LH secretion and 17ββ-estradiol concentration in the blood plasma and hypothalamus of goldfish (Carassius auratus gibelio B.) and common carp (Cyprinus carpio L.) treated with fadrozole (aromatase inhibitor) and GnRH analogues

Abstract

Fadrozole -a non-steroidal aromatase inhibitor was applied to common carp and goldfish to examine its ability to potentiate the stimulatory action of GnRH analogues on LH secretion in vivo. The goal of the project was to find a substitute for antidopaminergic drugs used with GnRH analogues in fisheries practice to stimulate ovulation in fish bred in captivity. The first trials on goldfish showed a moderate ability of fadrozole to potentiate salmon GnRH analogue stimulation, weaker than that obtained with pimozide (dopamine antagonist). No ovulation in fadrozole-treated fish was observed. Several experiments performed in two consecutive reproductive seasons (different treatment regimes and doses of fadrozole) neither improved nor confirmed the results obtained in the first year. The analysis of 17β-estradiol levels in the blood plasma and in hypothalami showed no changes in the concentration of this steroid in fadrozole-treated fish in comparison with the controls. This shows that fadrozole is not able to replace the antidopaminergic drugs used in fisheries practice and cannot be considered as a potential ovulation inducer in cyprinids.

PGF2α and gonadal steroid plasma levels of successful and unsuccessful spawning Piaractus mesopotamicus (Teleostei, Characiformes) females

“…Moreover, E 2 in vitro-treated follicles had significantly inhibited MIH output (Jalabert and Fostier 1984). However, in contrast to most studies, our results were more closely related to those of Mikolajczyk et al (2007) in goldfish (Carassius auratus) and common carp (Cyprinus carpio) where E 2 plasma levels remained similar during induced spawning. Therefore, in the present study, there was not an obvious inhibitory function of E 2 on P. mesopotamicus ovulation.…”

A CYP19 Based Sex Determination and Monosex Production in Aquaculture Species Oreochromis niloticus L. and a Cyprinid Cyprinus carpio L.

“…However, there was some estradiol level left in the circulation even after aromatase inhibition which could be due to two reasons; firstly the blood sample was pooled where specimens of both the genetic sexes might have been present and alternately some estradiol level may be needed for maintenance of testicular activity since Cyp19 gene is highly conserved in fish [12]. Our findings support the earlier findings of [31] where significant differences in concentrations of E 2 in the blood plasma and hypothalami between fadrozole (5, 50 or 500 μg kg -1 ) treatment groups of goldfish and C. carpio has been reported. Fadrozole in the doses of 0, 100, 500 and 1000 μg/fish has been reported to decrease the plasma E 2 in honeycomb grouper Epinephelus merra and Nile tilapia [32][33][34] which further supports our findings.…”

Inhibition of Aromatase Induces Partial Sex Change in a Cichlid Fish: Distinct Functions for Sex Steroids in Brains and Gonads

“…In addition, a compensatory response has previously been shown in other fish species after AI treatment, resulting in a reestablishment of normal E2 levels [Villeneuve et al, 2009a;Garcia-Reyero et al, 2014]. Also, goldfish and common carp treated with fadrozole do not show a reduction in E2 levels [Mikolajczyk et al, 2007]; however, androgen levels were not measured in this study. We observed a fast reaction to AI in the external phenotype, with treated females showing the appearance of male-typical traits after 14 days already.…”