ABSTRACT
Mesencephalic dopaminergic neurones seem to be the neurobiological substrate through which stress increases the propensity to self-administer drugs of abuse. The role of these neurones in reward and motivation has been emphasized in several good reviews2~·16•17. In particular, the release of dopamine in the nucleus accumbens is considered to be one of the major substrates of the addictive properties of drugs2~·"·17•
Several types of acute stress increase dopamine release in the nucleus accumbens46. Furthermore, repeated stress induces a long-lasting increase in the release of this neurotransmitter'6. In particular, in stressed subjects drug-induced dopamine release is increased<6. That stress-induced increase in dopamine release could mediate the effects of stress on drug selfadministration is supported by a supplementary set of observations. Indeed, when an increase in the activity of the dopaminergic projection to the nucleus accumbens is induced by other means, such as repeated amphetamine injections3,22A6 or lesions of specific brain areass, an increase in psychostimulant self-administration similar to the one induced by stress is also observed.
