Lorenz D N
Department of Human Development, University of Wisconsin, Green Bay 54311-7001.
Dev Psychobiol. 1994 Jan;27(1):39-52. doi: 10.1002/dev.420270105.
The present series of experiments was designed to determine the dose-response characteristics of the cholecystokinin suppression effect on rat pups ingesting through suckling and adult modes. Pups at 10-22 days of age were deprived of their dam and food for 6 hr. At test time, the subjects received intraperitoneal injections or intravenous infusions of CCK-8 at 2, 4, 8, or 16 micrograms/kg in saline, or the saline vehicle alone. The pups were permitted to ingest for 30 min immediately after the injection or during the infusion. Ingestion included taking milk from the dam by suckling or feeding from the substrate. Regardless of the route of administration, CCK-8 elicited a low level of suppression across all doses and all ages when pups ingested within the natural suckling situation. In marked contrast, pups ingesting from the substrate in the adult mode suppressed their intake of bovine light cream or chow pellets in a dose-related manner following injections of the peptide. The blockade of the CCK dose-related suppression effect during suckling indicates that a different set of mechanisms governs intake of milk from the mother. The results may be related to the level of arousal required to sustain motivated behaviors while pups engage in the different modes of ingestion.
本系列实验旨在确定胆囊收缩素对通过哺乳和成年模式摄食的大鼠幼崽的抑制作用的剂量反应特征。10至22日龄的幼崽被与其母鼠分离并禁食6小时。在测试时，实验对象腹腔注射或静脉输注以生理盐水配制的剂量为2、4、8或16微克/千克的CCK-8，或仅注射生理盐水。幼崽在注射后或输注期间立即被允许摄食30分钟。摄食包括通过哺乳从母鼠获取乳汁或从底物进食。无论给药途径如何，当幼崽在自然哺乳情况下摄食时，CCK-8在所有剂量和所有年龄段均引起低水平的抑制。与之形成显著对比的是，以成年模式从底物进食的幼崽在注射该肽后，其对牛低脂奶油或饲料颗粒的摄入量呈剂量相关的抑制。哺乳期间CCK剂量相关抑制作用的阻断表明，存在另一套机制来控制从母体摄取乳汁。这些结果可能与幼崽以不同摄食模式进行有动机行为时维持该行为所需的唤醒水平有关。
