中脑腹侧被盖区微量注射溴隐亭对伏隔核DOPAC含量的影响

EFFECTS OF BROMOCRIPTNE MICROINJECTION INTO VTA ON THE DOPAC LEVEL IN NUCLEUS ACCUMBENS

本工作在戊巴比妥钠麻醉的SD雄性大鼠上进行。结果表明:左侧腹侧被盖区(VTA)微量注射多巴胺(DA)受体激动剂溴隐亭(2.5μg/0.5μl,n=5)后,用微分脉冲伏安法(DPV)测定同侧伏隔核中多巴胺代谢产物——3、4双羟苯乙酸(DOPAC),峰值明显增高,注后50 min达到对照值的128％(P<0.01),注后80 min达到最高峰,为对照值的143％(P<0.01),作用的持续时间约2 h,在注后180 min恢复到对照值的111％(P>0.05)。左侧VTA预先微量注射SCH23390——一种高选择性的D_1受体阻断剂(2nmol/0.5μl,n=4).40min后再微量注射溴隐亭(2.5μg/0.5μl),同侧伏隔核中DOPAC氧化峰不再增高。结果提示:VTA微量注射溴隐亭可致中脑边缘多巴胺神经元活动增加,而这种增加作用可能是通过D_1受体中介的。

The experiment was performed in sodium pentobarbital annesthetized male SDrats. In vivo differential pulse voltammetry (DPV) was used to monitor a metabolite ofdopamine--3, 4--dihydroxyphenylacetic acid (DOPAC) level in the ipsilateral nucleus ac-cumbens following microinjection of bromocriptine (2.5 μg/0.5 μl,n=5) into left ven-tral tegmental area (VTA). The results indicated that after microinjection the ampli-tude of DOPAC peak increased gradually and reached to 128% and 143% compared tothe control at the 50th and 80th min respectively (P<0.01). The duration of the ef-fect was about two hours. One hundred and eighty min after injection, the amplitudeof DOPAC decreased to 111% of control (P<0.05). SCH23390(2 nmol/0.5 μl, n=4), a selective D_1 antagonist was given into left VTA 40 min prior to microinjectionof bromocriptine. In this group, the above--mentioned effect of bromocriptine wasblocked, the amplitude of DOPAC peak showed no increase. The results suggest thatthe microinjection of bromocriptine into VTA induces an increase cf activity of mesolim-bic dopaminergic neurons probably mediated by D_1 receptor.