Hudzik T J, Wessinger W D, McMillan D E
Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock 72205.
Drug Alcohol Depend. 1993 Oct;33(3):225-33. doi: 10.1016/0376-8716(93)90109-4.
Because cocaine and ethanol are frequently abused in combination, the present study was performed to assess the behavioral consequences of concurrent access to both of these drugs. Rats trained to respond for food under a fixed-ratio 40 (FR 40) schedule of reinforcement during four, 30-min periods each day (every 6 h) were given free access to a 5% (w/v) ethanol solution and to water. Once a stable baseline of food, ethanol and water intake was established, intravenous cocaine was made available under a fixed-ratio 1 (FR1) schedule. After cocaine self-administration had been established for 10 days, the ethanol was removed from the chambers for 3 days. After the ethanol was returned to the chambers, saline was substituted for cocaine for 3 days. Following saline substitution, animals were given increased cocaine availability. Before cocaine was made available, rats consumed primarily the ethanol solution, averaging 31.7 ml of the 5% solution (4.2 g/kg ethanol), 10.2 ml of water and 148 food pellets/day. When cocaine (0.2 mg/kg per injection, i.v.) was made available, rats self-administered an average of 40-85 injections per day. Self-administration of cocaine resulted in small decreases in ethanol and food intake, as well as some changes in the pattern of ethanol intake. However, removing the ethanol from the chambers had no effect upon food and cocaine intake. Substitution of saline for the cocaine altered the pattern, but not the amount of ethanol intake. There was a trend toward increased ethanol intake during the study, which may have been related to repeated cycles of cocaine availability.
由于可卡因和乙醇经常被同时滥用，因此开展了本研究以评估同时接触这两种药物的行为后果。训练大鼠在每天四个30分钟时间段（每6小时一次）内按照固定比例40（FR 40）强化程序为获取食物做出反应，让它们自由获取5%（w/v）乙醇溶液和水。一旦食物、乙醇和水的摄入量建立起稳定基线，便按照固定比例1（FR1）程序提供静脉注射可卡因。在可卡因自我给药建立10天后，将乙醇从实验箱中移除3天。乙醇重新放回实验箱后，用生理盐水替代可卡因3天。生理盐水替代后，增加动物获取可卡因的机会。在提供可卡因之前，大鼠主要饮用乙醇溶液，平均每天饮用31.7毫升5%的溶液（4.2克/千克乙醇）、10.2毫升水和148颗食物颗粒。当提供可卡因（静脉注射，每次0.2毫克/千克）时，大鼠平均每天自我给药40 - 85次。可卡因自我给药导致乙醇和食物摄入量略有下降，以及乙醇摄入模式出现一些变化。然而，将乙醇从实验箱中移除对食物和可卡因摄入量没有影响。用生理盐水替代可卡因改变了模式，但没有改变乙醇摄入量。在研究期间有乙醇摄入量增加的趋势，这可能与可卡因可获得性的重复周期有关。
