While a strength of postmortem studies is the ability to examine molecular events directly in the human brain, thorough knowledge of the subject such as drug history is limited. Toxicological data was, however, informative showing that morphine urine concentrations at death tended to be positively correlated with HOMER1 (most striatal subregions) and DLG4 (NAc) mRNA expression. The fact that these genes were reduced in heroin subjects suggests even lower expression in the non-intoxicated state. Interestingly, decreased striatal Homer150,51 or Dlg418 expression in animal models is associated with behavioral sensitization which would be predictive of addiction vulnerability.
