Progesterone and Estradiol Interaction in the Regulation of Rat Uterine Weight and Estrogen Receptor Concentration

Medlock, Kevin L.; Forrester, Tina M.; Sheehan, Daniel M.

doi:10.3181/00379727-205-43690

Cited by 31 publications

(22 citation statements)

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“…Although our study did not directly measure estrogen levels in plasma, ovariectomized animals demonstrated a significant loss in uterine weight, which in the past has been used as a reliable measure of estrogen deprivation at the end-organ site [34, 35, 36]. Our study may have, to some extent, underestimated the effect of estrogen on the CBF of control animals, insofar as select animals may have been examined at estrus.…”

Section: Discussionmentioning

confidence: 78%

Effects of Ovariectomy on Cerebral Blood Flow of Rats

Holschneider

Scremin²

1998

Neuroendocrinology

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Recent reports suggest that estrogens may enhance cognitive function in postmenopausal women and women suffering from dementia of the Alzheimer’s type. One of several proposed mechanisms of action of estrogen has been an improvement in cerebral blood flow (CBF). The current study examined the effects of estrogen deprivation resulting from ovariectomy on the CBF of rats using the quantitative autoradiographic ¹⁴C-iodoantipyrine technique. CBF was assessed in passively restrained, awake adult rats at 6 weeks following ovariectomy (n = 10) or sham surgery (n = 10). Rats demonstrated marked endometrial atrophy and a decrease in uterine weight (mean 78%) in response to ovariectomy. Ovariectomized animals did not differ from control animals both in the magnitude and the topography of cortical or subcortical CBF, including the medial preoptic area, amygdala, arcuate nucleus and anterior hypothalamus, areas previously associated with high estrogen binding. These results suggest that in young, surgically ovariectomized animals, hormonal factors do not significantly contribute to changes in basal CBF.

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Section: Discussionmentioning

confidence: 78%

Effects of Ovariectomy on Cerebral Blood Flow of Rats

Holschneider

Scremin²

1998

Neuroendocrinology

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“…A down regulation of steroid receptors (ER and progesterone receptor-binding activity) by oestrogen treatment has been reported in sheep uteri (Meikle et al, 2000), and the authors suggested that this down regulation is a mechanism to limit hormone action in the target cells. An oestrogen down regulation of ERS1 expression was also found in rat uteri, and the regulation is dose dependent, as demonstrated by the stimulating or inhibitory effects of low or high doses of oestrogens, respectively (Medlock et al, 1994).…”

Section: Adrenal Weightmentioning

confidence: 88%

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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“…Dissociation constants (Kd, nM) for cytosolic ER were similar (mean ± SEM: 0.31 ± 0.05, n = 16), except in Group V, which had higher values (1.45 ± 0.21, n = 4; P < 0.05). An increase in ER Kd values after E2 treatment has been found previously in rat uteri [21], but the biological implication of these differences in binding affinity is not clear. The affinity for cytosolic PR was similar in all groups (0.65 ± 0.07 nM, n = 20).…”

Section: Enzyme Immunoassay (Eia) Of Er Proteinmentioning

confidence: 90%

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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Progesterone and Estradiol Interaction in the Regulation of Rat Uterine Weight and Estrogen Receptor Concentration

Cited by 31 publications

References 0 publications

Effects of Ovariectomy on Cerebral Blood Flow of Rats

Effects of Ovariectomy on Cerebral Blood Flow of Rats

Sex steroid modulation of cortisol secretion in sheep

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

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