Ackroff K, Sclafani A
Department of Psychology, Brooklyn College, City University of New York 11210.
Physiol Behav. 1991 Jun;49(6):1047-60. doi: 10.1016/0031-9384(91)90330-q.
Rats given continuous access to 32% sucrose and Polycose solutions initially preferred sucrose but over days reversed their preference and drank more Polycose than sucrose. The role of taste and postingestive factors in this preference shift were investigated in several experiments. A strong and persistent preference for saccharin-sweetened Polycose over unsweetened Polycose was eliminated by intervening experience with a sucrose vs. Polycose choice test, suggesting that the postingestive effects modify the attractiveness of sweet taste. Osmolality differences between sucrose and Polycose were ruled out as an important factor; increasing the osmolality of Polycose by addition of glucose did not prevent the sucrose to Polycose preference shift. Rather, the shift in preference appears to result from some postingestive consequence of the fructose moiety contained in sucrose. This is indicated by the findings that rats did not reliably prefer a fructose-Polycose mixture to a sucrose solution in long-term tests, but developed preferences for maltose over sucrose solutions, and for glucose + Polycose over fructose + Polycose mixtures. Also, a 32% glucose solution was strongly preferred to a 32% fructose solution. Other studies examined the parameters of the sucrose to Polycose preference shift. The Polycose preference was accomplished by increases in both Polycose meal size and frequency. It occurred only with relatively concentrated solutions (16 and 32%) and was incomplete when the carbohydrates were presented in powdered form. Preexposure to Polycose enhanced the preference shift, whereas preexposure to sucrose retarded the development of the preference, suggesting that the shift occurs because Polycose is more rewarding, rather than because sucrose is more aversive. Polycose preference was lost after several days without the solutions but redeveloped in subsequent sucrose vs. Polycose choice tests. Thus the preference shift appears to be due to taste-postingestive consequence conditioning but its expression is dependent upon the nutritional state of the animal.
给予大鼠持续接触32%蔗糖溶液和聚葡萄糖溶液的机会，起初它们更喜欢蔗糖，但几天后偏好发生逆转，饮用聚葡萄糖比蔗糖更多。在几个实验中研究了味觉和摄食后因素在这种偏好转变中的作用。通过蔗糖与聚葡萄糖选择试验的干预经验，消除了对糖精甜味聚葡萄糖相对于未加糖聚葡萄糖的强烈且持续的偏好，这表明摄食后效应改变了甜味的吸引力。排除了蔗糖和聚葡萄糖之间的渗透压差异作为一个重要因素；通过添加葡萄糖增加聚葡萄糖的渗透压并不能阻止从蔗糖到聚葡萄糖的偏好转变。相反，偏好的转变似乎是由蔗糖中所含果糖部分的一些摄食后后果导致的。这由以下发现表明：在长期试验中，大鼠并没有可靠地偏好果糖 - 聚葡萄糖混合物而非蔗糖溶液，但对麦芽糖相对于蔗糖溶液产生了偏好，并且对葡萄糖 + 聚葡萄糖混合物相对于果糖 + 聚葡萄糖混合物产生了偏好。此外，32%的葡萄糖溶液比32%的果糖溶液更受强烈偏好。其他研究考察了从蔗糖到聚葡萄糖偏好转变的参数。聚葡萄糖偏好是通过聚葡萄糖餐量和频率的增加来实现的。它仅在相对浓缩的溶液（16%和32%）中出现，并且当碳水化合物以粉末形式呈现时转变并不完全。预先接触聚葡萄糖增强了偏好转变，而预先接触蔗糖则延迟了偏好的发展，这表明转变的发生是因为聚葡萄糖更具奖赏性，而不是因为蔗糖更具厌恶感。在没有这些溶液的几天后，聚葡萄糖偏好消失，但在随后的蔗糖与聚葡萄糖选择试验中又重新出现。因此，偏好转变似乎是由于味觉 - 摄食后后果的条件作用，但其表现取决于动物的营养状态。
