Ghrelin as a Promising Immunostimulant in Aquaculture: Mechanisms and Therapeutic Potential

Ghrelin, a peptide hormone originally known for its role in growth hormone secretion and appetite regulation, is a key immunomodulator in vertebrates, including fish. This hormone and its receptor (GHS-R) are widely expressed in immune cells—T cells, B cells, neutrophils, and macrophages—and tissues. In fish, Ghrelin modulates physiological processes (e.g., reproduction or energy balance) and improves immune defense mechanisms. Studies have demonstrated its ability to promote phagocytic activity, regulate cytokine production, and stimulate antimicrobial peptide production, enhancing resistance to pathogenic infections. Likewise, the development of ghrelin mimetics, like GHRP-6, with a wide range of functionalities, further increases the potential of their use in aquaculture, showing promising results in improving growth and immune responses in fish. Ghrelin and its analogs represent a promising alternative for boosting fish's immune response against pathogens. Thus, understanding Ghrelin's regulatory mechanisms in fish immunity may reveal practical applications for aquaculture practices, helping achieve fish welfare and sustainability. Keywords: Ghrelin; immune system; fish; growth hormone secretagogue; cytokines; antimicrobial activity