Induction of ovulation in goldfish, Carassius auratus, by pimozide and analogues of LH-RH

Abstract

The effects of intraperitoneal injections or pellet implantations of luteinizing hormone-releasing hormone analogues, des-Gly I'-[ D-ALA61-LH-RH-ethylamide (LRH-Aa) or des-Gly'"-[ D-T@]-LH-RH-ethylamide (LRH-At), respectively, and the combination of these treatments with pimozide, a dopamine antagonist, on serum gonadotropin (GtH) and ovulation in goldfish held at 18-20°C were investigated. Injections of LRH-Aa (0.1 @g/g body weight) or pellet implants of LRH-At (25 and 125 pg/fish) alone increased serum GtH levels, but were relatively ineffective for inducing ovulation in goldfish ('Y 26% rate of occurrence). Pimozide greatly potentiated the GtH release response to LRH-Aa injections or LRH-At pellet implantations. A high rate of occurrence of ovulation (87%) was observed within 24 h when pimozide was injected prior to or with the first of two injections of LRH-Aa, or following implan~tions of LRH-At pellets that give continuous release of LRH-At. These results are consistent with the idea that dopamine acts directly at the pituitary level as a GtH release-inhibitory factor in goldfish.

The effect of luteinizing hormone-releasing hormone analogue (LHRHa) in combination with different drugs with anti-dopamine and anti-serotonin properties on gonadotropin release and ovulation in the African catfish, Clarias gariepinus

“…Induction of oocyte maturation and/or ovulation has been reported in the carp (Sokolowska et al, 1978;Weil et al, 1980); goldfish (Lam et al, 1975) ; plaice, Pleuronectes platessa, and goby, Acanthogobius flavimanus (Aida et al, 1978;ayu, Plecoglossus altivelis (Hirose and Ishida, 1974) ; rainbow trout, Salmo gairdneri (Crim et al, 1983) ; and coho salmon, Oncorhynchus kisutch (Donaldson et al, 1981;Van Der Kraak et al, 1983 ) . On the other hand, in goldfish, single or multiple injections of LHRH or its analogues in different doses and regimes could not induce a very high rate of ovulation Sokolowska et al, 1984). Similarly, in the African catfish, in both previous (De Leeuw et al, 198513) and present investigations, a single intraperitoneal injection of LHRHa could not induce a high rate of ovulation.…”

“…In the African catfish, apomorphine depressed the release of GTH from perifused pituitary fragments and abolished the LHRHa-induced GTH release from both pituitary fragments and cell suspensions . Administration of pimozide (a DA antagonist) in goldfish Sokolowska et al, 1984)) common carp (Billard et al, 1983)) estradiol-treated eel (Dufour et al, 1984) and the African catfish (De Leeuw et al, 1985b) greatly potentiated the LHRHa-induced GTH release. Similarly, metoclopramide (another DA antagonist) also potentiated the LHRHainduced release of GTH in goldfish (Chang et al , 1984b).…”

“…This has considerably enhanced the prospect of inducing ovulation at the pituitary level, by stimulating the endogenous production of GTH to the preovulatory level. Thus, pimozide, a DA antagonist, which potentiates the effect of LHRHa to stimulate GTH release, has proved to be an efficient ovulation-inducing agent and the combination has been tried successfully in common carp, Cypriot curpio (Billard et al, 1983), goldfish Sokolowska et al, 1984) and the African catfish, Clarias guriepi~~ (De Leeuw et al, 1985a, b).…”

Reproduction potentiated in nematodes (Caenorhabditis elegans) and guppy fish (Poecilia reticulata) by adding a synthetic peptide to their aqueous environment

“…Implants and injections of pituitary material have been used in both freshwater and marine species for food production. In goldfish, Carassius auratus, analogues of luteinizing hormone-releasing hormone, injected or implanted as pellets and co-administered with a dopamine antagonist, caused almost nine out of 10 females to ovulate (Sokolowska et al, 1984). Peptide hormone treatment with IGF-I in the short-finned eel, Anguilla australis, yielded an increase in oocyte diameter (Lokman et al, 2007).…”

Induction of final oocyte maturation in Cyprinidae fish by hypothalamic factors: a review

“…The unsatisfactory potency of natural GnRH peptides was improved by synthesising a superactive GnRHa, which is able to induce a significant increase in LH levels even at centuple smaller doses than with the use of natural GnRH forms (Table 1), (Kouril et al, 1986(Kouril et al, , 2007. The range of effective doses of GnRHa varies from 5-100 μg/kg and in the case of DI from 5-20 mg/kg of effective matter (Kouril et al, 1986;Drori et al, 1994;Brzuska, 1999;Szabo et al, 2002;Glasser et al, 2004;Mikolajczyk et al, 2004;Rutaisire and Booth, 2004;Kucharcyzk et al, 2005;Heyrati et al, 2007 Due to the strong dopaminergic inhibition of LH secretion, typical for the family Cyprinidae, a majority of trials with ovulation induction using only GnRHa failed (Weil et al, 1980;Sokolowska et al, 1984). According to the results of other authors Yaron, 1995;Heyrati et al, 2007) and our own, the only exceptions to the strong dopaminergic activity in Cyprinidae we know are tench (Tinca tinca), (Kouril et al, 1986) and rudd (Scardinius erythrophthalmus), (Hamackova et al, 2001) in which even a dose of 1 μg/kg mGnRHa was able to stimulate ovulation in a small number of females.…”