新生期隔离增强雌性大鼠对可卡因自我给药及食物反应的习得。
Neonatal isolation enhances acquisition of cocaine self-administration and food responding in female rats.
作者信息
Kosten Therese A, Sanchez Hayde, Zhang Xiang Yang, Kehoe Priscilla
机构信息
Department of Psychiatry, Yale University School of Medicine, Room S-305 CMHC, 34 Park Street, New Haven, CT 06508, USA.
出版信息
Behav Brain Res. 2004 May 5;151(1-2):137-49. doi: 10.1016/j.bbr.2003.08.010.
We showed previously that neonatal isolation (ISO) enhances acquisition of cocaine self-administration in adult male rats without altering acquisition of food responding. Female rats show poorer performance in learning tasks and are differentially affected by stress compared to male rats. Thus, we investigated whether ISO alters acquisition of operant responding for cocaine and food in female rats with comparison to male rats. Litters were subjected to ISO or were non-handled (NH). Activity levels were assessed in adult rats. Then, rats were implanted with jugular catheters and allowed to self-administer cocaine under a fixed-ratio 1 (FR1) schedule of reinforcement using an escalating dose presentation procedure. Cocaine intake, discrimination of active versus inactive levers, and ineffective active lever responses were tabulated. Effects of non-contingent cocaine infusions (primes) and increasing FR on responding were then assessed. Other rats were allowed to lever press for food under an FR1 schedule (10 s time-out). ISO enhanced acquisition of operant responding for food and cocaine in female rats. The latter was demonstrated by better lever discrimination, emission of fewer ineffective responses, and superior performance in response to primes. Yet, NH females ingested more cocaine than ISO females during the initial acquisition phase. In male rats, ISO enhanced acquisition of cocaine self-administration but not food responding. Activity levels were unaffected by ISO or gender. These data confirm and extend our previous findings demonstrating the enduring effects of ISO on adult self-administration behavior and emphasize the importance of measuring behavioral patterns versus intake in acquisition studies.
我们之前的研究表明,新生期隔离(ISO)可增强成年雄性大鼠对可卡因自我给药的习得,而不改变对食物反应的习得。与雄性大鼠相比,雌性大鼠在学习任务中的表现较差,且受应激的影响也不同。因此,我们研究了与雄性大鼠相比,ISO是否会改变雌性大鼠对可卡因和食物操作性反应的习得。将同窝幼仔进行ISO处理或不进行处理(NH)。评估成年大鼠的活动水平。然后,给大鼠植入颈静脉导管,并使用递增剂量呈现程序,让它们在固定比率1(FR1)强化程序下自我给药可卡因。记录可卡因摄入量、主动杆与非主动杆的辨别以及无效主动杆反应。接着评估非条件性可卡因输注(激发)和增加FR对反应的影响。其他大鼠在FR1程序(10秒超时)下按压杠杆获取食物。ISO增强了雌性大鼠对食物和可卡因操作性反应的习得。后者表现为更好的杠杆辨别、发出更少的无效反应以及对激发的更好反应。然而,在初始习得阶段,NH雌性大鼠摄入的可卡因比ISO雌性大鼠多。在雄性大鼠中,ISO增强了可卡因自我给药的习得,但未增强对食物的反应。活动水平不受ISO或性别的影响。这些数据证实并扩展了我们之前的研究结果,证明了ISO对成年自我给药行为的持久影响,并强调了在习得研究中测量行为模式而非摄入量的重要性。