Efficacy of poly (lactic-co-glycolic acid) microparticles as a gonadotropin-releasing hormone analogue delivery system to stimulate ovulation of peled Coregonus peled

Abstract

The aim of the study was to determine the efficacy of poly (lactic-co-glycolic acid) microparticles as a carrier of gonadotropin-releasing hormone analogues (GnRHa) for induction of ovulation in peled Coregonus peled. Female peled were injected intraperitoneally with 1) saline solution only (control), 2) mammalian GnRHa at 25 µg/kg body weight, 3) GnRHa in 753-type microparticles at 50 µg/kg, or 4) GnRHa in 653-type microparticles at 50 µg/kg. Blood plasma samples were taken on days 0, 4, 8, and 12 post-injection. All hormone treatments induced synchronous ovulation and higher cumulative ovulation compared to controls. Hormone treatments did not affect relative fecundity or the percentage of eyed eggs. Testosterone level decreased toward the onset of ovulation. On day eight of the trial, the testosterone level was significantly lower in hormone-treated groups compared to the control group. The level of 17β-oestradiol showed a decreasing trend post-injection, with the lowest observed level on day eight. Our results demonstrate that ovulation can be induced in the peled by the sustained - release of GnRHa in poly (lactic-co-glycolic acid) microparticles, but the treatment does not improve reproductive performance.

Keywords

• induction of ovulation
• gnrha
• salmonids
• sustained drug release
• steroid feedback