Publications of Charlotte Cornil
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See detailDevelopment of perineuronal nets during ontogeny correlates with sensorimotor vocal learning in canaries
Cornez, Gilles ULiege; Collignon, Clémentine ULiege; Müller, Went et al

in eNeuro (2020), 7(2), 0361-192020

Songbirds are a powerful model to study vocal learning given that aspects of the underlying behavioral and neurobiological mechanisms are analogous in many ways to mechanisms involved in speech learning ... [more ▼]

Songbirds are a powerful model to study vocal learning given that aspects of the underlying behavioral and neurobiological mechanisms are analogous in many ways to mechanisms involved in speech learning. Perineuronal nets (PNNs) represent one of the mechanisms controlling the closing of sensitive periods for vocal learning in the songbird brain. In zebra finches, PNN develop around parvalbumin (PV)-expressing interneurons in selected song control nuclei during ontogeny and their development is delayed if juveniles are deprived of a tutor. However, song learning in zebra finches takes place during a relatively short period of development, and it is difficult to determine whether PNN development correlates with the end of the sensory or the sensorimotor learning period. Canaries have a longer period of sensorimotor vocal learning, spanning over their first year of life so that it should be easier to test whether PNN development correlates with the end of sensory or sensorimotor vocal learning. Here, we quantified PNN around PV-interneurons in the brain of male canaries from hatching until the first breeding season and analyzed in parallel the development of their song. PNN development around PV-interneurons specifically took place and their number reached its maximum around the end of the sensorimotor learning stage, well after the end of sensory vocal learning, and correlated with song development. This suggests that PNN are specifically involved in the termination of the sensitive period for sensorimotor vocal learning. [less ▲]

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See detailTestosterone or estradiol when implanted in the medial preoptic nucleus trigger short low-amplitude songs in female canaries
Vandries, Laura ULiege; Ghorbanpoor, Samar; Cornez, Gilles ULiege et al

in eNeuro (2019), 6(2), 0502-182019

In male songbirds, the motivation to sing is largely regulated by testosterone action in the medial preoptic area, whereas testosterone acts on song control nuclei to modulate aspects of song quality ... [more ▼]

In male songbirds, the motivation to sing is largely regulated by testosterone action in the medial preoptic area, whereas testosterone acts on song control nuclei to modulate aspects of song quality. Stereotaxic implantation of testosterone in the medial preoptic nucleus (POM) of castrated male canaries activates a high rate of singing activity, albeit with a longer latency than after systemic testosterone treatment. Systemic testosterone also increases the occurrence of male-like song in female canaries. We hypothesized that this effect is also mediated by testosterone action in the POM. Females were stereotaxically implanted with either testosterone or with estradiol targeted at the POM and their singing activity was recorded daily during 2 hours for 28 days until brains were collected for histological analyses. Following identification of implant localizations, 3 groups of subjects were constituted that had either testosterone or estradiol implanted in the POM or had an implant that had missed the POM (Out). Testosterone and estradiol in POM significantly increased the number of songs produced and the percentage of time spent singing as compared with the Out group. The songs produced were in general of a short duration and of poor quality. This effect was not associated with an increase in HVC volume as observed in males, but testosterone in POM enhanced neurogenesis in HVC, as reflected by an increased density of doublecortin-immunoreactive multipolar neurons. These data indicate that, in female canaries, testosterone acting in the POM plays a significant role in hormone-induced increases in the motivation to sing. [less ▲]

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See detailSteroid profiles in quail brain and serum: sex and regional differences and effects of castration with steroid replacement
Liere, Philippe; Cornil, Charlotte ULiege; de Bournonville, Marie-Pierre ULiege et al

in Journal of Neuroendocrinology (2019), 31(2), 12681

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See detailLa souris, le patient, et le faux expert. Décryptage d'une mystification.
Bakker, Julie ULiege; Balthazart, Jacques ULiege; Baron, Frédéric ULiege et al

Article for general public (2018)

La recherche sur animaux est actuellement encadrée de façon stricte en Wallonie comme dans toute l'Union Européenne (voir l'article de Marc Vandenheede publié dans le Vif). Cette législation et les ... [more ▼]

La recherche sur animaux est actuellement encadrée de façon stricte en Wallonie comme dans toute l'Union Européenne (voir l'article de Marc Vandenheede publié dans le Vif). Cette législation et les contrôles qui y sont associés induisent de nombreuses contraintes pratiques, des charges administratives et des coûts financiers importants que les chercheurs seraient certainement heureux d'éviter s'il existait une alternative à l'expérimentation animale. [less ▲]

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See detailAnatomically discrete sex differences in neuroplasticity in zebra finches as reflected by perineuronal nets.
Cornez, Gilles ULiege; Ter Haar, Sita M.; Cornil, Charlotte ULiege et al

in PLoS ONE (2015), 10(4), 0123199

Large morphological sex differences in the vertebrate brain were initially identified in song control nuclei of oscines. Besides gross differences between volumes of nuclei in males and females, sex ... [more ▼]

Large morphological sex differences in the vertebrate brain were initially identified in song control nuclei of oscines. Besides gross differences between volumes of nuclei in males and females, sex differences also concern the size and dendritic arborization of neurons and various neurochemical markers, such as the calcium-binding protein parvalbumin (PV). Perineuronal nets (PNN) of the extracellular matrix are aggregates of different compounds, mainly chondroitin sulfate proteoglycans, that surround subsets of neurons, often expressing PV. PNN develop in zebra finches song control nuclei around the end of the sensitive period for song learning and tutor deprivation, known to delay the end of the song learning sensitive period, decreases the numbers of PNN in HVC. We demonstrate here the existence in zebra finches of a major sex difference (males > females) affecting the number of PNN (especially those surrounding PV-positive cells) in HVC and to a smaller extent the robust nucleus of the arcopallium, RA, the two main nuclei controlling song production. These differences were not present in Area X and LMAN, the lateral magnocellular nucleus of the anterior nidopallium. A dense expression of material immunoreactive for chondroitin sulfate was also detected in several nuclei of the auditory and visual pathways. This material was often organized in perineuronal rings but quantification of these PNN did not reveal any sex difference with the exception that the percentage of PNN surrounding PV-ir cells in the dorsal lateral mesencephalic nucleus, MLd, was larger in females than in males, a sex difference in the opposite direction compared to what is seen in HVC and RA. These data confirm and extend previous studies demonstrating the sex difference affecting PNN in HVC-RA by showing that this sex difference is anatomically specific and does not concern visual or auditory pathways. [less ▲]

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See detailLocal modulation of steroid action: rapid control of enzymatic activity.
Charlier, Thierry D.; Cornil, Charlotte ULiege; Patte-Mensah, Christine et al

in Frontiers in Neuroscience (2015), 9

Estrogens can induce rapid, short-lived physiological and behavioral responses, in addition to their slow, but long-term, effects at the transcriptional level. To be functionally relevant, these effects ... [more ▼]

Estrogens can induce rapid, short-lived physiological and behavioral responses, in addition to their slow, but long-term, effects at the transcriptional level. To be functionally relevant, these effects should be associated with rapid modulations of estrogens concentrations. 17beta-estradiol is synthesized by the enzyme aromatase, using testosterone as a substrate, but can also be degraded into catechol-estrogens via hydroxylation by the same enzyme, leading to an increase or decrease in estrogens concentration, respectively. The first evidence that aromatase activity (AA) can be rapidly modulated came from experiments performed in Japanese quail hypothalamus homogenates. This rapid modulation is triggered by calcium-dependent phosphorylations and was confirmed in other tissues and species. The mechanisms controlling the phosphorylation status, the targeted amino acid residues and the reversibility seem to vary depending of the tissues and is discussed in this review. We currently do not know whether the phosphorylation of the same amino acid affects both aromatase and/or hydroxylase activities or whether these residues are different. 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 detailSex in the brain
Cornil, Charlotte ULiege

in International Innovation (2014), 157

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See detailInfluence of sexual genotype on agonistic behaviors and sex steroid levels of phenotypic males and females in the Nile tilapia (Oreochromis niloticus)
Gennotte, Vincent ULiege; Balagizi, Désiré Akonkwa; Mélard, Charles ULiege et al

Poster (2014)

Mechanisms of sex determination and differentiation are extremely labile in fish, as demonstrated by the numerous sex reversal experiments performed on teleosts. In Nile tilapia, sex reversal processes ... [more ▼]

Mechanisms of sex determination and differentiation are extremely labile in fish, as demonstrated by the numerous sex reversal experiments performed on teleosts. In Nile tilapia, sex reversal processes using exogenous sex steroids allow to produce individuals with atypical sexual genotypes that constitute major tools to investigate the mechanisms of sex determination and differentiation, from gonad differentiation to sexual differentiation of brain and behavior. The aim of this study was to assess the influence of sexual genotype and the role of circulating sex steroids on the expression of agonistic behaviors in Nile tilapia breeders. Observations were carried out on fights staged between one male (M) and one female (F) acclimatized in 250-L aquaria at 27°C. Agonistic behaviors were recorded (for 25 min) in five crosses (6 repetitions with different pairs): MXY×FXX (control), MXY×FXY, MXY×FYY, MXX×FXX and MYY×FXX. Quantified behaviors were: fin raising, throat swelling, chasing, lateral attack, frontal display, tail beating, mouth fighting and biting. For steroid assay, blood was sampled on 10 individuals of each phenotype/genotype combination. Testosterone (T), 17beta-estradiol (E2) and 11-ketotestosterone (11KT) were measured by radioimmunoassay. Expression of aggressive behaviors was significantly higher in couples with a XY or YY female than in MXY×FXX. The mean durations (in % of total time) of threatening behavior expression were respectively 41 ± 3 and 8 ± 1 %; and the mean frequencies of attacking behaviors were 110 ± 7 and 25 ± 5 n h-1. Expression level of agonistic behaviors in MXY staged with FXY or FYY seems to be adjusted to the aggressiveness level of females. Aggressiveness level was low and similar in MXY×FXX, MXX×FXX and MYY×FXX crosses. When comparing males together in these 3 crosses, only MXX showed a slightly but significantly higher expression of aggressive behaviors. Compared to normal MXY, MXX had significantly higher levels of circulating 11KT (16.0 ± 4.1 and 26.5 ± 4.2 ng mL-1 respectively), that could be related to their higher aggressiveness. However, no similar difference was reported between females. E2 concentrations were similar between males (mean: 4.0 ± 0.4 ng mL-1) and increased in females with the presence of Y chromosome(s) (FXX: 6.5 ± 1.4, FXY: 9.5 ± 1.7 and FYY: 14.1 ± 2.2 ng mL-1). These results raised the question of an involvement of E2 in the control of agonistic behaviors in females. No influence of the genotype was observed on T levels. Our results suggest that the presence of a Y chromosome increases aggressiveness in females. However, since the same relationship between aggressiveness and the Y chromosome is not observed in males, in which the level of aggressiveness is paradoxically higher in XX, we can hypothesize that the differences in aggressiveness are not directly dependant on the genotype but on the sex reversal procedures which young fry were exposed to during their sexual differentiation. These hormonal treatments could have permanently modified the development of the brain and consequently influenced the behavior of adults independently to their genotype. The role of endogenous steroids in agonistic behaviors needs further clarification. [less ▲]

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See detailAcute and Specific Modulation of Presynaptic Aromatization in the Vertebrate Brain
Cornil, Charlotte ULiege; Leung, Cary H.; Pletcher, Eric R. et al

in Endocrinology (2012), 153(6), 2562-7

Estrogens affect a diversity of peripheral and central physiological endpoints. Traditionally, estrogens were thought to be peripherally derived transcription regulators (i.e. slow acting). More recently ... [more ▼]

Estrogens affect a diversity of peripheral and central physiological endpoints. Traditionally, estrogens were thought to be peripherally derived transcription regulators (i.e. slow acting). More recently, we have learned that estrogens are also synthesized in neuronal cell bodies and synaptic terminals and have potent membrane effects, which modulate brain function. However, the mechanisms that control local steroid concentrations in a temporal and spatial resolution compatible with their acute actions are poorly understood. Here, using differential centrifugation followed by enzymatic assay, we provide evidence that estrogen synthesis within synaptosomes can be modulated more dramatically by phosphorylating conditions, relative to microsomes. This is the first demonstration of a rapid mechanism that may alter steroid concentrations within the synapse and may represent a potential mechanism for the acute control of neurophysiology and behavior. [less ▲]

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See detailSex differences in brain aromatase activity: genomic and non-genomic controls
Balthazart, Jacques ULiege; Charlier, Thierry ULiege; Cornil, Charlotte ULiege 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 detailAcute Stress Differentially Affects Aromatase Activity in Specific Brain Nuclei of Adult Male and Female Quail
Dickens, Molly J; Cornil, Charlotte ULiege; Balthazart, Jacques ULiege

in Endocrinology (2011), 52(11), 4242-51

The rapid and temporary suppression of reproductive behavior is often assumed to be an important feature of the adaptive acute stress response. However, how this suppression operates at the mechanistic ... [more ▼]

The rapid and temporary suppression of reproductive behavior is often assumed to be an important feature of the adaptive acute stress response. However, how this suppression operates at the mechanistic level is poorly understood.The enzyme aromatase converts testosterone to estradiol in the brain to activate reproductive behavior in male Japanese quail (Coturnix japonica). The discovery of rapid and reversible modification of aromatase activity (AA) provides a potential mechanism for fast, stress induced changes in behavior. We investigated the effects of acute stress on AA in both sexes by measuring enzyme activity in all aromatase-expressing brain nuclei before, during, and after 30 min of acute restraint stress. We show here that acute stress rapidly alters AA in the male and female brain and that these changes are specific to the brain nuclei and sex of the individual. Specifically, acute stress rapidly (5 min) increased AA in the male medial preoptic nucleus, a region controlling male reproductive behavior; in females, a similar increase was also observed, but it appeared delayed (15min) and had smaller amplitude. In the ventromedial and tuberal hypothalamus, regions associated with female reproductive behavior, stress induced a quick and sustained decrease in AA in females, but in males, only a slight increase (ventromedial) or no change (tuberal) in AA was observed. Effects of acute stress on brain estrogen production, therefore, represent one potential way through which stress affects reproduction. [less ▲]

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

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

Detailed reference viewed: 48 (10 ULiège)