Prolactin administration to seasonally anestrous mares: reproductive, metabolic, and hair-shedding responses
| Autor: | C L DePew, Donald L. Thompson, Rick Hoffman |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Muda
Blood Glucose Ovulation endocrine system medicine.medical_specialty Hydrocortisone media_common.quotation_subject Biology Fatty Acids Nonesterified Antibodies Anestrus Iodine Radioisotopes Estrus Ovarian Follicle Internal medicine biology.animal Genetics medicine Animals Horses Insulin-Like Growth Factor I media_common Ultrasonography Estrous cycle Pony Reproduction Thyroid Ovary Horse General Medicine Metabolism Luteinizing Hormone Prolactin Endocrinology medicine.anatomical_structure Fertility Animal Science and Zoology Female sense organs Seasons Follicle Stimulating Hormone Gonadotropins Food Science Hair |
| Zdroj: | Journal of animal science. 75(4) |
| ISSN: | 0021-8812 |
| Popis: | Eight pony mares received 4 mg of recombinant porcine prolactin (rpPRL) daily for 45 d beginning on January 15; eight control mares received vehicle. Reproductive end points and various indicators of metabolism, hair shedding, and thyroid activity were monitored. Prolactin concentrations peaked in mares treated with rpPRL at 94 +/- 19 ng/mL 2 h after injection and were 5.1 +/- 1.7 ng/mL 24 h after injection. Treatment with rpPRL increased (P.01) hair shedding within 14 d, which peaked at 28 d and then dropped precipitously. Binding of 125I-equine prolactin confirmed that antibodies were present in rpPRL-treated mares by 28 d, thus only data up to that time are included herein. The percentage of mares in estrus after 17 d of treatment was greater (P.05) for mares treated with rpPRL than for controls, although the average day of estrus onset did not differ (P.1). The date of first ovulation, determined from plasma progesterone concentrations, was hastened (P.005) in mares treated with rpPRL (February 6 +/- 3 d) relative to control mares (March 14 +/- 6 d). Concentrations of insulin-like growth factor I and nonesterified fatty acids were not affected (P.05) over time. There were minor differences between groups in thyroid hormone secretion. Various assessments of glucose and insulin indicated no perturbation (P.1) due to treatment with rpPRL. We conclude that prolactin mediates the onset of vernal hair shedding in mares and is in some way involved with ovulation. |
| Databáze: | OpenAIRE |
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