Technique to Induce Post-Traumatic Seizures in a Mouse Model via a Weight Drop Traumatic Injury

Protokół

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.  

1. Weight drop procedure

1. Place the mouse in an induction chamber. Set the flow of oxygen and vacuum to 1 L/min and the level of isoflurane gas to 3%−5%. Anesthetize the mouse for 5 min.
2. Remove the mouse from the induction chamber and place it on a foam pad. Test for the absence of a response to a toe or tail pinch.
3. Administer an analgesic (0.1 mg/kg buprenorphine) subcutaneously. If the electroencephalography (EEG) surgery is performed that same day, administer the buprenorphine subcutaneously in combination with the non-steroidal anti-inflammatory carprofen (5 mg/kg).
4. Administer the sodium lactate solution (3 µL per gram of the animal's weight) subcutaneously before or after the last impact. The sodium lactate solution can be mixed with the analgesics for quick administration in a single injection.
   NOTE: The sodium lactate solution contains a mixture of sodium chloride, potassium chloride, calcium chloride, and sodium lactate in water. This step helps to replace fluids and electrolytes, aiding recovery.
5. Position the head of the mouse under the weight drop tube (Figure 1A) and place a flat stainless steel disc (1.3 cm diameter, 1 mm thick, and 880 mg weight) in the center of the head, between the line of the eyes and ears.
   NOTE: This disc diffuses the impact across the surface of the skull (Figure 1B).
6. Remove the pin in the weight drop tube to release the 100 g weight rod from a height of 50 cm. To induce the sham injury for the control mice, remove the weight rod from the tube to prevent accidental release of the pin and weight drop.
   NOTE: The animal's head must be positioned flat, so that the rod free-falls on the entire surface of the disc.
7. Place the unconscious animal on its back for recovery on a heating pad covered with a sterile polylined absorbent towel. The righting reflex recovery time (i.e., the time it takes the mouse to right itself from its back) can be measured as a readout for the time spent unconscious.

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Wyniki

Figure 1: The mouse model of repetitive diffuse traumatic brain injury (TBI). (A) Weight drop device. (a1) Weight drop tube. (a2) A 100 g weight rod. (a3) Pin holding the rod. (a4) String to raise the rod up if changing the height or removing the rod from the weight drop tube. (a5). Foam pad for placing the animal under the weight drop tube. (B) Weight drop procedure. (b1) The stainless steel disc is positioned in the center of the head between the line of the eyes and ears. (b2 and b3) After visual confirmation that the animal's head is in the flat position and the foam pad is moved, place the animal's head under the weight drop tube. (b4) Release of the pin holding the weight rod, hitting the center of the stainless steel disc. (b5) The mouse is placed on a sterile towel immediately after the impact and loss of consciousness is assessed by measuring the time it takes for the animal to recover and right itself.

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Materiały

Name	Company	Catalog Number	Comments
Buprenorphine	Par Pharmaceuticals, Cos. Inc., Spring Valley, NY, USA	60969
C57BL/6 mice	Harlan/Envigo Laboratories Inc		male, 12-16 weeks old
C57BL/6 mice	The Jackson Laboratory		male, 12-16 weeks old
Carprofen	Zoetis Services LLC, Parsippany, NJ, USA	26357	NOTE: this drug is added during weight drop only if stereotactic electrode implantation will be performed on the same day
Fluriso liquid for inhalation anesthesia	MWI Veterinary Supply Co., USA	502017
Stainless steel disc			Custom made
Sterile poly-lined absorbent towels pads	Cardinal Health, USA	3520