Dietary Effects of Nanopowder Eggshells on Mineral Contents, Bone Turnover Biomarkers, and Regulators of Bone Resorption in Healthy Rats and Ovariectomy-Induced Osteoporosis Rat Model

Abstract

Postmenopausal osteoporosis is a critical issue for female health worldwide. This current study was designed to evaluate the role of nanopowder eggshell (NPES) in healthy and ovariectomy-induced osteoporosis rats. Fifty-six female rats were divided into healthy rats (35) and ovariectomized rats (21). The healthy rats were subdivided into five groups (G1-G5) and received one of the following treatments: saline, 20 or 40 mg/kg of calcium carbonate, and 20 or 40 mg/kg of NPES. The 21 ovariectomized rats were divided into three groups (G6-G8) and received either saline, 40 mg/kg of calcium carbonate, or 40 mg/kg of NPES. Biochemical and histopathological assessments of bone formation and resorption were performed. Biomarkers of bone formation (calcium and osteocalcin (OCN)) and calcium content in left femur ashes were significantly higher in healthy rats given 40-mg/kg NPES than in healthy control rats and healthy rats given 40-mg/kg calcium carbonate. The ovariectomized groups had significantly lower levels of vitamin D3, OCN, and osteoprotegerin (OPG) than the healthy control. Alanine transaminase (ALT), alkaline phosphatase (ALP), and receptor activator of nuclear factor-κB ligand (RANKL) were significantly increased in the ovariectomized group than in the healthy control group. Treatment with NPES and calcium carbonate reduced liver enzymes in ovariectomized rats. NPES treatment significantly increased Vit D3, OCN, OPG, and bone ash mineral content (calcium, magnesium, zinc, and phosphorus) in ovariectomized rats. NPES also increased femur cortical thickness, osteoblast number, and collagen fiber. The current study suggests that NPES can modulate bone turnover biomarkers and increase bone trace elements. Moreover, NPES alleviates bone resorption in ovariectomy-induced osteoporosis.

Keywords: Collagen fiber; Osteocalcin; Osteoporosis; Osteoprotegerin; Receptor activator of nuclear factor-κB ligand; Reused eggshells.