Center of Calcium and Bone Research (COCAB Faculty of Science, Mahidol University, Bangkok, Thailand;
Am J Physiol Endocrinol Metab. 2014 Jan 15;306(2):E177-88. doi: 10.1152/ajpendo.00556.2013. Epub 2013 Dec 3.
During lactation, osteoclast-mediated bone resorption and intestinal calcium hyperabsorption help provide extra calcium for lactogenesis. Since the suckling-induced surge of pituitary prolactin (PRL) rapidly stimulates calcium absorption in lactating rats, it is hypothesized that pre-suckling oral calcium supplementation should be an efficient regimen to shift the calcium source from bone to diet, thereby slowing lactation-induced osteopenia. Our results showed that 30-min suckling markedly stimulated maternal duodenal calcium transport, which returned to the baseline at 45 min. Lactating rats given 4 mg/kg per dose calcium via a gavage tube at 90 min pre-suckling 4 doses a day for 14 days prevented a decrease in bone mineral density (BMD) of long bones and vertebrae. On the other hand, a single-dose supplementation, despite the same amount of calcium per day, appeared less effective. Because glucose and galactose further stimulated duodenal calcium transport in lactating rats, pre-suckling calcium supplement containing both sugars successfully normalized plasma ionized calcium and led to better bone gain than that with calcium alone. A histomorphometric study revealed that lactating rats given pre-suckling calcium plus monosaccharide supplement manifested greater trabecular bone volume and thickness and exhibited less eroded surface than in vehicle-treated lactating rats. Beneficial effects of the 14-day calcium supplementation persisted until 6 mo postweaning in dams and also elevated the baseline BMD of the offspring. In conclusion, our proof-of-concept study has corroborated that pre-suckling calcium supplements, especially regimens containing monosaccharides, are efficient in preventing osteopenia in lactating rats and could increase bone density in both breastfeeding mothers and neonates.
哺乳期时，破骨细胞介导的骨吸收和肠道钙高吸收有助于为泌乳提供额外的钙。由于吮吸引起的垂体泌乳素（PRL）激增可迅速刺激哺乳期大鼠的钙吸收，因此假设在吮吸前口服补钙应是一种有效的方案，可将钙源从骨骼转移到饮食中，从而减缓哺乳期引起的骨质疏松症。我们的结果表明，30 分钟的吮吸可明显刺激母体十二指肠钙转运，45 分钟后恢复到基线。在吮吸前 90 分钟通过胃管给予哺乳期大鼠每天 4 次，每次 4 毫克/公斤剂量的钙，持续 14 天，可防止长骨和椎体的骨密度（BMD）下降。另一方面，单次补充剂，尽管每天的钙量相同，但效果似乎较差。由于葡萄糖和半乳糖进一步刺激哺乳期大鼠十二指肠钙转运，因此含有这两种糖的吮吸前钙补充剂可成功使血浆离子钙正常化，并导致骨量增加优于仅用钙补充剂。组织形态计量学研究表明，与给予载体的哺乳期大鼠相比，给予吮吸前钙加单糖补充剂的哺乳期大鼠表现出更大的小梁骨体积和厚度，并且侵蚀表面更少。14 天钙补充的有益作用一直持续到哺乳期后 6 个月，并提高了后代的基线 BMD。总之，我们的概念验证研究证实，吮吸前钙补充剂，特别是含有单糖的方案，可有效预防哺乳期大鼠的骨质疏松症，并可提高哺乳期母亲和新生儿的骨密度。
