NEUROANATOMY AND NEUROCHEMICAL MECHANISMS OF TIME-DEPENDENT SENSITIZATION

Time-dependent sensitization (TDS) is a phenomenon described in rodent s as an enhancement in the behavioral and neurochemical responses to i ntermittent exposure to psychostimulant drugs. Time-dependent sensitiz ation also occurs after repeated encounters with environmental stress. Several features of TDS parallel those of multiple chemical sensitivi ty (MCS) in humans, and these similarities have led to the hypothesis that MCS may be explained in part by a similar sensitization process t hat occurs in rodents. In the studies presented here, we discuss some of the critical features of TDS following repeated exposure to cocaine and environmental stress, including the anatomical and neurochemical pathways utilized in expressing TDS. In addition, we discuss the possi ble neurochemical basis for individual differences in responsiveness t o stimuli, including novelty and cocaine. The striking similarities be tween TDS and MCS suggest it may be possible to develop an animal mode l of MCS, using TDS in rodents as its basis.