17β-estradiol secretion in normal and hypophysectomized chick embryos

Weniger, J.-P.; Chouraqui, J; Zeis, A

doi:10.1051/rnd:19890107

Cited by 6 publications

(4 citation statements)

References 12 publications

(14 reference statements)

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“…Our second hypothesis, i.e., that estrogens are vasoactive in the chicken DA, was supported by our results. However, it should be noted that chicken DA relaxation was induced with concentrations of estrogen far greater than the high picomolar-nanomolar levels of free hormone found in the plasma of chicken embryos at this developmental stage (56). In many mammalian studies, vascular effects of estrogen in vitro require ϳ1,000 times higher concentrations of free hormone than are typically present in circulating plasma (57).…”

Section: Discussionmentioning

confidence: 92%

Effects of sex and estrogen on chicken ductus arteriosus reactivity

Flinsenberg

Sterren

Cleef

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

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Sex hormones have an important influence on cardiovascular physiology and pathophysiology and sex differences in vascular reactivity have been widely demonstrated. In the present study we hypothesized 1) the presence of sexual dimorphism in chicken ductus arteriosus (DA) responsiveness to contractile and relaxant stimuli and 2) that estrogens are vasoactive in the chicken DA. In vitro contractions (assessed with a wire myograph) induced by normoxia, KCl, 4-aminopyridine, norepinephrine, phenylephrine, U46619, or endothelin-1, as well as relaxations induced by ACh, sodium nitroprusside, BAY 41-2272, PGE(2), isoproterenol, forskolin,Y-27632, and hydroxyfasudil were not significantly different between males and females. The estrogen 17beta-estradiol elicited concentration-dependent relaxation of KCl-, phenylephrine-, and oxygen-induced active tone in male and female chicken DA. The stereoisomer 17alpha-estradiol showed lesser relaxant effects, and the selective estrogen receptor (ER) agonists 4,4',4''-(4-propyl-[(1)H]pyrazole-1,3,5-triyl)tris-phenol (ERalpha) and 2,3-bis(4-hydroxyphenyl)-propionitrile (ERbeta) did not show any effect. There were no sex differences in the responses to estrogen. Endothelium removal or the presence of the soluble guanylate cyclase inhibitor ODQ, the K(+) channel blockers tetraethylammonium, glibenclamide, and charybdotoxin, or the ER antagonist fulvestrant did not modify 17beta-estradiol-induced relaxation. CaCl(2) (30 muM-10 mM) induced concentration-dependent contraction in DA rings depolarized by 62.5 mM KCl or stimulated with 21% O(2) in Ca(2+)-free medium. Preincubation with 17beta-estradiol or the L-type Ca(2+) channel blocker nifedipine produced an inhibition of CaCl(2)-induced contractions. In conclusion, there are no sex-related differences in chicken DA reactivity. The estrogen 17beta-estradiol induces an endothelium-independent relaxation of chicken DA that is not mediated by ER activation. This relaxant effect is, at least partially, due to inhibition of Ca(2+) entry from extracellular space.

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Section: Discussionmentioning

confidence: 92%

Effects of sex and estrogen on chicken ductus arteriosus reactivity

Flinsenberg

Sterren

Cleef

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

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“…This raises the question as to whether the appearance of gonadal oestradiol is due to lutropin stimulation in the chicken embryo. In hypophysectomized chicken embryos, the ovary secretes oestradiol up to days 16-18 of incubation (Weniger and Zeis, 1987;Weniger et al, 1989). Furthermore, the number of lutropin binding sites in the ovaries of hypophysectomized chicken embryos is not different from that in intact embryos (Woods et al, 1989).…”

Section: Discussionmentioning

confidence: 99%

Evidence of sex reversal in the gonads of chicken embryos after oestrogen treatment as detected by expression of lutropin receptor

Akazome¹,

Mori²

1999

Reproduction

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In chicken embryos, there is a difference between the sexes in the onset of lutropin receptor mRNA expression in the gonads. The effects of oestrogen on lutropin receptor expression were studied to investigate the mechanism controlling this difference. Lutropin receptor mRNA expression was detected in the ovaries of sesame oil-treated control female embryos on day 12 of incubation, while no expression was found in the testes of the male controls. Oestradiol administration to genetically male embryos before sexual differentiation resulted in gonadal sex reversal which was characterized histologically by the proliferation of cortical cords and the presence of lacunae. Lutropin receptor expression was detected in the feminizing testis on day 12 of incubation. Administration of aromatase inhibitor (CGS 16949 A) to genetically female embryos before sexual differentiation inhibited the formation of cortical cords, although a relatively weak expression of lutropin receptor was detected. These results indicate that early expression of the lutropin receptor is regulated by oestrogen.

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“…In 1981, Woods and Brazzill regarded elevated plasma estradiol levels from Day 13.5 on as reflecting an increase in ovarian estradiol secretion in response to an enhanced secretion of LH by the hypophysis. However, when estradiol released into culture medium was measured, ovaries from hypophysectomized, sham-operated and intact 16-to 19-day-old embryos yielded the same amounts (Weniger and Zeis, 1987;Weniger et al, 1989;1 990a). So, evidence is rather against pituitary control of estrogen secretion at advanced stages.…”

Section: Regulation Of Estrogen Secretionmentioning

confidence: 97%

Estrogen Secretion by the Chick Embryo Ovary

Weniger¹

2009

Exp Clin Endocrinol Diabetes

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This is a review of work on estrogen secretion by the chick embryo ovary. The genetically female gonadal anlage secretes estrone and estradiol at the time of sex differentiation. Estradiol induces in a very short time interval the secretion of estradiol in the testis. However, it is not likely to play a role in normal ovarian sex differentiation, since neither anti-estrogens nor aromatase inhibitors disturb ovarian differentiation. Stimulation of estradiol secretion in vitro by LH is highest at early stages. Control of estradiol secretion by pituitary LH is suggested at early stages.

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17β-estradiol secretion in normal and hypophysectomized chick embryos

Cited by 6 publications

References 12 publications

Effects of sex and estrogen on chicken ductus arteriosus reactivity

Effects of sex and estrogen on chicken ductus arteriosus reactivity

Evidence of sex reversal in the gonads of chicken embryos after oestrogen treatment as detected by expression of lutropin receptor

Estrogen Secretion by the Chick Embryo Ovary

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