9 - The Effect of Raloxifene Treatment on Proximal Tibial Morphology and Bone Mineral Density in Ovariectomized Rats

Poster Board Number: 9
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Co-authors:

Jose Godoy, DVM, Ph.D - Assistant Professor, Veterinary Medicine, Long Island University

Abstract Body : Osteoporosis is a systemic skeletal disease, characterized by progressive decline of bone mass and deterioration of bone structure, that leads to reduced bone strength and an increase in the risk for bone fracture. It is triggered by bone remodeling imbalance, where bone resorption by osteoclasts exceeds bone formation by osteoblast. Raloxifene, a selective estrogen receptor modulator (SERM), is an FDA approved drug to treat osteoporosis in postmenopausal women. Raloxifene demonstrates an inhibitory effect on osteoclast and thus it decreases bone resorption and improves bone strength. In this study, we investigated the effect of oral administration of Raloxifene on rats that underwent ovariectomy (experimental group, emulating menopause, raloxifene dose 4 mg/kg/day for 15 days in nut cream, n = 5) compared to rats that underwent ovariectomy but did not receive Raloxifene (placebo group receiving nut cream alone for 15 days, n = 5). Left proximal tibiae (up to mid-diaphysis) from both groups were harvested and micro-CT scanned. After scan reconstruction and segmentation using the artificial intelligence (AI) deep learning toolbox (Dragonfly, ORS Inc.), cortical bone mineral content and cortical thickness were analyzed per slice starting distal to the tibial proximal growth plate (slice thickness = 10µm, about 1500 slices). The results revealed a statistically significant higher cortical bone mineral content (10 – 15%) along the entire studied length of the tibia (P ≤ 0.01) in the rats that received Raloxifene, indicating a protective effect of Raloxifene on bone mineral content. In addition, cortical bone thickness was higher in the rats that received Raloxifene, especially along the cranial border and the caudolateral aspect of the proximal tibiae. As life expectancy is constantly rising – the prevalence of osteoporosis increases and this in turn leads to more people suffering from skeletal fractures and a surge in economic burden. This study’s results support the ameliorative effect of Raloxifene on bone quality (cortical mineral content) as well as bone structure (cortical thickness) in tibiae from OVX rats.