| Objective:Hypoxic-ischemic brain damage (HIBD) continues to be a major problem in perinatal medicine because of the high mortality rate and neurological and intellectual impairment in the surviving infants. At present, despite scholars have done lots of investigation in the treatment of HIBD, no effective therapeutic strategies have yet been developed to counteract this condition in clinic, therefore, one of the most urgent tasks for obstetricians and neurologist is to develop therapeutic strategies. He-Ne laser acupoint irradiation is an non-invasive therapy and has soft, painless , sterille features, in addition it has an unique psycho and psychiatric rehabilitation function, so it is a therapeutic tool with applicated prospectAs a low energy laser, He-Ne laser has been applied in clinic because of its unique biological stimulation, but whether it could accelerate brain plerosis and development after neonatal brain injury has not been reported. For this reason our experiment adopted a generally accepted rat model with hypoxia-ischemia, selected "BaiHui"point; "DaZhui"point to study the effect of He-Ne laser acupoint irradiation on ultrastructural changes and expression of ChAT and BDNF after hypoxia-ischemia in neonatal rat brain, trying to find out the mechanisms and a safe therapeutic method for clinic.Methods: Seven-day-old rats (n =62) weighing 12-15g were randomly divided into three groups. I group (n =16), neither ligated nor exposed to hypoxia, served as controls. II group (n =24, 22 survivor) was exposed to hypoxic-ischemic conditions, ligation of the left common carotid artery followed by 2h of hypoxia with 8% oxygen 92% Nitrogen, in group (n =22,19 survivor) was treated with He-Ne laser acupoint irradiation in the next day following hypoxia. (He-Ne laser with wavelength of 632.8 nm, output power of 4mW,light spot diameter of 3mm, power density of 56.62 mW/cm 2and doses of 33.97 J/cm2, the exposure duration 10 min/d, 10 procedures for 1 course, 2 courses with 2d interval). 24h after hypoxia, three rats in group I and II respectively were randomly put to death for TTC staining. 22d later, three rats selected from each group were killed. The left side hippocampus from each rat was dissected out, the specimens were made ultrathin sections prepared for observation by an electron microscope H-7500. The 42 rats were subjected to perfusion-fixation, the left brains were regularly paraffin wax embedded, sectioned and stained by HE staining, Nissl staining, ChAT and BDNF immunohistochemical staining. The neurons were observed, the number of positive neurons counted under microscope and the grey scale values were masured, then data were statistically analysed. Results: (1) HE staining: the structure of neurons in hippocampus and cortex is clear in group I ; There is neuronal degeneration , necrosis and tissue structure clouding in group II; The neuronal denaturalization and necrosis relieve, cellular form and structure are in focus in group III.(2)Nissl staining : The neuronal cytoplasm is full of dark-blue colored Nissl bodies in group I (grey scale value: 122.90+12.10), a great number of nissl bodies are lost in group II, the grey scale value appears ascending tendency(188.31+10.43), there is obvious difference between I and II (p<0.05). There is a slight loss of Nissl bodies in group III, its grey scale value appears a descending tendency(130.56+6.16), there is marked diference between group II and group III (p<0.05).(3) The ultrastructural changes in hippocampus: The neuronal structure of hippocampus in group I is integra. nuclear membrane is clear, there are plenty of organells in cytoplasm. Mitochondrial cristae is clear and dense, RER and ribosomeare abundant, microfilament and microtubules array in good order; In group n the ultrastructural damage of neurons result in remarkably cellular edema and clouding nuclear membrane. Organells in cytoplasm decrease, mitochondrial cristae is poor structural integrity. The swollen RER attached fewer ribosomes, microfilament and microtubules arr...
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