Department of Animal Science, Chungbuk National University, Cheongju, Chungbuk, 361-763, Republic of Korea.
Amino Acids. 2014 Feb;46(2):353-66. doi: 10.1007/s00726-013-1622-x. Epub 2013 Dec 11.
Based on previous research with bovine peadipocytes, we hypothesized that infusion of arginine into the abomasum of Angus steers stimulates stearoyl-CoA desaturase (SCD) gene expression in bovine subcutaneous (s.c.) adipose tissue, and that this would be attenuated by conjugated linoleic acid (CLA). Growing Angus steers were infused abomasally with L-arginine 50 g/day; n = 13; provided as L-arginine HCl) or L-alanine (isonitrogenous control, 100 g/day; n = 11) for 14 days. For the subsequent 14 days, half of the steers in each amino acid group were infused with CLA (100 g/day). Body weight gain and average daily gain were unaffected (P > 0.15) by infusion of arginine or CLA into the abomasum. The plasma concentrations of cis-9, trans-11 and trans-10, cis-12 CLA were increased CLA infusion (P = 0.001) and infusion of arginine increased plasma arginine (P = 0.01). Compared with day 0, fatty acid synthase, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase enzyme activities in s.c. adipose tissue increased by day 14 in steers infused with either alanine or arginine (all P < 0.01). NADP-MDH activity was higher (P = 0.01) in steers infused with arginine than in steers infused with arginine plus CLA by day 28, but lipid synthesis in vitro from glucose and acetate was unaffected by infusion of either arginine or CLA (P > 0.40). By day 28, C/EBPβ and SCD gene expression was higher, and CPT1β gene expression was lower, in s.c. adipose tissue of steers infused with arginine than in steers infused with alanine (±CLA) (P = 0.05). CLA decreased adipose tissue oleic acid (18:1n-9) in alanine- or arginine-infused steers (P = 0.05), although CLA had no effect on SCD gene expression. The data indicate that supplemental arginine promotes adipogenic gene expression and may promote lipid accumulation in bovine adipose tissue. L-Arginine may beneficially improve beef quality for human consumption.
基于之前对牛前体脂肪细胞的研究，我们假设在 Angus 阉牛的皱胃中输注精氨酸会刺激牛皮下（s.c.）脂肪组织中的硬脂酰辅酶 A 去饱和酶（SCD）基因表达，而共轭亚油酸（CLA）会减弱这种作用。生长中的 Angus 阉牛每天通过皱胃输注 L-精氨酸 50 克；n = 13；提供 L-精氨酸盐酸盐）或 L-丙氨酸（等氮对照，100 克/天；n = 11）14 天。在随后的 14 天中，每个氨基酸组的一半阉牛输注 CLA（100 克/天）。精氨酸或 CLA 输注到皱胃中对体重增加和平均日增重没有影响（P > 0.15）。CLA 输注（P = 0.001）和精氨酸输注增加了血浆精氨酸（P = 0.01），使血浆中顺式-9、反式-11 和反式-10、顺式-12 CLA 的浓度增加。与第 0 天相比，输注丙氨酸或精氨酸的阉牛在第 14 天 s.c.脂肪组织中的脂肪酸合酶、葡萄糖-6-磷酸脱氢酶和 6-磷酸葡萄糖酸脱氢酶活性增加（均 P < 0.01）。NADP-MDH 活性在输注精氨酸的牛中高于输注精氨酸加 CLA 的牛（P = 0.01），但葡萄糖和醋酸盐的体外脂质合成不受精氨酸或 CLA 的影响（P > 0.40）。到第 28 天，输注精氨酸的阉牛的 C/EBPβ 和 SCD 基因表达更高，CPT1β 基因表达更低，而输注丙氨酸或 CLA 的阉牛的 s.c.脂肪组织中的 SCD 基因表达更高（±CLA）（P = 0.05）。CLA 降低了输注丙氨酸或精氨酸的阉牛的 s.c.脂肪组织中的油酸（18:1n-9）（P = 0.05），尽管 CLA 对 SCD 基因表达没有影响。数据表明，补充精氨酸可促进脂肪形成基因表达，并可能促进牛脂肪组织中的脂质积累。L-精氨酸可能有益于改善人类食用的牛肉质量。
