Cunningham Christopher L, Clemans Jessica M, Fidler Tara L
Department of Behavioral Neuroscience and Portland Alcohol Research Center L470, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, 97201-3098, USA.
Pharmacol Biochem Behav. 2002 Jun;72(3):659-68. doi: 10.1016/s0091-3057(02)00734-7.
Previous studies have shown that mice develop conditioned place preference (CPP) when ethanol is administered by intraperitoneal (ip) or intravenous (iv) injection. The present studies examined CPP in mice using the intragastric (ig) route of administration. Inbred mice were surgically implanted with chronic intragastric cannulae and exposed to an unbiased place conditioning procedure in which infusion of ethanol (2 or 4 g/kg) was paired with a conditioned stimulus (CS+). A different CS was paired with water. In Experiments 1-2, ethanol was infused just before exposure to CS+. Contrary to previous studies involving intraperitoneal injection, infusion of 4 g/kg ig ethanol produced a significant conditioned place aversion (CPA). However, when a 5-min delay was inserted between infusion and CS exposure (Experiments 3-4), the same dose produced CPP. These outcomes are not consistent with expectations derived from a recent study in selectively bred rats, suggesting that sensitivity to ethanol reward is enhanced by intragastric administration. However, the finding that intragastric ethanol can produce either CPP or CPA depending on dose and injection timing is consistent with previous intraperitoneal ethanol studies in mice. Although the parameters differ for each route of administration, it appears that the same underlying processes can be invoked to explain how manipulation of injection timing affects the direction of ethanol-induced place conditioning. More specifically, in both cases, CPA can be attributed to an initial, short-lived aversive effect, whereas CPP can be attributed to a delayed rewarding effect of ethanol.
先前的研究表明，当通过腹腔内（ip）或静脉内（iv）注射给予乙醇时，小鼠会产生条件性位置偏爱（CPP）。本研究使用胃内（ig）给药途径检测了小鼠的CPP。将近交系小鼠通过手术植入慢性胃内插管，并使其接受无偏倚的位置条件化程序，在此程序中，给予乙醇（2或4 g/kg）与条件刺激（CS+）配对。另一个不同的CS与水配对。在实验1-2中，在暴露于CS+之前即刻给予乙醇。与先前涉及腹腔注射的研究相反，给予4 g/kg胃内乙醇会产生显著的条件性位置厌恶（CPA）。然而，当在给药和CS暴露之间插入5分钟的延迟（实验3-4）时，相同剂量会产生CPP。这些结果与最近一项对选择性繁殖大鼠的研究结果不一致，这表明胃内给药会增强对乙醇奖赏的敏感性。然而，胃内乙醇根据剂量和注射时间可产生CPP或CPA这一发现与先前对小鼠进行的腹腔内乙醇研究一致。尽管每种给药途径的参数不同，但似乎可以调用相同的潜在过程来解释注射时间的操纵如何影响乙醇诱导的位置条件化的方向。更具体地说，在这两种情况下，CPA可归因于最初的、短暂的厌恶效应，而CPP可归因于乙醇的延迟奖赏效应。
