Retinol binding protein 4 in dairy cows: its presence in colostrum and alteration in plasma during fasting, inflammation, and the peripartum period
Retinol binding protein 4 in dairy cows: its presence in colostrum and alteration in plasma during fasting, inflammation, and the peripartum period
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DOI：
10.1017/s0022029909990276
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发表时间：
2010-02-01
影响因子：
2.1
通讯作者：
Kimura, Kazuhiro
中科院分区：
文献类型：
--
作者：
Eldaim, Mabrouk A. Abd;Kamikawa, Akihiro;Kimura, Kazuhiro
视黄醇结合蛋白4（RBP 4）是一种参与视黄醇转运的血浆蛋白，最近在啮齿动物中的证据表明，RBP 4也是一种改变胰岛素敏感性的代谢调节剂。为了评估反刍动物中RBP 4水平是如何调节的，我们使用蛋白质印迹分析测定了牛血浆和牛奶中的RBP 4浓度。非妊娠非泌乳（对照）奶牛的血浆RBP 4水平约为45 μ g/ml，在60小时禁食期间持续，但在脂多糖（LPS）给药后4小时显著降低。基础血浆视黄醇浓度约为30微克/分升，但这下降到约三分之一和一半的这些值在禁食和LPS攻击后8小时，分别。奶牛分娩前3-6 d血浆RBP 4和视黄醇水平与对照组相当。然而，在分娩当天，两者均显著降低，并在产犊后两周恢复到基础水平。有趣的是，在初乳中清楚地检测到RBP 4（16.4 +/- 5.6 μ g/ml），但在产犊后7天和15天的奶牛的乳汁中仅微弱地检测到RBP 4。初乳中的视黄醇浓度几乎是血浆中的10倍，而乳汁中的浓度与血浆中的浓度相当。这些结果表明，RBP 4和视黄醇水平独立调节的生理和病理生理条件下，RBP 4，如视黄醇，从母体商店转移到小牛通过初乳。
Retinol-binding protein 4 (RBP4) is a plasma protein involved in retinol transportation, and recent evidence in rodents suggests that RBP4 is also a metabolic regulator that modifies insulin sensitivity. To assess how RBP4 levels are regulated in ruminants, we determined the RBP4 concentrations in bovine plasma and milk using Western blot analysis. Plasma RBP4 levels in non-pregnant non-lactating (control) cows were around 45 mu g/ml, which were sustained during 60-h fasting, but decreased significantly 4 h after lipopolysaccharide (LPS) administration. Basal plasma retinol concentration was around 30 mu g/dl, but this decreased to approximately one-third and one-half of these values during fasting and 8 h after LPS challenge, respectively. Plasma RBP4 and retinol levels in cows 3-6 d before parturition were comparable to those of the controls. However, on the day of parturition both were significantly decreased and had returned to basal levels by two weeks after calving. Interestingly, RBP4 was clearly detected in colostrum (16.4 +/- 5.6 mu g/ml) but was only faintly detected in milk from cows at 7 d and 15 d after calving. Retinol concentrations in colostrum were almost 10-fold higher than those in plasma, while those in milk were comparable to those in plasma. These results suggest that RBP4 and retinol levels are independently regulated under physiological and pathophysiological conditions and that RBP4, like retinol, is transferred from maternal stores to calves through colostrum.