Cerebrin and small cardioactive peptides enhance feed intake in Pacific abalone (Haliotis discus hannai): An integrative molecular and in vivo study

Feeding behavior in marine gastropods, including Pacific abalone ( Haliotis discus hannai ), is critical for growth and aquaculture productivity, but its molecular regulation mechanism remains poorly understood. Herein, we identified and characterized two conserved neuropeptides—cerebrin and small cardioactive peptides (SCPs)—in Pacific abalone. Transcriptomic mining of cerebral ganglion datasets recovered full-length precursors: a cerebrin precursor (258 bp coding sequence [CDS]; 85 aa) encoding a 17-aa amidated peptide (NGGTLDSLFNLPDLSDN-NH 2 ), and an SCP precursor (342 bp CDS; 113 aa) encoding two amidated peptides—SCP A (SGYLAFPRM-NH 2 ) and SCP B (MNYLAFPRM-NH 2 ). Both genes showed four-exon architectures and strong conservation of the NGGT and YLAFPRM motifs across mollusks, as supported by multiple sequence alignment and phylogenetic analyses that clustered abalone sequences within gastropod clades. Developmental expression profiles were stage specific: cerebrin expression was highest in 3 months post-fertilization juveniles, whereas SCP peaked at the pre-settlement larval stage (6 days post-fertilization). During a 7-day feeding period followed by 7 days of refasting, cerebrin and SCP expression in buccal musculature increased significantly (6-fold at D7 for cerebrin ; 20-fold at D4 for SCP relative to D0, p < 0.05), with minimal changes in the cerebral ganglion and intestine, implicating peripheral roles in radular and odontophore activity. Functional assays corroborated these effects: in vivo administration of synthetic peptides (10 nmol/day for 3 days) significantly increased feed intake compared to saline controls ( p < 0.05), with SCP A showing the greatest efficacy (0.51 ± 0.15 g per individual vs. 0.03 ± 0.02 g in saline controls). These results demonstrate the orexigenic functions of cerebrin and SCPs, elucidate their feeding regulation mechanisms, and highlight their potential as molecular targets to improve feeding efficiency and resilience in abalone aquaculture. • Cerebrin and small cardioactive peptide precursors were identified and characterized in Pacific abalone. • mRNA profiling showed stage-specific expression across developmental stages. • Expression in buccal musculature peaked during feeding, highlighting radular activity. • Peptide administration in vivo significantly increased feed intake, confirming orexigenic roles and aquaculture potential.