Sensitization of glutamate release and N-methyl-D-aspartate receptor response by transient dopamine pretreatment in prefrontal cortex of rats.

We studied biochemically the effect of transient dopamine pretreatment on the regulation of glutamate transmission in medial prefrontal cortex of rats in vivo and in vitro. Aversive stimuli transiently increased the glutamate concentration and its repetition reduced the response in the medial prefrontal microdialysate of freely moving rats. The rate of habituation obeyed linear regression. The medial prefrontal intracellular calcium response to repetitive N-methyl-D-aspartate perfusion showed linearly regressive desensitization in fluorescence videomicroscopy of the fura-2 stained slice in vitro. Transient dopamine treatment 10-20 min prior to repetition restored both decreased responses in a linearly regressive manner, also indicating that their decrease was not due to fatigue. These findings suggest that the effect of transient dopamine pretreatment continues redundantly to sensitize/resensitize subsequent pre- and postsynaptic prefrontal glutamate transmission in an orderly manner.