Acute treatment with antidepressant drugs selectively increases the expression of c-fos in the rat brain.

Rats were treated acutely, ip, with saline vehicle or an antidepressant: iprindole (15 mg/kg), nortriptyline (15 mg/kg), A75200 (10 mg/kg), fluoxetine (15 mg/kg), desipramine (10 mg/kg), bupropion (20 mg/kg) or tranylcypromine (7.5 mg/kg). Mapping the neuroanatomical distribution at 64 sites of the immediate early gene, c-fos revealed several patterns: first, increased counts of Fos-like neurons were found in all but one instance; second, drugs which had dopaminergic effects (bupropion and tranylcypromine) were more likely to potentiate c-fos reactivity than were the other drugs; third, Fos-like counts were more likely to be significantly elevated in structures bordering brain ventricles; fourth, only in the central amygdala were the Fos-like counts higher in all seven drug groups relative to the saline group. It remains to be seen whether or not this shared substrate is therapeutically significant.