Effects of estradiol and progesterone on the reproductive tract and on uterine sex steroid receptors in female lambs

Meikle, A.; Tasende, C.; Rodriguez, Myrian Roxana; Garófalo, E.G.

doi:10.1016/s0093-691x(97)00343-9

Cited by 54 publications

(58 citation statements)

References 13 publications

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“…The results confirm previous observations [22] that the prepubertal ewe has high uterine concentrations of physiologically active steroid receptors. The initial effect of estradiol on receptor levels was inhibitory, but the subsequent response was to increase receptor expression.…”

Section: Discussionsupporting

confidence: 91%

“…Previous studies demonstrated that ER and PR are present in high concentrations in different uterine layers in prepubertal lambs [7], and that these receptor proteins are physiologically active before ovarian cyclicity begins [22]. Treatment with P decreased concentrations of both receptors [22], and this down-regulation has also been reported for sheep and adult females of other species [16,17,32,36].…”

Section: Introductionmentioning

confidence: 72%

“…Treatment with P decreased concentrations of both receptors [22], and this down-regulation has also been reported for sheep and adult females of other species [16,17,32,36]. Treatment with estradiol-17β (E2) also decreased concentrations of uterine ER and PR in lambs [22], which was unexpected since it is different from previous findings in adult ewes in which such a treatment caused up-regulation of the steroid receptors [32,36]. Down-regulation of receptor expression may be the consequence of inactivation of the receptors, inhibition of receptor synthesis, and/or stimulation of the receptor turnover.…”

Section: Introductionmentioning

confidence: 92%

“…This "processing" found in the regulatory action of E2 on its receptor was also reported in the same specie by other authors [3,13,33], but no data as such has been reported for sheep. The heterologous down-regulation observed also in PR uterine expression after E2 treatment in lambs [22] was unforeseen, and no mechanism of action for this has yet been proposed.…”

Section: Introductionmentioning

confidence: 98%

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A biphasic action of estradiol on estrogen and progesterone receptor expression in the lamb uterus

et al. 2000

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-Regulation of the uterine expression of estrogen and progesterone receptors was studied in 20 three-month-old lambs that were not treated or treated with estradiol-17β. Determinations of receptors were performed by binding assays in the nuclear and cytosolic fractions, receptor mRNAs by solution hybridization, and estrogen receptor protein by an enzyme-immunoassay. Estradiol treatment decreased the receptor binding capacity of both receptors and the levels of immunoreactive estrogen receptor 12 h after injection in the absence of decreased receptor mRNAs, suggesting that the initial decrease is due to degradation of the proteins or that mRNAs are translated into new receptor proteins at a reduced rate. The mRNA levels increased after estradiol treatment suggesting that the replenishment phase consists of synthesis of new receptors rather than recycling of inactivated receptors.estrogen / progesterone / receptor / uterus / lamb Résumé -Action biphasique de l'oestradiol sur l'expression des récepteurs aux oestrogènes et à la progestérone dans l'utérus de l'agnelle. La régulation de l'expression des récepteurs aux oestrogènes et à la progestérone au niveau de l'utérus a été étudiée chez des agnelles immatures âgées de 3 mois (n = 20), traitées et non traitées avec oestradiol-17β. Les déterminations des récepteurs ont été faites par des essais de liaison dans les fractions nucléaires et cytosoliques, les ARNm des récepteurs par la méthode d'hybridation en solution et la protéine du récepteur aux oestrogènes par un essai immuno-enzymatique. Le traitement à l'oestradiol réduit la capacité de liaison des deux récepteurs et les niveaux des récepteurs aux oestrogènes immunoréactifs 12 h après l'injection en absence d'une diminution des ARNm des récepteurs, suggèrent que la réduction initiale est due à la dégradation des Reprod. Nutr. Dev. 40 (2000) 283-293 283

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 98%

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A biphasic action of estradiol on estrogen and progesterone receptor expression in the lamb uterus

et al. 2000

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“…However, adrenal sensitivity depends on actual MC2R protein content and even if mRNA is frequently used as a predictor of protein content it may not always present a direct relationship as has been described before (Meikle et al, 2000), thus, post-transcriptional events might affect receptor activation and/or receptor turnover. Although the time between steroid replacement and adrenal sampling was determined to allow for protein synthesis and has been used in other studies (Clark et al, 1992;Meikle et al, 1997Meikle et al, , 2000, it cannot be ruled out that a critical window was missed.…”

Section: Adrenal Weightmentioning

confidence: 99%

Sex steroid modulation of cortisol secretion in sheep

Lier

Carriquiry

Meikle

2014

Animal

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There is strong evidence that the gonads modulate the hypothalamic-pituitary-adrenal axis. To investigate these sex differences at the adrenal glands of sheep we compared the cortisol response to ACTH (experiment 1) and measured the relative expression of oestrogen receptor alpha (ERS1), androgen receptor (AR), melanocortin 2 receptor (MC2R) and steroid acute regulatory protein (STAR) mRNA in adrenal glands (experiment 2) of gonadectomised rams and ewes either with or without sex steroid replacement. In experiment 1 six castrated adult rams and four ovariectomised adult ewes were used in two ACTH trials. On each trial blood samples were taken every 15 min for 4 h through an indwelling jugular catheter and each animal received 0.5 mg of an ACTH analogue i.v., immediately after the sample at 1 h from the beginning of the trial. Four days after the first trial the males received 100 mg of Testosterone Cyclopentilpropionate (TC) i.m. and the females received 2.5 mg of Oestradiol Benzoate (EB) i.m. At 72 h after TC or EB administration the second trial was performed. In experiment 2 the adrenal glands were obtained from gonadectomised adult rams (n = 8) and adult ewes (n = 8). Four rams received 100 mg of TC i.m. and four females received 0.5 mg of EB i.m. Blood samples were taken at 0, 12, 24, 48 and 72 h relative to steroid replacement and the animals were thereafter slaughtered. Cortisol, testosterone and 17β-oestradiol were determined by radioimmunoanalysis. The transcripts of ERS1, AR, MC2R and STAR were determined by real-time reverse transcription PCR in adrenal tissue. Cortisol secretion was higher in female sheep than in male sheep, and higher in EB-treated than non-treated ewes. No difference in cortisol secretion was observed between TC-treated and non-treated rams. Gonadectomised rams treated with TC presented greater AR mRNA and MC2R mRNA expression than males without the steroid replacement. Gonadectomised ewes treated with EB tended to present lower AR mRNA than the ones without steroid replacement. Gonadectomised rams with TC also had greater AR mRNA, ERS1 mRNA and MC2R mRNA expression than ewes treated with EB. The relative amount of STAR transcript was not different among the different groups. The results confirm sex differences in ACTH-induced cortisol secretion in sheep, as well as in the expression of the receptor proteins for both 17β-oestradiol and testosterone in the sheep adrenal gland. However, the underlying mechanisms for sex steroid modulation remain unresolved.Keywords: sex steroids, gonadectomy, adrenal, receptors, sheep ImplicationsDifferent stressors result in different responses from the hypothalamus-pituitary-adrenal (HPA) axis and stress can reduce reproductive performance in mammals. Considering the different roles of males and females in reproduction, it is reasonable to think that each sex has its own strategy for dealing with the effects of stress. There is abundant evidence that the gonads affect the way the HPA axis responds to stress. Understanding the regulatory pathways of...

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