Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Foundation, Hannover30173, Germany.
Institute of Animal Nutrition and Dietetics, Vetsuisse Faculty Zurich, University of Zurich, Zurich8057, Switzerland.
Br J Nutr. 2024 Oct 14;132(7):874-886. doi: 10.1017/S0007114524002150. Epub 2024 Oct 15.
Ruminants can recycle nitrogen (N) and phosphorus (P), which are essential for vital body processes. Reduced N- and P-intake in ruminants is desirable for economic and ecologic reasons. Simultaneous modulation of mineral homoeostasis and bone metabolism occurs in young goats. This study aimed to investigate potential effects of dietary N- and/or P-restriction on molecular changes in bone metabolism. The twenty-eight young male goats were fed a control diet, an N-reduced diet, a P-reduced diet or a combined N- and P-reduced diet for 6-8 weeks. The N-restricted goats had lower plasma Ca concentration and higher plasma osteocalcin (OC) and CrossLaps concentrations. The P-restricted goats had reduced plasma inorganic phosphate (P) concentrations and increased plasma Ca concentrations. Due to the initiation of a signalling pathway that inhibits the fibroblast growth factor 23 (FGF23) expression, this was lower with P-restriction. Consequently, lower P concentrations were the main factor influencing the reduction in FGF23. The changes in mineral homoeostasis associated with P-restriction led to a reduction in OC, bone mineral content and mineral density. Simultaneously, bone resorption potentially increased with P-restriction as indicated by an increased receptor activator of NF-κB ligand/osteoprotegerin (OPG) ratio and an increase in OPG mRNA expression. Additionally, the increased mRNA expression of the calcitonin receptor during P-restriction points to a higher number of osteoclasts. This study demonstrates an impairment of bone remodelling processes in young goats by N- or P-restriction. With P-restriction, bone mineralisation rate was potentially reduced and bone quality impaired, while with N-restriction, bone remodelling increased.
反刍动物可以回收氮 (N) 和磷 (P)，这是生命过程所必需的。出于经济和生态原因，反刍动物减少 N 和 P 的摄入量是可取的。在年轻山羊中，矿物质稳态和骨代谢同时发生调节。本研究旨在研究饮食 N 和/或 P 限制对骨代谢分子变化的潜在影响。28 只年轻雄性山羊分别用对照日粮、N 减少日粮、P 减少日粮或 N 和 P 联合减少日粮饲养 6-8 周。N 限制组山羊的血浆 Ca 浓度较低，而血浆骨钙素 (OC) 和 CrossLaps 浓度较高。P 限制组山羊的血浆无机磷 (P) 浓度降低，血浆 Ca 浓度升高。由于抑制成纤维细胞生长因子 23 (FGF23) 表达的信号通路的启动，P 限制时 FGF23 减少。因此，较低的 P 浓度是影响 FGF23 减少的主要因素。与 P 限制相关的矿物质稳态变化导致 OC、骨矿物质含量和矿物质密度降低。同时，由于受体激活因子 NF-κB 配体/骨保护素 (OPG) 比值增加和 OPGmRNA 表达增加，P 限制导致骨吸收潜在增加。此外，P 限制时降钙素受体的 mRNA 表达增加表明破骨细胞数量增加。本研究表明，N 或 P 限制会损害年轻山羊的骨重塑过程。P 限制时，骨矿化率可能降低，骨质量受损，而 N 限制时，骨重塑增加。
