The effect of cocaine abuse on plasma levels of sulfated dopamine and salsolinol in alcoholics.

This study investigated the effect of cocaine abuse on peripheral dopamine and its tetrahydroisoquinoline metabolite salsolinol in chronic alcoholics. Specifically, the concentration of dopamine sulfate and salsolinol sulfate was measured in plasma samples obtained from the blood of a group of alcoholics (n = 40) and alcoholics with cocaine dependence (n = 55). The concentrations of sulfoconjugated dopamine and salsolinol were measured by a radioenzymatic technique. The results of this study showed that chronic alcoholics (627 +/- 195 pg/ml) and alcoholics with cocaine addiction (409 +/- 76 pg/ml) had significantly (p < 0.05) elevated levels of salsolinol sulfate (mean +/- SEM) in their plasma as compared to controls (99.5 +/- 7.5 pg/ml). However, alcoholics with cocaine dependence produced significantly (p < 0.01) higher concentration of dopamine sulfate in their plasma (7520 +/- 1299 pg/ml) as compared to chronic alcoholics (3896 +/- 438 pg/ml) and controls (2124 +/- 104 pg/ml). Differences in plasma dopamine sulfate among alcoholics with cocaine dependence vs. alcoholics without cocaine dependence may be interpreted as a reflection of increased extracellular dopamine metabolism associated with chronic cocaine exposure.