DiBattista D
Psychology Department, Brock University, St. Catharines, Ontario.
Physiol Behav. 1990 Feb;47(2):253-7. doi: 10.1016/0031-9384(90)90139-u.
Because adult rats have very low levels of the intestinal enzyme lactase, the ingestion of appreciable quantities of the disaccharide lactose may cause gastrointestinal distress. The present experiment was designed to demonstrate that adult rats will learn to avoid previously neutral stimuli which have been paired with lactose ingestion. Adult rats ingested both a novel solution [either tap water (WA) or 0.1% saccharin (SA)] and a novel food substance (49% powdered lab chow + 50% added disaccharide + 1% saccharin) during a single conditioning session. The added disaccharide was either sucrose (group SU-SA), lactose (groups HL-SA and HL-WA), or equal amounts of these two disaccharides (group LL-SA); a fifth group (LC-SA) consumed a sucrose-containing diet to which lithium chloride was added (5 mg per 1 g of diet). Separate feeding tests and drinking tests, carried out over several weeks, were used to assess the extent of conditioned taste avoidance. In the four feeding tests, rats were allowed to ingest powdered lab chow with added saccharin (but without added disaccharide), while in the four drinking tests, rats chose between tap water and a 0.1% saccharin solution. Group HL-SA demonstrated a substantial conditioned avoidance in both feeding and drinking tests, but group HL-WA showed avoidance only in feeding tests. Conditioned avoidance was weak in group LL-SA; the strongest avoidance was observed in lithium chloride-treated rats (group LC-SA). Results are related to previous research and to the hypothesis that a learned avoidance of milk may facilitate the weaning process in mammals.
由于成年大鼠肠道中的乳糖酶水平非常低，摄入大量二糖乳糖可能会导致胃肠道不适。本实验旨在证明成年大鼠会学会避开之前与摄入乳糖配对的中性刺激物。在一次条件训练中，成年大鼠同时摄入一种新型溶液[自来水（WA）或0.1%糖精（SA）]和一种新型食物物质（49%粉状实验室饲料+50%添加的二糖+1%糖精）。添加的二糖要么是蔗糖（SU-SA组），要么是乳糖（HL-SA组和HL-WA组），要么是这两种二糖的等量混合物（LL-SA组）；第五组（LC-SA组）食用添加了氯化锂（每1克饲料5毫克）的含蔗糖饮食。在几周内进行的单独喂食测试和饮水测试用于评估条件性味觉回避的程度。在四次喂食测试中，大鼠被允许摄入添加了糖精（但未添加二糖）的粉状实验室饲料，而在四次饮水测试中，大鼠在自来水和0.1%糖精溶液之间进行选择。HL-SA组在喂食和饮水测试中均表现出显著的条件性回避，但HL-WA组仅在喂食测试中表现出回避。LL-SA组的条件性回避较弱；在氯化锂处理的大鼠（LC-SA组）中观察到最强的回避。研究结果与先前的研究以及一种假设相关，即对牛奶的习得性回避可能有助于哺乳动物的断奶过程。
