Effects of estradiol and 11-ketotestosterone pre-treatment on artificial induction of maturation in silver female shortfinned eels (Anguilla australis)

Damsteegt, Erin L.; Thomson‐Laing, Georgia; Wylie, Matthew J.; Lokman, P. Mark

doi:10.1371/journal.pone.0229391

Cited by 8 publications

(6 citation statements)

References 49 publications

(54 reference statements)

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“…As such, steroid implants could be applied in assisted reproduction protocols for European eel as slow-release systems to initiate vitellogenesis and to reduce the number of weekly CPE injections, potentially improving oocyte quality and leading to production of more viable and robust larvae. Indeed, the combined 17 MT + E2 treatment reduced the number of weeks of weekly PE injections from ∼14 down to ∼10 weeks, similar to a recent study in shortfinned eels ( Damsteegt et al, 2020 using salmon PE). Still, because in this study 17 MT was likely associated with increased mortality, a lower dose of 17MT, or 11KT, may prove to be a better option for application.…”

Section: Discussionsupporting

confidence: 82%

Steroid implants for the induction of vitellogenesis in feminized European silver eels (Anguilla anguilla L.)

et al. 2022

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Assisted propagation of the European eel will lead to a closed production cycle supplying the aquaculture industry with juvenile glass eels. Females require long-term weekly treatment with pituitary extract (PE), which is stressful and causes abnormalities in oogenesis. We tested the effects of 17α-methyltestosterone (17 MT), as potent androgen activating the androgen receptor, and 17β-estradiol (E2), as an inducer of vitellogenesis, to shorten the duration of PE treatment.Four groups of feminized eels were subjected to a simulated migration and subsequent injection with implants containing 17 MT (17 MT-group), E2 (E2-group) or 17 MT plus E2 (17 MT + E2-group) to test for synergistic effects, or without any steroids as controls (C-group). The effects of a 2-months treatment were investigated by determining the eye index (EI), hepatosomatic and gonadosomatic index (HSI and GSI, respectively), plasma steroid concentrations by liquid chromatography mass spectrometry (LCMS), gonadal histology, expression of androgen receptors a and b (ara, arb); estrogen receptor 1 (esr1); FSH receptor (fshr); vitellogenin receptor (vtgr) and aromatase (cyp19), and the required number of weekly PE injections to fully mature. For many parameters, both the 17 MT and E2 groups showed an increase vs. controls, with the 17 MT + E2 group showing a synergistic effect, as seen for EI, GSI (3.4 for 17 MT and for E2, 6.6 for 17 MT + E2), oocyte diameter and ara, arb and esr1 expression. Concentrations of almost all focal steroids decreased with simulated migration and steroid treatment. Only eels of the 17 MT-group showed increased expression of cyp19 and of fshr, while fshr expression increased 44-fold in the 17 MT + E2 group, highlighting that co-implantation is most effective in raising fshr mRNA levels. Specific for eels of the E2 groups were vitellogenesis-associated changes such as an increase of HSI, plasma E2, and presence of yolk in the oocytes. Steroid treatments reduced the duration of PE treatment, again synergistically for co-implantation. In conclusion, E2 is necessary to start vitellogenesis, but 17 MT has specific effects on cyp19 and fshr expression. The combination is necessary for synergistic effects and as such, steroid implants could be applied in assisted reproduction protocols for European eel to improve oocyte quality leading to the production of more vital larvae.

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Section: Discussionsupporting

confidence: 82%

Steroid implants for the induction of vitellogenesis in feminized European silver eels (Anguilla anguilla L.)

et al. 2022

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“…Although T is considered in the synthesis of E 2 and 11-KT [68,69], several studies have detected the presence of high androgen concentration during the reproduction cycle of females [70,71]. However, in the present study, there were no differences in plasma T profile between experimental groups.…”

Section: Avt System Influences the Brain-pituitary-gonads Axis Of Ste...contrasting

confidence: 86%

Arginine-Vasotocin Neuronal System in Steindachneridion parahybae (Siluriformes: Pimelodidae) and Its Influence on Artificially Induced Spawning in Captivity

Honji,

Araújo,

de Mello

et al. 2024

Fishes

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This study summarizes new data on induced spawning of Steindachneridion parahybae, focusing on the aggressive behavior of females. This study characterizes the vasotocinergic system using immunohistochemistry, highlighting the potential influence of arginine-vasotocin (AVT) on reproductive physiology. Two experimental groups were proposed: (A) control, with one female in the aquarium, and (B) experimental, with two females in the same aquarium. Dominant (D) females presented a more aggressive behavior and did not show any injury. They apparently had a length and body mass higher than injured nondominant (ND) females. The analysis identified positive AVT immunoreactive (ir) neurons exclusively within the preoptic area, including parvocellular, magnocellular, and gigantocellular subpopulations, containing fibers-ir extending into the pituitary gland. Cellular and nuclear areas were greater in D compared to ND in the magnocellular subpopulation. There were no differences between parvocellular and gigantocellular subpopulations. There was a difference on the steroid plasma profile of cortisol (more in ND than in D) and 17α,20β-dihydroxy-4-pregnen-3-one (more in D than in ND). Furthermore, control and D females presented higher optical densities for AVT-ir, gonadotropin-releasing hormone-ir, and luteinizing hormone-ir than ND. In general, there were no differences in the results of female (control group) with D females. The AVT system is highly complex, possibly counting multiple sites of action during artificial reproduction and acting directly and/or indirectly associated with behavioral and physiological changes in S. parahybae females when induced to spawning.

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“…Androgens (T and 11‐KT) are steroids that play physiological roles mainly established in males (more than females) (for review, Schulz et al ., 2010). Nonetheless, several studies have detected the presence of high androgen levels during RC in females (Akhavan et al ., 2019; Damsteegt et al ., 2020; Rahdari et al ., 2020; Thomson‐Laing et al ., 2018, 2019), including in some Neotropical species, such as Arapaima gigas (Amaral et al ., 2019) and R. quelen (Barcellos et al ., 2001). In this study, T and 11‐KT plasma concentrations also changed during the RC of females, with an increase in T and 11‐KT concentrations from the PRV to VTG stages, suggesting an involvement in PRV oocyte growth.…”

Section: Discussionmentioning

confidence: 99%

“…In this study, T and 11‐KT plasma concentrations also changed during the RC of females, with an increase in T and 11‐KT concentrations from the PRV to VTG stages, suggesting an involvement in PRV oocyte growth. The analysis of 11‐KT levels is more informative than that of T because T can be converted into E 2 via the aromatase enzyme and thus T levels may not necessarily reflect androgen activity (Damsteegt et al ., 2020; Rahdari et al ., 2020). In addition, after AIS, S. parahybae females showed higher 11‐KT values followed by a decrease 6 h after hand‐stripping, suggesting an important role of this androgen during final maturation and ovulation.…”

Section: Discussionmentioning

confidence: 99%

“…Several studies indicated that these steroids are responsible for gamete quality (Bobe and Labbé, 2010; Rajakumar and Senthilkumaran, 2020; Zohar et al ., 2010) and are indicators of failure in captive breeding (Mylonas et al ., 2010). In females, the best‐known steroids are oestrogens, mainly 17β‐oestradiol (E 2 ), because one of the main actions of oestrogens is to stimulate the synthesis and secretion of vitellogenin (Reading et al ., 2017); the progestogens, 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (17α,20β‐DHP), responsible for the induction of final maturation and ovulation in teleost fish, as well as its precursor 17α‐hydroxyprogesterone (17α‐OHP), which are progestogens commonly studied in teleost fish when kept in captivity (Rajakumar and Senthilkumaran, 2020); and the androgens, mainly 11‐ketotestosterone (11‐KT) and testosterone (T), which, although reported in several plasmas of female teleosts, still have the precise function of these androgens in female fish under investigation (mainly 11‐KT) (Damsteegt et al ., 2020; Rahdari et al ., 2020).…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of ovarian maturation during the annual reproductive cycle of the endangered fish Steindachneridion parahybae (Siluriformes: Pimelodidae) in captivity

Honji

Araújo

Caneppele³

et al. 2022

Journal of Fish Biology

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To characterize the female reproductive biology of the endangered species Steindachneridion parahybae in captivity, the authors used the concentration of gonadal steroids and the oocyte development during the annual reproductive cycle (RC) and after artificial induced spawning (AIS) until 48 h. Three stages of gonadal maturation were identified, based on morphological and physiological features: early maturation or previtellogenic (PRV) oocyte, advanced maturation or vitellogenic (VTG) oocyte and regression (REG) or follicular atresia. They identified and characterized the following stages of germ cells: oogonia, perinucleolar and cortical alveoli, and VTG and atretic oocytes during RC. The oestradiol levels were higher in PRV than those in VTG and REG during the RC, whereas androgens showed higher levels of oestradiol in VTG than those in PRV and REG. The progestogen levels remained unchanged during the whole RC. The final oocyte maturation (FOM) was achieved after AIS and postovulatory follicles (POF) were identified. Plasma concentration of progestogens (17α,20β‐dihydroxy‐pregnen‐3‐one and 17α‐hydroxyprogesterone) increased considerably after AIS, remaining high up to 6 h after AIS, and progressively decreased over time after AIS. During RC, the lack of FOM and POFs reveals that captivity negatively impacts S. parahybae reproduction. Nonetheless, the VTG stage of oocytes, reached during RC, is suitable for ovulation induction with artificial hormone manipulation, enabling the reproduction of this species in captivity and being essential for the success of fish farming and/or fish conservation programmes (conservationist aquaculture).

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Effects of estradiol and 11-ketotestosterone pre-treatment on artificial induction of maturation in silver female shortfinned eels (Anguilla australis)

Cited by 8 publications

References 49 publications

Steroid implants for the induction of vitellogenesis in feminized European silver eels (Anguilla anguilla L.)

Steroid implants for the induction of vitellogenesis in feminized European silver eels (Anguilla anguilla L.)

Arginine-Vasotocin Neuronal System in Steindachneridion parahybae (Siluriformes: Pimelodidae) and Its Influence on Artificially Induced Spawning in Captivity

Dynamics of ovarian maturation during the annual reproductive cycle of the endangered fish Steindachneridion parahybae (Siluriformes: Pimelodidae) in captivity

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