| Summary: | 碩士 === 國立中興大學 === 生命科學系所 === 101 === Osteoporosis is a disease characterized by low bone mass and structural deterioration of bone tissue, leading to bone embrittle and increase fractures risk .The incidence of osteoporosis increases with age and occurs most frequently in postmenopausal women due to estrogen deficiency, as the balance between bone resorption and bone-formation shifts towards increased levels of bone-resorption. among various preventions and cures for osteoporosis .An increase in calcium intake is the most commonly recommended preventive. kefir product is a kind of fermented dairy products made with kefir grains. Fermentation of milk causes degradation of milk proteins into various peptides with health-promoting effects including immunomodulating, antithromobotic calcium-absorption enhancing, and antimicrobial bioactivities. In previous study, the effects of these fermented milk products were benefits on bone metabolism in growing and aged rat models. The aim of this study is to investigate kefir’s effect on osteo-protection. Experiments were divided into two part. Firstly, we using Caco-2 in vitro cell model to assess the effects of kefir product on the calcium uptake, the changes in cytosolic calcium concentration before and after kefir addition analyzed by a fluorometric system using fluo-3 as the Ca2+-sensing probe. Secondly, fifty-six 16-week-old female Sprague-Dawley rats were divided into 7 groups: Sham (normal), Ovariectomized rats (OVX; negative control), OVX rats treated with kefir product of graded doses (dose translation from human to rat, 1X, 2X and 4X, kefir body weight/day), Alendronate 2.5 (OVX/ALN), Rebone (OVX/Rebone) 800 mg/kg body weight per day for 12 weeks. Sham group were treated with phosphate buffered saline. Serum alkaline phosphatase (ALP) and C-terminal telopeptide of type I collagen (CTX) were assessed as the bone turnover markers. Trabecular bone mineral density (BMD) and bone volume (BV/TV), trabecular thickness degree (Tb. Th), trabecular number (Tb.N), trabecular separation (Tb. Sp. ) were determined from distal femurs using a desktop μ-CT system. The mechanical properties (hardness and modulus) of the distal femur were calculated from nanoindentation. Our results showed that kefir product could increase human intestine-like Caco-2 cell calcium uptake. Biochemical markers showed that kefir product treatment groups reduced resorption marker CTX versus OVX group (p < 0.05). Micro-CT data showed that kefir product treatment groups had higher trabecular bone volume/tissue volume (BV/TV) and bone mineral density (BMD) versus OVX group (p < 0.05). Biomechanical data also showed that kefir treatment groups maintained bone stiffness, and hence resistance against breaking. In conclusion, kefir treatment increased calcium uptake in human intestine-like Caco-2 cell model. Oral administration of kefir product in ovariectomized rats could significantly decreased levels of bone turnover markers and prevent ovariectomy-induced bone loss, deterioration of trabecular microarchitecture, and biomechanical reduction .
|
|---|
