Changes in preoptic estradiol concentrations during male sexual behavior
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1
University of Liège, GIGA Neurosciences, Belgium
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2
University of Massachusetts, Psychological and Brain Sciences, United States
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3
University of Maryland, Psychology, United States
Besides its long-term control by steroids, male sexual behavior is also modulated by membrane-initiated effects of neuroestrogens in the short-term (within minutes). These effects are thought to depend on short-term variations in the local production of estrogens, through rapid fluctuations of the enzymatic activity of brain aromatase, the enzyme that synthesizes estradiol (E2) from testosterone. Studies in male Japanese quail have shown that a sexual interaction with a female leads to a decrease in the activity of brain aromatase within minutes. These effects occur mainly within the medial preoptic nucleus (POM), a sexually dimorphic structure of the preoptic area that plays a key role in the activation of male sexual behavior and contains the highest aromatase activity (AA) in the brain. However recent studies showed that AA does not always reflect local E2 concentration. For example, while an acute stress decreases AA in the POM, E2 concentration increases in the same conditions. Here we used in vivo microdialysis to quantify changes in E2 concentration in the male POM during sexual interactions with a female. A series of experiments conducted to validate the in vivo dialysis and RIA methods showed that (1) E2 concentration in the dialysate change linearly with the concentration of a bath containing known amounts of E2 in which the probe was placed, (2) an increase in preoptic E2 concentration is observed after retrodialysis of testosterone and (3) preoptic E2 levels also increase after a peripheral injection of E2. Together these results suggest that in vivo dialysis is a suitable method to assay E2 in the range of brain concentrations suspected to be present in physiological conditions. With this approach, we showed during two independent experiments that E2 concentrations increase in the POM during sexual interactions with a female. Birds that had their cannula placed outside the POM did not show any increase in E2 levels. The E2 increase in the POM could serve to maintain motivation during the entire sexual encounter. The decrease of AA observed ex vivo after copulation would then reflect a compensatory mechanism to restore baseline pre-copulatory conditions.
Acknowledgements
This research was supported by grants from the NIH (R01 MH50388) to GFB, JB and CAC, from the the University of Liège (Crédits spéciaux) to JB and CAC and the Fonds Léon Frédéricq. MPdB’s first year salary was supported by the Fonds Léon-Frédéricq and CdB’s salary was supported by a non-FRIA grant provided by the University of Liège. CAC is a F.R.S-FNRS Research Associate.
Keywords:
Estradiol,
Sexual Behavior,
Aromatase,
Preoptic Area,
Neurosteroids
Conference:
12th National Congress of the Belgian Society for Neuroscience, Gent, Belgium, 22 May - 22 May, 2017.
Presentation Type:
Poster Presentation
Topic:
Integrative Systems: Neuroendocrinology, Neuroimmunology, and Homeostatic Challenge
Citation:
De Bournonville
M,
De Bournonville
C,
Ball
G,
Balthazart
J and
Cornil
CA
(2019). Changes in preoptic estradiol concentrations during male sexual behavior.
Front. Neurosci.
Conference Abstract:
12th National Congress of the Belgian Society for Neuroscience.
doi: 10.3389/conf.fnins.2017.94.00014
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Received:
01 May 2017;
Published Online:
25 Jan 2019.
*
Correspondence:
Miss. Marie-Pierre De Bournonville, University of Liège, GIGA Neurosciences, Liège, 4000, Belgium, mpdebournonville@doct.ulg.ac.be