Endocrine responses in mares and geldings with high body condition scores grouped by high vs. low resting leptin concentrations1
| Autor: | Donald L. Thompson, N. K. Huff, L.R. Gentry, W. A. Storer, J. A. Cartmill |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
endocrine system
medicine.medical_specialty Triiodothyronine Insulin medicine.medical_treatment Leptin digestive oral and skin physiology General Medicine Biology Prolactin Endocrinology Internal medicine Genetics medicine Endocrine system Animal Science and Zoology hormones hormone substitutes and hormone antagonists Body condition Dexamethasone Food Science medicine.drug Hormone |
| Zdroj: | Journal of Animal Science. 81:2311-2321 |
| ISSN: | 1525-3163 0021-8812 |
| Popis: | Previous observations from this laboratory indicated that horses with high BCS could have resting plasma leptin concentrations ranging from low (1 to 5 ng/mL) to very high (10 to 50 ng/mL). To study the possible interactions of leptin secretion with other endocrine systems, BCS and plasma leptin concentrations were measured on 36 mares and 18 geldings. From mares and geldings that had a mean BCS of at least 7.5, five with the lowest (low leptin) and five with the highest (high leptin) leptin concentrations were selected. Jugular blood samples were collected twice daily for 3 d from the 20 selected horses to determine average resting hormone concentrations. Over the next 12 d, glucose infusion, injection of thyrotropin-releasing hormone (TRH), exercise, and dexamethasone treatment were used to perturb various hormonal systems. By design, horses selected for high leptin had greater (P 0.10) in concentrations of IGF-1, prolactin, or thyroid-stimulating hormone (TSH). Horses selected for high leptin had a greater (P = 0.0365) insulin response to i.v. glucose infusion than horses selected for low leptin. Mares had a greater (P = 0.0006) TSH response and tended (P = 0.088) to have a greater prolactin response to TRH than geldings; the T3 response was greater (P = 0.047) in horses selected for high leptin. The leptin (P = 0.0057), insulin (P < 0.0001), and glucose (P = 0.0063) responses to dexamethasone were greater in horses selected for high leptin than in those selected for low leptin. In addition, mares had a greater (P < 0.0001) glucose response to dexamethasone than geldings. Cortisol concentrations were decreased (P = 0.029) by dexamethasone equally in all groups. In conclusion, differences in insulin, T3, and GH associated with high vs. low leptin concentrations indicate a likely interaction of these systems with leptin secretion in horses and serve as a starting point for future study of the cause-and-effect nature of the interactions. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|