We are investigating how developmental influence on sex differences in the brain may underlie the sex differences in drug addiction. We use in vivo microdialysis to study changes in brain chemistry (dopamine, serotonin) from freely moving rats, immunohistochemistry to look at changes in proteins expressed after drug taking behavior, viral vector technology, and cocaine self-administration to assess drug abuse liability and addictive tendencies. In collaboration with other laboratories we are also using in vivo voltammetry to measure rapid changes in dopamine in the brain, and electrophysiology in behaving animals.