Pituitary Response to Repeated Copulation and/or Gonadotropin-Releasing Hormone Administration in Llamas and Alpacas1
| Autor: | George H. Stabenfeldt, Bill L. Lasley, Murray E. Fowler, P W Bravo |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
endocrine system
medicine.medical_specialty Pituitary gland Gonadotropin RH media_common.quotation_subject Pregnanediol Glucuronide Cell Biology General Medicine Gonadotropin-releasing hormone Biology medicine.anatomical_structure Combined treatment Endocrinology Reproductive Medicine Internal medicine medicine Corpus luteum Ovulation hormones hormone substitutes and hormone antagonists Hormone media_common |
| Zdroj: | Biology of Reproduction. 47:884-888 |
| ISSN: | 1529-7268 0006-3363 |
| DOI: | 10.1095/biolreprod47.5.884 |
| Popis: | The response of the pituitary gland and ovary to repeated copulatory periods and/or gonadotropin-releasing hormone (GnRH, i.v. 1000 micrograms) administration was determined in llamas and alpacas. Eighty adult females (41 llamas and 39 alpacas with ovulatory follicles) were divided into three general groups for each species as follows: copulation (one or two copulations at either 6- or 24-h intervals) GnRH treatment (one or two treatments at either 6- or 24-h intervals), and combined treatment (copulation followed by GnRH treatment, or GnRH followed by copulation at either 6- or 24-h intervals). An additional control (nontreated) group was composed of 4 llamas and 4 alpacas. The first copulation or treatment with GnRH provoked LH release sufficient to cause ovulation in most of the females (alpacas, 89%; llamas, 92%); urinary pregnanediol glucuronide values, used to verify ovulation, were significantly elevated 48 h after copulation and/or GnRH treatment. A second stimulus, copulation or GnRH, provoked no LH response with concentrations similar to those in nontreated controls and in females not ovulating. Llamas and alpacas thus were refractory to a second copulatory or GnRH stimulus with regard to LH release for up to 24 h following an initial ovulatory release of LH. |
| Databáze: | OpenAIRE |
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