Stress Selectively Increases Fos Protein in Dopamine Neurons Innervating the Prefrontal Cortex

Stress-induced alterations in expression of c-fos protein (Fos) in mesencephalic dopamine (DA) neurons of the rat were examined in order to discern which midbrain DA neurons are metabolically activated by stress. Re-straint stress for 30 min increased the number of DA neurons exhibiting Fos-like immunoreactivity in the ven-tral tegmental area (VTA), but not in the substantia nigra or retrorubral field. Stress elicited an increase in the number of DA neurons expressing Fos in specific nuclei within the VTA. Administration of the anxiogenic /9-car-boline FG 7142 also increased the total number of VTA DA neurons expressing Fos protein, whereas pretreat-ment with an anxiolytic benzodiazepine (diazepam) par-tially prevented the stress-induced increase in Fos ex-pression. Restraint stress for 30 min increase