Does brain 3,4-dihydroxyphenylacetic acid reflect dopamine release?

After sulpiride (75 mg kg-1) administration, a significant increase in dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) occurred in the rat striatum. No attenuation in the sulpiride-induced dopamine and DOPAC increase was seen in the striatum from rats previously treated with benztropine (25 mg kg-1). On the other hand, in the benztropine + sulpiride-treated group, HVA levels were significantly lower compared with those of rats to which only sulpiride had been given. The results presented suggest that under appropriate conditions, as when sulpiride is used, dopamine can be deaminated before its release has occurred.