Cholecystokinin infused in the celiac and cranial mesenteric arteries reduces food intake and increases Fos-like immunoreactivity in the enteric and the dorsal vagal complex neurons

Cholecystokinin (CCK) is a peptide secreted by the I-cells of the small intestine and evokes a variety of responses e.g. reduction of meal size (MS) and prolongation of the intermeal interval (IMI, time between two consecutive meals). We have shown that the areas supplied by the celiac artery (CA, supplies stomach and upper duodenum) and the cranial mesenteric artery (CMA supplies small and part of the large intestine) contain site of actions controlling the previous feeding responses, MS and IMI length, in free feeding, undisturbed Sprague Dawley rats maintained on normal rat chow. Here, we determined activation of the enteric neurons and dorsal vagal complex (DVC) by two forms of CCK, CCK-8, the most used commercial form and CCK-58, the only endocrine form of the peptide infused in the CA, CMA and the femoral artery (FA, control) prior to the onset of the dark cycle. Sixty minutes following the infusion all rats were sacrificed and Fos-like immunoreactivity (Fos-LI) was quantified in the myenteric and the submucosal plexuses of the duodenum and in the hindbrain areas that control food intake e.g. the dorsal motor nucleus of the vagus (DVC), area postrema (AP) and nucleus tractus solitarius (NTS). We found that CCK-58 infused in the CA and CMA but not in the FA increased Fos-LI in the myenteric and the submucosal plexuses and the DVC. In Conclusion, these results provide further evidence that the areas supplied by the CA and CMA contains sites of action controlling MS and IMI length by CCK-58.