Tews J K, Greenwood J, Pratt O E, Harper A E
Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison 53706.
J Nutr. 1988 Jun;118(6):756-63. doi: 10.1093/jn/118.6.756.
Studies were undertaken to determine if dietary disproportions of amino acids would alter flux into brain of the amino acid present in the diet in a growth-limiting concentration. Rats were adapted to a lysine-limiting diet before receiving a meal of this control diet, alone or with added lysine or homoarginine (a competitor for lysine transport) or both, before intravenous infusion of [14C]lysine. The brain-to-plasma radioactivity ratio was lower in rats fed extra lysine or homoarginine than in rats fed the control diet, whereas lysine flux and brain lysine concentration were high in rats fed extra lysine alone. Flux and concentration were lower in rats fed homoarginine + lysine than in rats fed extra lysine alone. Other rats were fed a valine-limiting diet containing added valine, norleucine (a competitor for valine transport) or both, before [14C]valine was infused. Valine flux and brain valine concentrations were higher in rats fed extra valine than in control rats, whereas flux was lower in the group fed norleucine alone. Valine flux was higher in rats fed norleucine + valine than in the rats fed norleucine alone. Our studies show that dietary disproportions of amino acids can alter the flux of specific amino acids across the blood-brain barrier.
开展了多项研究，以确定膳食中氨基酸比例失调是否会改变以生长限制浓度存在于膳食中的氨基酸进入大脑的通量。在静脉注射[14C]赖氨酸之前，先让大鼠适应赖氨酸限制饮食，然后给它们喂食这种对照饮食，单独喂食或添加赖氨酸或高精氨酸（赖氨酸转运的竞争剂）或两者都添加。喂食额外赖氨酸或高精氨酸的大鼠的脑-血浆放射性比值低于喂食对照饮食的大鼠，而单独喂食额外赖氨酸的大鼠的赖氨酸通量和脑赖氨酸浓度较高。喂食高精氨酸+赖氨酸的大鼠的通量和浓度低于单独喂食额外赖氨酸的大鼠。在注射[14C]缬氨酸之前，给其他大鼠喂食含有添加缬氨酸、正亮氨酸（缬氨酸转运的竞争剂）或两者都含有的缬氨酸限制饮食。喂食额外缬氨酸的大鼠的缬氨酸通量和脑缬氨酸浓度高于对照大鼠，而单独喂食正亮氨酸的组的通量较低。喂食正亮氨酸+缬氨酸的大鼠的缬氨酸通量高于单独喂食正亮氨酸的大鼠。我们的研究表明，膳食中氨基酸比例失调可改变特定氨基酸穿过血脑屏障的通量。
