Comparison of [D-Arg6, Trp7, Leu8, Pro9NEt]-luteinizing hormone-releasing hormone (sGnRH-A), and [D-Ala6, Pro9NEt]-luteinizing hormone-releasing hormone (LHRH-A), in combination with pimozide, in stimulating gonadotropin release and ovulation in the goldfish, Carassius auratus

Abstract
LHRH-A and sGnRH-A were tested, in the presence or absence of pimozide (Pim), for their ability to stimulate increases in serum gonadotropin (GtH) levels and ovulation in prespawning female goldfish. In the absence of Pim, sGnRH-A was more active than LHRH-A in terms of stimulating serum GtH levels; neither peptide given alone was effective in stimulating ovulation. Pim potentiated the activity of both peptides; high dosages of either peptide, plus a high dosage of Pim, were highly effective in stimulating serum GtH and ovulation. A low dosage of sGnRH-A, plus a low dosage of Pim, were also effective in stimulating serum GtH and ovulation; however, a low dosage of LHRH-A plus a low dosage of Pim were ineffective. The time to ovulation following injections, for those treatments that were highly effective in inducing ovulation, was highly predictable, and oocyte fertility and viability were high. These results indicate that sGnRH-A, in the presence of Pim, is effective in stimulating ovulation in goldfish at dosages about 10-fold less than for LHRH-A. The basis for the differences in potency between sGnRH-A and LHRH-A is discussed.

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