Characterization of peri-implant bone tissue in hypertensive and estrogen-deficient rats after the synergistic action of losartan and alendronate sodium

Abstract

This study aims to characterize morphologically and structurally the tissue produced at the bone-implant interface in spontaneously hypertensive ovariectomized rats that will have implants placed in their tibiae, and to analyze how the associated treatment of systemic losartan and local sodium alendronate might influence the peri-implant bone healing. Material and methods: 96 spontaneously hypertensive adult rats submitted to ovariectomy (OVX) or sham surgery (SHAM). Thirty days after these surgeries, an implant will be placed on a tibia of each animal. The analyzes will be divided into three groups: Biomechanics and molecular, calcified tissues and decalcified tissues. In the Biomechanical and molecular group, eight tibias will be used for the biomechanical evaluation by removal torque. After removal of the implants, the peri-implant bones will be harvested for real-time PCR analysis. In the calcified tissues group, eight tibias will be used in the analysis of micro computerized tomography to evaluate bone volume, number of trabeculae, separation between trabeculae and trabecular thickness. Afterwards they will be processed in the EXAKT system, then the epifluorescence microscopy will be done to evaluate the bone dynamics of the calcein and alizarin fluorochromes. Finally, histometric analysis by means of Stevenel blue and alizarin red staining, for the measurement of the linear of bone-implant contact and the area of newly formed bone. In the decalcified tissues group, eight tibias will be submitted to immunohistochemical analysis with antibodies against osteoprotegerin (OPG), activator of nuclear kappa B ligand receptor (RANKL), osteocalcin (OC), Vascular Endothelial Growth Factor (VEGF), and adhesion molecule platelet endothelial cell (PECAM-1). Another part of the slides will be used for histological analysis, with evaluation of bone maturation, presence of inflammatory process and cellular morphology. Within the groups of analyzes, the animals will be divided into subgroups, as submitted to ovariectomy surgery or sham surgery, and whether submitted to the implants placement treated with alendronate sodium (ALE). In all subgroups losartan 30 mg / kg v.o will be administered for seven days prior to implant placement until euthanasia. Therefore, the subgroups will be SHR SHAM, SHR SHAM ALE, SHR OVX and SHR OVX ALE. All the quantitative results will be submitted to statistical analysis adopting a level of significance of 5%. (AU)