ABSTRACT
This chapter focuses on the use of in situ hybridization to study gene expression and regulation in one of the brain circuits most strongly tied to drug abuse. Drug-induced alterations in neuronal gene expression can serve as markers for drug impact on specific neurons and specific genes. It is also possible that drug-induced changes in gene expression can contribute to some of the phenomena of drug tolerance and withdrawal. Both of these phenomena, prominently associated with several abused drugs; require a biochemical "memory" process that changes current nervous system function based on past exposure of the nervous system to drugs. The state of expression of particular classes of genes is one of the major potential biochemical repositories for information storage in the brain. It has been postulated that "adaptive" information, such as memory, could be encoded, at least in part, by biochemical changes in gene expression.
