Rocha B A, Odom L A, Barron B A, Ator R, Wild S A, Forster M J
Department of Pharmacology, UNTHSC/FW, Fort Worth, TX 76107, USA.
Psychopharmacology (Berl). 1998 Jul;138(1):82-8. doi: 10.1007/s002130050648.
The present study compared cocaine-induced hyperlocomotion and cocaine i.v. self-administration in DBA/2J and C57BL/6J mice. In the locomotor activity experiment, these strains were tested for hyperlocomotion after i.p. cocaine injection (0-60.0 mg/kg), using a Digiscan Animal Activity Monitoring System. In the cocaine i.v. self-administration experiment, they were compared for their ability to acquire and maintain cocaine self-administration in operant chambers with levers as the manipulanda. Animals were first trained to respond for food as a reinforcer (condensed milk solution); they were then submitted to surgical i.v. insertion of an in-dwelling catheter, and required to respond for i.v. cocaine (0.25-4.0 mg/kg per injection) as a reinforcer. DBA/2J mice showed significantly higher maximal cocaine-induced hyperlocomotion, more rapid acquisition of cocaine self-administration, and significantly lower rates of cocaine self-administration. Cocaine concentration in the brains of DBA/2J and C57BL/6J mice failed to differ following i.p. injection, suggesting that distribution factors were not involved in the differential responses to cocaine. Although not conclusive, this pattern of effects may suggest that cocaine has greater reinforcing efficacy in DBA/2J mice, confirming genetic make-up as a determinant factor in cocaine taking behavior.
本研究比较了DBA/2J和C57BL/6J小鼠中可卡因诱导的运动亢进及静脉注射可卡因的自我给药情况。在运动活动实验中，使用Digiscan动物活动监测系统，对这些品系的小鼠腹腔注射可卡因（0 - 60.0毫克/千克）后测试其运动亢进情况。在静脉注射可卡因自我给药实验中，比较它们在以杠杆为操作装置的操作性条件反射箱中获取并维持可卡因自我给药的能力。动物首先接受训练，以食物（浓缩乳溶液）作为强化物做出反应；然后通过手术在静脉内插入留置导管，并要求它们以静脉注射可卡因（每次注射0.25 - 4.0毫克/千克）作为强化物做出反应。DBA/2J小鼠表现出显著更高的可卡因诱导的最大运动亢进、更快地获取可卡因自我给药行为，以及显著更低的可卡因自我给药速率。腹腔注射后，DBA/2J和C57BL/6J小鼠大脑中的可卡因浓度没有差异，这表明分布因素与对可卡因的不同反应无关。尽管尚无定论，但这种效应模式可能表明可卡因在DBA/2J小鼠中具有更强的强化效力，证实了基因构成是可卡因摄取行为的一个决定因素。
