Exogenous Progesterone and Progestins as Used in Estrous Synchrony Regimens do not Mimic the Corpus Luteum in Regulation of Luteinizing Hormone and 17β-Estradiol in Circulation of Cows1
| Autor: | T. T. Stumpf, J. E. Kinder, M. W. Wolfe, Andrea S. Cupp, L. A. Werth, Roger J. Kittok, Mark S. Roberson, N. Kojima |
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| Rok vydání: | 1992 |
| Předmět: |
Estrous cycle
medicine.medical_specialty medicine.drug_class Ovary Cell Biology General Medicine Biology Melengestrol acetate chemistry.chemical_compound Endocrinology medicine.anatomical_structure Reproductive Medicine chemistry Estrogen Internal medicine medicine Gonadotropin Luteinizing hormone Progesterone Congeners Corpus luteum |
| Zdroj: | Biology of Reproduction. 47:1009-1017 |
| ISSN: | 1529-7268 0006-3363 |
| DOI: | 10.1095/biolreprod47.6.1009 |
| Popis: | Our working hypothesis was that the low concentrations of progesterone (P4) and synthetic progestins administered in hormonal regimens to control estrous cycles of cows would have similar effects on secretion of LH and 17 beta-estradiol (E2). In addition, we hypothesized that concentrations of exogenous P4 typical of the midluteal phase of the estrous cycle and the corpus luteum (CL) would have similar effects on LH and E2, and the effects would be different from those of synthetic progestins and low concentrations of P4. Cows (n = 29) were randomly assigned to one of five treatment groups: 1) one Progesterone Releasing Intravaginal Device (1PRID; n = 6); 2) two PRIDs (2PRID; n = 6); 3) norgestomet, as in Syncro-Mate-B regimen (SMB; n = 6); 4) melengestrol acetate (MGA; 0.5 mg/day; n = 5); and 5) control (CONT; n = 6). Treatments were administered for 9 days (Day 0 = initiation of treatment). All cows from 1PRID, 2PRID, SMB, and MGA groups were injected with prostaglandin F2 alpha (PGF2 alpha) on Days 2 and 5 of the treatment period to regress CL. Cows in the 1PRID and SMB groups were also administered exogenous estrogen according to the respective estrous synchronization protocol for these products. Daily blood samples were collected from Day 0 to 35 to determine concentrations of P4. On Day 8, blood samples were collected at 15-min intervals for 24 h to determine pattern of LH secretion. On Day 9, all treatments ceased and cows in the CONT group received injections of PGF2 alpha.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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