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See detailSex differences in perineuronal nets and parvalbumin expression in the zebra finch (taeniopygia guttata) song system.
Cornez, Gilles ULg; Ter Haar, Sita; Cornil, Charlotte ULg et al

Poster (2014, June 25)

Songbirds including zebra nches (Taeniopygia guttata) have been widely used as a model for studying vocal learning and the associated neural plasticity. Recently, two neural markers for critical periods ... [more ▼]

Songbirds including zebra nches (Taeniopygia guttata) have been widely used as a model for studying vocal learning and the associated neural plasticity. Recently, two neural markers for critical periods in brain plasticity were suggested to be related to song learning in males: parvalbumin (PV) expression would be associated with the onset of experience-dependent plasticity whereas perineuronal nets (PNN, chondroitin sulfate proteoglycans surrounding neurons) would limit potential plasticity at the end of sensitive phases (Balmer et al., 2009). Here we explored sex differences in PNN in the zebra finch song system. [less ▲]

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See detailAcute regulation of sexual motivation by neuro-estrogens
Cornil, Charlotte ULg

Scientific conference (2014, April 04)

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See detailRelationships between rapid changes in local aromatase activity and estradiol concentrations in male and female quail brain.
Dickens, M. J.; de Bournonville, Catherine ULg; Balthazart, Jacques ULg et al

in Hormones and behavior (2014), 65(2), 154-164

Estradiol-17beta (E2) synthesized in the brain plays a critical role in the activation of sexual behavior in many vertebrate species. Because E2 concentrations depend on aromatization of testosterone ... [more ▼]

Estradiol-17beta (E2) synthesized in the brain plays a critical role in the activation of sexual behavior in many vertebrate species. Because E2 concentrations depend on aromatization of testosterone, changes in aromatase enzymatic activity (AA) are often utilized as a proxy to describe E2 concentrations. Utilizing two types of stimuli (sexual interactions and acute restraint stress) that have been demonstrated to reliably alter AA within minutes in opposite directions (sexual interactions=decrease, stress=increase), we tested in Japanese quail whether rapid changes in AA are paralleled by changes in E2 concentrations in discrete brain areas. In males, E2 in the pooled medial preoptic nucleus/medial portion of the bed nucleus of the stria terminalis (POM/BST) positively correlated with AA following sexual interactions. However, following acute stress, E2 decreased significantly (approximately 2-fold) in the male POM/BST despite a significant increase in AA. In females, AA positively correlated with E2 in both the POM/BST and mediobasal hypothalamus supporting a role for local, as opposed to ovarian, production regulating brain E2 concentrations. In addition, correlations of individual E2 in POM/BST and measurements of female sexual behavior suggested a role for local E2 synthesis in female receptivity. These data demonstrate that local E2 in the male brain changes in response to stimuli on a time course suggestive of potential non-genomic effects on brain and behavior. Overall, this study highlights the complex mechanisms regulating local E2 concentrations including rapid stimulus-driven changes in production and stress-induced changes in catabolism. [less ▲]

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See detailSex in the brain
Cornil, Charlotte ULg

in International innovation (2014), 157

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See detailMechanism of the medium-duration afterhyperpolarization in rat serotonergic neurons
Alix, Philippe ULg; Venkatesan, Kumar; Scuvée-Moreau, Jacqueline et al

in European Journal of Neuroscience (2014), 39(2), 186-196

Most serotonergic neurons display a prominent medium-duration afterhyperpolarization (mAHP), which is mediated by small conductance Ca2+-activated K+ (SK) channels. Recent ex vivo and in vivo experiments ... [more ▼]

Most serotonergic neurons display a prominent medium-duration afterhyperpolarization (mAHP), which is mediated by small conductance Ca2+-activated K+ (SK) channels. Recent ex vivo and in vivo experiments have suggested that SK channel blockade increases the firing rate and/or bursting in these neurons. The purpose of this study was therefore to characterize the source of Ca2+ which activates the mAHP channels in serotonergic neurons. In voltage clamp experiments, an outward current was recorded at -60 mV after a depolarizing pulse to + 100 mV. A supra-maximal concentration of the SK channel blockers apamin or (-)- bicuculline methiodide blocked this outward current. This current was also sensitive to the broad Ca2+ channel blocker Co2+ and was partially blocked by both ω-conotoxin and mibefradil, which are blockers of N-type and T-type Ca2+ channels, respectively. Neither blockers of other voltage-gated Ca2+ channels nor DBHQ, an inhibitor of Ca2+-induced Ca2+ release, had any effect on the SK current. [less ▲]

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See detailEstrogens control female sexual motivation and receptivity in quail.
de Bournonville, Catherine ULg; Ball, Gregory, F.; Balthazart, Jacques ULg et al

Poster (2013, November 10)

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See detailActivation of estrogen receptor beta (ERb) by estrogens rapidly regulates male sexual motivation
Seredynski, Aurore; Ball, Gregory F.; Kelly, Martin J. et al

Conference (2013, September 13)

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See detailNeuro-estrogens and sexual behavior
Cornil, Charlotte ULg

Conference (2013, July 19)

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See detailNeuroestrogens Rapidly Regulate Sexual Motivation But Not Performance
Seredynski, Aurore ULg; Balthazart, Jacques ULg; Christophe, Virginie et al

in Journal of Neuroscience (2013), 33(1), 164-174

Estrogens exert pleiotropic effects on reproductive traits, which include differentiation and activation of reproductive behaviors and the control of the secretion of gonadotropins. Estrogens also ... [more ▼]

Estrogens exert pleiotropic effects on reproductive traits, which include differentiation and activation of reproductive behaviors and the control of the secretion of gonadotropins. Estrogens also profoundly affect non-reproductive traits, such as cognition and neuroprotection. These effects are usually attributed to nuclear receptor binding and subsequent regulation of target gene transcription. Estrogens also affect neuronal activity and cell-signaling pathways via faster, membrane-initiated events. How these two types of actions that operate in distinct timescales interact in the control of complex behavioral responses is poorly understood. Here, we show that the central administration of estradiol rapidly increases the expression of sexual motivation, as assessed by several measures of sexual motivation produced in response to the visual presentation of a female but not sexual performance in male Japanese quail. This effect is mimicked by membrane-impermeable analogs of estradiol, indicating that it is initiated at the cell membrane. Conversely, blocking the action of estrogens or their synthesis by a single intracerebroventricular injection of estrogen receptor antagonists or aromatase inhibitors, respectively, decreases sexual motivation within minutes without affecting performance. The same steroid has thus evolved complementary mechanisms to regulate different behavioral components (motivation vs performance) in distinct temporal domains (long- vs short-term) so that diverse reproductive activities can be properly coordinated to improve reproductive fitness. Given the pleiotropic effects exerted by estrogens, other responses controlled by these steroids might also depend on a slow genomic regulation of neuronal plasticity underlying behavioral activation and an acute control of motivation to engage in behavior. [less ▲]

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See detailFemale sexual and social behaviors are controlled by estrogens
de Bournonville, Catherine ULg; Ball, Gregory F; Balthazart, Jacques ULg et al

Poster (2013)

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See detailFemale sexual motivation is controlled by estrogens in quail
de Bournonville, Catherine ULg; Ball, Gregory F; Balthazart, Jacques ULg et al

Poster (2013)

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See detailLocal estradiol synthesis in the brain and its implication in male and female sexual motivation of Japanese quail
de Bournonville, Catherine ULg; Schmit, Mélanie; Ball, Gregory F et al

in Trabajos del Instituto Cajal (2013)

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See detailAre neuroestrogens implicated in sexual motivation? Development of experimental protocols.
de Bournonville, Catherine ULg; Schmit, Mélanie; Ball, Gregory F et al

Poster (2013)

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See detailRapid control of reproductive behaviour by locally synthesised oestrogens: focus on aromatase.
Cornil, Charlotte ULg; Seredynski, Aurore ULg; de Bournonville, Catherine ULg et al

in Journal of Neuroendocrinology (2013), 25(11), 1070-8

Oestrogens activate nucleus- and membrane-initiated signalling. Nucleus-initiated events control a wide array of physiological and behavioural responses. These effects generally take place within ... [more ▼]

Oestrogens activate nucleus- and membrane-initiated signalling. Nucleus-initiated events control a wide array of physiological and behavioural responses. These effects generally take place within relatively long periods of time (several hours to days). By contrast, membrane-initiated signalling affects a multitude of cellular functions in a much shorter timeframe (seconds to minutes). However, much less is known about their functional significance. Furthermore, the origin of the oestrogens able to trigger these acute effects is rarely examined. Finally, these two distinct types of oestrogenic actions have often been studied independently such that we do not exactly know how they cooperate to control the same response. The present review presents a synthesis of recent work carried out in our laboratory that aimed to address these issues in the context of the study of male sexual behaviour in Japanese quail, which is a considered as a suitable species for tackling these issues. The first section presents data indicating that 17b-oestradiol, or its membrane impermeable analogues, acutely enhances measures of male sexual motivation but does not affect copulatory behaviour. These effects depend on the activation of membrane-initiated events and local oestrogen production. The second part of this review discusses the regulation of brain oestrogen synthesis through post-translational modifications of the enzyme aromatase. Initially discovered in vitro, these rapid and reversible enzymatic modulations occur in vivo following variations in the social and environment context and therefore provide a mechanism of acute regulation of local oestrogen provision with a spatial and time resolution compatible with the rapid effects observed on male sexual behaviour. Finally, we discuss how these distinct modes of oestrogenic action (membrane- versus nucleus-initiated) acting in different time frames (short- versus long-term) interact to control different components (motivation versus performance) of the same behavioural response and improve reproductive fitness. [less ▲]

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See detailDistinct Neuroendocrine mechanisms control neural activity underlying sex differences in sexual motivation and performance
Balthazart, Jacques ULg; Corbisier de Méaultsart, Céline; Ball, Gregory et al

in European Journal of Neuroscience (2013), 37(5), 735-42

Sexual behavior can be usefully parsed into an appetitive and a consummatory component. Both appetitive and consummatory male-typical sexual behaviors (respectively, ASB and CSB) are activated in male ... [more ▼]

Sexual behavior can be usefully parsed into an appetitive and a consummatory component. Both appetitive and consummatory male-typical sexual behaviors (respectively, ASB and CSB) are activated in male Japanese quail by testosterone (T) acting in the medial preoptic nucleus (POM), but never observed in females. This sex difference is based on a demasculinization (= organizational effect) by estradiol during embryonic life for CSB, but a differential activation by T in adulthood for ASB. Males expressing rhythmic cloacal sphincter movements (RCSMs; a form of ASB) or allowed to copulate display increased Fos expression in POM. We investigated Fos brain responses in females exposed to behavioral tests after various endocrine treat- ments. T-treated females displayed RCSM, but never copulated when exposed to another female. Accordingly they showed an increased Fos expression in POM after ASB but not CSB tests. Females treated with the aromatase inhibitor Vorozole in ovo and T in adulthood displayed both male-typical ASB and CSB, and Fos expression in POM was increased after both types of tests. Thus, the neural circuit mediating ASB is present or can develop in both sexes, but is inactive in females unless they are exposed to exogenous T. In contrast, the neural mechanism mediating CSB is not normally present in females, but can be pre- served by blocking the embryonic production of estrogens. Overall these data confirm the difference in endocrine controls and probably neural mechanisms supporting ASB and CSB in quail, and highlight the complexity of mechanisms underlying sexual differentiation of behavior. [less ▲]

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See detailRAPID MODULATION OF AROMATASE ACTIVITY IN THE VERTEBRATE BRAIN
Charlier, Thierry; Cornil, Charlotte ULg; Balthazart, Jacques ULg

in Journal of Experimental Neuroscience (2013)

Numerous steroid hormones, including 17-estradiol (E2), activate rapid and transient cellular, physiological, and behavioral changes in addition to their well-described genomic effects. Aromatase is the ... [more ▼]

Numerous steroid hormones, including 17-estradiol (E2), activate rapid and transient cellular, physiological, and behavioral changes in addition to their well-described genomic effects. Aromatase is the key-limiting enzyme in the production of estrogens, and the rapid modulation of this enzymatic activity could produce rapid changes in local E2 concentrations. The mechanisms that might mediate such rapid enzymatic changes are not fully understood but are currently under intense scrutiny. Recent studies in our laboratory indicate that brain aromatase activity is rapidly inhibited by an increase in intracellular calcium concentration resulting from potassium- induced depolarization or from the activation of glutamatergic receptors. Phosphorylating conditions also reduce aromatase activity within minutes, and this inhibition is blocked by the addition of multiple protein kinase inhibitors. This rapid modulation of aromatase activity by phosphorylating conditions is a general mechanism observed in different cell types and tissues derived from a variety of spe- cies, including human aromatase expressed in various cell lines. Phosphorylation processes affect aromatase itself and do not involve changes in aromatase protein concentration. The control of aromatase activity by multiple kinases suggests that several amino acids must be concomitantly phosphorylated to modify enzymatic activity but site-directed mutagenesis of several amino acids alone or in combination has not to date revealed the identity of the targeted residue(s). Altogether, the phosphorylation processes affecting aro- matase activity provide a new general mechanism by which the concentration of estrogens can be rapidly altered in the brain. [less ▲]

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See detailNeurochemical control of rapid stress-induced changes in brain aromatase activity
Dickens, Molly; Cornil, Charlotte ULg; Balthazart, Jacques ULg

in Journal of Neuroendocrinology (2013), 25(4), 329-39

In the male brain, the medial preoptic nucleus (POM) is known to be a critical relay for the activation of sexual behaviour, with the aromatisation of testosterone into 17b-oestradiol (E2) playing a key ... [more ▼]

In the male brain, the medial preoptic nucleus (POM) is known to be a critical relay for the activation of sexual behaviour, with the aromatisation of testosterone into 17b-oestradiol (E2) playing a key role. Acute stress has been shown to differentially modulate the aromatase enzyme in this and other brain nuclei in a sex-specific manner. In POM specifically, stress induces increases in aromatase activity (AA) that are both rapid and reversible. How the physiological processes initiated during an acute stress response mediate sex- and nuclei- specific changes in AA and which stress response hormones are involved remains to be determined. By examining the relative effects of corticosterone (CORT), arginine vasotocin (AVT, the avian homologue to arginine vasopressin) and corticotrophin-releasing factor (CRF), the present study aimed to define the hormone profile regulating stress-induced increases in AA in the POM. We found that CORT, AVT and CRF all appear to play some role in these changes in the male brain. In addition, these effects occur in a targeted manner, such that modulation of the enzyme by these hormones only occurs in the POM rather than in all aromatase-expressing nuclei. Similarly, in the female brain, the experimental effects were restricted to the POM but only CRF was capable of inducing the stress-like increases in AA. These data further demonstrate the high degree of specificity (nuclei-, sex- and hormone-specific effects) in this system, highlighting the complexity of the stress–aromatase link and suggesting modes through which the nongenomic modulation of this enzyme can result in targeted, rapid changes in local oestrogen concentrations. [less ▲]

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