GnRHa-mediated stimulation of the reproductive endocrine axis in captive Atlantic bluefin tuna, Thunnus thynnus
| Autor: | Alberto García, H. Gordin, Yonathan Zohar, A. Belmonte, F. de la Gándara, C.R. Bridges, I. Meiri-Ashkenazi, G. De Metrio, Antonio Medina, H. Rosenfeld, Constantinos C. Mylonas, Gilad Heinisch, R. Vassallo-Aguis, Christian Fauvel, Aldo Corriero |
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| Jazyk: | angličtina |
| Rok vydání: | 2012 |
| Předmět: |
Male
Ovulation medicine.medical_specialty Acuicultura media_common.quotation_subject Endocrine System Gonadotropin-Releasing Hormone 03 medical and health sciences Endocrinology Internal medicine medicine Endocrine system Animals Testosterone Centro Oceanográfico de Murcia 14. Life underwater Sexual Maturation 030304 developmental biology media_common 0303 health sciences Germinal vesicle biology Tuna Reproduction 04 agricultural and veterinary sciences Luteinizing Hormone biology.organism_classification 040102 fisheries 0401 agriculture forestry and fisheries Animal Science and Zoology Female Vitellogenesis Seasons Thunnus Hormone |
| Zdroj: | General and Comparative Endocrinology e-IEO. Repositorio Institucional Digital de Acceso Abierto del Instituto Español de Oceanografía instname |
| ISSN: | 0016-6480 |
| DOI: | 10.1016/j.ygcen.2011.09.013 |
| Popis: | A controlled-release implant loaded with GnRH agonist (GnRHa) was used to induce spawning in Atlantic bluefin tuna (Thunnus thynnus) during two consecutive reproductive seasons. The fish were implanted underwater and sampled between days 2 and 8 after treatment. At the time of GnRHa treatment, females were in full vitellogenesis and males in spermiation. There was a rapid burst of pituitary luteinizing hormone (LH) release at day 2 after treatment in GnRHa-treated fish, and circulating LH remained elevated up to day 8 after treatment. In contrast, control fish had significantly lower levels in the plasma, but higher LH content in the pituitary, as observed in many other cultured fishes that fail to undergo oocyte maturation, ovulation and spawning unless induced by an exogenous GnRHa. Plasma testosterone (T) and 17β-estradiol (E2) were elevated in response to the GnRHa treatment in females, while 11-ketotestosterone (11-KT) but not T was elevated in males. Even though oocyte maturation and ovulation did occur in GnRHa-induced fish, no significant elevations in 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P) or 17,20β,21-trihydroxy-4-pregnen-3-one (20β-S), in either the free, conjugated or 5β-reduced,3α-hydroxylated forms was observed in fish sampled within 6 days after treatment. Interestingly, a significant peak in plasma free 17,20β-P levels occurred in both males and females at day 8 after treatment. Histological sections of the ovaries in these females contained oocytes at the migrating germinal vesicle stage, suggesting the role of this hormone as a maturation-inducing steroid in Atlantic bluefin tuna. In conclusion, the GnRHa implants activated effectively the reproductive endocrine axis in captive Atlantic bluefin tuna broodstocks, through stimulation of sustained elevations in plasma LH, which in turn evoked the synthesis and secretion of the relevant sex steroids leading to gamete maturation and release. Sí |
| Databáze: | OpenAIRE |
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