Expression of N-cadherin and alphaN-catenin in the degeneration/regeneration process of rat skeletal muscle after nerve injury.

The authors investigated the expression of N-cadherin and alphaN-catenin (which is strongly related to N-cadherin function) in the denervation/reinnervation process using a rat sciatic nerve and gastrocnemius model. In a rat model, the right sciatic nerve was exposed at the mid-thigh region, and the nerve was transected with small scissors. Then, the nerve was sutured using 10-0 monofilament perineurial nylon sutures. At various periods up to 24 weeks after the operation, the gastrocnemius muscle of the treated hindlimbs was removed. Four rats were used at each time point in both groups. N-cadherin and alphaN-catenin expressions were detected by Western blot analysis and immunofluorescent staining with anti N-cadherin and alphaN-catenin antibodies. The level of N-cadherin was already elevated in the first postoperative week, and the level in the second postoperative week was almost the same as in the first. The level decreased gradually after the fourth postoperative week and, in the ninth postoperative week, returned to almost the same as the control level. The level of alphaN-catenin was almost the same as the control (1.0) within the second postoperative week. After the fourth postoperative week, the level elevated gradually, with a peak in the sixth postoperative week. The level then decreased and returned almost to that of the control after the twelfth postoperative week. Immunofluorescent staining was observed along the muscular membrane in all specimens of both proteins, and the time course of the degree of immunofluorescent staining was similar to the results of Western blot analysis. These results suggest that N-cadherin and alphaN-catenin expressions are elevated in the degeneration/regeneration processes of the muscle after nerve injury, but that the kinetics between the two proteins differ.