MECHANISMS OF SKELETAL RECONSTITUTION AFTER LACTATION

繁殖过程中的母体效率对物种繁殖至关重要。 哺乳动物骨骼在怀孕期间为胎儿骨骼提供矿物质，在哺乳期间为产奶提供矿物质。 在生殖周期中，母体骨骼会发生巨大变化，有些变化可能有助于保护骨骼的完整性。 哺乳期后尤其是“合成代谢”，但机制尚不清楚。 为了进一步确定在生殖周期期间和之后发生的母体骨骼适应和机制，提出了以下目标。 1）。确定从妊娠晚期到哺乳期过渡期间骨骼中的细胞和组织事件。 我们推测，在妊娠后期和哺乳期持续吸收的增加是破骨细胞形成率增加，寿命延长和细胞凋亡减少的结果。 2)确定从哺乳期到断奶后过渡期间骨骼中发生的细胞和组织事件。 假设骨形成的增加与成骨细胞形成速率的增加有关，但骨吸收的减少是破骨细胞活性降低、骨形成减少但细胞凋亡增加的结果。 3)确定断奶后降钙素（CT）水平的增加是否与骨质疏松功能降低相关，并为哺乳后恢复期建立“环境”。 我们怀疑与催乳素减少有关，但与雌激素增加和发情开始有关。 4)哺乳动物生殖周期中的重塑期是否有变化？ 这将根据具有皮质内骨重塑的物种的存档材料来确定。 5)在哺乳后的“恢复”阶段，适度的骨骼负荷是否能改善骨量、结构、强度和动力学？ 我们的假设是，在此期间，骨骼负荷将对骨骼质量和结构产生协同效应。 这些研究将提供关于成年女性骨骼生命中可能最具活力和“合成代谢”的时期的新知识，并可能为生殖能力结束后的疾病治疗提供新的见解。

Maternal efficiency during reproduction is essential for species propagation. The mammalian skeleton provides mineral for the fetal skeleton during pregnancy and milk production during lactation. Dramatic changes occur in the maternal skeleton during the reproductive cycle and some may serve to protect skeletal integrity. The post-lactation period is particularly 'anabolic', but mechanistically not understood. To further define the maternal skeletal adaptations and mechanisms that occur during and after the reproductive cycle, the following aims are proposed. 1). To determine the cellular and tissue events in the skeleton during the transition from late pregnancy to lactation. We hypothesize that the increases in resorption in late pregnancy and sustained during lactation are the result of an increased rate of osteoclast formation, prolongation of lifespan and a decrease in apoptosis. 2) To determine the cellular and tissue events in the skeleton that occur during the transition from lactation to post-weaning. The hypothesis is that increases in bone formation are associated with an increased rate of osteoblast formation but decreased resorption is the result of decreased osteoclast activity, decreased formation but increased apoptosis. 3) To determine if the post-weaning increase in calcitonin (CT) levels is correlated with decreased osteoclastic functions, and establishes the "milieu" for the post-lactational recovery phase. We suspect correlation with decreases in prolactin, but increased estrogen and initiation of estrus. 4) Is there a change in the remodeling period during the reproductive cycle in mammals? This will be determined from archived materials from a species that has intracortical bone remodeling. 5) Does moderate skeletal loading improve bone mass, structure, strength and dynamics during the post-lactation 'recovery' phase? Our hypothesis is that skeletal loading will have synergistic effects on skeletal mass and structure during this period. These studies will provide new knowledge on perhaps the most dynamic and "anabolic" period in the life of the adult female skeleton and may provide new insights into treatments of diseases after reproductive capacity has ended.