| Cerebral palsy (CP) is one of the most serious nervous system diseases that threats children's health,sixty or seventy percent of which is spastic, so spastic cerebral palsy (SCP) has become the focus on the experimental and clinical study. With the development of medical level and the increase of low birth weight infants at survival rate,the incidence of CP has worldwide increased year by year. To date,many scholars at home and abroad dedicated for the study of CP disease. With the depth of research, preparation and usage of animal models has become an important means of researching SCP further. Therefore, it is great significance that we establish a practical SCP model for the experimental research and clinical work.Many studies have chosen 2-day-old or 4-day-old neonatal rats, in the experimental on cerebral palsy model.However, we found that the smaller day- old rats, the higher the mortality rate of animals in the pre-experiment. Therefore,we used 5-day-old newborn Wistar rats as research subjects and construct neonatal rats SCP model through bilateral carotid artery ligation.In the experiment,we did so in order to simulate the changes of neurology and pathology on neonatal rats after SCP, we explore the method of evaluating the model further.The concrete methods are as follows: the clean five-day-old Wistar neonatal rats were randomly divided into experimental and control group. Bilateral carotid ligation was used to perform on brain damage in the experimental group, while the neck skin was cut only in the control group.The experiment was carried out in two steps: first, twenty rats in each group were measured weight on postnatal first day (P6), postnatal third day (P8),postnatal seventh day (P12) and postnatal fifteenth day (P20),and their neurobehavior were tested on postnatal twenty-fifth day(P30),then we analyzed the statistical data; second, sixteen neonatal rats in each group were chosed for the following experiment:we observed the pathological changes of brain tissue under light microscope after HE staining at the time points of P6,P7,P15 and P25, respec- tively.The experimental results are as follows: (1) the general situation after operation:the survival rate was 100%(36/36) in the control group,while the survival rate was 85.71% (36/42)in the experimental group.Depression,decreased limbs move- ments,dulled reaction and appetite loss were found in the experiment rats;while the spirit of control rats recovered,limbs action remained active and sensitive and they fed gradually increased six hours later.(2) body weight change: the body weight of two groups rats was no significant difference before surgery;the body weight of control rats showed normal growth after surgery,while the body weight of experimental rats showed slow growth,and there was significant difference at body weight aspect between the experimental groups and the control groups after postoperation(P<0.05).(3)pathological change: we observed the pathological change of the model groups as follows:①microglial cells infiltrated and aggregated in the white matter;②astrocytes were hypertrophic and proliferative;③white matter structure was sparse and disorderly;④periventricular leukomalacia lesions were formed and oligoden- drocytes reduced between cysts;⑤lateral ventricle was enlarged and its'shape was irregular; however,the pathology of the control rats wasn't observed abnormal in principle.(4) Neurobehavioral study changes: the average dropping time of experimental rats was 2.25±0.79 minutes in the suspension test, while it was 4.15±0.67 minutes in the control group,there was statistical difference between the two groups(P<0.05); the average time of heading up in the experimental rats was 12.25±1.21seconds in the slope test,while it was 3.35±0.93 seconds in the control group, there was significant difference between the two groups(P<0.05);the average score of experimental rats was 4.30±0.92 in open field test, while it was 12.50±1.15 in the control group, there was statistical difference between the two groups(P<0.05); the average score of experimental rats was 0.85±0.67 in the caught refusal test, while it was 4.80±0.77 in the control group,there was statistical difference between the two groups(P<0.05);the average score of experimental rats was 7.80±0.62 in muscle tone test, while it was 9.90±0.46 in the control group,it was statistical difference between the two groups(P<0.05);the average score of the experimental rats was 9.50±0.89 in the voluntary movement test, while it was 10.00±0.00 in the control group, there was statistical difference between the two groups(P<0.05). In inclined plate experi- ment,eight experimental rats were both positive in two indicators and another twelve emerged positive in one indicator, while control group were negative. Compared with the control rats,experimental rats showed insensitive response, decreased spontaneous movement, slow activity,reduced flexibility and stability in the exercise, meanwhile, we observed that their muscle tone was abnormal. Through the experimental research, we can draw four conclusions: (1) Through the ligation on bilateral carotid artery with five-day-old neonatal rats ,we can successfully construct an spastic cerebral palsy model. (2)Compared with the control rats, experimental rats grow slowly in body weight. (3)The main pathol- ogical change of spastic cerebral palsy model is in the white matter, whose damage is related closely to cerebral palsy. (4)The model is so practical that we can use it on research which relates to cerebral palsy further.
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