果糖过量摄入对青春期大鼠骨骼发育影响及机制研究

Adolescences, as an important consumer groups of fructose-rich food like soft drinks, sweets and so on, intake large amounts of fructose. It has been proven that excessive fructose intake and adolescent obesity has a close relationship. Research suggests that large amounts of fructose has a negative regulatory role on adolescence bone development, but the mechanism remains unclear. Our previous work found that adolescent rats which intook excessive fructose possessed lower bone mineral density than the normal diet of control group. It was also found that excessive fructose intake may regulate the bone growth and development by Wnt signaling pathway. And our another work first time confirmed that the tyrosine phosphatase-1 (SHP1) could regulate bone osteogenesis of mesenchymal stem cells differentiation by adjusting Wnt pathways. This project intends to adopt the method of both animal and cell experiment。 After setting the different doses of fructose intake group, the excessive fructose intake influences on adolescent rats bone growth and development were explored. The influences of excessive fructose intake on the SHP1 and Wnt/beta-catenin signaling pathways were also analsysed, thus illustrating the mechanism of fructose intake on the inhibition of adolescence bone growth and development. This study is expected to provide data support for fully understanding the effects of fructose to the body health, as well as to provide theoretical basis for adolescent bone dietary guidance.

青春发育期青少年作为软饮料、甜品等富含果糖食品的重要消费群体，其大量果糖摄入已被证明与青少年肥胖等具有密切关系。有研究提示，大量果糖摄入对青春期机体骨骼发育具有负调节作用，但机制尚不清楚。申请人前期研究发现，果糖过量摄入的青春期大鼠骨密度低于正常饮食的对照组，同时发现果糖过量摄入可能通过Wnt信号通路调节机体骨组织生长发育。而项目组前期研究首次证实酪氨酸磷酸酶-1（SHP1）能够通过调节Wnt通路进而调节骨间充质干细胞的成骨分化。本项目拟采用动物实验和细胞实验相结合的方法，通过设置不同剂量的果糖摄入组，探讨果糖过量摄入对青春期大鼠骨骼生长发育的影响，分析其对SHP1以及Wnt／β-catenin信号通路的作用，进而阐明果糖过量摄入抑制青春期机体骨骼生长发育的机制，该研究结果有望为全面了解果糖对机体健康影响提供数据支持，为青春期骨骼发育膳食指导提供理论依据。

青春发育期人群作为软饮料、甜品等富含果糖食品的重要消费群体，其大量果糖摄入已被证明与青少年肥胖及骨骼发育等具有密切关系。本项目拟通过动物实验，探究果糖摄入对青春期机体骨骼发育的影响及潜在机制。按照项目设计，本研究选取3周龄雄性SD大鼠，给予10%和20%果糖水溶液自由饮用，同时以正常饮水和葡萄糖水溶液作为对照组。通过10周的喂养，20%果糖组大鼠骨骼微结构表现显著差于对照组和10%糖水组。按照项目设计进行骨组织SHP1蛋白表达检测显示，果糖过量摄入组与对照组和葡萄糖组SHP1的表达量没有显著差异，说明原项目科学假设“果糖过量摄入通过抑制SHP1的表达，从而抑制其对Wnt／β-catenin信号通路的调节作用，最终抑制青春期机体骨骼发育。”不成立。项目根据结果尝试探索新的机制，并将研究焦点聚焦于“肠骨轴”。通过对各组大鼠盲肠内容物菌群测序发现，果糖摄入组大鼠肠道菌群稳态存在差异，过量摄入果糖降低了瘤胃球菌科(Ruminococcaceae)的相对丰度，增加了乳酸菌(Lactobacillus)的相对丰度。而额外的葡萄糖摄入增加了拟杆菌(Bacteroides)的相对丰度。有趣的是，额外的果糖摄入量增加了梭菌(Clostridium)的相对丰度，而额外的葡萄糖摄入量则减少了该菌属的相对丰度。通过KEGG通路推断发现能量代谢途径变化可能为其潜在机制。为了进一步验证该机制，通过中心碳代谢产物检测分析发现各组大鼠能量代谢发生了不同的变化。果糖1,6二磷酸和二羟丙酮磷酸在果糖组不仅高于对照组，同时也高于葡萄糖组。而相反，柠檬酸和苏氏异柠檬酸的水平在葡萄糖组相较于对照组和果糖组呈现上升的趋势。通过骨代谢标记物检测发现，虽然骨吸收标记物在葡萄糖和果糖组均低于对照组，但骨形成标记物在果糖组表达显著低于葡萄糖组。因此，项目组推断果糖过量摄入可能通过改变肠道菌群组成，影响青春期机体能量代谢，最终抑制骨组织成骨分化，抑制骨骼发育。该研究结果为青春期控制软饮料、甜品等的摄入提供了数据支持，为青春期骨骼发育膳食指导提供理论依据。