Dopamine D1 receptor protein is elevated in nucleus accumbens of human, chronic methamphetamine users

Animal data have long suggested that an adaptive upregulation of nucleus ac cumbens dopamine D1 receptor function might underlie part of the dependency on drugs of abuse. We measured by quantitative immunoblotting protein leve ls of dopamine DI and, for comparison, D2 receptors in brain of chronic use rs of methamphetamine, cocaine, and heroin. As compared with the controls, brain dopamine DI receptor concentrations were selectively increased (by 44 %) in the nucleus accumbens of the methamphetamine users, whereas a trend w as observed in this brain area for reduced protein levels of the dopamine D 2 receptor in all three drug groups (-25 to -37%; P < 0.05 for heroin group only). Our data support the hypothesis that aspects of the drug-dependent state in human methamphetamine users might be related to increased dopamine D1 receptor function in limbic brain.