Temporal Changes Occur in the Neuroendocrine Control of Gonadotropin Secretion in Aging Female Rats: Role of Progesterone1
| Autor: | Houng-Wei Tsai, Angelica P. Olcott, Philip S. LaPolt, John K. H. Lu |
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| Rok vydání: | 2004 |
| Předmět: |
Estrous cycle
endocrine system medicine.medical_specialty medicine.drug_class Stimulation Cell Biology General Medicine Biology Neuroendocrinology Gonadotropin secretion Follicle-stimulating hormone Endocrinology Reproductive Medicine Internal medicine medicine Ovariectomized rat Gonadotropin Luteinizing hormone hormones hormone substitutes and hormone antagonists |
| Zdroj: | Biology of Reproduction. 71:845-852 |
| ISSN: | 1529-7268 0006-3363 |
| DOI: | 10.1095/biolreprod.104.029090 |
| Popis: | The present study examined the gonadotropin surge-inducing actions of estradiol (E2), both alone and with progesterone (P4), in middle-aged, early persistent-estrous (PE) female rats that had become PE within 35 days. In addition, we also assessed the effect of P4 on the mating-induced gonadotropin surges in these acyclic animals. Early PE rats were ovariectomized and received E2 implants (Day 0). On Day 4, an s.c. injection of P4 (0.5 mg/ 100 g body weight) at 1200 h markedly increased plasma P4 and elicited both LH and FSH surges, whereas vehicle-treated controls displayed no rise in P4 or gonadotropins. This observation confirms that at middle age, female rats no longer respond to the positive-feedback stimulation of E2 on gonadotropin surges whenever the estrous cyclicity ceases. As PE continued, such a surge-inducing action of E2 plus P4 became diminished after 75 days of PE and disappeared thereafter. When caged with males, vehicle-treated early PE rats display a mating-induced increase in ... |
| Databáze: | OpenAIRE |
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