| Objective: Hypoxic-ischemic brain damage(HIBD) could result in neonatal morbidity and mortality, some patients with HIBD developed into cerebral palsy and mental retardation. At present, no effective therapeutic strategies have yet been developed to counteract this condition in clinic. Recently, neural stem cells have been isolated from various regions and various development periods of the mammalian brain. CNS of mammalian can take part in repairing the injured neuronal web and function, Today the mechanisms of neuronal self-repair following insults to the mammalian brain has been scarce. The limited ability of the mature CNS to generate new neural cells limits the self-repair capacity of the damaged brain. However, more and more theories demonstrated that one of most important treatment is to build up the self-restore of brain'nerve for HIBD patients. He-Ne laser acupoint irradiation is an non-invasive therapy and has soft, painless, sterile features, in addition it has an unique psycho and psychiatric rehabilitation function, so it is a therapeutic tool with applicated prospect. But whether it could accelerate brain plerosis and development after HIBD neonatal brain has not been reported. For this reason our experiments 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 the weight the wet weight ratio of left/right hemisphere and the ability of learning and memory and expression of MAP2 BrdU and Nestin after hypoxia-ischemia inneonatal rats brain, trying to find out the mechanisms, in order to give a safe therapeutic method and a new idea for clinic.Methods: Seven-day-old rats (n =91) weighing 12-15g were randomly divided into four groups. I group (n =23, 21 survivor), neither ligated nor exposed to hypoxia. II group (n =23,21 survivor) was exposed to hypoxic-ischemic conditions, ligation of the left common carotid artery followed by 2h of hypoxia with 8% oxygen 92% nitrogen. Ill group (n =23, 22 survivor) was treated with He-Ne laser unacupoint irridation in the next day following hypoxic-ischemic conditions, the other is same as IV. IV group (n =22) was treated with He-Ne laser acupoint irradiation in the next day following hypoxic-ischemic conditions. (He-Ne laser with wavelength of 632.8 ran, output power of 4mW,light spot diameter of 3mm, power density of 56.62 mW/cm 2 and doses of 33.97 J/cm2 , the exposure duration 10 min/d, lOd for 1 course, 2 courses with 2d interval). 48h after hypoxic-ischemic conditions, three rats in group I and II respectively were randomly put to death for TTC staining. All the rats was weighted and recorded the change of avoirdupois after the two period of treatment. Six rats were randomly selected from every group rats when the second period of treatment was over. The rest rats were checked by Y style maze to determine the ability of learning memory of rats . The rest rats were subjected to perfusion-fixation, the left brains were regularly paraffin wax embedded, sectioned and stained by MAP2,BrdU and Nestin immunohistochemical staining. The neurons were observed, the number of positive neurons counted under microscope, then data were statistically analysed with spss 10.0. Results: ?Weight quantifying: group II (23.99±1.84, 67.84 + 3.78) and groupl!!(23.59 + 2.58, 67.55 + 2.85) are less in the avoirdupois of rats, compared with group IV (27.34 + 2.78, 74.31 + 2.16), the difference is obvious (p <0.05);however thegroup IV were higher slightly than the group 1 (26.85 ±2.64, 73.15 + 2.41), the difference is not obvious (p >0.05).(2)The wet weight ratio of left/right hemisphere : the wet weight ratio of left/right hemisphere (97.50 + 5.09) in the group IV were higher than those in the group 11(75.33 ±7.50) and III (72.83 ±7.33) .the difference is obvious (p<0.05).However.compared the group I (100.00±3.74) , the difference is not obvious (p >0.05). ?The ability of learning and memory determining:the result showed that the ability of learning (23.06±4.74) and memory (17.13±2.99) in the group IV were obviously higher than those in the group II (35.92±5.88,27.25±5.63 )and IIK 33.94 ±4.68, 26.94 ±3.15) ,the difference is obvious (p <0.05).However, compared with the group I (23.58±3.94, 17.33+3.45) , the difference is not obvious (p >0.05). ?MAP2 immunohistochemical staining :The Map2 was expressed constitutively in the neuron of cortex and hippocampus of group IV,However the level of Map2 expression in the group group Hand III was obviously decreased ,there was no obvious difference between group I and IV.?BrdU immunohistochemical staining: The BrdU positive cells were mainly located in subgranular zone of dentate gyrus in every neonatal rat brain; BrdU positive cells are less in subgranular zone of dentate gyrus of group 1(11.00±l .86), compared with group I , there was a considerable increase in group II (19.33±2.42) and III (19.69±4.17) (p <0.05); a marked increase in group IV (24.06±3.55) , when compared with group II and III(p <0.05).?Nestin immunohistochemical staining: The nestin positive neurons distribute widely in CA1, CA2, CA3 and dentate gyrus of hippocampus formation in every neonatal rat,the nestin positive cells were mainly located in subgranular zone of dentate gyrus in every neonatal rat brain; group II (27.83±3.88) and III (28.38±2.66) increased markedly, as compared with group I (21.58±2.19) ,there was significant difference (p <0.05);increased markedly in group IV (37.63±2.00) , compared with group II and III, There was obvious difference (p <0.05).Conclusions: ? Hypoxia-ischemia can promote the reflective proliferation of subgranular zone of dentate gyrus neural cells. ?He-Ne laser acupoint irradiation may promote the neonatal rats'vegetate, improve its ability of learning and memory, can increase dendrite'growth, can obviously promote the reflective proliferation of dentate gyrus neural cells in neonatal rat brain after hypoxia-ischemia , which may be the one of important mechanism to promote the reconstruct and growth of brain, and so on to facilitate the recovery of brain function after the scathe of brain.@He-Nelaser irradiation has a point specificity for treatmenting the neonatal rat brain afterhypoxia-ischemia.
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