Evaluation of the potency of
azagly-nafarelin (GnRH analogue), administered in combination with different
formulations of pimozide, on LH secretion, ovulation and egg quality in
common carp (Cyprinus carpio L.) under laboratory, commercial
hatchery and natural conditions
T. Mikolajczyk, J. Chyb, P. Szczerbik, M.
Sokolowska-Mikolajczyk, P. Epler, W.J. Enright, M. Filipiak, B. Breton-2004
Aquaculture, 234(1-4): 447-460
Abstract:
The study was performed in order to evaluate the
effects of the GnRH analogue, azagly-nafarelin (AZAGLY), in combination with
pimozide (dopamine receptor antagonist), on LH secretion, ovulation and egg
quality of common carp. Experiments were performed in laboratory, commercial
hatchery and natural conditions during 3 consecutive years (1998–2000).
AZAGLY action was compared with GnRH agonists already used in aquaculture
practice: D-Arg6 Des-Gly10 salmon GnRH analogue
(sGnRHa) and D-Ala6 Des-Gly10 LHRH analogue, a
component of a commercially available product, Ovopel. In addition, the
potency of pimozide, administered to fish using different formulations
(suspensions or solutions), to potentiate the action of AZAGLY or sGnRHa was
tested. It was shown that combined treatment of AZAGLY+pimozide (in
dissolved form) is highly efficient in stimulating LH secretion and
ovulation in common carp. The number of ovulated females as well as egg
quality is not different and in some cases even better than after Ovopel
treatment. The best results were obtained when the total dose of AZAGLY (20
µg kg-1 b.w.) and pimozide (5 mg kg-1 b.w.) was
administered in two portions (10+90%) at 6- or 12-h intervals. Additional
experiments performed in 1998 showed that the relatively low potency of
AZAGLY and sGnRHa treatment in 1998 experiments was caused by the
insufficient inhibition of dopamine action by pimozide administered
intraperitoneally in a form of suspension. Significantly higher LH
concentrations were obtained if pimozide was given in a dissolved form.
Combined treatment of AZAGLY+pimozide was also shown to be very effective in
stimulating the natural spawning of common carp under an unfavourable
thermal regime.
(Department of Ichthyobiology and Fisheries,
University of Agriculture, ul. Spiczakowa 6, 30-199, Cracow-Mydlniki,
Poland, e-mail: tmikolaj@ar.krakow.pl)