References of "Charlier, Thierry"
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See detailEstrogen activation revisited: control of local metabolism in the brain
Charlier, Thierry ULg

Scientific conference (2012)

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See detailModulation of steroid action: Importance of coactivators
Charlier, Thierry ULg

Scientific conference (2012)

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See detailSex differences in brain aromatase activity: genomic and non-genomic controls
Balthazart, Jacques ULg; Charlier, Thierry ULg; Cornil, Charlotte ULg et al

in Frontiers in Endocrinology (2011), 2

Aromatization of testosterone into estradiol in the preoptic area plays a critical role in the activation of male copulation in quail and in many other vertebrate species. Aromatase expression in quail ... [more ▼]

Aromatization of testosterone into estradiol in the preoptic area plays a critical role in the activation of male copulation in quail and in many other vertebrate species. Aromatase expression in quail and in other birds is higher than in rodents and other mammals, which has facilitated the study of the controls and functions of this enzyme. Over relatively long time periods (days to months), brain aromatase activity (AA), and transcription are markedly (four- to sixfold) increased by genomic actions of sex steroids. Initial work indicated that the preoptic AA is higher in males than in females and it was hypothesized that this differential production of estrogen could be a critical factor responsible for the lack of behavioral activation in females. Subsequent studies revealed, however, that this enzymatic sex difference might contribute but is not sufficient to explain the sex difference in behavior. Studies of AA, immunoreactivity, and mRNA concentrations revealed that sex differences observed when measuring enzymatic activity are not necessarily observed when one measures mRNA concentrations. Discrepancies potentially reflect post-translational controls of the enzymatic activity. AA in quail brain homogenates is rapidly inhibited by phosphorylation processes. Similar rapid inhibitions occur in hypothalamic explants maintained in vitro and exposed to agents affecting intracellular calcium concentrations or to glutamate agonists. Rapid changes in AA have also been observed in vivo following sexual interactions or exposure to short-term restraint stress and these rapid changes in estrogen production modulate expression of male sexual behaviors. These data suggest that brain estrogens display most if not all characteristics of neuromodulators if not neurotransmitters. Many questions remain however concerning the mechanisms controlling these rapid changes in estrogen production and their behavioral significance. [less ▲]

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See detailOrganizing effects of sex steroids on brain aromatase activity in quail
Cornil, Charlotte ULg; Ball, Gregory F; Balthazart, Jacques ULg et al

in PLoS ONE (2011), 6(4), 19196

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See detailHuman and Quail Aromatase Activity Is Rapidly and Reversibly Inhibited by Phosphorylating Conditions
Charlier, Thierry ULg; Harada, Nobuhiro; Balthazart, Jacques ULg et al

in Endocrinology (2011), 152(11), 4199-210

Besides their slow genomic actions, estrogens also induce rapid physiological responses. To be functionally relevant, these effects must be associated with rapid changes in local concentrations of ... [more ▼]

Besides their slow genomic actions, estrogens also induce rapid physiological responses. To be functionally relevant, these effects must be associated with rapid changes in local concentrations of estrogens. Rapid changes in aromatase activity (AA) controlled by calcium-dependent phosphorylations of the enzyme can alter in a rapid manner local estrogen concentrations, but so far this mechanism was identified only in the avian (quail) brain. We show here that AA is also rapidly down-regulated by phosphorylating conditions in quail ovary homogenates and in various cell lines transfected with human aromatase (HEK 293, Neuro2A, and C6). Enzymatic activity was also rapidly inhibited after depolarization of aromatase-expressing HEK 293 cells with 100 mm KCl, and activity was fully restored when cells returned to control conditions. Western blot analysis demonstrated that the reduction of enzymatic activity is not due to protein degradation. We next investigated by site-directed mutagenesis the potential implication in the control of AA of specific aromatase residues identified by bioinformatic analysis. Mutation of the amino acids S118, S247, S267, T462, T493, or S497 to alanine, alone or in combination, did not block the rapid inhibition of enzymatic activity induced by phosphorylating conditions, but basal AA was markedly decreased in the S118A mutant. Altogether, these results demonstrate that the rapid inhibition of AA is a widespread and fully reversible process and that phosphorylation of specific residues modulate AA. These processes provide a new general mechanism by which local estrogen concentration can be rapidly altered in the brain and other tissues. [less ▲]

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See detailMultiple measures elucidate glucocorticoid responses to environmental variation in predation threat
Clinchy, Michael; Zanette, Liana; Charlier, Thierry ULg et al

in Oecologia (2011), 166

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See detailRapid regulation by glutamate of aromatase activity
Charlier, Thierry ULg; Ball, Gregory; Balthazart, Jacques ULg

Poster (2011)

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See detailRapid effects of aggressive interactions on aromatase activity and oestradiol in discrete brain regions of wild male white-crowned sparrows
Charlier, Thierry ULg; Newman, Amy EM; Heimovics, Sarah A et al

in Journal of Neuroendocrinology (2011), 23

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See detailOwn song selectivity in the songbird auditory pathway: Suppression by norepinephrine
Poirier, Colline; Boumans, Tiny; Vellema, Michiel et al

in PLoS ONE (2011), 6(5), 20131

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