Retardation of ovarian growth and depression of serum steroid levels in the tilapia, Oreochromis mossambicus, by cortisol implantation

Foo, J.T.W.; Lam, T.J.

doi:10.1016/0044-8486(93)90364-5

Cited by 61 publications

(32 citation statements)

References 25 publications

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“…It is well known that ER and Vg are under estrogenic regulation [10,12], and a decrease in plasma E2 and gonadotropin (GTHs) levels were reported after cortisol implantation in maturing female brown trout [8], which could explain the decrease of plasma Vg. In tilapia, cortisol implants also decreased E2 levels and ovary size [30]. However, under our experimental conditions, cortisol implants did not affect plasma E2 levels, excluding a possible indirect implication of E2 in the inhibitory effects of cortisol on rtER and rtVg expression.…”

Section: Discussionmentioning

confidence: 78%

Transcriptional Interference Between Glucocorticoid Receptor and Estradiol Receptor Mediates the Inhibitory Effect of Cortisol on Fish Vitellogenesis1

Lethimonier

Flouriot

Valotaire

et al. 2000

Biology of Reproduction

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In oviparous species, the synthesis of vitellogenin (Vg) takes place in the liver according to a strictly estrogen-dependent mechanism that first involves an up-regulation of the estrogen receptor (ER) by its own ligand. However, reports from the literature indicate that in trout stress or cortisol may cause a reduction of cytosolic E2-binding sites in the liver and a decrease in plasma Vg levels. To investigate the mechanisms underlying these effects, in vivo and in vitro experiments were designed in rainbow trout (Oncorhynchus mykiss). The results demonstrate that cortisol implanted into maturing females caused a marked decrease of rainbow trout ER (rtER) and rainbow trout Vg (rtVg) mRNA levels in the liver. In vitro experiments on hepatocyte aggregates also showed that dexamethasone (Dex) caused a strong decrease in the basal and E2-stimulated rtER mRNA and to a lesser extent rtVg mRNA. These effects were specific as no other hormones were able to mimic the inhibitory action of Dex. A study of rtER mRNA stability indicated that the effects of glucocorticoids are likely to take place at the transcriptional level. This was further indicated by transfection experiments in CHO-K(1) cells, which showed that rainbow trout glucocorticoid receptor (rtGR) strongly inhibited the E2-stimulated transcriptional activity of the rtER promoter. Taken together, these results indicate that the rtGR exerts a transcriptional interference on the expression of the rtER that may explain some of the negative effects of stress or cortisol on vitellogenesis.

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Section: Discussionmentioning

confidence: 78%

Transcriptional Interference Between Glucocorticoid Receptor and Estradiol Receptor Mediates the Inhibitory Effect of Cortisol on Fish Vitellogenesis1

Lethimonier

Flouriot

Valotaire

et al. 2000

Biology of Reproduction

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“…In Oreochromis mossambicus, Foo and Lam (1993) observed a delayed reproductive activity due to low level of E 2 after cortisol treatment. Consistent with Biswas (2005), this present study found that plasma estradiol-17β levels in the experimental group were low immediately after the first spawning.…”

Section: Discussionmentioning

confidence: 99%

“…Consistent with Biswas (2005), this present study found that plasma estradiol-17β levels in the experimental group were low immediately after the first spawning. The low levels in turn may have retarded the ovarian growth due to reduced vitellogenesis (Foo and Lam, 1993). As the estradiol levels increased, synthesis of vitellogenin by the liver for active exogenous vitellogenesis in the oocyte may have been induced (Nagahama, 1994).…”

Section: Discussionmentioning

confidence: 99%

Untitled

Onumah¹,

Wessels²,

Wildenhayn³

et al. 2010

Turk. J. Fish. Aquat. Sci.

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This study investigated the effects of stocking density and photoperiod manipulation in relation to plasma estradiol-17β (E 2 ) profile to enhance spawning activity in female Nile tilapia using F1 clonal crosses. The fish were divided into experimental and control groups and subjected to a combination of stocking density and photoperiod treatments (40 kg/m 3 ; 6L:18 D, 40 kg/m 3 ; 12 L:12 D and transferred into single compartments at 12 L:12 D; 14 kg/m 3 ; 12L:12D, respectively). Blood samples were taken by caudal puncture from both experimental and control fish for estradiol profile analysis. Results showed that experimental fish exhibited significantly higher number of spawns per day, total and relative fecundity, hatching and swim-up rates (P<0.05). Regression analyses revealed a significant positive relationship between fish size (body weight), and total and relative fecundity (P<0.001). It was also revealed that E 2 levels demonstrated a pattern based on completed reproductive cycle in the experimental fish. The study therefore established that a combination of stocking density and photoperiod treatments can be adopted to manipulate the timing of spawning activity in female Nile tilapia without having adverse effect on other reproductive parameters such as egg qualities and fecundity. Findings further suggested that the effects of exogenous factors on manipulation of spawning activities of female Nile tilapia may be achieved as a result of hormonal changes including E 2 levels.

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“…Contreras-Sánchez et al (1998) found similar results in Oncorhynchus mykiss submitted to moderate stress during vitellogenesis. The results obtained in this study can be attributed to other factors such as: stress due to confinement, affecting the quality and size of oocytes during maturation (Foo and Lam, 1993;Campbell et al (1994); Sumpter et al (1994); Pankhurts and Van der Kraak, 1997), and/or the environmental quality of contention ponds (Schreck, 1981;Wendelaar-Bonga, 1997) and/or the nutritional conditions of females (Watanabe, 1990;Izquierdo et al, 2001), specially the accumulation of lipides in vitellogenesis (Wiegand, 1996). On the other hand, wild females capable of overcoming stress during the procedure have responded to induction and produced eggs of bigger diameter.…”

Section: Discussionmentioning

confidence: 87%

“…However, it is possible that physiological responses to stress might have affected ontogenesis and larval development in a different way, as much as the nutritional conditions of females (Lam, 1985;Foo and Lam, 1993;Campbell et al, 1994), and/or the incubation of eggs and manipulation of larvae, also affecting reproductive products (Laine and Rajasilta, 1999;Schreck, 2000).…”

Section: Discussionmentioning

confidence: 99%

Criação e domesticação de fêmeas de Brycon siebenthalae destinadas a reprodução

Castellanos¹,

Zaniboni‐Filho

Pardo-Carrasco

et al. 2004

Acta Sci. Anim. Sci.

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ABSTRACT. Brycon siebenthalae (yamú) (Characidae) have quite an untamable "nature", with intense, enduring responses to stress. Three groups of females were induced to spawn in order to study the effects of manipulation during breeding. Groups one and two were formed by four year-old specimens bred in earth ponds. Females from group one and two were subjected to monthly and anual "domestication" practices, respectively, from the time they were six months old. The third group of females was brought from the natural environment. It was observed that females bred and monthly tamed had better induction responses, relative fecundity and post-spawn survival. The physiological responses to different stress situations during the reproductive procedure did not significantly affect (p>0.05) fertility and embryonic and larval survival among groups.Key words: Brycon siebenthalae, domestication, reproduction, yamú.RESUMO. Criação e domesticação de fêmeas de Brycon siebenthalae destinadas a reprodução. Brycon siebenthalae (yamú) (Characidae) tem uma natureza indomável, apresentando respostas ao estresse intensas e duradouras. Três grupos de fêmeas foram tratados com hormônios gonadotróficos para induzir a maturação final e desova, buscando avaliar o efeito da manipulação das fêmeas durante o período de maturação gonadal. O primeiro e segundo grupo eram formados por peixes de quatro anos de idade criados em viveiros de terra. As fêmeas do primeiro grupo foram submetidas ao manejo mensal de "domesticação" a partir do sexto mês de idade. O segundo grupo foi submetido a esse manejo com freqüência anual. O terceiro grupo de fêmeas foi capturado do ambiente natural. As fêmeas submetidas ao manejo mensal apresentaram melhores resultados referente a resposta ao tratamento hormonal, a fecundiade relativa e a sobrevivência após o manejo da reprodução. Os distintos procedimentos de manejo das fêmeas durante a maturação gonadal não afetaram (p>0,05) a taxa de fertilização e a sobrevivência dos ovos e larvas provenientes dos diferentes grupos.Palavras-chave: Brycon siebenthalae, domesticação, reprodução, yamú.

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Retardation of ovarian growth and depression of serum steroid levels in the tilapia, Oreochromis mossambicus, by cortisol implantation

Cited by 61 publications

References 25 publications

Transcriptional Interference Between Glucocorticoid Receptor and Estradiol Receptor Mediates the Inhibitory Effect of Cortisol on Fish Vitellogenesis1

Transcriptional Interference Between Glucocorticoid Receptor and Estradiol Receptor Mediates the Inhibitory Effect of Cortisol on Fish Vitellogenesis1

Untitled

Criação e domesticação de fêmeas de Brycon siebenthalae destinadas a reprodução

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