The modulatory effect in vitro of oestradiol-17β, testosterone or cortisol on the output of 17α-hydroxy-20β dihydroprogesterone by rainbow trout (Salmo gairdneri) ovarian follicles stimulated by the maturational gnadotropin s-GtH

International audienceThe effect of oestradiol-17β, testosterone or cortisol in the incubation medium (1μg/ml upon s-GtH-induced 17α-hydroxy-20β-dihydroprogesterone (17α,20β-OH-P) secretion by trout ovarian follicles in vitro was investigated in order to elucidate by which mechanism these steroids were able to modulate s-GtH efficiency on the maturation of intrafollicular oocytes with the germinal vesicle initially in subperipheral position. Oestradiol inhibited significantly 17α, 20β-OH-P output by the follicles of the two females tested at all doses of s-GtH (3.91-500 ng/ml). Testosterone and cortisol stimulated significantly 17α, 20β-0H-P output by follicles only at doses of GtH below 31.25 ng/ml. The physiological relevance and implications of these findings have been discussed

Production of fertilizable oocytes from follicles of rainbow trout (Salmo gairdnerii) following in vitro maturation and ovulation

International audienceTrout ovarian follicles were taken in vivo with oocytes showing a peripheral germinal vesicle and incubated at 10 C with hormones to complete maturation. PGFSUB-2 was added after 6, 7 or 8 days of incubation and ovulations were recorded 24 hours later. By this means, trout pituitary extract, pure trout gonadotropin t-GtH, or 17 -hydroxy-20 -dihydro-progesterone (17 -20 P) was equally effective for production of fertilizable oocytes after 7 + 1 days of incubation. After only 6-day maturation incubation, PGFSUB-2 was already able to induce successful ovulation, but fertilizability was near zero; after 8-day maturation incubation, responsiveness to PGFSUB-2 was lost. The dose of 17 -20 P required for further successful ovulation response to PGFSUB-2 was more than 10 times higher than required for GVBD completion only, and a 24-hour exposure of follicles to 17 -20 P action at the beginning of incubation was more efficient than a 4-hour exposure or continuous exposure. When follicles with oocytes already engaged in the process of maturation in vivo (incubation started at any time between stage 1SUP-+ and GVBD) were transferred in vitro, addition of t-GtH or 17 -20 P enhanced further ovulation response to PGFSUB-2 . These facts show that 17 -20 P, the most likely mediator of oocyte maturation in trout, is also able to induce follicle preparation to ovulation. But this preparation to ovulation needs higher doses and longer exposure to 17 -20 P action than oocyte maturation induction does; this also implies longer exposure to high doses of t-GtH in vivo. Fertilization of eggs produced in the above conditions shows that in vitro maturation and ovulation must be very similar to the natural processes in vivo.Des follicules ovariens de Truite arc-en-ciel présentant des ovocytes au stade de la vésicule germinative périphérique (fig. 1, stade 1° avant induction naturelle de la maturation) ont été incubés à 10°C en présence d’hormones destinées à induire la maturation. L’ovulation a été induite par PGF 2α ajoutée au milieu pendant 24 h, après 6, 7 et 8 jours d’incubation. Dans ces conditions, l’extrait hypophysaire de Truite, la gonadotropine pure t-GtH ou la 17 α hydroxy-20 β dihydroprogestérone (17α-20 βP) se sont révélées aptes à produire des ovocytes fécondables après 7 + 1 jours d’incubation. Après seulement 6 jours d’incubation, l’ovulation en réponse à l’action de PGF 2α est déjà possible, mais la fécondabilité est quasi nulle. Après 8 jours, la sensibilité à PGF 2α a diminue (tabl. 1, 2, 3). La dose de17α-20 βP nécessaire à l’ovulation ultérieure sous l’action de PGF 2α est plus de 10 fois supérieure à celle qui serait nécessaire à la seule maturation ovocytaire (fig. 2). Une exposition de 24 h en début d’incubation à l’action de la 17α-20 βP est plus efficace qu’une exposition de 4 h ou continue (tabl. 4). Lorsque des follicules sont placés en incubation alors que la maturation ovocytaire est déjà engagée in vivo (à n’importe quel moment depuis le stade 1+ jusqu’à l’éclatement dela vésicule germinative ; voir fig. 1). l’action de t-GtH ou de la 17α-20 β augmente le pourcentage d’ovulations induites par PGF 2α. Ces faits démontrent que la 17α-20 βP qui est le médiateur le plus vraisemblable de la maturation ovocytaire chez la Truite peut aussi induire la préparation du follicule à l’ovulation ; celle-ci requiert cependant des doses et des temps d’action supérieurs à ceux strictement nécessaires à l’induction de la maturation ovocytaire, ce qui implique aussi que l’action de t-GtH in vivo doit s’effectuer à un niveau et avec une durée supérieurs. La fécondation des oeufs produits dans ces conditions démontre que les processus de maturation et d’ovulation contrôlés in vitro doivent être très voisins des processus naturels

The modulatory effect in vitro of oestradiol-17β, testosterone or cortisol on the output of 17α-hydroxy-20β-dihydroprogesterone by rainbow trout (Salmo gairdneri) ovarian follicles stimulated by the maturational gonadotropin s-GtH

International audienc

Effects of fomesafen and fomesafen-Agral 90 mixture on cell redox environment in the pond snail Lymnaea stagnalis.

Effects of fomesafen and fomesafen-Agral 90 mixture on cell redox environment in the pond snail Lymnaea stagnalis.. 4. World Congress of SETA

The modulatory effect in vitro of oestradiol-17β, testosterone or cortisol on the output of 17α-hydroxy-20β-dihydroprogesterone by rainbow trout (Salmo gairdneri) ovarian follicles stimulated by the maturational gonadotropin s-GtH

International audienc

Sex ratio and potential fecundity of atlantic salmon (Salmo salar L.) caugh by anglers on the Elorn river (Northern Brittany, France) during 1979 and 1980

Sex ratio and potential fecundity of atlantic salmon (Salmo salar L.) caugh by anglers on the Elorn river (Northern Brittany, France) during 1979 and 198

Effects of fomesafen and fomesafen-agral R90 mixture on cell redox environment in the pond snail Lymnaea stagnalis.

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Cell redox environment and detoxication enzyme activities Lymnaea stagnalis exposed to diquat and fomesafen with and without Agral 90

Cell redox environment and detoxication enzyme activities Lymnaea stagnalis exposed to diquat and fomesafen with and without Agral 90. 15. Europe Annual Meeting of SETA

The adjuvant Agral 90 as a modulator of hemocyte-mediated immune responses induced by diquat and fomesafen in Lymnaea stagnalis.

The adjuvant Agral 90 as a modulator of hemocyte-mediated immune responses induced by diquat and fomesafen in Lymnaea stagnalis.. 15. Europe Annual Meeting of SETA

In vitro stimulation of vitellogenin incorporation into trout oocytes by salmon pituitary extracts

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