c-Fos response to administration of catecholamines into brain by microdialysis

The present studies investigated the use of microdialysis for the infusion of catecholamines into the brain in studies of immediate early gene (IEG) activation. c-Fos like immunoreactivity was examined histochemically in cortical tissue surrounding a dialysis probe implanted in the medial prefrontal cortex. No c-fos reactivity was observed at 48 h post implantation in control animals not probe-infused or infused 2 h earlier with Ringer's buffer. Marked reactivity was found in animals infused with a solution of norepinephrine (NE). The latter was blocked by coinfusion of the beta adrenoceptor antagonist, timolol. It is concluded that direct infusion of NE by dialysis can induce c-fos expression in cells of the cerebral cortex and that this effect is primarily via beta-adrenoceptors. Microdialysis therefore represents a useful technique in studies of IEG responses to brain catecholamines.