Thiels E, Alberts J R
Department of Psychology, Indiana University, Bloomington 47405.
Dev Psychobiol. 1991 Jan;24(1):19-38. doi: 10.1002/dev.420240103.
We examined in rat pups the relation between the decline of suckling and the emergence of independent ingestion, and the role of milk delivery conditional on nipple attachment in the maintenance of suckling. Fifteen-day-old litters were reared for either 5 or 10 days, and 20-day-old litters for 5 days by either a thelectomized (no nipples), ligated (nipples but no milk), or intact (nipples and milk) dam. Pups' food and water intakes were monitored daily, and their suckling, feeding, and drinking behaviors were videorecorded for 24 hr in the presence of their foster dam (Day 19 or 24) and for 24 hr in the presence of an intact, lactating dam (Day 20 or 25). There were no differences between treatment conditions with respect to either the onset or rate of increase of independent feeding or drinking. Pups reared by a thelectomized dam for 10 days displayed a pronounced, lasting depression of suckling. Twenty-five-day-old pups reared by a ligated dam displayed suckling levels comparable to those of control pups; in the presence of the ligated dam, however, their tendency to attach to a nipple was notably reduced. The implications of the findings for our understanding of the weaning process are discussed.
我们研究了幼鼠中吮乳行为的减少与自主摄食行为出现之间的关系，以及在维持吮乳行为中乳头附着条件下乳汁供应的作用。将15日龄的幼仔由切除乳头（无乳头）、结扎乳头（有乳头但无乳汁）或完整（有乳头且有乳汁）的母鼠饲养5天或10天，将20日龄的幼仔由上述母鼠饲养5天。每天监测幼仔的食物和水摄入量，并在其寄养母鼠在场时（第19天或第24天）以及在完整的泌乳母鼠在场时（第20天或第25天）对它们的吮乳、进食和饮水行为进行24小时视频记录。在自主进食或饮水的开始时间或增加速率方面，各处理条件之间没有差异。由切除乳头的母鼠饲养10天的幼仔表现出明显且持久的吮乳行为抑制。由结扎乳头的母鼠饲养的25日龄幼仔表现出与对照幼仔相当的吮乳水平；然而，在结扎乳头的母鼠在场时，它们附着在乳头上的倾向明显降低。讨论了这些发现对我们理解断奶过程的意义。
