Striatal 3-methoxytyramine as an index of dopamine release effects of electrical stimulation.

Electrical stimulation of the substantia nigra elicited frequency-dependent increases in striatal 3-methoxytyramine (3-MT). Subsequently, successive increases in dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were measured. Inhibition of nigrostriatal cell firing with HA-966 resulted in decreased striatal 3-MT, but in this case elevated DOPAC and HVA were also observed. These data indicate that 3-MT is a reliable index of dopamine (DA) release but that concurrent measurements of DOPAC, HVA and DA provide the most reliable interpretation of drug effects on dopaminergic function.