Azzara A V, Sclafani A
Department of Psychology, Brooklyn College and The Graduate School, The City University of New York, 11210, USA.
Physiol Behav. 1998 Jun 15;64(4):535-41. doi: 10.1016/s0031-9384(98)00113-9.
Prior research indicates that glucose conditions much stronger flavor preferences in rats than does fructose. This could occur because intestinal absorption of fructose is much slower than that of glucose and because fructose malabsorption may have aversive consequences. Fructose absorption is facilitated when glucose is also present in the gut. The present study therefore compared the flavor conditioning effects of maltose (a glucose + glucose disaccharide) to those of sucrose (a glucose + fructose disaccharide). In Experiment 1, rats had different flavors paired with intragastric infusions of 32% maltose (CS+M), 32% sucrose (CS+S), and water (CS-) 23 h/day. In subsequent two-bottle tests, both CS+ solutions were strongly preferred to the CS-, but the CS+M was also preferred (78%) to the CS+S. Experiment 2A revealed that the rats also learned to prefer a CS+M to a CS+S when 16% sugar infusions were used. In Experiment 2B, the same rats preferred a flavor paired with 16% maltose to a flavor paired with 8% maltose. They did not reliably prefer a flavor paired with 16% sucrose to a flavor paired with 8% maltose. These results demonstrate that the postingestive actions of maltose are more reinforcing than those of sucrose. This indicates that fructose is less reinforcing than glucose even when malabsorption is not a factor. In contrast to their preference for the CS+M over the CS+S, the rats preferred sucrose to maltose when drinking the sugars by mouth. Therefore, sugar preferences mediated by oral taste receptors differ from those conditioned by postoral nutrient detectors.
先前的研究表明，与果糖相比，葡萄糖能使大鼠产生更强的口味偏好。出现这种情况的原因可能是果糖在肠道的吸收比葡萄糖慢得多，且果糖吸收不良可能会产生厌恶后果。当肠道中同时存在葡萄糖时，果糖的吸收会更容易。因此，本研究比较了麦芽糖（一种葡萄糖 + 葡萄糖二糖）和蔗糖（一种葡萄糖 + 果糖二糖）的口味条件作用效果。在实验1中，大鼠每天23小时将不同口味与胃内注入32%的麦芽糖（CS+M）、32%的蔗糖（CS+S）和水（CS-）配对。在随后的双瓶测试中，两种CS+溶液都比CS-更受青睐，但CS+M也比CS+S更受青睐（78%）。实验2A表明，当使用16%的糖注入时，大鼠也学会了更喜欢CS+M而不是CS+S。在实验2B中，同样的大鼠更喜欢与16%麦芽糖配对的口味，而不是与8%麦芽糖配对的口味。它们并没有可靠地表现出更喜欢与16%蔗糖配对的口味，而不是与8%麦芽糖配对的口味。这些结果表明，麦芽糖的摄入后作用比蔗糖更具强化作用。这表明，即使不存在吸收不良的因素，果糖的强化作用也比葡萄糖弱。与它们对CS+M优于CS+S的偏好相反，大鼠在口服糖时更喜欢蔗糖而不是麦芽糖。因此，由口腔味觉受体介导的糖偏好与由口腔后营养探测器调节的糖偏好不同。
