Immunoexpression of RANK Ligand and Osteoprotegerin After The Local Use of the Growth Hormone in Critical-sized Defects in Rat Calvaria

Objectives: The aim of this study was to evaluate the immunoexpression of RANKL and OPG, the local effect of GH in the repair of bone defects in rat calvaria.
Methods: Seventy-two male rats were divided in three groups: Group C (control), Group E (sponge and membrane) and Group GH (GH, sponge and membrane). In the calvaria of all animals, a 5 mm critical-size defect was created. In Group C, the defects were filled only with blood clot; in Group E, defects were filled with hydrolyzed collagen sponge and covered with bovine cortical membrane; in Group GH, defects were filled with hydrolyzed collagen sponge soaked in GH and covered with bovine collagen membrane. The animals were euthanized in a postoperative of 15 or 60 days.
Results: . Descriptive immunohistochemical analysis with RANKL and OPG was performed. The results showed that Group C, 15 days, had a greater immunoreactivity of RANKL. In the other groups and postoperative times, the immunostaining was similar for both markers.
Conclusions: We conclude that the growth hormone (GH) does not favor a greater immunoreactivity of RANKL and OPG in the bone repair process when applied locally in rat calvaria.