The Study On Ventral Posterior Medial Hypothalamus Of Rats After Traumatic Brain Injury Electrophysiological Changes

Object:Electrophysiological nerve cells through experimental observation of traumatic brain injury and the severity of the medial hypothalamus nuclear abdominal pain-sensitive neurons of the relevance of discharge frequency .Method:1. Experimental animal and groups:Male Wistar rats 40, weight between 270-290g. Purchased from the Experimental Animal Center of Shanxi Medical University.All of rats are randomly divided into four groups.The group of traumatic brain injury in accordance with mild, moderate, severe are divided into 3 groups.And other group is sham operated.(N=10). We will keep the rats to different cage to eating and drinking .2. Animal model of TBI:The Feeney method is on basis of falling objects traumatogenesis.Made an impact device which is producted by Instrument factory in academy of military medical Sciences.The headend of strik staff'dameter is 4.5mm,height is 2.5mm, peripheral meatus'height is 40cm, maintain vertical 90°, Every 1cm every pores, to prevent the strik hammer whereabouts of intraductal compression resistance in the air.We use urethane to anaesth(1.2mg·kg-1)with intraperitoneal injection. After satisfaction of the anaesth,the rat is fixed on stereotaxis instrument.When we make the model of TBI,Cutdown epicranium and undermine periost along the midian line. The incisal opening is 2cm,right bregmatic bone can be exposed. We use dental desk-top electrodill to burr hole with diameter of 5mm which is situated at 1.5mm behind arcuate suture,2.5mm right of linea mediana.We must retain the integrity of cerebral dura mater.Take the head of strik staff onto the hole,stike hammer(20g)will drop down along peripheral meatus with different height 10cm and 30cm,we can produce mild and moderate model of cerebral contusion in right parietal..Anoter, strike hammer(40g) drop down from 25cm height , can produce severe cerebral contusion.Vulnerate impact are 0.028N·s,0.048 N·s and 0.088 N·s. We must retain the integrity of cerebral dura mater and block the bony window with oscera. The group of traumatic brain injury in accordance with mild, moderate, severe are divided into 3 groups. The sham operated group only cutdown epicranium,open bony window,but have nothing brain injured.3. Discharge Record :To observe the change of discharge frequency in rat's nucleus ventralis posteromedialis thalami's pain sensitive neuron. According to rat brain stereotactic atlas,we find the rat's VPM. The mild, moderate, severe and sham operated group will be bit at the right side of the bone window,and be recorded in left by metel electrode which is made by FHC company.Result: The discharge frequency in the mild, moderate, severe and sham operated group increase gradually.Through variance analysis,the difference between groups has statistical significance.(p<0.01) The variance between every two groups is predominancy.Conclusion:We can evaluate experimental animal's nocuity reception and intervention study effect through observe the change of electrophysiology in nucleus ventralis posteromedialis thalami's pain sensitive neuron after brain injured.