Ovarian Control of Gonadotropin Hormone-Releasing Hormone Pulse Generator Activity in the Rhesus Monkey: Duration of the Associated Hypothalamic Signal
| Autor: | Ernst Knobil, Ming-Dao Chen, Cynthia L. Williams, Masugi Nishihara, Kevin T. O'Byrne, J. Hotchkiss, Jean-Christophe Thalabard |
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| Rok vydání: | 1993 |
| Předmět: |
endocrine system
medicine.medical_specialty genetic structures medicine.drug_class Ovariectomy Endocrinology Diabetes and Metabolism Central nervous system Hypothalamus Ovary Biology Gonadotropin-Releasing Hormone Cellular and Molecular Neuroscience Endocrinology Internal medicine medicine Animals Endocrine and Autonomic Systems musculoskeletal neural and ocular physiology Pulse generator Macaca mulatta Electrophysiology body regions Kinetics medicine.anatomical_structure Female Gonadotropin Luteinizing hormone hormones hormone substitutes and hormone antagonists Hormone |
| Zdroj: | Neuroendocrinology. 57:588-592 |
| ISSN: | 1423-0194 0028-3835 |
| DOI: | 10.1159/000126411 |
| Popis: | The activity of the GnRH pulse generator in the rhesus monkey is associated with abrupt increases in multiunit electrical activity (MUA) volleys recorded from the mediobasal hypothalamus that precede each pulse of LH in the peripheral circulation. In long-term ovariectomized animals the duration of these MUA volleys is 10-25 min and consists of a brief initial 'overshoot' followed by a plateau phase that ends in a rapid decline to baseline activity. In intact monkeys, however, the MUA volley lasts only 1-3 min, a duration equivalent to the overshoot in ovariectomized animals. In addition, the maximal frequency of neuronal activity during each MUA volley is reduced in normal animals when compared to castrates. As shown in earlier studies, estradiol given to ovariectomized monkeys causes a reduction in the duration of MUA volleys to that characteristic of intact animals within 3-5 h. In contrast to this acute effect of estradiol, the increase in MUA volley duration following ovariectomy is a gradual phenomenon, 4-6 weeks being required to achieve the MUA volley duration observed in long-term ovariectomized monkeys. A similar slow time course was observed for the increase in maximal neuronal frequency during each MUA volley. This protracted effect of ovariectomy on MUA volley duration and firing rate may be the consequence of hypothalamic remodelling but this consideration must be tempered by the observation that estradiol reverses these phenomena within hours. |
| Databáze: | OpenAIRE |
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