Oral salmon acylated ghrelin increases food intake in common carp (Cyprinus carpio) via ghrelin receptors, likely through sensory nerves rather than systemic absorption.

Single-shot dietary trials in common carp

“Experimental diets containing sAG (ranging from 0.001 to 13.04 µg/g) were prepared and fed to carp at 2.0 % of body weight (BW) in single-shot trials.”

Common carp (Cyprinus carpio)

“This study clarified the local mechanism of action and assessed the aquaculture potential of orally administered salmon acylated ghrelin (sAG) on feed intake in common carp (Cyprinus carpio).”

Plasma ghrelin levels remained unchanged despite increased intake

“Despite this behavioral effect, plasma ghrelin levels remained unchanged, as measured by both N-terminal and salmon-specific C-terminal radioimmunoassays, confirming that sAG was not systemically absorbed.”

The orexigenic effect was abolished by ghrelin receptor antagonist or capsaicin

“The orexigenic effect was abolished by pretreatment with the ghrelin receptor antagonist [D-Lys3]-GHRP-6 or with capsaicin, demonstrating local sAG action via growth hormone secretagogue receptor signaling and peripheral sensory neurons (likely vagal afferents).”