Figure 21.

Phorbol 12-myristate 13-acetate (PMA) reversed the inhibitory effect of tetrabenazine (TBZ) on [³H]dopamine release in rat striatum. Striatal slices were prepared from non-treated and TBZ-pretreated (1 mg/kg sc 60 min before the experiment) rats, loaded with [³H]dopamine and superfused. The resting and the electrical stimulation (40 V, 10 Hz, 2-msec for 3 min in fraction 16)-induced [³H]dopamine release was determined as a fractional rate. (A) PMA was added from fraction 10 in a concentration of 1 µmol/L to striatal slices obtained from TBZ-pretreated rats and was maintained throughout the experiment. (B) TBZ pretreatment decreased the electrical stimulation-induced [³H]dopamine release from striatum: the release was 2.78 ± 0.19 in control and 1.21 ± 0.19 percent of content in tetrabenazine-pretreated rat striatum, # p < 0.05. PMA (1 µmol/L) increased the electrical stimulation-induced [³H]dopamine release in non-treated and TBZ-pretreated rat striatum by 178 and 475%, respectively. Student t-statistics for two-means, * p < 0.05, ** p < 0.01, mean ± S.E.M., n = 6-8.