Smith L A, Lang W J
Pharmacol Biochem Behav. 1980 Aug;13(2):215-20. doi: 10.1016/0091-3057(80)90076-3.
After rats at reduced body weight had established responding by lever pressing for nicotine injections under a food delivery schedule (FT60 sec) for 1 hr daily sessions for 14 days, the rate of responding was maintained over a second 14-day period even after removal of the schedule. However, the rate was not maintained by rats lever pressing for normal saline without the schedule over the second 14-day period after self administration had been established for nicotine under the schedule. Other rats maintained at reduced body weight were allowed to lever press for nicotine over a 28-day period without the food delivery schedule. Their rate of self administration increased from initially low levels until at the end of the 28-day period the rate had reached that of rats self administering nicotine adjunctive to the food delivery schedule throughout the same period. Without the schedule, rats at reduced body weight self administering normal saline or rats at normal body weight self administering nicotine, continued to lever press only at very low rates throughout the 280-day period. It is suggested that rats maintain self administration of nicotine if the behavior can be established for a critical intake of nicotine over a critical period of time. The food delivery schedule appears only to hasten the establishment of the behavior but is not essential for self administration of nicotine by rats.
在体重减轻的大鼠按照每天1小时、每次食物投放间隔60秒的食物投放时间表通过按压杠杆获取尼古丁注射来建立反应14天后，即使在移除该时间表后，反应速率在第二个14天期间仍得以维持。然而，在按照该时间表建立了尼古丁自我给药后，在第二个14天期间，为获取生理盐水而按压杠杆的大鼠在没有该时间表的情况下，其反应速率并未维持。其他体重减轻的大鼠在没有食物投放时间表的情况下，被允许在28天内按压杠杆获取尼古丁。它们的自我给药速率从最初的低水平开始增加，直到28天结束时，该速率已达到在同一时期内与食物投放时间表同时进行尼古丁自我给药的大鼠的速率。在没有该时间表的情况下，体重减轻的大鼠自我给药生理盐水或正常体重的大鼠自我给药尼古丁，在整个280天期间仅以非常低的速率继续按压杠杆。有人提出，如果在关键时间段内针对关键尼古丁摄入量能够建立起行为，大鼠会维持尼古丁的自我给药。食物投放时间表似乎只是加速了行为的建立，但对于大鼠自我给药尼古丁并非必不可少。
