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1.  Distinctive Profiles of Gene Expression in the Human Nucleus Accumbens Associated with Cocaine and Heroin Abuse 
Drug abuse is thought to induce long-term cellular and behavioral adaptations as a result of alterations in gene expression. Understanding the molecular consequences of addiction may contribute to the development of better treatment strategies. This study utilized highthroughput Affymetrix microarrays to identify gene expression changes in the post-mortem nucleus accumbens of chronic heroin abusers. These data were analyzed independently and in relation to our previously reported data involving human cocaine abusers, in order to determine which expression changes were drug specific and which may be common to the phenomenon of addiction. A significant decrease in the expression of numerous genes encoding proteins involved in presynaptic release of neurotransmitter was seen in heroin abusers, a finding not seen in the cocaine-abusing cohort. Conversely, the striking decrease in myelin-related genes observed in cocaine abusers was not evident in our cohort of heroin subjects. Overall, little overlap in gene expression profiles was seen between the two drug-abusing cohorts: out of the approximately 39 000 transcripts investigated, the abundance of only 25 was significantly changed in both cocaine and heroin abusers, with nearly one-half of these being altered in opposite directions. These data suggest that the profiles of nucleus accumbens gene expression associated with chronic heroin or cocaine abuse are largely unique, despite what are thought to be common effects of these drugs on dopamine neurotransmission in this brain region. A re-examination of our current assumptions about the commonality of molecular mechanisms associated with substance abuse seems warranted.
PMCID: PMC2239258  PMID: 16710320
human; post-mortem; nucleus accumbens; heroin; microarray; cocaine
2.  Gene expression profile of the nucleus accumbens of human cocaine abusers: evidence for dysregulation of myelin 
Journal of neurochemistry  2004;88(5):1211-1219.
Chronic cocaine abuse induces long-term neural adaptations as a consequence of alterations in gene expression. This study was undertaken to identify those transcripts differentially regulated in the nucleus accumbens of human cocaine abusers. Affymetrix microarrays were used to measure transcript abundance in 10 cocaine abusers and 10 control subjects matched for age, race, sex, and brain pH. As expected, gene expression of cocaine- and amphetamine-regulated transcript (CART) was increased in the nucleus accumbens of cocaine abusers. The most robust and consistent finding, however, was a decrease in the expression of a number of myelin-related genes, including myelin basic protein (MBP), proteolipid protein (PLP), and myelin-associated oligodendrocyte basic protein (MOBP). The differential expression seen by microarray for CART as well as MBP, MOBP, and PLP was verified by RT–PCR. In addition, immunohistochemical experiments revealed a decrease in the number of MBP-immunoreactive oligodendrocytes present in the nucleus accumbens and surrounding white matter of cocaine abusers. These findings suggest a dysregulation of myelin in human cocaine abusers.
PMCID: PMC2215309  PMID: 15009677
cocaine; human; microarray; myelin basic protein; nucleus accumbens; post-mortem
3.  Gene Expression Profiling in the Brains of Human Cocaine Abusers 
Addiction biology  2005;10(1):119-126.
Chronic cocaine abuse induces long-term neurochemical, structural and behavioural changes thought to result from altered gene expression within the nucleus accumbens and other brain regions playing a critical role in addiction. Recent methodological advances now allow the profiling of gene expression in human postmortem brain. In this article, we review studies in which we have used Affymetrix oligonucleotide microarrays to identify transcripts that are differentially expressed in the nucleus accumbens of cocaine abusers in comparison to well-matched control subjects. Of the approximately 39 000 gene transcripts interrogated, the expression of only a fraction of 1% is significantly modified in cocaine abusers. Found within this list are equivalent incidences of increased and decreased transcript abundance, including known gene transcripts clustered into several functional categories. A striking exception is a group of myelin-related genes, consisting of multiple transcripts representing myelin basic protein (MBP), proteolipid protein (PLP) and myelin-associated oligodendrocyte basic protein (MOBP), which as a group are substantially decreased in cocaine abusers compared to controls. These data, suggesting a possible dysregulation of myelin in cocaine abusers, are discussed in the context of myelin-related changes in other human brain disorders. Finally, the effects of cocaine abuse on the profile of gene expression in some other brain regions critical for addiction (the prefrontal cortex and ventral midbrain) are briefly reviewed.
PMCID: PMC2215307  PMID: 15849025

Results 1-3 (3)