Effects of NGF and TrkA on GAP-43^＋ nerve regeneration in rat autotransplanted splenic tissue

Objective:To study the time-course of the regeneration of GAP-43+ nerve, and the effects of NGF and TrkA on this process. Methods: Adult Wistar rats underwent splenectomy and splenic autotransplantation, or sham-operation. On day 7, 14, 30, 60, 90, 120, and 180 after surgery, the density of GAP-43+ nerve fibers in spleen tissues were measured with the immunohistochemistry followed by computer image analysis. The expressions of GAP-43, NGF and TrkA were determined with in situ hybrdization, and their mRNA levels were detected with RT-PCR and image analysis qualification. Results: (1)The GAP-43+ nerve fibers began their regeneration on 30 d after operation and extended from greater omentum into splenic autotransplants. Density of the nerve fibers gradually became greater and almost normal 180 d after operation. (2) In splenic autografts, the mRNA expression of GAP-43, NGF and TrkA appeared on day 30 after the operation, gradually reached the peak on day 90. Conclusion: The renascent GAP-43+ nerve fibers may come from the greater omentum packaging the splenic autografts and NGF and TrkA can promote the nerval regeneration in the autotransplant spleen tissues.