Expression of alpha, beta, and gamma catenins in vascularized and nonvascularized nerve grafts during the regeneration process.

The authors investigated the expression of three kinds of catenins (alpha, beta, gamma) in vascularized and non-vascularized nerve grafts, using the rat sciatic nerve model. The vascularized nerve, 15 mm in length, was elevated with its nutrient vessels in the left hindlimb of rats. In the right hindlimb, a 15-mm segment of the sciatic nerve was elevated (resected) without the nutrient vessels as a non-vascularized nerve. Both nerves were sutured to the original site. At various periods up to 14 weeks after operation, the entire graft was removed. Expression of three catenins was detected by Western blot analysis and histochemical staining, using the antibody to each catenin. The level of beta catenin increased during nerve regeneration in both the vascularized and non-vascularized grafts, while the level of alpha and gamma catenins did not increase in both grafts. There was no difference in the level of the three catenins between the two methods of nerve grafting. Histochemical findings showed that at the 4th and 14th postoperative weeks, alpha and gamma catenins were stained diffusely in both grafts, while beta catenin was stained around the regenerating axons in both grafts. The degree of beta catenin was greater in the 4th postoperative week than in the 14th postoperative week, but no obvious difference in the degree of staining of the three catenins between two grafts was found. These results suggest that beta catenin may play a different role from alpha and gamma catenins in nerve regeneration, and that the expression of these catenins is not influenced by vascularization of the nerve graft.