可卡因固定比率自身给药大鼠模型的建立

目的：建立稳定的可卡因固定比率自身给药大鼠模型，并提高其成功率。方法：16只大鼠随机分为对照组和模型组，每组8只。2组大鼠全部行右侧颈静脉长期置管术，术后第6天起进行每天2小时的自身给药训练，训练程序为固定比率的FR1程序（即大鼠触碰鼻触一次可获得药物注射一次），模型组注射药物为浓度为5mg／ml的可卡因溶液（50μl／次），对照组为生理盐水（50μl／次），每次注射后20秒内为不应期，当大鼠连续3天触鼻频率最高值与最低值的差值小于均数标准差的1／4后，FR1模式下的大鼠自身给药训练成功。结果：通过8-11天训练，模型组8只SD大鼠全部形成稳定的自身给药行为，且与对照组相比，触鼻次数明显增加，P〈0．01。结论：通过静脉自身给药训练，盐酸可卡因可使大鼠建立稳定的自身给药模型：通过改善手术质量、加强术后维护，可明显提高模型成功率。

Establishment of the Fixed Radio Cocaine Self-administration Model in Sprague-Dawley Rats

Objective： To establish the fixed radio cocaine self-administration rat model and to improve achievement ratio. Meth- ods： Sixteen rats were divided randomly into two groups： control group and model group （n=8）. Build up the fixed radio cocaine self-ad- ministration rat model by the surgical and self-administration training procedures developed for rats. An indwelling silastie catheter was placed into the right jugular vein .5 days after the surgery ,all the 16 rats with intrajugular catheters were placed in operant chambers for a 2 h self-administration session everyday. The rats in model group were trained to nose-poke for cocaine （50 μl per infusion） under a fixed-ratio-1 schedule of reinforcement, while the rats in control group got saline （ 50 μl per infusion） for one nose poke, a 20 s timeout period during which responses had no scheduled consequences followed each drug infusion. When the variation of response rates was less than 25% of the standard deviation over 3 consecutive days, the model were established successfully. Results： Through 8-11 days, all the eight rats in model group achieved stable behavior of cocaine self-administration. Compare with the rats in control group, the times of nose-poke is obviously higher, P〈0.01. Conclusion： By intravenous cocaine self-administration training ,the rat could be trained to establish the fixed radio cocaine self-administration model. The achievement ratio of this model could be improved obviously by promote the quality of surgery and the postoperative care.