[Effects of bromocriptine microinjection into VTA on the DOPAC level in nucleus accumbens]

The experiment was performed in sodium pentobarbital anesthetized male SD rats. In vivo differential pulse voltammetry (DPV) was used to monitor a metabolite of dopamine-3,4-dihydroxyphenylacetic acid (DOPAC) level in the ipsilateral nucleus accumbens following microinjection of bromocriptine (2.5 micrograms/0.5 microliters, n = 5) into left ventral tegmental area (VTA). The results indicated that after microinjection the amplitude of DOPAC peak increased gradually and reached to 128% and 143% compared to the control at the 50th and 80th min respectively (P < 0.01). The duration of the effect was about two hours. One hundred and eighty min after injection, the amplitude of DOPAC decreased to 111% of control (P > 0.05). SCH23390 (2 nmol/0.5 microliters, n = 4), a selective D1 antagonist was given into left VTA 40 min prior to microinjection of bromocriptine. In this group, the above-mentioned effect of bromocriptine was blocked, the amplitude of DOPAC peak showed no increase. The results suggest that the microinjection of bromocriptine into VTA induces an increase of activity of mesolimbic dopaminergic neurons probably mediated by D1 receptor.