Potential role of microglia and prostaglandins in the sexual differentiation of brain and behavior of Japanese quail
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1
Laboratory of Behavioral Neuroendocrinology, Neuroendocrinology Unit, GIGA Neurosciences, University of Liège, Belgium
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2
Laboratory for the Analysis of Medicines, Department of Pharmacy, CIRM, University of Liège, Belgium
Sexual differentiation of brain and behavior is a developmental process during which irreversible differences are established between male and female brains, leading to sexually dimorphic behaviors in adulthood. These differences are mainly caused by estradiol (E2) which acts during a critical period to masculinize male rats but demasculinize female quail, revealing a dichotomy between mammals and birds. Brain masculinization by estrogens in rats also involves prostaglandin E2 (PGE2), a pro-inflammatory hormone, and microglia, the resident macrophages of the brain, which are present in larger quantities, especially in their activated form, in males. This study aimed to assess the role of PGE2 in brain sexual differentiation of Japanese quail and determine whether microglia differ in number and morphology between sexes during embryonic development, as the larger amount of microglia in male rats could suggest an inflammatory reaction due to a maternal immune response against male fetus(es). Our results showed that the inhibition of COX, the enzymes producing prostanoids such as PGE2, during the sensitive period to estrogens decreased copulation frequency in males but did not affect females. Regarding microglia, a sexual difference was found between embryonic day 9 and 12 in the medial preoptic nucleus (POM) with females possessing more microglia, especially of the activated form, than males. Finally, PGE2 was detected during embryonic development and its levels increased with age without revealing any significant sex difference. This absence of sex difference in preoptic PGE2 levels thus suggests that another prostanoid than PGE2 may masculinize the brain and behavior of quail. Furthermore, microglia could partake in demasculinization as they are more prevalent in females during the sensitive period. Finally, as quail develop in an egg, it is likely that this sex difference does not stem from a maternal immune response.
Keywords:
Japanese quail,
Microglia,
Prostaglandins,
Brain sexual differentiation,
sex differences & hormone effects
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:
Delage
C,
Nys
G,
Fillet
M and
Cornil
CA
(2019). Potential role of microglia and prostaglandins in the sexual differentiation of brain and behavior of Japanese quail.
Front. Neurosci.
Conference Abstract:
12th National Congress of the Belgian Society for Neuroscience.
doi: 10.3389/conf.fnins.2017.94.00103
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Received:
20 Apr 2017;
Published Online:
25 Jan 2019.
*
Correspondence:
Ms. Charlotte Delage, Laboratory of Behavioral Neuroendocrinology, Neuroendocrinology Unit, GIGA Neurosciences, University of Liège, Liège, Belgium, c.delage@doct.ulg.ac.be