Effect of caerulein on expression of the immediate-early genes c- fos and zif/268 in the rat brain

The effect of caerulein, an analog of cholecystokinin-8, on expression of the immediate-early genes c- fos and zif/268 was studied in the rat brain using Northern blot analysis and an in situ hybridization technique. Intraperitoneal injection of caerulein did not change the basal c- fos and zif/268 expression. Administration of the convulsant, pentylenetetrazole (PTZ), caused a dramatic increase of c- fos and zif/268 mRNAs in the hippocampus and dentate gyrus. Pretreatment with caerulein suppressed the PTZ-induced c- fos and zif/268 expression. It is considered that systemically administrated caerulein modifies neuronal activities by exerting a suppressed effect on induction of the immediate-early genes.