Abstract
A new water-in-oil-in-water (W/O/W) type emulsion using lipophilized gelatin (LG) and cotton-seed oil was developed for a novel method of hormone administration in fishes. LG was prepared by attaching palmitic anhydride to gelatin. The best conditions for preparing stable emulsions were determined where the final concentrations of LG in the emulsion and the volume ratio of LG solution to cotton-seed oil were 2% and 1:2, respectively. Hormone releasing properties of LG emulsion were compared with a water-in-oil (W/O) type emulsion prepared with Freund's incomplete adjuvant (FIA) and saline solution by monitoring plasma profiles of salmon gonadotropin (sGtH) II in the Japanese eel. sGtH II is gradually released from the LG emulsion. LG emulsion had hormone-releasing properties different from those of the saline solution and the FIA emulsion. Immature female Japanese eel (BW, 566 to 1017 g) received a weekly intramuscular injections (total of 10 injections) of the LG emulsion, the FIA emulsion or the saline solution, each of which contained sGtH fraction. The LG emulsion was found to be more effective in inducing ovarian maturation. In mature eel, final maturation and ovulation could be induced by simultaneous administration of sGtH fraction and 17α-hydroxyprogesterone using LG W/O/W emulsion.
Published Version
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