Tyrka A, Smith G P
Department of Psychiatry, Cornell University Medical College, White Plains, NY.
Pharmacol Biochem Behav. 1993 May;45(1):243-6. doi: 10.1016/0091-3057(93)90113-8.
When 10% sucrose is infused intraorally on postnatal days (PN) 7, 14, and 21, raclopride, a D2 dopaminergic antagonist, does not affect intake at any age and SCH23390, a D1 antagonist, does not affect intake on PN 7 but a large dose decreases intake on PN 14 and 21. To determine if this differential effect of the antagonists on PN 14 and 21 remains after further postnatal development, we studied adult rats in this intraoral intake test. Female (n = 77) and male (n = 81) adult rats, approximately 43 or 96 days old, were deprived for 4 h before intraoral infusion of 10% sucrose. Each rat was tested once and this was its first experience with sucrose. SCH23390 (133 or 267 micrograms/kg), raclopride (357 or 714 micrograms/kg), or saline vehicle was given IP at -15 min. The larger dose of SCH23390 significantly decreased intake of rats that were approximately 43 and 96 days old, but neither dose of raclopride changed intake at either age. These results suggest that D1, but not D2, receptors are necessary components of the central neural network that processes the unconditioned gustatory stimulus of 10% sucrose into mouthing and swallowing movements that maintain ingestion in late preweanling and adult rats under these conditions.
在出生后第（PN）7、14和21天经口注入10%蔗糖时，D2多巴胺能拮抗剂雷氯必利在任何年龄均不影响摄入量，D1拮抗剂SCH23390在PN7时不影响摄入量，但大剂量时会降低PN14和21时的摄入量。为了确定拮抗剂在PN14和21时的这种差异效应在出生后进一步发育后是否仍然存在，我们在这项经口摄入量测试中研究了成年大鼠。雌性（n = 77）和雄性（n = 81）成年大鼠，年龄约43或96天，在经口注入10%蔗糖前禁食4小时。每只大鼠测试一次，这是其首次接触蔗糖。在-15分钟时腹腔注射SCH23390（133或267微克/千克）、雷氯必利（357或714微克/千克）或生理盐水载体。较大剂量的SCH23390显著降低了约43天和96天龄大鼠的摄入量，但两种剂量的雷氯必利在两个年龄时均未改变摄入量。这些结果表明，在这些条件下，D1受体而非D2受体是中枢神经网络的必要组成部分，该网络将10%蔗糖的非条件味觉刺激转化为口部动作和吞咽动作，以维持断奶前后期和成年大鼠的摄食。
