[Animal Modeling]-Establishment of post-traumatic epilepsy animal model by microinjection

  1. Modeling material animal: Wistar rat, male, weight 200-250g, drug: isopentobarbital, FeCl3 solution, equipment: rat stereotaxic system, wireless Bluetooth EEG monitoring system, high-speed dental drill, dental tray powder , Micro syringe.

  2. Modeling method After weighing, the rats were anesthetized by intraperitoneal injection of 2% isopentobarbital solution (50 mg/kg) and fixed in a stereotactic fixation device. Cut off the hair on the crown, disinfect the skin on the crown regularly, and then cut the crown along the midline of the head. The length of the incision is approximately 3 cm. Peel off the fascia above the head to expose the skull. Use a high-speed dental drill to drill a 2 mm diameter hole 3 mm behind the left skull coronal suture and 2 mm next to the sagittal suture. In addition, punch 5 holes in a hole with a diameter of 2 mm to place the electrode. The location of the holes follows the method used by D'Ambrosio. In other words, the origin is the seepage spring, the sagittal suture line passes through the Y axis and passes through the origin, the straight line perpendicular to the Y axis is the X axis, and the unit of the coordinate axis is mm. The coordinates of the hole are (4,0), (4,-6), (-4,0), (-4,-6), and finally a hole with a diameter of 2mm is made in the center. The frontal bone (Figure 1.1). Using a micro-syringe, 5μl of FeCl3 solution with a concentration of 100 mmol/L and a pH of 1.5 was uniformly injected into the rat sensorimotor cortex within 5 minutes with a needle penetration depth of 3 mm. After injecting the solution, hold the needle for 5 minutes to prevent the liquid from overflowing.

  EEG recording: A blunt pure silver wire is placed on the dura mater of the hole with electrodes, and the silver wire is fixed to the skull with tooth powder. The other end of the silver wire is connected to a wireless Bluetooth EEG monitoring system to monitor the EEG of the rat.

  3. The iron model principle has the effect of causing epilepsy.

  4. Changes after model construction During anesthesia, rats sometimes tremble slightly, and basically have no spontaneous activity. Approximately 2.5 hours after the model was established, the rats began to attack. The attack takes the form of tilting the head to the right and rotating the body clockwise around the bottom of the tail. The duration is about 0.5 to 1 minute. Within nearly three hours, the rats began to experience typical epic seizures. The form of the attack is to twist the body to the right, lift the upper body, bend the whole body to make it hard, squeeze the limbs violently, turn it over and jump, the height of the jump is about 20 to 30 cm. At the same time, it can be seen that the eyes of the rats are torn, the eyeballs bulge out, and urinary incontinence is accompanied. The seizure lasts about 1 minute. After the attack, the mouse lay down to rest and was paralyzed. After about 5-10 minutes, the mouse resumes normal activities. Within 3-5 hours after the model is established, a seizure occurs every 10-20 minutes. Within 6-8 hours after the establishment of the model, the frequency of epileptic seizures in rats gradually decreased to once every 0.5-1 hour. In the spectacular epileptic seizure, the rat performs an automatic chewing cross. Within 24 hours to one week after the establishment of the model, the frequency of epileptic seizures in rats decreased, about one seizure per day, mainly manifested by automatic chewing and involuntary body cramps. Two weeks after the establishment of the model, the frequency of epileptic seizures in rats further decreased, about once every 2-5 days.

  Three hours after the model was established, a spike wave with a frequency significantly faster than the background wave and a significantly higher amplitude than the background wave appeared. An epileptic wave occurred in the sensorimotor cortex at the injection site on the left. At the same time, the area of the sensorimotor cortex on the other side of the injection side was obvious, and epileptic waves appeared. The behavioral symptoms of the rats became stiff, and the limbs twitched; the day was mainly sudden waves and sharp waves, accompanied by intermittent seizures. Scattered sharp waves and sharp slow wave activity.

  5. Precautions During the experiment, the weight of the rat should be within the required range as much as possible. This type of rat has a high tolerance and is easy to fix the head with a stereotactic fixation device. Injection speed and needle retention are also important. Surgical instruments must be strictly disinfected. The surgical trauma should be as small as possible, and the operation should be strictly sterile to prevent surgical infection. Pay attention to the depth when drilling the skull. If there is a skull, stop immediately. This is a breakthrough to prevent heavy bleeding. After the surgical operation, the rats can be separated and awakened for 3-5 hours, and then placed in a cage to prevent the first awakened rat from licking or biting the wound of the unconscious rat. In the breeding room, try to maintain the best temperature and humidity for the rats.