Breakpoint determination and ethanol self-administration using an across-session progressive ratio procedure in the rat
Breakpoint determination and ethanol self-administration using an across-session progressive ratio procedure in the rat
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DOI：
10.1097/00000374-199910000-00003
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发表时间：
1999-10-01
影响因子：
3.2
通讯作者：
Samson, HH
中科院分区：
文献类型：
--
作者：
Czachowski, CL;Samson, HH
背景资料：渐进比率时间表用于确定“断点”或受试者愿意执行的“工作”量的限制，以获得一个断点。强化功效是从断点值推断出来的，断点值通常是在一个单一的会话中通过增加连续演示所需的响应数量来测量的。这个程序是不可行的，但是，当评估的强化功效的物质，可以改变作为其生理作用的函数，在自我administration.Methods的情况下：本研究利用了一个程序，增加了响应要求在单一的日常会话，而不是在一个会话。在每个日常会话中完成响应要求导致呈现允许自我施用乙醇20分钟的饮用管。该程序可以评估乙醇导向的食欲（杠杆按压次数）和消费（舔次数和摄入量）行为。在雄性Long Evans大鼠中，使用蔗糖替代固定比例（FR）4时间表启动了对10%乙醇的可靠反应。然后进行四次连续的断点测定，通过返回FR 4时间表来重新建立基线responsibility.Results：结果表明，从第一次到第二次测定，断点值有所增加，然后在以下三次测定中保持稳定。个体大鼠达到高达240次杠杆按压的断点，以获得10%乙醇，并在1.0 g/kg范围内保持乙醇摄入量。然而，乙醇摄入量（g/kg）在所有4次测定中均保持稳定（平均值为0.86 +/- 0.06至1.01 +/- 0.10）。此外，乙醇摄入量与先前的食欲反应无关，因为在断点之前的阶段（高FR）和随后的基线阶段（FR 4）的摄入量之间没有差异。该模型提供了对不同机制的评估，该机制介导了饮用可测量量的乙醇的受试者中的乙醇寻求与乙醇消耗，食欲行为不会因乙醇的药理作用而改变。
Background: Progressive ratio schedules are used to determine the "breakpoint" or limit to the amount of "work" that a subject is willing to perform to obtain a reinforcer. Reinforcing efficacy is inferred from the breakpoint values, which are typically measured in a single session by increasing the number of responses required for successive reinforcer presentations. This procedure is not feasible, however, when assessing the reinforcing efficacy of a substance that can change as a function of its physiological actions during self-administration, as in the case of ethanol.Methods: The present study made use of a procedure that increased the response requirement across single daily sessions rather than within a session. Completion of the response requirement in each daily session resulted in the presentation of a drinking tube that allowed for self-administration of ethanol for a 20-min period. This procedure made possible the assessment of ethanol-directed appetitive (number of lever presses) and consummatory (number of licks and intake volume) behaviors. Reliable responding for 10% ethanol was initiated using sucrose-substitution on a fixed ratio (FR) 4 schedule in male Long Evans rats. Then four successive breakpoint determinations were made which were separated by a return to the FR4 schedule to re-establish baseline responding.Results: The results indicated that there was an increase in breakpoint values from the first to the second determination, which was then stable over the following three determinations. Individual rats reached breakpoints as high as 240 lever presses to receive access to 10% ethanol and maintained ethanol intake over sessions in the 1.0 g/kg range. Ethanol intake (g/kg), however, was stable across all four determinations (mean 0.86 +/- 0.06 to 1.01 +/- 0.10). Moreover, ethanol intake was not related to the preceding appetitive responding, as no differences between intake on the session before a breakpoint (high FR) and the following baseline period (FR4) were observed.Conclusions: This model provides an assessment of the distinct mechanisms that mediate ethanol-seeking versus ethanol consumption in subjects that drink measurable amounts of ethanol, with the appetitive behaviors not altered by the pharmacological effects of ethanol.