Paronis Carol A, Gasior Maciej, Bergman Jack
Preclinical Pharmacology Laboratory/ADARC, McLean Hospital, 115 Mill Street, Belmont, MA 02478, USA.
Psychopharmacology (Berl). 2002 Oct;163(3-4):283-91. doi: 10.1007/s00213-002-1180-5. Epub 2002 Jul 30.
The relative reinforcing strength of cocaine can be characterized by the distribution of operant behavior during the availability of other reinforcing stimuli.
To develop a procedure to rapidly evaluate the relative reinforcing strength of cocaine in monkeys.
Monkeys were trained to respond on two levers under concurrent fixed-ratio 30 (FR30) schedules of reinforcement. Responding on one lever resulted in food delivery, responding on the alternative lever resulted in delivery of IV saline or cocaine (0.032 or 0.1 mg/kg per injection). Daily sessions consisted of three 30-min components separated by 10-min timeout periods. The availability of saline, 0.032, or 0.1 mg/kg per injection cocaine varied across components, and only in an ascending order. The relative reinforcing strength of 0.0032-0.32 mg/kg per injection cocaine was examined by substituting different unit doses for the training doses of cocaine. Effects of cocaine pretreatment on response distribution were determined by giving IM injections of 0.1-1.8 mg/kg cocaine 10 min prior to sessions of saline availability.
Increasing unit doses of cocaine monotonically increased the distribution of responding on the injection-lever and monotonically deceased response rates. Responding occurred predominantly on the food-lever during availability of saline or 0.0032 mg/kg per injection cocaine, whereas availability of 0.032-0.32 mg/kg per injection produced >90% of responding on the injection-lever. Availability of 0.01 mg/kg per injection cocaine resulted in approximately equal levels of responding on the food- and injection-levers. Presession IM cocaine injections dose-dependently increased responding on the injection-lever.
Stable behavior can be maintained under concurrent FR schedules of food and cocaine presentation in monkeys, and the distribution of behavior on food- and injection-levers is dependent on the available dose of cocaine.
可卡因的相对强化强度可通过在其他强化刺激可获得期间的操作性行为分布来表征。
开发一种快速评估猴子体内可卡因相对强化强度的程序。
训练猴子在同时进行的固定比率30（FR30）强化程序下对两个杠杆做出反应。对一个杠杆的反应会导致食物递送，对另一个杠杆的反应会导致静脉注射生理盐水或可卡因（每次注射0.032或0.1毫克/千克）。每日实验由三个30分钟的部分组成，中间间隔10分钟的休息时间。每次注射生理盐水、0.032或0.1毫克/千克可卡因的可获得性在各部分有所不同，且仅按升序排列。通过用不同单位剂量替代训练剂量的可卡因来检查每次注射0.0032 - 0.32毫克/千克可卡因的相对强化强度。通过在生理盐水可获得性实验前10分钟肌肉注射0.1 - 1.8毫克/千克可卡因来确定可卡因预处理对反应分布的影响。
可卡因单位剂量增加会使注射杠杆上的反应分布单调增加，反应率单调下降。在生理盐水或每次注射0.0032毫克/千克可卡因可获得期间，反应主要发生在食物杠杆上，而每次注射0.032 - 0.32毫克/千克可卡因时，注射杠杆上的反应占比>90%。每次注射0.01毫克/千克可卡因时，食物杠杆和注射杠杆上的反应水平大致相等。实验前肌肉注射可卡因剂量依赖性地增加了注射杠杆上的反应。
在猴子同时接受食物和可卡因呈现的FR程序下可维持稳定行为，食物杠杆和注射杠杆上的行为分布取决于可卡因的可用剂量。
