References of "Balthazart, Jacques"
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See detailAge-dependent and age-independent effects of testosterone in male quail
Cornil, Charlotte ULg; Schmit, Mélanie; de Bournonville, Catherine ULg et al

in General and Comparative Endocrinology (2014), 208C

Various studies in rodents recently concluded that puberty should be considered as a second period of organization of brain and behavior and that action of sex steroids at that time is long lasting and ... [more ▼]

Various studies in rodents recently concluded that puberty should be considered as a second period of organization of brain and behavior and that action of sex steroids at that time is long lasting and possibly permanent. We tested this notion in male Japanese quail that had been castrated before 3 weeks post- hatch by analyzing whether a similar treatment with exogenous testosterone initiated at 3, 5 or 7 weeks post-hatch has a differential influence on the development of testosterone-dependent morphological, behavioral and neural characteristics that are known to be sexually differentiated. The growth of the androgen-dependent cloacal gland was significantly faster when testosterone treatment was initiated later in life indicating that the target tissue is not ready to fully respond to androgens at 3 weeks post- hatch. The three groups of birds nevertheless developed a gland of the same size typical of intact sexually mature birds. When adults, all birds expressed copulatory behavior with the same frequencies and laten- cies and they displayed the same level of aromatase activity and of vasotocinergic innervation in the pre- optic area as gonadally intact males despite the fact that they had been treated with testosterone for different durations starting at different ages. Surprisingly, the frequency of cloacal sphincter contractions, a measure of appetitive sexual behavior, was significantly higher when testosterone treatment had been initiated later. Together these data provide no clear evidence for an organizational action of testosterone during sexual maturation of male quail but additional experiments should investigate whether estrogens have such an action in females. [less ▲]

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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 detailIs it useful to view the brain as a secondary sexual characteristic?
Ball, Gregory F.; Balthazart, Jacques ULg; McCarthy, Margaret M.

in Neuroscience and biobehavioral reviews (2014), 46 Pt 4

Many sex differences in brain and behavior related to reproduction are thought to have evolved based on sexual selection involving direct competition for mates during male-male competition and female ... [more ▼]

Many sex differences in brain and behavior related to reproduction are thought to have evolved based on sexual selection involving direct competition for mates during male-male competition and female choice. Therefore, certain aspects of brain circuitry can be viewed as secondary sexual characteristics. The study of proximate causes reveals that sex differences in the brain of mammals and birds reflect organizational and activational effects of sex steroids as articulated by Young and collaborators. However, sex differences in brain and behavior have been identified in the cognitive domain with no obvious link to reproduction. Recent views of sexual selection advocate for a broader view of how intra-sexual selection might occur including such examples as competition within female populations for resources that facilitate access to mates rather than mating competition per se. Sex differences can also come about for other reasons than sexual selection and recent work on neuroendocrine mechanisms has identified a plethora of ways that the brain can develop in a sex specific manner. Identifying the brain as sexually selected requires careful hypothesis testing so that one can link a sex-biased aspect of a neural trait to a behavior that provides an advantage in a competitive mating situation. [less ▲]

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See detailReprint of: Policy decisions on endocrine disruptors should be based on science across disciplines: A response to Dietrich et al.
Gore, A. C.; Balthazart, Jacques ULg; Bikle, D. et al

in Hormones and behavior (2014)

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See detailEndogenous versus exogenous markers of adult neurogenesis in canaries and other birds: advantages and disadvantages.
Balthazart, Jacques ULg; Ball, Gregory F.

in The Journal of comparative neurology (2014), 522(18), 4100-20

Although the existence of newborn neurons had originally been suggested, but not broadly accepted, based on studies in adult rodent brains, the presence of an active neurogenesis process in adult ... [more ▼]

Although the existence of newborn neurons had originally been suggested, but not broadly accepted, based on studies in adult rodent brains, the presence of an active neurogenesis process in adult homoeothermic vertebrates was first firmly established in songbirds. Adult neurogenesis was initially studied with the tritiated thymidine technique, later replaced by the injection and detection of the marker of DNA replication 5-bromo-2'-deoxyuridine (BrdU). More recently, various endogenous markers were used to identify young neurons or cycling neuronal progenitors. We review here the respective advantages and pitfalls of these different approaches in birds, with specific reference to the microtubule-associated protein, doublecortin (DCX), that has been extensively used to identify young newly born neurons in adult brains. All these techniques of course have limitations. Exogenous markers label cells replicating their DNA only during a brief period and it is difficult to select injection doses that would exhaustively label all these cells without inducing DNA damage that will also result in some form of labeling during repair. On the other hand, specificity of endogenous markers is difficult to establish due to problems related to the specificity of antibodies (these problems can be, but are not always, addressed) and more importantly because it is difficult, if not impossible, to prove that a given marker exhaustively and specifically labels a given cell population. Despite these potential limitations, these endogenous markers and DCX staining in particular clearly represent a useful approach to the detailed study of neurogenesis especially when combined with other techniques such as BrdU. [less ▲]

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See detailDissociable effects of social context on song and doublecortin immunoreactivity in male canaries.
Alward, Beau A.; Mayes, Wade D.; Peng, Katherine et al

in The European journal of neuroscience (2014), 40(6), 2941-7

Variation in environmental factors such as day length and social context greatly affects reproductive behavior and the brain areas that regulate these behaviors. One such behavior is song in songbirds ... [more ▼]

Variation in environmental factors such as day length and social context greatly affects reproductive behavior and the brain areas that regulate these behaviors. One such behavior is song in songbirds, which males use to attract a mate during the breeding season. In these species the absence of a potential mate leads to an increase in the number of songs produced, while the presence of a mate greatly diminishes singing. Interestingly, although long days promote song behavior, producing song itself can promote the incorporation of new neurons in brain regions controlling song output. Social context can also affect such neuroplasticity in these song control nuclei. The goal of the present study was to investigate in canaries (Serinus canaria), a songbird species, how photoperiod and social context affect song and the incorporation of new neurons, as measured by the microtubule-associated protein doublecortin (DCX) in HVC, a key vocal production brain region of the song control system. We show that long days increased HVC size and singing activity. In addition, male canaries paired with a female for 2 weeks showed enhanced DCX-immunoreactivity in HVC relative to birds housed alone. Strikingly, however, paired males sang fewer songs that exhibited a reduction in acoustic features such as song complexity and energy, compared with birds housed alone, which sang prolifically. These results show that social presence plays a significant role in the regulation of neural and behavioral plasticity in songbirds and can exert these effects in opposition to what might be expected based on activity-induced neurogenesis. [less ▲]

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See detailFos expression in monoaminergic cell groups in response to sociosexual interactions in male and female Japanese quail.
Iyilikci, Onur; Baxter, Samantha; Balthazart, Jacques ULg et al

in Behavioral neuroscience (2014), 128(1), 48-60

Monoaminergic neurotransmitters regulate different components of sexual behaviors, but how the different monoaminergic cell groups selectively regulate these behaviors is not well understood. We examined ... [more ▼]

Monoaminergic neurotransmitters regulate different components of sexual behaviors, but how the different monoaminergic cell groups selectively regulate these behaviors is not well understood. We examined the potential contribution of these different cell groups in the control of different aspects of sexual behaviors in male and female quail. We used double-label immunohistochemistry, labeling the protein product of the immediate early gene, Fos, along with tyrosine hydroxylase (TH) or tryptophan hydroxylase (TPH), markers for catecholaminergic or indolaminergic cells, respectively. Rhythmic Cloacal Sphincter Movements (RCSM) were recorded as a measure of male appetitive sexual behavior. Consummatory sexual behaviors were evaluated based on the species-typical copulation sequence. Enhanced Fos expression in the medial preoptic nucleus and bed nucleus of the stria terminalis was observed in association with both physical and visual contact to the opposite sex for males, but not for females. Fos induction associated with physical contact was observed in the ventral tegmental area and anterior periaqueductal gray in both sexes. In males only, the number of Fos-immunoreactive (ir) cells increased in the visual contact condition in these 2 dopaminergic cell groups, however no significant effect was observed for double-labeled TH-Fos-ir cells. In addition, consummatory but not appetitive sexual behavior increased Fos expression in TPH-ir cells in the raphe pallidus of males. This increase following physical but not visual contact agrees with the notion that activation of the serotoninergic system is implicated in the development of sexual satiation but not activated by simply viewing a female, in contrast to the dopaminergic system. [less ▲]

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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 detailPolicy decisions on endocrine disruptors should be based on science across disciplines: A response to Dietrich, et al.
Gore, A. C.; Balthazart, Jacques ULg; Bikle, D. et al

in Frontiers in neuroendocrinology (2014), 35(1), 2-5

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See detailEndocrine disruptors: A relevant issue for neuroendocrinology also!
Balthazart, Jacques ULg; Levine, Jon E.

in Frontiers in neuroendocrinology (2014), 35(1), 1

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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 detailc-fos down-regulation inhibits testosterone-dependent male sexual behavior and the associated learning
Niessen, Neville-Andrew ULg; Balthazart, Jacques ULg; Ball, Gregory et al

in European Journal of Neuroscience (2013)

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See detailModulation of testosterone-dependent male sexual behavior and the associated neuroplasticity.
Charlier, Thierry; Seredynski, Aurore ULg; Niessen, Neville-Andrew ULg et al

in General and Comparative Endocrinology (2013)

Steroids modulate the transcription of a multitude of genes and ultimately influence numerous aspects of reproductive behaviors. Our research investigates how one single steroid, testosterone, is able to ... [more ▼]

Steroids modulate the transcription of a multitude of genes and ultimately influence numerous aspects of reproductive behaviors. Our research investigates how one single steroid, testosterone, is able to trigger this vast number of physiological and behavioral responses. Testosterone potency can be changed locally via aromatization into 17b-estradiol which then activates estrogen receptors of the alpha and beta subtypes. We demonstrated that the independent activation of either receptor activates different aspects of male sexual behavior in Japanese quail. In addition, several studies suggest that the specificity of testosterone action on target genes transcription is related to the recruitment of specific steroid receptor coactivators. We demonstrated that the specific down-regulation of the coactivators SRC-1 or SRC-2 in the medial preoptic nucleus by antisense techniques significantly inhibits steroid-dependent male-typical copulatory behavior and the underlying neuroplasticity. In conclusion, our results demonstrate that the interaction between several steroid metabolizing enzymes, steroid receptors and their coactivators plays a key role in the control of steroid-dependent male sexual behavior and the associated neuroplasticity in quail. [less ▲]

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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 detailPolicy decisions on endocrine disruptors should be based on science across disciplines: a response to Dietrich et al.
Gore, A. C.; Balthazart, Jacques ULg; Bikle, D. et al

in Andrology (2013), 1(6), 802-5

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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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