Cholecystokinin- and dexfenfluramine-induced anorexia compared using devazepide and c-fos expression in the rat brain

It has been proposed that there might be a link between the anorectic actions of cholecystokinin (CCK) and serotonin (5HT). The present study compared the patterns of c-fos protein-like immunoreactivity (FLI) induced in rat brain by CCK and the indirect 5HT agonist dexfenfluramine (DFEN), as well as the ability for devazepide, a CCK-A receptor antagonist, to antagonize both anorexia and FLI induced by these agents. Devazepide reversed the anorectic effect of CCK but not that of DFEN in food deprived rats. The FLI induced by CCK and DFEN occurred in similar brain regions, but in different subdivisions. Such regions included the bed nucleus of the stria terminalis (BST), the lateral central nucleus of the amygdala (CeL), and the lateral parabrachial nucleus (LPB). Devazepide abolished the FLI induced by CCK in most of these brain regions, but had no effect on FLI induced by DFEN. These results suggest that the LPB-CeL/BST pathway might be responsible for the anorectic effects of both CCK and DFEN, but different parts or neuronal populations in these structures might be differentially engaged by CCK and DFEN. The putative interaction between CCK and 5HT might happen along this pathway, rather than in the periphery.