Lespine A, Periquet B, Jaconi S, Alexandre M C, Garcia J, Ghisolfi J, Thouvenot J P, Siegenthaler G
Groupe d'Etudes en Nutrition Infantile, Hôpital Purpan, Toulouse, France.
J Lipid Res. 1996 Dec;37(12):2492-501.
Perfusion feeding in rats induced a decrease in circulating retinol despite an adequate supply of vitamin A. We studied the effect of total parenteral nutrition (TPN) on the retinol specific carrier in rat, analyzing holo-RBP (bound to retinol) and apo-RBP (without retinol) in serum and in liver. Vitamin A-sufficient (A+) and -deficient (A-) rats were characterized in terms of vitamin A and RBP status and then perfused (TPN-A+ and TPN-A-) or orally pair-fed (O-A+ and O-A-) with vitamin A. In A+ rats, a decrease in serum retinol (2.6-fold) and an increase in apo-RBP was concomitant with a massive accumulation of RBP in the liver. In TPN-A rats, both circulating RBP and liver total RBP were decreased. In TPN-A+ rats, there was a decrease in circulating retinol (2.4-fold) in parallel to a decrease of serum and liver RBP protein and mRNA. We provide evidence that infused retinyl palmitate was not responsible for serum retinol and RBP decrease and that retinol depletion was not due to vitamin A deficiency. Whatever the vitamin A status, TPN may induce in rats a down-regulation of hepatic RBP synthesis, which may, at least partially, explain the alteration of retinol and RBP in serum.
尽管维生素A供应充足，但大鼠的灌注喂养仍导致循环视黄醇减少。我们研究了全胃肠外营养（TPN）对大鼠视黄醇特异性载体的影响，分析了血清和肝脏中全RBP（与视黄醇结合）和脱辅基RBP（无视黄醇）。根据维生素A和RBP状态对维生素A充足（A+）和缺乏（A-）的大鼠进行表征，然后用维生素A进行灌注（TPN-A+和TPN-A-）或口服配对喂养（O-A+和O-A-）。在A+大鼠中，血清视黄醇降低（2.6倍）和脱辅基RBP增加与肝脏中RBP的大量积累同时发生。在TPN-A大鼠中，循环RBP和肝脏总RBP均降低。在TPN-A+大鼠中，循环视黄醇降低（2.4倍），同时血清和肝脏RBP蛋白及mRNA也降低。我们提供的证据表明，输注的棕榈酸视黄酯与血清视黄醇和RBP降低无关，视黄醇消耗也不是由于维生素A缺乏所致。无论维生素A状态如何，TPN均可诱导大鼠肝脏RBP合成下调，这可能至少部分解释了血清中视黄醇和RBP的改变。
