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

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.