The effects of equine somatotropin (eST) on follicular development and circulating plasma hormone profiles in cyclic mares treated during different stages of the estrous cycle
| Autor: | R.A Godke, B.S Leise, L.A Kincaid, A.A Leonardi–Cattolica, M.R Sullivan, Donald L. Thompson, R.A Cochran |
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| Rok vydání: | 1999 |
| Předmět: |
Ovulation
endocrine system medicine.medical_specialty Time Factors animal diseases media_common.quotation_subject Body weight Endocrinology Estrus Ovarian Follicle Food Animals biology.animal Internal medicine Follicular phase medicine Animals Horses Insulin-Like Growth Factor I Progesterone reproductive and urinary physiology media_common Estrous cycle Estradiol biology urogenital system Pony Horse Luteinizing Hormone Hormones Growth Hormone Female Animal Science and Zoology Plasma estradiol Hormone |
| Zdroj: | Domestic Animal Endocrinology. 16:57-67 |
| ISSN: | 0739-7240 |
| DOI: | 10.1016/s0739-7240(98)00046-0 |
| Popis: | The effects of exogenous equine somatotropin (eST) administration on ovarian activity and plasma hormone levels were evaluated on horse and pony mares. The objectives of this study were to determine the effects of eST on follicular development and circulating concentrations of leutinizing hormone (LH), estradiol, progesterone, and insulin-like growth factor I (IGF-I) in cyclic horse and pony mares. Sixteen mares received daily injections (im) of eST at a concentration of 25 mg/kg body weight on either Days 6 through 12 (Treatment A) or 13 through 19 (Treatment B) postovulation. In addition, contemporary mares were similarly given the carrier vehicle and served as controls (Treatments C and D). Blood samples were collected at 24-hr intervals and ultrasonographic evaluations were performed on the ovaries of each mare at 48-hr intervals beginning on the first day of treatment and ending either on the day of ovulation or 5 d postovulation. Circulating levels of insulin-like growth factor-I (IGF-I) were increased in treated mares by Day 3 posttreatment (P , 0.05). Also, mares in Treatment B exhibited a decrease in plasma estradiol concentrations (P , 0.05) when compared with control mares on Days 1 through 5 postovulation of the post-treated estrous cycle. In addition, circulating leutinizing hormone levels were different for mares in Treatment A compared with controls on Days 28 through 21 pre-ovulation (P , 0.05). All follicles present on the ovaries of each mare were measured and placed into one of five categories based on their diameter. Neither the mean number of follicles per size category ˜ 8m m in diameter nor the mean follicular diameter within each size category differed among treatment and control mares. However, eST treatment significantly increased the number of follicles ¶ 7m m on the ovaries of mares treated early in the estrous cycle when compared with control mares on Days 3 and 7 post-treatment and at the onset of standing estrus. © Elsevier Science Inc. 1999 |
| Databáze: | OpenAIRE |
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