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Sex steroid levels in female koi (Cyprinus carpio carpio) broodstock injected with recombinant GnRH
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Arash Ramzani1   , Sakineh Yeganeh1 , Sedigheh Mohammadzadeh2 |
1- Department of Fisheries, Faculty of Animal Science and Fisheries, Sari Agricultural Sciences and Natural Resources University, Sari, Iran
2- Faculty of Veterinary Medicine, Amol University of Special Modern Technology, Amol, Iran |
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Abstract: (10 Views) |
Introduction
The control of fish reproduction in a captive setting can be achieved through the manipulation of various environmental elements, including photoperiod, water temperature, and the selection of spawning grounds (Yeganeh et al., 2022). Given the limited understanding of the biological needs of certain species and the impracticability of replicating environmental conditions to achieve natural reproduction, one viable approach is to employ hormones. A problem in final maturity induction in the carp family is the high activity of dopamine as an inhibitor in the final maturity and spawning step. A recombinant GnRH combined with dopamine receptor antagonists was employed to facilitate the final maturation process in both goldfish (Carassius auratus) and koi carp. (Mohammadzadeh et al., 2020b, 2021a; Yeganeh et al., 2022). No study is so far available on the effects of recombinant GnRH (rGnRH) without anti-dopamine antagonist in koi carp. Therefore, this study aims to investigate the possible use of rGnRH without anti-dopamine antagonist in female koi carp.
Methodology
The investigation was conducted to examine the effects of recombinant gonadotropin-releasing hormone (rGnRH) administered alone or in combination with domperidone on the reproductive function and sex steroid levels in female koi carp (Cyprinus carpio). For the purpose of this study, female koi carps with an average weight of 415.25 ± 94.52 g were divided into four experimental groups. Each group was subjected to a specific injection procedure. The first group received a control injection of 0.9% NaCl. The second group was injected with 5 mg/kg body weight of domperidone (Dop). The third group received an injection of 25 μg/kg body weight of rGnRH (rGn). The fourth group was injected with 25 μg/kg body weight of rGnRH with 5 mg/kg of domperidone (rGnDop). To investigate the levels of sex steroids, samples of blood were obtained prior to administration and at the time points of 6, 12, and 24 hours following the injection.
Result
All the female koi carp of rGn and rGnDop treatments spawned, but none of the females spawned in the NaCl and Dop treatments. There was notable difference among spawned fish during the latency period, with the rGn treatment yielding the longest latency compared to the shorter latency period in the rGnDop treatment. The hormonal treatments had an impact on the levels of sex steroids, namely 17β estradiol (E2), testosterone (T), and 17α, 20β-dihydroxy-4-pregnen-3-one (DHP). The level of E2 decreased in rGn and rGnDop 6, 12 and 24 h after injection. T and DHP levels increased in rGn and rGnDop treatments at 6 and 12 h after the injection and then decreased at 24 h post-injection.
Discussion and conclusion
The findings of the final induction of maturity in female koi breeders illustrate that the administration of rGnRH, both with and without anti-dopamine, exerts a natural influence on the physiological process of koi fish reproduction. Furthermore, it is noteworthy that these interventions do not lead to any abnormalities in the reproductive system at different stages of the artificial reproduction of this species. The elevation of DHP levels in breeders treated with rGnRH without domperidone exhibits a comparable pattern to those treated with rGnRH alongside domperidone. Consequently, it is advisable to utilize rGnRH without anti-dopamine for the purpose of inducing the final maturation of koi carp.
Conflict of interest
The authors declare that they have no conflict of interest.
Acknowledgments
The authors would like to thank the Sari Agricultural Sciences and Natural Resources University (SANRU). |
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| Keywords: Recombinant GnRH, Ovulation synchronization, Koi, Spawning, Anti-dopamine |
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Full-Text [PDF 698 kb]
(4 Downloads)
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Type of Study: Research |
Subject:
تكثير و پرورش
Received: 2025/06/3 | Accepted: 2026/07/1
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