Abstract: 0bjeetive To examine the change of synaptic plasticity in VTA—NAc(Vental tegment area—Nucleu accumbens，VTA—NAc)circle in heroin-addicted rats．Methods Sprague-Dawley rats(180～220 g)were randomly divided into control group and heroin—treated group．Heroin were injected subcutaneously twice a day according to the principle of daily increasing dose to establish the model of heroin—dependence．Withdrawal was precipitated by administering the opioid antagonist naloxone to examine whether the heroin—addicted model was established．The control group was given equivalent volume of saline．For induction of LTP，high·frequency stimulations were applied to VTA and NAc，and population spike was recorded in vivo．Results 1)The withdrawal symptom is according with the scoring indications of the established heroin—addicted model of rats．2)The PS amplitude of LTP induced from NAc and VTA in heroin—addicted rats was significantly lower than control group(P<0．05)。Conclusion Heroin can influence synaptic plasticity in VTA—NAc circle in heroin—addicted rats．

Key words: Heroin, VTA, NAc, LTP, PS

摘要： 目的观察海洛因依赖大鼠中脑腹侧被盖区(vental tegment area，VTA)一伏隔核(nucleu accumbens，NAc)突触 传递可塑性的变化。方法sD雄性大鼠40只(180～220 g)。随机分成对照组、海洛因依赖组(以下称依赖组)。按 剂量递增原则，皮下注射海洛因，2次／d(9：00 am，16：00 pm)，连续9 d(首日海洛因剂量3 me,／kg，逐日递增 3 mg／kg)，第10天用纳络酮催促戒断，确定大鼠海洛因成瘾模型成功建立。对照组按同样方式注射等量0．9％ NaCl水溶液。海洛因依赖模型建立后，每天继续给海洛因维持量(27 mg／kg)。按大鼠脑立体定位图谱分别刺激 VTA和NAc，并分别在NAc和VTA引导群体峰电位(Population spike，PS)(刺激参数：5 V，200 HZ，波宽300 p,s)。 结果1)建立的海洛因依赖模型组大鼠催促戒断症状的评分符合成瘾模型评分标准；2)海洛因依赖组分别高频刺 激VTA和NAc，并分别在NAc和VTA引导长时程增强(10ng—term potentiation，LTP)，其LTP的Ps低于对照组 (P<0．05)。结论1)提示VTA和NAc之间存在着突触传递的通路；2)提示在海洛因的作用下，该通路的突触传 递发生了可塑性的变化。

关键词: 海洛因依赖, 中脑腹侧被盖区, 伏隔核, 长时程增强, 群峰电位