Differential Effects of Various Estradiol-17beta Treatments on Follicle-Stimulating Hormone Peaks, Luteinizing Hormone Pulses, Basal Gonadotropin Concentrations, and Antral Follicle and Luteal Development in Cyclic Ewes1
| Autor: | D.M.W. Barrett, Pawel M. Bartlewski, R. Duggavathi, Norman C. Rawlings, K.L. Davies, E.T. Bagu |
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| Rok vydání: | 2007 |
| Předmět: |
endocrine system
medicine.medical_specialty medicine.drug_class Biology Luteal phase 03 medical and health sciences Follicle-stimulating hormone 0302 clinical medicine Internal medicine Follicular phase medicine 030219 obstetrics & reproductive medicine 0402 animal and dairy science 04 agricultural and veterinary sciences Cell Biology General Medicine Antral follicle 040201 dairy & animal science Gonadotropin secretion medicine.anatomical_structure Endocrinology Reproductive Medicine Gonadotropin Luteinizing hormone Corpus luteum hormones hormone substitutes and hormone antagonists |
| Zdroj: | Biology of Reproduction. 77:252-262 |
| ISSN: | 1529-7268 0006-3363 |
| Popis: | In a previous study, 10-day estradiol implant treatment truncated the FSH peaks that precede follicular waves in sheep, but subsequent ovine FSH (oFSH) injection reinitiated wave emergence. The present study's objectives were to examine the effects of a 20-day estradiol and progesterone treatment on FSH peaks, follicle waves, and responsiveness to oFSH injection. Also, different estradiol doses were given to see whether a model that differentially suppressed FSH peaks, LH pulses, or basal gonadotropin secretion could be produced in order to study effects of these changes on follicular dynamics. Mean estradiol concentrations were 11.8 +/- 0.4 pg/ml, FSH peaks were truncated, wave emergence was halted, and the number of small follicles (2-3 mm in diameter) was reduced (P < 0.05) in cyclic ewes given estradiol and progesterone implants (experiment 1). On Day 15 of treatment, oFSH injection failed to induce wave emergence. With three different estradiol implant sizes (experiment 2), estradiol concentrations were 5.2, 19.0, 27.5, and 34.8 (+/-4.6) pg/ml in control and treated ewes, respectively. All estradiol treatments truncated FSH peaks, except those that created the highest estradiol concentrations. Experiment 2-treated ewes had significantly reduced mean and basal FSH concentrations and LH pulse amplitude and frequency. We concluded that 20-day estradiol treatment truncated FSH peaks, blocking wave emergence, and reduced the small-follicle pool, rendering the ovary unresponsive to oFSH injection in terms of wave emergence. Varying the steroid treatment created differential FSH peak regulation compared with other gonadotropin secretory parameters. This provides a useful model for future studies of the endocrine regulation of ovine antral follicular dynamics. |
| Databáze: | OpenAIRE |
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