Many fish species display some form of reproductive disorder in captivity. Captive fish reared in conditions outside the natural spawning environment show a failure of the pituitary to release the maturational gonadotropin luteinizing hormone thus necessitating administration of the hormone to induce spawning. A controlled sustained-release delivery system can conquer the issue of short half-life of gonadotropin releasing hormone (GnRH) in blood and avoid the necessity of using re-injections. Sustained release of GnRHa can induce long-term enhancement in semen production and multiple spawning in species with asynchronous or multiple batch group synchronous ovarian physiology. The most recent development is the incorporation of GnRHa into microparticles of biodegradable polymers that release the drug during a certain period of time ranging from days to weeks. The most attractive polymeric candidate used as a carrier for administering a pharmaceutical products is poly(lactic-co-glycolic acid); (PLGA). PLGA has excellent biodegradability and biocompatibility and is generally recognised as safe by international regulatory agencies including the European Medicines Agency and the United States Food and Drug Administration. This review describes methods of hormonal treatment in fish, highlights the advantage of sustained drug delivery system and discusses the potential of PLGA microparticles as a tool for achieving successful reproduction.
Sustained drug delivery system in fish and the potential for use of PLGA microparticles: a review
