Chronic Compression Injury Model of the Sciatic Nerve (CCI)

Model Construction

1. Preoperative Preparation

• Experimental Animals: C57BL/6JCya, 8-9 weeks old, female, weighing 20-30g.
• Experimental Equipment: 8-0 suture, 6-0 suture, curved forceps, ophthalmic scissors, electric hair clipper, 27G cushion needle.
• Experimental Reagents: 1.25% tribromoethanol, povidone-iodine, medical alcohol, saline solution.

2. Operation

• Administer intraperitoneal anesthesia by injecting 0.2ml of 1.25% tribromoethanol per 10g of body weight. Once anesthesia is effective, use an electric hair clipper to remove hair from the lateral thigh to the femoral region of the left hind limb;
• Place the animal in a prone position, securing all four limbs to the surgical board, and disinfect the skin in the surgical area with an alcohol swab. Make a 1.5cm incision in the skin of the left thigh;
• Using curved forceps, bluntly dissect the biceps femoris along the muscle texture to expose the sciatic nerve. Use a fixed hook to slightly retract the muscles for a clear surgical view. Gently separate the sciatic nerve about 7mm from the main trunk before the trifurcation using forceps;
• At 2mm anterior to the trifurcation, ligate the sciatic nerve with 8-0 suture combined with a 27G cushion needle, making four ligatures. The tightness of the ligation should elicit slight twitching of the calf muscles or toes during knotting. Remove the cushion needle after ligation. The interval between ligatures is approximately 1mm, resulting in a ligated nerve length of about 4-5mm;
• Moisten the surgical area with saline or PBS, and sequentially suture the muscle, subcutaneous tissue, and skin with 6-0 suture. Clean the wound and disinfect with povidone-iodine;
• Equip the mouse with a self-made Elizabethan collar, keep it warm until recovery, and house it individually, continuing to wear the collar for 3-4 days until the wound heals.

3. Treatments and Behavioral Assessments

• Von Frey testing, ethanol (EtOH) stimulation, and the Hargreaves test were conducted on mice one and two weeks post-surgery to evaluate the success of model construction. After confirming successful model establishment, female CCI mice were administered 30 mg/kg of gabapentin via intraperitoneal injection. Behavioral assessments using the same three tests were subsequently performed following gabapentin treatment to evaluate its effects.

Validation Data

1. Behavior Test

(A)

(B)

(C)

Figure 1. The von frey, 100% EtOH stimulation and hargreaves test of CCI model one and two weeks post-surgery. One and two weeks after CCI induction (A-B), baseline tests showed that the female CCI mice were more sensitive to mechanical and cold stimuli than the Wild-Type (WT) mice. In the two weeks post-surgery, 30 mg/kg of gabapentin was injected intraperitoneally into female CCI mice (C). After treatment, there was no significant difference in sensitivity to stimuli between the female CCI mice and the WT mice.