Motta Glen E, Jackson Evelyn M, Klein Marissa L, Shan Hui, Pang Jihai, Wilson William K, McMahan C Alex
Department of Pathology, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA.
Lipids. 2003 Dec;38(12):1213-20. doi: 10.1007/s11745-003-1181-y.
We tested the hypothesis that breast- vs. formula-feeding differentially affects the enzymatic activity of three sterol hydroxylases critical in the initial steps of bile acid formation. Thirty baboons were either breast-fed or formula-fed for the first 14 wk of life before weaning to baboon chow. At 14 and 34 wk of age, liver biopsies were assayed for cholesterol 7alpha-hydroxylase (CYP7A1), 27-hydroxycholesterol-7alpha-hydroxylase (CYP7B1), and cholesterol 27-hydroxylase (CYP27A1). We also determined the kinetics of 3H-27-hydroxycholesterol (27-OHC) turnover in vivo at both ages. At 14 wk of age, hepatic CYP7A1 activity was low but sevenfold higher among formula-fed vs. breast-fed baboons. By 34 wk, CYP7A1 activity had increased nearly 10-fold in both infant diet groups, and the sevenfold difference in CYP7A1 between previously breast- and formula-fed animals persisted. There were no differences in CYP7B1 activities between infant diet groups at either 14 or 34 wk of age although the activity increased in both groups by about 50% from 14 to 34 wk. CYP27A1 activity also increased between 14 and 34 wk of age, and, compared with CYP7A1, relatively small differences in CYP27A1 activity due to infant diet were observed at each age. Plasma 27-OHC turnover had a half-time of 2-4 min. We had previously reported that after weaning, the total bile acid synthesis rate was higher among baboons that were formula-fed than among breast-fed animals. The present results suggest that this difference is most likely due to significantly higher CYP7A1 activity among formula-fed vs. breast-fed animals.
母乳喂养与配方奶喂养对胆汁酸形成初始步骤中起关键作用的三种甾醇羟化酶的酶活性有不同影响。30只狒狒在出生后的前14周内分别采用母乳喂养或配方奶喂养，之后断奶改喂狒狒食物。在14周龄和34周龄时，对肝脏活检样本进行胆固醇7α-羟化酶（CYP7A1）、27-羟胆固醇-7α-羟化酶（CYP7B1）和胆固醇27-羟化酶（CYP27A1）的检测。我们还测定了这两个年龄段的3H-27-羟胆固醇（27-OHC）在体内的周转率。在14周龄时，肝脏CYP7A1活性较低，但配方奶喂养的狒狒中该活性比母乳喂养的高7倍。到34周时，两个婴儿饮食组的CYP7A1活性均增加了近10倍，之前母乳喂养和配方奶喂养的动物之间CYP7A1活性的7倍差异依然存在。在14周龄和34周龄时，婴儿饮食组之间的CYP7B1活性均无差异，不过两组的活性从14周龄到34周龄均增加了约50%。CYP27A1活性在14周龄到34周龄之间也有所增加，并且与CYP7A1相比，在每个年龄段观察到的因婴儿饮食导致的CYP27A1活性差异相对较小。血浆27-OHC周转率的半衰期为2 - 4分钟。我们之前曾报道，断奶后，配方奶喂养的狒狒的总胆汁酸合成率高于母乳喂养的动物。目前的结果表明，这种差异很可能是由于配方奶喂养的动物中CYP7A1活性显著高于母乳喂养的动物。
