■骨质疏松和相关骨折,体力活动减少,代谢功能障碍是绝经后妇女严重的健康问题。大豆蛋白由于其生物活性成分的累加或协同作用,可能会抵消绝经对骨骼和代谢健康的负面影响。
为了评估卵巢切除术(OVX)和大豆蛋白饮食(SOY)对女性骨骼结局的影响,选择性饲养低有氧运动(LCR)大鼠作为更年期模型。
■在27周龄时,LCR大鼠(N=40)接受了OVX或假手术(SHAM),并被随机分配到两种等热量和等氮植物蛋白为基础的饮食治疗中的一种:1)大豆蛋白(大豆;豆粕);或者,2)控制(CON,玉米麸质粉),导致四个治疗组。在为期30周的饮食干预期间,动物可以随意获取食物和水;每周测量体重和食物摄入量。完成为期30周的干预后,使用EchoMRI测量身体成分;动物禁食过夜,安乐死,收集血液和后肢。骨形成的血浆标志物(骨钙蛋白,OC;I型前胶原的N端前肽,P1NP)和再吸收(抗酒石酸酸性磷酸酶,TRAP5b;I型胶原的C末端端肽,CTx)使用ELISA测量。使用μCT评估胫骨骨小梁微结构和皮质几何形状;并使用扭转载荷来评估皮质生物力学特性。使用荧光测定法测量股骨的晚期糖基化终产物(AGE)含量,并且相对于通过比色OH-脯氨酸测定法测量的胶原蛋白含量来表达。双因素方差分析或ANOVCA用于测试卵巢状态的显着主要和交互影响(OVSTAT:OVX与SHAM)和饮食(大豆与CON);最终体重作为体重依赖性皮质几何形状和生物力学特性的协变量。
■OVX的CTx明显高于SHAM;SOY不影响骨转换标志物。OVX对小梁微结构产生不利影响,BV/TV降低证明了这一点,小梁厚度(Tb.Th),骨小梁数(Tb.N),和连接密度(康涅狄格州。D),并通过增加小梁分离(Tb。Sp)和结构模型指数(SMI)。SOY仅在卵巢完整的动物中增加BV/TV。OVX或SOY对胫骨皮质几何形状没有影响。在SHAM和OVX大鼠中,SOY显着提高了全骨强度和刚度;SOY还增加了组织水平的刚度,并倾向于增加组织水平的强度(p=0.067)。OVX或SOY对AGE含量没有影响。
■大豆蛋白改善雌性低适应大鼠皮质骨生物力学特性,无论卵巢激素状态。
BACKGROUND: Osteoporosis and related fractures, decreased physical activity, and metabolic dysfunction are serious health concerns for postmenopausal women. Soy protein might counter the negative effects of menopause on bone and metabolic health due to the additive or synergistic effects of its bioactive components.
OBJECTIVE: To evaluate the effects of ovariectomy (OVX) and a soy-protein diet (SOY) on bone outcomes in female, low-capacity running (LCR) rats selectively bred for low aerobic fitness as a model of menopause.
METHODS: At 27 weeks of age, LCR rats (N = 40) underwent OVX or sham (SHAM) surgery and were randomized to one of two isocaloric and isonitrogenous plant-protein-based dietary treatments: 1) soy-protein (SOY; soybean meal); or, 2) control (CON, corn-gluten meal), resulting in four treatment groups. During the 30-week dietary intervention, animals were provided ad libitum access to food and water; body weight and food intake were measured weekly. At completion of the 30-week intervention, body composition was measured using EchoMRI; animals were fasted overnight, euthanized, and blood and hindlimbs collected. Plasma markers of bone formation (osteocalcin, OC; N-terminal propeptide of type I procollagen, P1NP) and resorption (tartrate-resistant acid phosphatase, TRAP5b; C-terminal telopeptide of type I collagen, CTx) were measured using ELISA. Tibial trabecular microarchitecture and cortical geometry were evaluated using μCT; and torsional loading to failure was used to assess cortical biomechanical properties. Advanced glycation end-product (AGE) content of the femur was measured using a fluorimetric assay, and was expressed relative to collagen content measured by a colorimetric OH-proline assay. Two-factor ANOVA or ANOVCA was used to test for significant main and interactive effects of ovarian status (OV STAT: OVX vs. SHAM) and DIET (SOY vs. CON); final body weight was included as a covariate for body-weight-dependent cortical geometry and biomechanical properties.
RESULTS: OVX had significantly greater CTx than SHAM; SOY did not affect bone turnover markers. OVX adversely affected trabecular microarchitecture as evidenced by reduced BV/TV, trabecular thickness (Tb.Th), trabecular number (Tb.N), and connectivity density (Conn.D), and by increased trabecular separation (Tb.Sp) and structural model index (SMI). SOY increased BV/TV only in ovary-intact animals. There was no effect of OVX or SOY on tibial cortical geometry. In SHAM and OVX rats, SOY significantly improved whole-bone strength and stiffness; SOY also increased tissue-level stiffness and tended to increase tissue-level strength (p = 0.067). There was no effect of OVX or SOY on AGE content.
CONCLUSIONS: Soy protein improved cortical bone biomechanical properties in female low-fit rats, regardless of ovarian hormone status.