Comparative analysis of alveolar intramembranous bone repair in female C57BL/6 mice under stropause chemically induced by ovariectomy and aging

Abstract

After menopause, vertiginous decrease of these hormones lead to an imbalance of its remodeling capacity, leading to osteopenia and osteoporotic conditions, as well as to a deficiency in healing process. Due to the relevance of this theme, a number of studies are developed using different approaches, with special attention to animal models, which permit some manipulation that reproduce this systemic condition, even in younger animals. However, the effects of the induced menopause on bone healing process still need investigations. In this way, the present study aims to analyze and compare intramembranous bone healing after tooth extraction using female mice in physiologically, chemically and surgical induced estropause phase and ovarectomy simulation. Forty female C57BL/6J mice, ages between 4-18 months, mean weight of 30 grams, will be divided in four groups: ID - physiological post-stropause (18 months), SHAM - fictitious ovariectomy (4 months), VCD - medicated with 4 vinylcyclohexene diepoxide (VCD) 160 mg/kg/day, IP, for 20 consecutive days, (4 months), and OVX - under ovariectomy (4 months). Once persistent diestrum is confirmed, all the animals will undergo the extraction of the upper right incisor, and the time points for the analysis will be set at 7 and 21 days post-operatory. Maxillae will be scanned with microCT, and afterwards they will be decalcified for the confectioning of the histological slices stained with H&E and Goldner trichrome for histopathological and histomorphometric analysis, and with Picrosirius-red for the analysis of collagenous matrix birefringence. Immunohistochemistry will be used to investigate bone metabolism markers as TRAP, OPG, and RANKL. Biochemical analyzes will be performed by measuring the levels of calcium, phosphate, alkaline phosphatase (FAL) and total TRACP. Results will undergo statistical analysis and level of significance will be set at 5%. (AU)