Tyrka A, Smith G P
Department of Psychiatry, Cornell University Medical College, NY.
Pharmacol Biochem Behav. 1991 Aug;39(4):955-61. doi: 10.1016/0091-3057(91)90059-b.
To investigate the role of dopaminergic mediation of the positive reinforcing effect of sucrose during development, we tested the effects of the D-1 antagonist, SCH 23390, on the intake of 10% sucrose in 7-, 14-, and 21-day-old rats during independent ingestion (pups lick sucrose from the floor of a beaker) or during continuous intraoral infusion of sucrose. SCH 23390 inhibited intake more in independent ingestion tests than in intraoral catheter tests. At 7 and 14 days this difference was qualitative--SCH 23390 was efficacious in independent ingestion tests, but not in intraoral catheter tests. At 21 days the difference was quantitative--SCH 23390 decreased intake in both tests, but was more potent in independent ingestion tests. SCH 23390 decreased intake during independent ingestion tests without changing latency to eat or time-sampled activity scores at 7 and 14 days, but not at 21 days; thus the inhibition of intake is not accounted for by a generalized motor deficit at 7 and 14 days. Possible explanations for the differential potency include density of reinforcement, pattern of central dopamine metabolism, and interference with the appetitive movements required to maintain contact with the sucrose in the independent ingestion test.
为了研究多巴胺能介导在发育过程中对蔗糖阳性强化作用的影响，我们测试了D-1拮抗剂SCH 23390对7日龄、14日龄和21日龄大鼠在自主摄取（幼崽从烧杯底部舔食蔗糖）或持续口腔内输注蔗糖期间10%蔗糖摄入量的影响。在自主摄取试验中，SCH 23390对摄入量的抑制作用比口腔内插管试验中更强。在7日龄和14日龄时，这种差异是质性的——SCH 23390在自主摄取试验中有效，但在口腔内插管试验中无效。在21日龄时，这种差异是量性的——SCH 23390在两种试验中均降低了摄入量，但在自主摄取试验中作用更强。在7日龄和14日龄时，SCH 23390在自主摄取试验中降低了摄入量，同时没有改变进食潜伏期或时间抽样活动评分，但在21日龄时没有这种作用；因此，在7日龄和14日龄时，摄入量的抑制并非由全身性运动缺陷所致。对不同效力的可能解释包括强化密度、中枢多巴胺代谢模式以及在自主摄取试验中对维持与蔗糖接触所需的摄食动作的干扰。
