What question did this study set out to answer?

To determine whether a follicular phase rise in estradiol triggers a GnRH surge in ewes and whether this neuroendocrine response differs between breeding season and anestrus.

September 1, 1990Endocrinology

The Estradiol-Induced Surge of Gonadotropin-Releasing Hormone in the Ewe*

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To determine whether a follicular phase rise in estradiol triggers a GnRH surge in ewes and whether this neuroendocrine response differs between breeding season and anestrus.
Ovariectomized ewes during the breeding season received estradiol and progesterone implants to mimic luteal levels, with portal blood collection apparatus surgically installed.
Progesterone implants were removed to simulate luteolysis; ewes were treated either by removing estradiol implants (n = 6) or adding estradiol implants 16 h later to simulate the follicular phase rise (n = 6).
The estradiol rise protocol was replicated in anestrous ewes (n = 5) following an artificially induced luteal phase.
Estradiol treatment induced a massive GnRH surge (73- to 394-fold over presurge values) that initiated simultaneously with the LH surge across both seasons.
The GnRH surge persisted well beyond the conclusion of the LH surge, showing no seasonal differences in amplitude or time course.
Control ewes lacking the estradiol rise displayed regular GnRH and LH pulses every 1–2 hours without generating a surge of either hormone.

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Implication

Controlled animal experiment demonstrates that follicular estradiol induces a massive GnRH surge in ewes across seasons, indicating robust neuroendocrine regulation.

Cite This Study

Moenter et al. (1990) studied this question.

synapsesocial.com/papers/6a6fe4a3e71d69abee08426f https://doi.org/10.1210/endo-127-3-1375

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Implication

Controlled animal experiment demonstrates that follicular estradiol induces a massive GnRH surge in ewes across seasons, indicating robust neuroendocrine regulation.

The Estradiol-Induced Surge of Gonadotropin-Releasing Hormone in the Ewe*

Key Points

Discussion

Implication

Cite This Study

The Estradiol-Induced Surge of Gonadotropin-Releasing Hormone in the Ewe*

Key Points

Discussion

Implication

Cite This Study

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