Controlled release opportunities for oral peptide delivery in aquaculture

Over the last decade, fish supplies for human consumption have reached over 1100 million tons. Due to overfishing, future increases in demand can only be met from the aquaculture industry. This will require increased research in areas such as the control and manipulation of fish reproduction. There is increasing interest in the oral delivery of peptides that control gamete reproduction. However, compared to mammalian species, little is known abou t the barriers to peptide delivery and methods to improve such delivery. Th e three major barriers to peptide delivery are the enzymatic barriers sourc ed from the host luminal and membrane bound peptidases, the immunological c ells present within both the enterocytes and underlying connective tissue a nd the physical barrier of the epithelial cells. Furthermore, the anatomy a nd physiology of the gastrointestinal tract of these species are markedly d ifferent when compared to higher vertebrates and therefore must be consider ed when designing appropriate delivery systems. Research to date has focuse d on the oral delivery and subsequent pharmacodynamic responses to the pept ides associated with growth and reproduction. However, minimal work has bee n undertaken to overcome the identified barriers and therefore any future i nvestigations need to attend to these obstacles before the oral delivery of bioactive peptides can become a commercial reality. (C) 1999 Elsevier Scie nce B.V. All rights reserved.