The induction and suppression of c- fos expression in the rat brain by cholecystokinin and its antagonist L364,718

Abstract

Immunohistochemical techniques were used to map c- fos expression in the rat brain after the i.p. administration of CCK-8 (8 μg/kg). C- fos expression was observed in the rostral and the caudal parts of the nuclei of the solitary tract (NTS), and the paraventricular nuclei (PVN) in the hypothalamus. The c- fos expression in these areas was suppressed by the administration of L364,718 (120 μg/kg). Since L364,718 is known to be a powerful selective antagonist to the peripheral CCK-A receptors, these data suggest that the effects produced by exogenous CCK are due to peripheral receptors that project to the NTS.