Glendinning John I, Feld Natalie, Goodman Leora, Bayor Rouane
Department of Biological Sciences, Barnard College, Columbia University, 3009 Broadway, New York, NY 10027, United States.
Physiol Behav. 2008 Oct 20;95(3):476-83. doi: 10.1016/j.physbeh.2008.07.017. Epub 2008 Jul 17.
Little is known about why animals differ in daily intake of oils. Here, we tested the hypothesis that the oral acceptability of oil is a key determinant of daily intake. To this end, we examined short- and long-term ingestive responses of eight mouse strains (FVB/NJ, SWR/J, SM/J, C57BL/6J, BALB/cJ, 129P3/J, DBA/2J and AKR/J) to Intralipid, a stable emulsion of soybean oil. In Experiment 1, we compared orosensory responsiveness (as indicated by initial licking rates) of eight mouse strains to a range of concentrations of Intralipid and sucrose. We included sucrose because there are two natural alleles of Tas1r3 (the gene that encodes the T1R3 sweet taste receptor), and strains with the Tas1r3Sac-b allele exhibit higher daily intake of sucrose and oil than strains with the Tas1r3Sac-d allele. All strains exhibited concentration-dependent increases in lick rates for both sucrose and Intralipid, but the extent of these increases varied greatly across strains. The strains with the Tas1r3Sac-b allele licked more vigorously for sucrose at concentrations < or =0.3 M, but not for Intralipid at any concentration. In Experiment 2, we ran the mice through 24-h preference tests, in which they had a choice between water and each of four concentrations of Intralipid (1, 5, 10 and 20%). The strains differed greatly in daily intake of Intralipid, particularly at the 1 and 5% concentrations. Regression analyses revealed that strain differences in orosensory responsiveness reliably predicted strain differences in daily intake of 1 and 5% Intralipid, but not 10 or 20% Intralipid. These findings indicate (i) that Tas1r3 genotype does not modulate orosensory stimulation from oil, (ii) that orosensory stimulation contributes to strain differences in daily intake of dilute oil emulsions, but not concentrated ones, and (iii) that daily intake of concentrated oil emulsions is controlled primarily by post-oral satiety mechanisms.
关于动物每日油脂摄入量为何存在差异，目前所知甚少。在此，我们验证了一个假设，即油脂的口腔可接受性是每日摄入量的关键决定因素。为此，我们研究了八种小鼠品系（FVB/NJ、SWR/J、SM/J、C57BL/6J、BALB/cJ、129P3/J、DBA/2J和AKR/J）对大豆油稳定乳剂英脱利匹特（Intralipid）的短期和长期摄食反应。在实验1中，我们比较了八种小鼠品系对一系列浓度的英脱利匹特和蔗糖的口腔感觉反应性（以初始舔舐速率表示）。我们纳入蔗糖是因为编码T1R3甜味受体的基因Tas1r3存在两种天然等位基因，携带Tas1r3Sac - b等位基因的品系比携带Tas1r3Sac - d等位基因的品系每日蔗糖和油脂摄入量更高。所有品系对蔗糖和英脱利匹特的舔舐速率均呈现浓度依赖性增加，但不同品系增加的程度差异很大。携带Tas1r3Sac - b等位基因的品系在浓度≤0.3 M时对蔗糖舔舐更有力，但对任何浓度的英脱利匹特均无此现象。在实验2中，我们让小鼠进行24小时偏好测试，在此测试中它们可在水和四种浓度（1%、5%、10%和20%）的英脱利匹特之间进行选择。不同品系对英脱利匹特的每日摄入量差异很大，尤其是在1%和5%浓度时。回归分析显示，口腔感觉反应性的品系差异可靠地预测了1%和5%英脱利匹特每日摄入量的品系差异，但不能预测10%或20%英脱利匹特的摄入量差异。这些发现表明：（i）Tas1r3基因型不会调节来自油脂的口腔感觉刺激；（ii）口腔感觉刺激导致稀油乳剂每日摄入量的品系差异，但对浓油乳剂无此影响；（iii）浓油乳剂的每日摄入量主要由口腔后饱腹感机制控制。
