The Establishment Of SD Rat Model Of Spastic Cerebral Palsy

Objective: At present, there are lots of studies about the methods to setup the animal models of the spastic cerebral palsy (SPC) home andabroad.However, due to the lack of scientificalness, the models' symptoms areatypical and can only last for a short time, which are becoming the mainobstacles for the further and systematic study in this field. So far, not one idealmodel has been found. Through the improvement and innovation which basedon the past research, we fixed the rats on the stereotaxic instrument solidly andgive the accurate orientation of the rats' pyramidal tract according to the brainof rats radiostereostatics anatomy atlas. Inject the absolute ethyl alcohol intothe rats' pyramidal tract to make the pyramidal tract necrosis.This experimentsimulated the anatomy and the pathological changes of the spastic cerebralpalsy. Postoperative rats emerge buckling spasms symptoms, and flexorincreased tension. Besides, the signs and symptoms lasted for a long time, andthey have good stability. In this way, we successfully establish a kind of newstable animal model of the spastic cerebral palsy, which can be well replicatedand the symptoms can last for a long time. This experiment lay a goodfoundation for the further study of the basic research of the SPC's clinicaldiagnosis and treatment.Methods：Select16adult SD rats, male. Divide the rats into4groups(A, B, C, D) with random number table method and each group contains4rats.A, B and C group are the experimental groups and the D group is the matchedgroup. First, Intraperitoneal injection of anesthesia with10%hydrationchlorine aldehyde, then fixed the rats on the stereotaxic instrument solidly,cropping the hair and disinfection. Second, select the after the cranial roofmidline incision about2cm long, cut the skin step by step, expose the anteriorfontanelle and sagittal seam, according to the brain of rats radiostereostaticsanatomy atlas, at the position of the anterior fontanelle back10mm, the sagittal seam left0.8mm, drill the cranial top with dental drill about1mm indiameter, Insert the microinjector into the cranium for9.7mm vertically. Third,A, B and C group inject respectively5μ l,15μ l,25μ l absolute ethyl alcoholinto the cranium slowly, After fully stopping the bleeding, hold the drillinghole on the cranium with a little bone wax, Last, rinse off the cut withphysiological saline and sew up the incision. For the D group rats, Insert themicroinjector into the cranium for9.7mm vertically, without any reagent, andthe rest of the operation is the same with the experimental group. After theoperation, comparing the experimental group with the contrast group carefully,observe the rat's symptoms and signs. After the Three experimental group rats'symptoms become stable (about72hours after), take the most typical one rat,after anesthesia, Put the rats on the sterile work station, regularly makedisinfection, and spread sheet. Firstly, disconnect the the cranial wound suture,clean the wound area and subcutaneous haematomas, according to the originalincision direction, respectively extend the incision forward to the nasal tip,backward to the neck and expose the whole skull. With the fret saw, sawacross the brows, and join at the inions through the tempus to the blackheadsawlines. pry the cranial cover bone across the brows with the emei chisel, cutthe spinal canal at the foramen magnum with small bone scissors, thenseparate the spinal cord, cut off the smell brain and the optic nerve with themicroscopic scissors, put the sharp knives into sella turcica to separate thepituitary. take out the whole brain along with the pituitary,rinse it with salinewater and immerse it in formalin solution for three days. Then take the wholebrain specimen for pathological analysis. The rest of the rats are bred normallyand keep a close eye on their temperament, behavior, their living conditionsand the main spasticity index which including the spirit state, feeding anddrinking condition, body spasms, body muscle tension and the duration of thesymptoms every day.Results: Group A postoperative rats, in12hours,revealed no activemovements or diet, with the right limbs buckling spasticity. Compared withthe left side, the flexor muscle tension increased; in24hours, revealed a small amount of activities and diet, the mental state got better, and the right bodybuckling spasticity continued. When moving actively or driven by, the ratsalways made clockwise circular motion, and the circle diameter was60cm; in48hours, the rats' diet was a bit poor compared with the normal ones', but theinitiative activities and the diet increased, with mental state improving andbuckling spasticity continuing; in72hours, the rats' drinking water andfeeding gradually became normal, so did the mental state and initiativeactivities. The right limbs buckling spasms symptoms became stable and thebuckling spasticity lasted about six to eight weeks. Group B postoperative rats,in18hours, revealed no active movements or diet, with the right limbsbuckling spasticity obviously. Compared with the left side, the flexor muscletension increased; in36hours, the rats started a few active feeding/drinkingwater and a little active activities, with the mental state better. When movingactively or driven by, the rats always made clockwise circular motion, and thecircle diameter was20cm; In48hours, the rats' diet was still a bit poorcompared with the normal ones', but initiative activities and the diet increased,with mental state improving and buckling spasticity continuing; in72hours,the rats' drinking water and feeding gradually became normal, so did themental state and active activities. The right limbs buckling spasms symptomsbecame stable and the buckling spasticity lasted about8to14weeks. Group Cpostoperative rats within24hours revealed no active movements or diet, withright limbs body buckling convulsion extremely. Compared with the left side,the flexor muscle tension increased extremely. Meanwhile, the head and thewhole body turned to the right side. In48hours, the rats still revealed noinitiative activities or diet, with the spirit weak. When moving actively ordriven by, the rats always went round In circles. They couldn't stand up, withthe head and the whole body leaning to the right side seriously. Bucklingspasms symptoms continued; in72hours, the spirit was extremely weak, stillwith no initiative activity or diet, and the body was angular obviously,buckling spasms symptoms went on. Because they couldn't stand up to drinkor eat normally, finally all the rats died in one week. Group D postoperative rats (the matched group) within24hours, the rats' diet was a bit poorcompared with the normal ones', and so did the mental state. The paralysissymptoms on the right limbs couldn't be found any more. There were nodifferences between both limbs nether on the physical activities, nor on theflexor muscle tension; In48hours, the mental state recovered almost normal,the activities and diet became gradually normal, too; in72hours, activities andthe diet became completely normal.The mental state also fully recovered.After carefully comparasion, the group B postoperative rats' buckling spasmssymptoms are the most typical one. The group B postoperative rats' braintissue pathology results show that: the experimental side of pyramidal tract haspresented empty sample necrosis, and both necrosis parts and necrosis rangewere accurately, the opposite and other brain organizations without anydamage.Conclusions: With this method, the postoperative rats' signs andsymptoms not only typical but also lasted for a long time. More major is theycan be well replicated and have good stability. The operation process is simpleand specification, the orientation is accurate. The Pathological results furtherproved that the signs and symptoms are caused by the empty sample necrosisof pyramidal tract. A better dose of the chemical ablation agent (absolute ethylalcohol) in the process of model production is15μ l, but it is not the best.Then we can carry on further research about what the best dose is, how aboutthe dose-effect relation and time-effect relation and so on,all needs furtherimprovement and exploration.