Buffenstein R, Jarvis J U, Opperman L A, Cavaleros M, Ross F P, Pettifor J M
Department of Physiology, Medical School, University of the Witwatersrand, Parktown, South Africa.
Eur J Endocrinol. 1994 Apr;130(4):402-9. doi: 10.1530/eje.0.1300402.
Mole-rats (Family Bathyergidae) have no obvious source of calciol. They live in an environment devoid of sunlight and consume a herbivorous diet. Calciol status, metabolism and expression were examined in six species of Bathyergids. Serum levels of calcidiol in all species were < 5 micrograms/l and those of calcitriol were low (18.0 +/- 11.0 (SD) ng/l, N = 57) when compared to other rodents. Within 72 h of injecting animals with tritium-labelled calciol, most of the labelled prohormone had been metabolized to more polar metabolites. Three times more tritium-labelled calcitriol (19.3 +/- 2.9%) was present than (24R)-hydroxycalcidiol (6.2 +/- 10%). The natural absence of detectable circulating concentrations of calcidiol and the threefold greater amount of calcitriol to (24R)-hydroxycalcidiol produced indicate that calciol naturally is in short supply. Calciol-dependent calbindins were absent in the duodenum. Calbindin-D28k was present in the Purkinje cells of the cerebellum and in some collecting ducts and proximal and distal convoluted tubules of the kidney. Calbindin-D9k also was present but was localized uniquely in the juxtaglomerular cells of the five southern African species. These data confirm that Bathyergid mole-rats naturally have an impoverished calciol status. Despite the presence of calbindins in renal tissues, the functional importance of this hormone in calbindin synthesis and other normal mole-rat physiology is not known.
裸鼹鼠（滨鼠科）没有明显的骨化二醇来源。它们生活在没有阳光的环境中，以草食性食物为食。对六种滨鼠科动物的骨化二醇状态、代谢和表达进行了检测。与其他啮齿动物相比，所有物种的血清骨化二醇水平均<5微克/升，血清骨化三醇水平较低（18.0±11.0（标准差）纳克/升，N = 57）。给动物注射氚标记的骨化二醇后72小时内，大部分标记的激素原已代谢为极性更强的代谢产物。存在的氚标记骨化三醇（19.3±2.9%）是（24R）-羟基骨化二醇（6.2±10%）的三倍。自然情况下无法检测到循环中的骨化二醇浓度，且骨化三醇与（24R）-羟基骨化二醇的生成量之比为三倍，这表明骨化二醇天然供应不足。十二指肠中不存在依赖骨化二醇的钙结合蛋白。钙结合蛋白-D28k存在于小脑的浦肯野细胞以及肾脏的一些集合管、近端和远端曲管中。钙结合蛋白-D9k也存在，但仅定位于五个南部非洲物种的球旁细胞中。这些数据证实，滨鼠科裸鼹鼠自然情况下骨化二醇状态不佳。尽管肾组织中存在钙结合蛋白，但这种激素在钙结合蛋白合成和裸鼹鼠其他正常生理过程中的功能重要性尚不清楚。
