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See detailSite-specific effects of aromatase inhibition on the activation of male sexual behavior in male Japanese quail (Coturnix japonica)
de Bournonville, Marie-Pierre ULiege; Vandries, Laura ULiege; Ball, Gregory et al

in Hormones and Behavior (2019), 108

Aromatization within the medial preoptic nucleus (POM) is essential for the expression of male copulatory behavior in Japanese quail. However, several nuclei within the social behavior network (SBN) also ... [more ▼]

Aromatization within the medial preoptic nucleus (POM) is essential for the expression of male copulatory behavior in Japanese quail. However, several nuclei within the social behavior network (SBN) also express aromatase. Whether aromatase in these loci participates in the behavioral activation is not known. Castrated male Japanese quail were implanted with 2 subcutaneous Silastic capsules filled with crystalline testosterone and with bilateral stereotaxic implants filled with the aromatase inhibitor Vorozole targeting the POM, the bed nucleus of the stria terminalis (BST) or the ventromedial nucleus of the hypothalamus (VMN). Control animals were implanted with testosterone and empty bilateral stereotaxic implants. Starting 2 days after the surgery, subjects were tested for the expression of consummatory sexual behavior (CSB) every other day for a total of 10 tests. They were also tested once for appetitive sexual behavior (ASB) as measured by the rhythmic cloacal sphincter movements displayed in response to the visual presentation of a female. CSB was drastically reduced when the Vorozole implants were localized in the POM, but not in the BST nor in the VMN. Birds with implants in the BST showed a longer latency to show CSB in the first 6 tests than controls, suggesting a role of the BST in the acquisition of the full copulatory ability. ASB was not significantly affected by aromatase blockade in any region. These data confirm the key role played by the POM in the control of male sexual behavior and suggest a minor role for aromatization in the BST or VMN. [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 detailRapid testosterone-induced growth of the medial preoptic nucleus in male canaries.
Shevchouk, Olesya T.; Ball, Gregory F.; Cornil, Charlotte ULiege et al

in Physiology and Behavior (2019), 204

Testosterone activates singing within days in castrated male songbirds but full song quality only develops after a few weeks. Lesions of the medial preoptic nucleus (POM) inhibit while stereotaxic ... [more ▼]

Testosterone activates singing within days in castrated male songbirds but full song quality only develops after a few weeks. Lesions of the medial preoptic nucleus (POM) inhibit while stereotaxic testosterone implants into this nucleus increase singing rate suggesting that this site plays a key role in the regulation of singing motivation. Testosterone action in the song control system works in parallel to control song quality. Accordingly, systemic testosterone increases POM volume within 1-2days in female canaries, while the increase in volume of song control nuclei takes at least 2weeks. The current study tested whether testosterone action is associated with similar differences in latencies in males. Photosensitive castrated male canaries were implanted with testosterone-filled Silastic implants and control castrates received empty implants, while simultaneously the photoperiod was switched from short- to long-days. Brains were collected from all subjects two days later. Plasma testosterone was elevated in testosterone-treated but not in controls. HVC volumes were not affected, but testosterone significantly increased the POM volume as identified by the dense group of aromatase-immunoreactive neurons, the number and somal area of these neurons and the fractional area they cover in POM. Testosterone-treated females from a previous experiment had a smaller POM volume in similar conditions suggesting the existence of a stable sex difference potentially affecting singing behavior. Thus testosterone induces male POM growth and aromatase expression in this nucleus within two days without affecting HVC size, further supporting the notion that testosterone increases singing motivation via its action in POM. [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 detailCorrelation between song learning and perineuronal nets development in song control system nuclei of juvenile canaries
Cornez, Gilles ULiege; Collignon, Clémentine ULiege; Müller, Wendt et al

Poster (2018, November 05)

Perineuronal nets (PNN) are aggregations of extracellular matrix components surrounding the soma of specific neurons, mainly GABAergic interneurons expressing the calcium binding protein parvalbumin (PV ... [more ▼]

Perineuronal nets (PNN) are aggregations of extracellular matrix components surrounding the soma of specific neurons, mainly GABAergic interneurons expressing the calcium binding protein parvalbumin (PV+). In mammals, the development of PNN limits synaptogenesis around PV+ neurons and PNNs have been identified as a marker of the end of sensitive periods for brain plasticity in several neuronal systems. In songbirds, vocal learning requires exposure to conspecific vocalizations by male tutors during a sensitive period. This is followed by a sensorimotor period when birds progressively match their vocalizations with the memorized tutor’s song until the fully mature song is crystallized. In a closed-ended learner, the zebra finch, PNN expression in select song nuclei is higher in males than in females and higher in adults than in juvenile males. The timing of PNN appearance in the developing zebra finch brain correlates with the timing of sensitive periods for song learning. We also showed that PNN are more densely expressed in the song control system of zebra finches than in two open-ended learners, the European starling and the canary and that testosterone (T) induces song crystallization in early spring and increases the number of PNN in castrated canaries. Together these data suggest that PNN might regulate the end of the sensitive period(s) for vocal learning during ontogeny. To elucidate this question further, we quantified PNN expression at critical time points during the first year of life in canaries and correlated these data with their song development. Brains were collected from groups of males (n=6-8/group) at time points corresponding to specific vocal developmental stages: first spring (subsong), summer (early plastic song), fall (plastic song), winter (ongoing song crystallization), and second spring (fully crystallized song/adults). In winter, one additional group received T implants to test whether this accelerates PNN development and song crystallization. The number of PNN reached their maximum in the fall in HVC but only in the winter in RA and Area X. In the group treated with T there was no further enhancement of PNN expression over what was observed in untreated birds at the same age. Total song duration and song developmental score only reached their maximum in the spring and were enhanced by T in the winter. Other song characteristics such as the energy or bandwidth were already at the adult levels during the winter. Most of these song measurements correlated with the number of PNN in the song nuclei suggesting that PNN contribute to song crystallization that starts in the winter and is completed at the onset of spring. [less ▲]

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See detailExpérimentation animale: la recette d'une polémique scientifique
Muraille, Eric; de kerchove, Alban; Muylkens, Benoit et al

Article for general public (2018)

La majorité du grand public accepte l’expérimentation animale à condition que celle-ci contribue à l’amélioration de la santé humaine et qu’aucune autre alternative n’existe. En face, les opposants ... [more ▼]

La majorité du grand public accepte l’expérimentation animale à condition que celle-ci contribue à l’amélioration de la santé humaine et qu’aucune autre alternative n’existe. En face, les opposants décrédibilisent la recherche et stigmatise une profession à des fins idéologiques. Relevé de leurs arguments. [less ▲]

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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 detailAnalyse détaillée de la seconde version de l’avant-projet de Code du bien-être animal wallon. Lecture commentée au 21/03/2018 du Chapitre 8 (Expérimentation animale)
Drion, Pierre ULiege; Corhay, Albert ULiege; Haubruge, Eric ULiege et al

Report (2018)

La compétence « bien-être animal », auparavant fédérale, a été régionalisée en juillet 2014. Ce projet de code vise à remplacer les dispositions légales en vigueur (la Loi de 1984 telle que modifiée par ... [more ▼]

La compétence « bien-être animal », auparavant fédérale, a été régionalisée en juillet 2014. Ce projet de code vise à remplacer les dispositions légales en vigueur (la Loi de 1984 telle que modifiée par les décrets du Gouvernement wallon). Certains éléments sont repris tels quels de la Directive 2010/63. Cela est nécessaire car la Directive européenne en tant que telle n’a pas de force obligatoire en Belgique. Elle doit être transcrite par un instrument législatif (avant, la Loi de 1984 et ses modifications, aujourd’hui, le projet de code pour la Région wallonne). Certains aspects semblent flous, mais renvoient à des dispositions que le Gouvernement doit encore prendre (au travers d’arrêtés du Gouvernement wallon, comme le faisaient avant les nombreux arrêtés royaux et du gouvernement qui réglementent la matière). Les arrêtés d’exécution devront obligatoirement tenir compte de la Directive européenne et s’inspirer de dispositions actuellement en vigueur. [less ▲]

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See detailRapid effects of steroids in the brain: Introduction to special issue
Remage-Healey, L.; Choleris, E.; Balthazart, Jacques ULiege

in Hormones and Behavior (2018), 104

[No abstract available]

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See detailRapid changes in auditory processing in songbirds following acute aromatase inhibition as assessed by fMRI
Van der Linden, A.; Balthazart, Jacques ULiege

in Hormones and Behavior (2018), 104

Contribution to Special Issue on Fast effects of steroids. This review introduces functional MRI (fMRI) as an outstanding tool to assess rapid effects of sex steroids on auditory processing in seasonal ... [more ▼]

Contribution to Special Issue on Fast effects of steroids. This review introduces functional MRI (fMRI) as an outstanding tool to assess rapid effects of sex steroids on auditory processing in seasonal songbirds. We emphasize specific advantages of this method as compared to other more conventional and invasive methods used for this purpose and summarize an exemplary auditory fMRI study performed on male starlings exposed to different types of starling song before and immediately after the inhibition of aromatase activity by an i.p. injection of Vorozole™. We describe how most challenges that relate to the necessity to anesthetize subjects and minimize image- and sound-artifacts can be overcome in order to obtain a voxel-based 3D-representation of changes in auditory brain activity to various sound stimuli before and immediately after a pharmacologically-induced depletion of endogenous estrogens. Analysis of the fMRI data by assumption-free statistical methods identified fast specific changes in activity in the auditory brain regions that were stimulus-specific, varying over different seasons, and in several instances lateralized to the left side of the brain. This set of results illustrates the unique features of fMRI that provides opportunities to localize and quantify the brain responses to rapid changes in hormonal status. fMRI offers a new image-guided research strategy in which the spatio-temporal profile of fast neuromodulations can be identified and linked to specific behavioral inputs or outputs. This approach can also be combined with more localized invasive methods to investigate the mechanisms underlying the observed neural changes. © 2018 Elsevier Inc. [less ▲]

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See detailDifferential control of appetitive and consummatory sexual behavior by neuroestrogens in male quail
Cornil, Charlotte ULiege; Ball, Gregory; Balthazart, Jacques ULiege

in Hormones and Behavior (2018), 104

Estrogens exert pleiotropic effects on multiple physiological and behavioral traits including sexual behavior. These effects are classically mediated via binding to nuclear receptors and subsequent ... [more ▼]

Estrogens exert pleiotropic effects on multiple physiological and behavioral traits including sexual behavior. These effects are classically mediated via binding to nuclear receptors and subsequent regulation of target gene transcription. Estrogens also affect neuronal activity and cell-signaling pathways via faster, membrane-initiated events. Although the distinction between appetitive and consummatory aspects of sexual behavior has been criticized, this distinction remains valuable in that it facilitates the causal analysis of certain behavioral systems. Effects of neuroestrogens produced by neuronal aromatization of testosterone on copulatory performance (consummatory aspect) and on sexual motivation (appetitive aspect) are described in male quail. The central administration of estradiol rapidly increases expression of sexual motivation, as assessed by two 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 in- tracerebroventricular injection of estrogen receptor antagonists or aromatase inhibitors, respectively, decreases sexual motivation within minutes without affecting performance. The same steroid has thus evolved com- plementary 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. Changes in preoptic aromatase activity and estradiol as well as glutamate concentrations are observed during or immediately after copulation. The interaction between these neuroendocrine/neurochemical changes and their functional significance is discussed. [less ▲]

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See detailThe regulation of birdsong by testosterone: Multiple time-scales and multiple sites of action
Alward, Beau; Cornil, Charlotte ULiege; Balthazart, Jacques ULiege et al

in Hormones and Behavior (2018), 104

Sex steroid hormones act during early development to shape the circuitry upon which these same hormones act in adulthood to control behavioral responses to various stimuli. The “organizational” vs ... [more ▼]

Sex steroid hormones act during early development to shape the circuitry upon which these same hormones act in adulthood to control behavioral responses to various stimuli. The “organizational” vs. “activational” dis- tinction was proposed to explain this temporal difference in hormone action. In both of these cases steroids were thought to act genomically over a time-scale of days to weeks. However, sex steroids can affect behavior over short (e.g., seconds or minutes) time-scales. Here, we discuss how testosterone controls birdsong via actions at different sites and over different time-scales, with an emphasis on this process in canaries (Serinus canaria). Our work shows that testosterone in the medial preoptic nucleus regulates the motivation to sing, but not aspects of song performance. Instead, different aspects of song performance are regulated by long-term actions of testos- terone in steroid-sensitive cortical-like brain regions and the syrinx, the avian vocal production organ. On the other hand, acute aromatase inhibition rapidly reduces the availability of estrogens and this reduction is cor- related with reductions in the motivation to sing and song performance. Thus, testosterone and its estrogenic metabolites regulate distinct features of birdsong depending on the site and temporal window of action. The number of brain areas expressing androgen receptors is higher in species producing learned vocalization as compared to species that produce unlearned calls. An appealing scenario is that rapid effects of steroids in specific brain regions is a derived trait secondary to the widespread genomic effects of steroids in systems where steroids coordinate morphological, physiological, and behavioral traits. [less ▲]

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See detailSteroids and the brain: 50 years of research, conceptual shifts and the ascent of non-classical and membrane-initiated actions
Balthazart, Jacques ULiege; Choleris, E.; Remage-Healey, L.

in Hormones and Behavior (2018), 99

This brief commentary reviews key steps in the history of steroid endocrinology that have resulted in important conceptual shifts. Our understanding of the “Fast Effects of Steroids” now reflect ... [more ▼]

This brief commentary reviews key steps in the history of steroid endocrinology that have resulted in important conceptual shifts. Our understanding of the “Fast Effects of Steroids” now reflect substantial progress, including the major concept that steroids act rapidly on a variety of physiological and behavioral responses, via mechanisms that are too fast to be fully accounted for by classical receptor-dependent regulation of gene transcription. Several so-called ‘non-classical’ mechanisms have been identified and include binding to membrane receptors and regulating non genomic signaling cascades. We survey the discovery of steroids, the initial characterization of their intracellular receptors, key progress in the understanding of the genomic effects of steroids and then the progressive discovery of the rapid non-classical and membrane-initiated actions of steroids. Foundational discoveries about brain steroid synthesis in neural processes and terminals has converged with emerging evidence for the rapid actions of steroids on brain and behavior. Had the rapid effects of steroids in the central nervous system been discovered first, these molecules would likely now be considered as a class of neurotransmitter. © 2018 Elsevier Inc. [less ▲]

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See detailTiming of perineuronal nets development in the zebra finch song control system correlates with developmental song learning
Cornez, Gilles ULiege; Jonckers, Elisabeth; ter Haar, Sita et al

in Proceedings of the Royal Society. Biological Sciences (2018)

The appearance of perineuronal nets (PNN) represents one of the mechanisms that contribute to the closing of sensitive periods for neural plasticity. This relationship has mostly been studied in the ... [more ▼]

The appearance of perineuronal nets (PNN) represents one of the mechanisms that contribute to the closing of sensitive periods for neural plasticity. This relationship has mostly been studied in the ocular dominance model in rodents. Previous studies also indicated that PNN might control neural plasticity in the song control system (SCS) of songbirds. To further elucidate this relationship, we quantified PNN expression and their localization around parvalbumin interneurons at key time-points during ontogeny in both male and female zebra finches and correlated these data with the well-described development of song in this species. We also extended these analyses to the auditory system. The development of PNN during ontogeny correlated with song crystallization although the timing of PNN appearance in the four main telencephalic song control nuclei slightly varied between nuclei in agreement with the established role these nuclei play during song learning. Our data also indicate that very few PNN develop in the secondary auditory forebrain areas even in adult birds, which may allow constant adaptation to a changing acoustic environment by allowing synaptic reorganization during adulthood. [less ▲]

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See detailBehavioral evidence for sex steroids hypersensitivity in castrated male canaries
Shevchouk, Olesya ULiege; Ghorbanpoor, Samar; Smith, Ed et al

in Hormones and Behavior (2018)

In seasonally breeding songbirds such as canaries, singing behavior is predominantly under the control of tes- tosterone and its metabolites. Short daylengths in the fall that break photorefractoriness ... [more ▼]

In seasonally breeding songbirds such as canaries, singing behavior is predominantly under the control of tes- tosterone and its metabolites. Short daylengths in the fall that break photorefractoriness are followed by in- creasing daylengths in spring that activate singing via both photoperiodic and hormonal mechanisms. However, we observed in a group of castrated male Fife fancy canaries maintained for a long duration under a short day photoperiod a large proportion of subjects that sang at high rates. This singing rate was not correlated with variation in the low circulating concentrations of testosterone. Treatment of these actively singing castrated male canaries with a combination of an aromatase inhibitor (ATD) and an androgen receptor blocker (flutamide) only marginally decreased this singing activity as compared to control untreated birds and did not affect various measures of song quality. The volumes of HVC and of the medial preoptic nucleus (POM) were also unaffected by these treatments but were relatively large and similar to volumes in testosterone-treated males. In contrast, peripheral androgen-sensitive structures such as the cloacal protuberance and syrinx mass were small, similar to what is observed in castrates. Together these data suggest that after a long-term steroid deprivation singing behavior can be activated by very low concentrations of testosterone. Singing normally depends on the acti- vation by testosterone and its metabolites of multiple downstream neurochemical systems such as catechola- mines, nonapeptides or opioids. These transmitter systems might become hypersensitive to steroid action after long term castration as they probably are at the end of winter during the annual cycle in seasonally breeding temperate zone species. [less ▲]

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See detailL’expérimentation animale reste indispensable (OPINION)
Amorim, Christiani; Andris, Fabienne; Arckens, Lut et al

Article for general public (2017)

Trop fréquemment, l’expérimentation animale est présentée comme une pratique archaïque. Elle a bien changé. Et 100 % des patients traités le sont grâce aux concepts et techniques développés grâce à elle.

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See detailPerinueronal nets development correlates with developmental and adult neuroplasticity related to song learning in the songbird brain
Cornez, Gilles ULiege; Jonckers, Elisabeth; Ter Haar, Sita et al

Poster (2017, November 13)

erineuronal nets (PNN) are aggregations of extracellular matrix components surrounding the soma of specific neurons, mainly GABAergic interneurons expressing the calcium binding protein parvalbumin (PV ... [more ▼]

erineuronal nets (PNN) are aggregations of extracellular matrix components surrounding the soma of specific neurons, mainly GABAergic interneurons expressing the calcium binding protein parvalbumin (PV+). In mammals, the development of PNN limits synaptogenesis around PV+ neurons and PNNs have been validated as a marker characterizing the end of critical periods for visual system development. In songbirds, song learning is limited to critical periods during ontogeny in closed-ended learners such as zebra finches and to specific phases of the annual cycle in open-ended learners such as canaries that are able to modify their song seasonally. Developmental and adult sensitive periods for song learning are associated with neuroplasticity in song control nuclei, including major morphological changes reflecting neurogenesis and synaptic reorganization The hormonal control of developmental and seasonal neuroplasticity is relatively well documented in songbirds but little is known about its possible regulation by PNN. Interspecific comparisons indicate however that more PNN are present in the song control nuclei of closed-ended compared to open-ended learners suggesting a relationship with song plasticity. To explore the expression of PNN throughout development, we used male and female zebra finch brains collected at different key ages in the song learning process (10, 20, 30, 40, 50, 60, 90, 120 days post-hatch, dph) and we quantified the expression of PNN and their colocalization around PV+ interneurons. The number of PNN and the % of PNN surrounding PV+ interneurons increased progressively during developmental song learning in 3 song control nuclei (HVC, RA and Area X). Females who never sing in this species had fewer PNN than males in HVC and RA, two song control nuclei involved in song production, and their number never increased with age so that they became different from males for all ages after 50 dph. Two separate experiments used adult male and female canaries treated with a subcutaneous Silastic implant filled with testosterone or left empty in control subjects to mimic what happens in the spring when the seasonal plasticity of the song ends and the song crystalizes. Testosterone significantly increased the number of PNN in these forebrain song control nuclei in both sexes. Together these data demonstrate that an increased expression of PNN in the songbird brain correlates with the end of sensitive periods for song plasticity and might thus limit further synaptic reorganization at the end of these periods of behavioral and neural plasticity. [less ▲]

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See detailRapid changes in preoptic estradiol concentration during male sexual behavior
de Bournonville, Marie-Pierre ULiege; de Bournonville, Catherine; Ball, Gregory et al

Poster (2017, November 11)

Estrogens such as estradiol (E2) exert pleiotropic effects on physiological and behavioral responses such as neuroprotection, aggression or reproduction. Estrogens derived from local brain synthesis ... [more ▼]

Estrogens such as estradiol (E2) exert pleiotropic effects on physiological and behavioral responses such as neuroprotection, aggression or reproduction. Estrogens derived from local brain synthesis (neuroestrogens) are critical for the regulation of different functions including the control of male sexual behavior. Classically, E2 acts through effects initiated in the nucleus to regulate male sexual function. Along with these long-term effects, E2 also acts rapidly (within minutes) via membrane-initiated events. 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. In Japanese quail, rapid modulations of brain aromatase activity (AA) have been reported after sexual interactions or exposure to an acute stress. These changes take place mainly in the medial preoptic nucleus (POM), a sexually differentiated structure that plays a key role in the control of male sexual behavior and where aromatase is densely expressed. Yet, it has recently been shown that, in the short term, AA does not always reflect local E2 concentration. This study was designed to determine by in vivo microdialysis whether local E2 concentrations fluctuate during sexual interactions and test whether these changes parallel the decrease in AA observed ex vivo after copulation. We first conducted a series of experiments to validate the microdialysis and E2 assay. When dialysis probes were placed in successive baths containing known increasing amounts of E2, proportional changes in E2 concentration were measured in the dialysate. Moreover, a rise in E2 concentration was detected after in vivo retrodialysis of testosterone only if the probe was located within the POM and, after a peripheral injection of E2, a sharp rise of E2 was detected regardless of the probe location. Together these results show that in vivo microdialysis is a valid method to assess endogenous fluctuations of brain E2 concentrations in behaving animals. Two independent experiments then identified a rise in E2 concentrations in POM during sexual interactions. This increase occurred within 10 min after the initiation of the sexual interaction and was specific to the POM as there was no increase in E2 concentrations in males that had their cannula outside of this area. Together these data confirm that rapid changes in AA measured ex vivo cannot be considered as a reliable proxy for E2 concentrations. The discrepancies could originate either from the different time resolution related to the two techniques or from differences in the microenvironment in which aromatase functions in vivo and during ex vivo assays. [less ▲]

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See detailAvant-projet de décret relatif au Code wallon du Bien-être des animaux Lecture commentée au 04 juillet 2017 des chap. 4, 8, 11
Drion, Pierre ULiege; Seutin, Vincent ULiege; Balthazart, Jacques ULiege et al

Report (2017)

La compétence « bien-être animal », auparavant fédérale, a été régionalisée en juillet 2014. Ce projet de code vise à remplacer les dispositions légales en vigueur (la Loi de 1984 telle que modifiée par ... [more ▼]

La compétence « bien-être animal », auparavant fédérale, a été régionalisée en juillet 2014. Ce projet de code vise à remplacer les dispositions légales en vigueur (la Loi de 1984 telle que modifiée par les décrets du Gouvernement wallon). Certains éléments sont repris tels quels de la Directive 2010/63. Cela est nécessaire car la Directive européenne en tant que telle n’a pas de force obligatoire en Belgique. Elle doit être transcrite par un instrument législatif (avant, la Loi de 1984, aujourd’hui, le projet de code). Certains aspects semblent flous, mais renvoient à des dispositions que le Gouvernement doit encore prendre (au travers d’arrêtés du Gouvernement wallon, comme le faisaient avant les nombreux arrêtés royaux et du gouvernement qui réglementent la matière). Les arrêtés d’exécution devront obligatoirement tenir compte de la directive européenne et s’inspirer de dispositions actuellement en vigueur. [less ▲]

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See detailChanges in preoptic estradiol concentrations during male sexual behavior
de Bournonville, Marie-Pierre ULiege; de Bournonville, Catherine; Ball, Gregory et al

in Frontiers in Neuroscience (2017, May 30)

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 ... [more ▼]

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. [less ▲]

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