Estradiol Increases Multiunit Electrical Activity in the A15 Area of Ewes Exposed to Inhibitory Photoperiods1
| Autor: | Bernadette Delaleu, Jean-Claude Thiéry, Benoît Malpaux, Robert L. Goodman |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
Estrous cycle
medicine.medical_specialty animal structures genetic structures Dopaminergic Cell Biology General Medicine Biology Inhibitory postsynaptic potential Electrophysiology chemistry.chemical_compound Endocrinology Reproductive Medicine chemistry Hypothalamus Internal medicine Ovariectomized rat medicine Neurotransmitter Luteinizing hormone |
| Zdroj: | Biology of Reproduction. 63:1352-1357 |
| ISSN: | 1529-7268 0006-3363 |
| DOI: | 10.1095/biolreprod63.5.1352 |
| Popis: | Seasonal anestrus in ewes results from an increase in response to the negative feedback action of estradiol (E2). This increase in the inhibitory effects of E2 is controlled by photoperiod and appears to be mediated, in part, by dopaminergic neurons in the retrochiasmatic area of the hypothalamus (A15 group). This study was designed to test the hypothesis that E2 increases multiunit electrical activity (MUA) in the A15 during inhibitory long days. MUA was monitored in the retrochiasmatic area of 14 ovariectomized ewes from 4 h before to 24 h after insertion of an E2-containing implant subcutaneously. In six of these ewes, MUA activity was also monitored before and after insertion of blank implants. Three of the 14 ewes were excluded from analysis because E2 failed to inhibit LH. When MUA was recorded within the A15, E2 produced a gradual increase in MUA that was sustained for 24 h. Blank implants failed to increase MUA in the A15 area, and E2 did not alter MUA if recording electrodes were outside the A15. These data demonstrate that E2 increases MUA in the A15 region of ewes and are consistent with the hypothesis that these neurons mediate E2 negative feedback during long photoperiods. |
| Databáze: | OpenAIRE |
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