Pérez C, Ackroff K, Sclafani A
Department of Psychology, Brooklyn College, NY, USA.
Physiol Behav. 1996 Mar;59(3):467-74. doi: 10.1016/0031-9384(95)02085-3.
Food-deprived rats were trained to associate one flavor (CSProt) with intragastric (IG) infusions of protein (PROT; 10% calcium caseinate), a second flavor (CSCHO) with IG infusions of carbohydrate (CHO; 10% protein), and a third flavor (CS-) with IG water infusions during 30 min/day training sessions. (The CS flavors were cherry, grape, and orange saccharin solutions.) In subsequent two-bottle tests the rats reliably preferred both the CSProt 2nd CSCHO to the CS- and equally preferred the CSProt and CSCHO. The preference for the two nutrient-paired flavors was not altered by IG preloads of PROT or CHO delivered as three loads 120, 40, and 5 min prior to testing. However, single oral + gastric preloads of CSCHO + IG CHO and CSProt + IG PROT 45 min prior to test selectively increased the preference for the CSProt and CSCHO, respectively. In subsequent gastric-only and oral-only tests single IG preloads of PROT and CHO, but not CSProt and CSCHO preloads, selectively altered the rats' preference for CSCHO vs. CSProt. In a second experiment with new rats, oral + gastric preloads again selectively altered the preference for the CSCHO vs. CSProt, but gastric-only preloads failed to have this effect. These results demonstrate that rats can learn to associate different flavors with the postingestive effects of different nutrients, and modify their flavor preferences after nutrient preloads. Oral + gastric preloads were most effective in altering flavor preferences, whereas gastric-only preloads had inconsistent effects and oral-only preloads were ineffective.
在每天30分钟的训练过程中，对食物匮乏的大鼠进行训练，使其将一种味道（CSProt）与胃内（IG）注入蛋白质（PROT；10%酪蛋白钙）联系起来，将第二种味道（CSCHO）与胃内注入碳水化合物（CHO；10%蛋白质）联系起来，将第三种味道（CS-）与胃内注入水联系起来。（CS味道分别是樱桃、葡萄和橙子糖精溶液。）在随后的双瓶测试中，大鼠确实更偏好CSProt和CSCHO，而不是CS-，并且对CSProt和CSCHO的偏好程度相同。在测试前120、40和5分钟分三次进行胃内预负荷注入PROT或CHO，并不会改变大鼠对这两种与营养物质配对味道的偏好。然而，在测试前45分钟进行一次口服加胃内预负荷注入CSCHO + IG CHO和CSProt + IG PROT，会分别选择性地增加大鼠对CSProt和CSCHO的偏好。在随后仅进行胃内和仅进行口服的测试中，单独的胃内预负荷注入PROT和CHO，而不是CSProt和CSCHO预负荷，会选择性地改变大鼠对CSCHO与CSProt的偏好。在对新大鼠进行的第二个实验中，口服加胃内预负荷再次选择性地改变了大鼠对CSCHO与CSProt的偏好，但仅进行胃内预负荷并没有这种效果。这些结果表明，大鼠能够学会将不同味道与不同营养物质的消化后效应联系起来，并在营养预负荷后改变它们的味道偏好。口服加胃内预负荷在改变味道偏好方面最为有效，而仅进行胃内预负荷的效果不一致，仅进行口服预负荷则无效。
