Effect of dietary phosphorus intake and age on intestinal phosphorus absorption efficiency and phosphorus balance in male rats.
Effect of dietary phosphorus intake and age on intestinal phosphorus absorption efficiency and phosphorus balance in male rats.
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DOI：
10.1371/journal.pone.0207601
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发表时间：
2018
期刊：
影响因子：
3.7
通讯作者：
Hill Gallant KM
中科院分区：
文献类型：
--
作者：
Vorland CJ;Lachcik PJ;Aromeh LO;Moe SM;Chen NX;Hill Gallant KM
肠道磷吸收是全身磷代谢的重要组成部分，限制膳食磷吸收作为慢性肾病患者治疗矿物质骨紊乱的治疗靶点尤其值得关注。然而，肠道磷吸收的机制和调控尚未得到充分的研究，并且基于吸收评估技术的结果存在差异。体外实验显示，膳食磷摄入水平和年龄对肠道钠依赖性磷酸盐转运的影响相当一致。但是，少数使用体内技术的研究与这些体外研究相冲突。因此，本研究采用原位结扎环法研究了不同年龄大鼠日粮磷摄入水平对磷吸收的影响。雄性Sprague-Dawley大鼠（n = 72）在10、20和30周龄时分别饲喂低（0.1%）、正常（0.6%）或高（1.2%）磷饲料，采用3 × 3因子设计（n = 8/组）。采用33P放射性同位素，在空肠结扎环吸收试验之前，给大鼠喂食指定的饮食2周。用代谢笼测定祭祀前最后4天的钙磷平衡，并在祭祀时采血进行生化。我们的研究结果表明，与20周龄和30周龄的大鼠相比，10周龄大鼠的磷吸收量更高，这与主要磷酸盐转运体NaPi-2b的基因表达更高，以及更高的全身磷平衡和净磷吸收量有关。饲粮磷摄入水平不影响空肠磷吸收和NaPi-2b基因表达。我们的结果与使用体外技术的研究结果形成对比，但证实了其他使用原位或体内方法的啮齿动物研究的结果。因此，需要进一步的研究，采用更多的生理方法的磷吸收评估。
Intestinal phosphorus absorption is an important component of whole-body phosphorus metabolism, and limiting dietary phosphorus absorption is particularly of interest as a therapeutic target in patients with chronic kidney disease to manage mineral bone disorders. Yet, mechanisms and regulation of intestinal phosphorus absorption have not been adequately studied and discrepancies in findings exist based on the absorption assessment technique used. In vitro techniques show rather consistent effects of dietary phosphorus intake level and age on intestinal sodium-dependent phosphate transport. But, the few studies that have used in vivo techniques conflict with these in vitro studies. Therefore, we aimed to investigate the effects of dietary phosphorus intake level on phosphorus absorption using the in situ ligated loop technique in three different aged rats. Male Sprague-Dawley rats (n = 72), were studied at 10-, 20-, and 30-weeks-of-age on a low (0.1%), normal (0.6%), or high (1.2%) phosphorus diet in a 3x3 factorial design (n = 8/group). Rats were fed their assigned diet for 2-weeks prior to absorption testing by jejunal ligated loop as a non-survival procedure, utilizing 33P radioisotope. Metabolic cages were used for determination of calcium and phosphorus balance over the final four days prior to sacrifice, and blood was collected at the time of sacrifice for biochemistries. Our results show that phosphorus absorption was higher in 10-week-old rats compared with 20- and 30-week-olds and this corresponded to higher gene expression of the major phosphate transporter, NaPi-2b, as well as higher whole-body phosphorus balance and net phosphorus absorption. Dietary phosphorus intake level did not affect jejunal phosphorus absorption or NaPi-2b gene expression. Our results contrast with studies utilizing in vitro techniques, but corroborate results of other rodent studies utilizing in situ or in vivo methods. Thus, there is need for additional studies that employ more physiological methods of phosphorus absorption assessment.