CHANGES IN INNERVATION OF LONG BONES AFTER INSERTION OF AN IMPLANT - IMMUNOCYTOCHEMICAL STUDY IN GOATS WITH ANTIBODIES TO CALCITONIN-GENE-RELATED PEPTIDE AND B-50 GAP-43/

In this study, we describe the distribution of fibres that contain cal citonin gene-related peptide in normal bones and in bones that are rem odeling after insertion of an implant. With routine histology and anti bodies to calcitonin gene related peptide, small neural and free-runni ng fibres staining positively for calcitonin gene-related peptide were found in the periosteum, endosteum, and cortical bone of the tibia in the goat. In many cases, the free-running fibres were associated with blood vessels that entered the bone through Volkmann's canals. The en dosteal blood supply was destroyed as a result of insertion of the imp lant. The necrotic bone was no longer innervated, as shown by the lack of staining for the antibodies. At 6 weeks, a repair phase started wi th revascularization and remodeling of the necrotic endosteal bone. Du ring this repair phase, there was increased innervation with fibres co ntaining calcitonin gene-related peptide in the remodeling cavities at the interface between living and necrotic bone. These fibres ended bl indly, with many large varicosities, and could be demonstrated by immu nostaining with monoclonal antibodies to B-50/growth associated protei n-43, an antibody to outgrowing neuronal fibres. The correlative occur rence between extensive sprouting of fibres containing calcitonin gene -related peptide and the remodeling of necrotic endosteal bone suggest s that sensory fibres with calcitonin gene-related peptide have a regu latory role in the control of angiogenesis or of bone remodeling assoc iated with the insertion of an implant, or with both processes.