treatment of HIE. According to the theory of traditional Chinese medicine, we adopted the principle of "supply earlier heaven essence, regulate root of later heaven, restore brain marrow, strengthen bone, resolve tetany" to perform acupuncture on points of Controlling Vessel,Governing Vessel and Bladder Channel to cure 26 cases of HIE in the clinical practice. The result revealed that many of the children got recovered. Furthermore, CT and MRI scan showed that the patients' hypogenetic cortex attained restoration and external hydrocephalus disappeared after accepting acupuncture-therapy. However, the mechanism of acupuncture on HIE has not completely known yet. Our former experiments showed that acupuncture could evoke the proliferating potential of neural stem cells in the hypoxic-ischemic injured cortex of neonatal rats, and that most of the proliferating neural stem cells differentiated into neurons. Many other experiments revealed that acupuncture could stimulate the central nervous system to secret neurotrophic factors while it was used to treat diseases of central nervous system. According to these findings, we assume that acupuncture evoke the proliferating potential of neural stem cells and promote the proliferating neural stem cells differentiate into neurons through improving the local micro-circumstance in the brains of the HIE sufferers(such as changing the secretion of neurotrophic factors) after cerebral hypoxic-ischemic injury had occurred. And the new born cells stimulated by acupuncture furthermore compensate the neurons that were lost during hypoxic-ischemic insult, which ultimately contributes to the alleviation of symptoms and signs of HIE. The technology of gene chips is an advanced biotechnology that appeared not long ago but developed quickly. This technology is prominently characterized by high-level efficiency and large information, which could examine hundreds of thousands of genes at the same time. Therefore, we can examine a great deal of genes that take part in the course of all kind of diseases quickly and effectively using gene chips, which offers a new method for fundamental and clinical research of acupuncture on HIE.Objective The current study was designed to examine the expression profile of genes of neurotrophic factors and receptors in cerebral cortex of HIE model rats after performing acupuncture on points of Controlling Vessel,Governing Vessel and Bladder Channel using microarrays, and to explore the molecular mechanism of the treatment of acupuncture to cerebral hypoxic-ischemic injury, thus providing a new theoretical instruction for clinical acupuncture-therapy on neonatal HIE.Methods A total of 10 7-day-old Sprague-Dsawley(SD) rats were randomly divided into 2 groups(5 rats in each group): Acupuncture therapy group and HIE control group. All rats underwent left carotid artery ligation followed by exposure to 8ï¼…O₂ for 2 hours to establish the model of neonatal HIE. In the acupuncture therapy group, acupuncture was performed on points of Controlling Vessel,Governing Vessel and Bladder Channel once daily after the day when the HIE model was established, and persisting for 14 days. The HIE control group did not accept acupuncture. After the day when the acupuncture therapy was finished, the two group rats were all sacrificed and the cerebral cortex that suffered from hypoxic-ischemic injury were taken, total mRNA isolated, and then using GEArray Q series neurotrophin and receptors microarrays to examine the expression profile of genes of neurotrophic factors and receptors, screening the genes that were expressed differently in the two groups. The result of microarray was furthermore confirmed by RT-PCR.Results 1. After acupuncture for 14 days, 48 genes(50ï¼…of total genes on microarray) were expressed differently in the two groups, of which 40 genes(83.3ï¼…of differently expressed genes), such as genes of brain-derived neurotrophic factor(BDNF),ciliary neurotrophic factor (CNTF),ciliary neurotrophic factor receptor(CNTFR),basic fibroblast growth factor(bFGF) and fibroblast growth factor receptor type 1(FGFR1) were up regulated, and 8 genes(16.7ï¼…of differently expressed genes), such as genes of neuregulin 1(Nrg1),neuregulin 4(Nrg4) and tyrosine kinase C(TrkC) were down regulated. The genes that were up regulated involved in neurotrophins and receptors,neuropeptides and receptors,growth factors and receptors,cytokines and receptors,signaling molecules and apoptosis related genes, while the down-regulated genes only involved in neurotrophins and receptors,neuropeptides and receptors,cytokines and receptors,and chemokine receptors. 2. The result of microarray was consistent with the result of RT-PCR.Conclusions 1. Acupuncture can regulate the expression of a great deal of genes of neurotrophic factors and receptors in cerebral cortex of neonatal SD rats after cerebral hypoxic-ischemic injury, and many of the differently expressed genes were up regulated, a few were down regulated. 2. The mechanism of acupuncture on neonatal HIE is that acupuncture regulates the expression of a great deal of neurotrophic factors and receptors in the local micro-circumstance that suffered from hypoxic-ischemic injury. Those neurotrophic factors and receptors then evoke the proliferating potential of neural stem cells and promote the proliferating neural stem cells differentiate into neurons through interaction and regulating the expression of each other, and protect neurons that suffered from hypoxic-ischemic injury at the same time. The total effects finally cause repairing of the injured brain tissues. 3. Acupuncture also regulates the expression of genes involving in neuropeptides and receptors, growth factors and receptors,cytokines and receptors,signaling molecules and apoptosis related genes, which indicates that the mechanism of acupuncture on neonatal HIE is very complicated. There may be many targets and pathways involving in it. 4. GEArray Q series neurotrophin and receptors microarrays could examine the expression profile of genes of neurotrophic factors and receptors in cerebral cortex of HIE model rats after acupuncture quickly and effectively, and the results are credible.