The Impact of Ghrelin and a Chitosan-Alginate Nanocarrier on Growth Axis Gene Expression in Common Carp (Cyprinus carpio)

Increasing growth efficiency in aquaculture through bioactive compounds such as growth hormone-releasing peptides (GHRPs) is a novel strategy in the fisheries industry. This study investigated the effects of two peptides, Ghrelin 12 and A-Ghrelin 12 (its acylated form), both in free and encapsulated forms within chitosan-alginate nanoparticles, on the expression of growth-related genes (IGF1, NPY, and GHS-R1a) in common carp fingerlings. First, the optimal peptide dose (100 µg per kg of feed) was determined in a preliminary trial. The fish were then divided into seven groups: control, free Ghrelin 12, free A-Ghrelin 12, chitosan-alginate encapsulated Ghrelin 12, chitosan encapsulated Ghrelin 12, a mixture of Ghrelin 12 and nanoparticles (non-encapsulated), and an empty nanoparticle group. After four weeks of feeding, samples were taken from the brain and liver tissues, and gene expression was assessed using Real-Time PCR.

The results showed that Ghrelin 12 and A-Ghrelin 12 peptides, especially in their encapsulated forms, significantly increased the expression of IGF1, NPY, and GHS-R1a genes and led to improved weight gain and growth in the fish. The greatest effect was observed in the group treated with chitosan-alginate encapsulated A-Ghrelin 12, indicating the effective role of the nanocarrier in enhancing peptide stability and absorption. Furthermore, A-Ghrelin 12 demonstrated similar or superior performance to Ghrelin 12 in growth stimulation. This study confirms the efficacy of using growth-stimulating peptides combined with nano-encapsulation technology in aquaculture and paves the way for future research on optimizing bioactive formulations.