| Summary: | The spatial distribution of two isoforms of Ghrelin (Ghrelin‐1 and ‐2), two isoforms of Cholecystokinin (CCK‐L and ‐N) and peptide YY (PYY) was assessed by Q‐PCR in four GI‐tract segments covering stomach, pyloric caeca, midgut and hindgut after feeding a single meal to Atlantic salmon. Both CCK‐L and CCK‐N levels increased within 1.5 hours past feeding (hpf). At this time the stomach was still ca 80% full (the gastric evacuation half‐time was 4.5 hrs), the gallbladder was almost completely empty and chyme had started to be transferred into the midgut. During the 24 hpf there were both temporal and spatial differences between the expression profile of the CCK isoforms. PYY expression increased at 1.5 hpf, and then decreased after 3 hpf. Feeding had only minor effects on the Ghrelin isoforms expression. Taken together this suggests that CCK and PYY have in part similar roles in regulating digestive processes to that observed in higher vertebrates. The two isoforms of CCK appear to have different functions. The data did not identify a role for Ghrelin related to digestion or appetite comparable to the orexigenic role described in humans.
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