| Background and object:Hypoxic-ischemic brain injury (hypoxic-ischemic brain damage.HIBD) is due to part of the brain tissue or complete anoxia, cerebral blood flow reduction or suspension of brain damage caused eventually cause nerve cell apoptosis and necrosis.One of the high incidence of neonatal population, called hypoxic-ischemic encephalopathy (Hypoxic-ischemic encephalopathy, HIE).Refers to perinatal asphyxia brain damage caused by severe cases can cause permanent neurological damage, it is a common cause of childhood neurological injury.Perinatal asphyxia is a major cause of this disease.Those who cause blood circulation and impaired gas exchange between mother and fetus so that the concentration of oxygen can cause suffocation by loweringCaused by intrauterine asphyxia accounted for 50% of the delivery process suffocation accounted for 40%, caused by congenital diseases accounted for 10%.Since almost all of the energy of the brain from oxidation of glucose, newborn brain metabolism is very strong, cerebral oxygen consumption accounts for almost half of the whole body oxygen consumption.Pathogenesis of the disease are as follows:Brain glycogen little, so thanks to the brain glucose and blood circulation supply,When hypoxia ischemia in various tissues and organs of the body, the brain most affected, can cause the following changes:1.Energy metabolism:the role of glycolysis in brain tissue during hypoxia increased by 5 to 10 times, can cause metabolic acidosis;2.Ventilatory dysfunction: CO2 reserving that PaCO2 increased, resulting in respiratory acidosis;3.Anaerobic metabolism in the brain due to the large reduction in ATP production, lack of energy sources on the one hand, the metabolic oxidation process is greatly damage the brain, a large number of neuronal death. On the other hand so that the sodium pump operation obstacles, sodium chloride inside brain cells increased intracellular edema;4.Cerebral microvascular hypoxia and reduce blood flow is caused by cerebral ischemia, and increased vascular permeability caused by produce vasogenic brain edema, intracranial pressure will further aggravate;5.When the hypoxic-ischemic reperfusion injury caused by oxygen free radicals and calcium overload increases, amino acids excited, large release of various cytokines, inducing a series of complex cascade resulting in neuronal damage.Pathological basis of the disease is hypoxic-ischemic injury. The main cause hypoxic brain edema and neuronal necrosis, ischemia is mainly caused cerebral infarction and leukomalacia.Clinical manifestations:1.Term appropriate for gestational age children with asphyxia or intrauterine distress yield significant history;2.There are different levels of consciousness, light only irritability or lethargy; heavy inhibited, coma;3.Children full anterior fontanelle, suture separation, increased head circumference, brain edema;4.Seizures:more common in severe cases, seizures may be focal or multifocal atypical, clonic and tonic type myoclonic,Episodes ranging in more than 24 hours after birth onset, within 24 hours of hair of significantly increased incidence of sequelae;5.Muscle tension change;6.Abnormal primitive reflexes:reflex activity such as hugging, diminished or disappeared. Sucking reflex diminished or disappeared;7.Severe cases of central respiratory failure, respiratory rhythm arrhythmia, apnea, and nystagmus, pupil changes brain stem injury,Children with severe HIE even survive often suffer severe central nervous system sequelae of cerebral palsy, mental retardation, epilepsy and the like.Current clinical treatment for HIE mainly confined to nursing and supportive therapy.For a long time, research and development of effective treatments HIE drugs is an important task neonatal medical research.n recent years, neural stem cells in embryonic and adult individuals found in the nervous system as well as the success of in vitro hypoxic-ischemic encephalopathy cell transplantation and gene therapy, to provide a new method.In understanding the efficacy of these regimens its mechanism of action studies, HIE animal model has played a very important role.In understanding the efficacy of these regimens its mechanism of action studies, HIE animal model has played a very important role.The experiment simulated warehouse environment combined with low-pressure plateau Swimming rats.Methods established in the plateau region of neonatal hypoxic-ischemic encephalopathy model observed behavior, pathological changes of brain tissue, brain and red blood cells TTC staining for HIE in the plateau region clinical research foundation experiment preparation.Methods:10-day-old 32 newborn SD rats were divided into four groups, namely A group(control group)and three test groups:B group(2000m group), C group(4000m group), D group(6000m group). Control rats reared in a barrier environment, test group rats were placed in a simulated cabin with plateau low pressure environment, making newborn cerebral and plateau ischemia and hypoxia model with sports. Movement is carried in the cabin swimming groove 60 min/d of swimming,and no less than 20 hours a day at high altitude low pressure environment simulation cabin in life time. Use Zea Longa 5 point scale standard to measure behavioral scores of the 3th 7th 11th 15th day, and samples were collected in the 15th day to see red blood cell morphologydand in the scanning electron microscope. HE staining and TTC staining of brain tissue in animal models before sacrificed.After making a successful model, divided into three groups:normal group(n=8), ischemia group (n=8) and NSCs transplanted group (n=8). Rotarod test and Morris test were performed at 5,7. 14.21 days after treatment to measure the behaviors of the rats. Hematoxylin-eosin staining was used to observe the pathological changes of brain damage in neonatal rats.Results:1.Neurological Rating:Behavior were normal control group, the behavior score of 0 points,The behavior of rats in the experimental group abnormalities, mainly as abnormal limb sensory and motor dysfunction and balance function.Experimental group rates with elevation rises, the extent of abnormal behavior was positively correlated with altitude.And the experimental group increased gradually in the first 3,7,11,15d behavioral ratings,The data show that at high altitude hypoxia longer the severe brain damage,Experimental results show that the control group was significant (p<0.05) with the difference between the experimental group and control group 6000m altitude difference was significant (p<0.01).2.Pathology of brain tissue:Control group brain nerve cells, glial cell size, shape normal, no brain edema,At an altitude of 2000m cerebral cortex atrophy, neuronal cell edema, mild hyperplasia of glial cells,At an altitude of 4000m moderate atrophy of the cerebral cortex, neurons moderate edema, moderate hyperplasia of glial cells; severe edema ependymal cells at an altitude of 6000m chamber.3.TTC staining:TTC (2,3,5-triphenyl tetrazolium chloride) is a fat-soluble light-sensitive compound,It is the respiratory chain pyridine-nucleotide structure of the enzyme system of a proton acceptor,Normal tissues dehydrogenase reaction with red,While dehydrogenase activity decreased in the ischemic tissue, not react, it will not produce changes pale.Group TTC staining red, ischemia and hypoxia performance does not appear,Altitude 2000m mild changes in the cerebral cortex appear pale small pieces;4000m altitude cerebral cortex can obviously see the pale area;6000m above sea level, nearly half appeared pale area.Image-Pro Plus to make use of 2000m above sea level in brain hypoxia area of 26.6%,4000m altitude cerebral hypoxia group area was 34.3% group 6000m altitude cerebral hypoxia area of 56.6%, while the control group was normal.4.RBC electron microscope:In the scanning electron microscope you can see in the control group showed a double-concave disc-shaped red blood cells;At an altitude of 2000m under the electron microscope showed mild changes are cap-like structure;At an altitude of 4000m at the performance of irregular shape;At an altitude of 6000m performance serrated portion of red blood cells will be empty, disintegrating.Treatment after neural stem cells Rotarod test: motor function recovered gradually and restored to near the normal level on the 21th day in MSC group and there was a significant difference between MSC group and HIE group on the 14th day (P<0.05). Morris test:escape latency shortened gradually with increasing training days and the differences were significant among the three group (P<0.01). Compared with HIE group, escape latency significantly shortened in MSC group at each time points (P<0.05). Pathological results showed that hippocampal neuron edema, nuclear chromatin structure is not clear, and vacuoles appeared in HIE group. Compared with HIE group, pathological changes in brain were significantly lessened.ConclusionIn this study, combined plateau and low voltage cabin with motion to make model of neonatal hypoxic-ischemic encephalopathy (HIE)by simulating Plateau Environment, the model is stable and reliable than other methods and more in line with the pathogenesis of hypoxic-ischemic brain injury, closing to clinical and can be used in related research.Mesenchymal stem cells can promote the recovery of neurological function in rats. |
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