References of "Balthazart, Jacques"
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See detailDopamine modulates male sexual behavior in Japanese quail in part via actions on noradrenergic receptors
Cornil, Charlotte ULg; Dejace, C.; Ball, G. F. et al

in Behavioural Brain Research (2005), 163(1), 42-57

In rats, dopamine (DA) facilitates male sexual behavior through its combined action on D1- and D2-like receptors, in the medial preoptic area (MPOA) as well as other brain areas. In Japanese quail ... [more ▼]

In rats, dopamine (DA) facilitates male sexual behavior through its combined action on D1- and D2-like receptors, in the medial preoptic area (MPOA) as well as other brain areas. In Japanese quail, systemic injections of dopaminergic drugs suggested a similar pharmacology but central injections have never been performed. Recent electrophysiological experiments demonstrated that DA effects in the MPOA of quail are mediated mainly through the activation of alpha(2)-noradrenergic receptors. Previous studies of DA action on behavior used specific dopaminergic agonists/antagonists and therefore unintentionally avoided the potential cross-reaction with a-receptors. The present study was thus designed to investigate directly the effects of DA on male sexual behavior and to test whether the interaction of DA with heterologous receptors affects this behavior. Intracerebroventricular (i.c.v.) injection of DA or NE inhibited copulation in a dose-dependent manner. Systemic injections of yohimbine, an alpha(2)-noradrenergic antagonist, modulated copulation in a bimodal manner depending on the dose injected. Interestingly, a behaviorally ineffective dose of yohimbine markedly reduced the inhibitory effects of DA when injected 15 min before. Together, these results show for the first time that i.c.v. injections of DA itself inhibit male sexual behavior in quail and suggest that the interaction of DA with alpha(2)-receptors has behavioral significance. (C) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailThe effect of auditory distractors on song discrimination in male canaries (Serinus canaria)
Appeltants, D.; Gentner, T. Q.; Hulse, S. H. et al

in Behavioural Processes (2005), 69(3), 331-341

Male songbirds such as canaries produce complex learned vocalizations that are used in the context of mate attraction and territory defense. Successful mate attraction or territorial defense requires that ... [more ▼]

Male songbirds such as canaries produce complex learned vocalizations that are used in the context of mate attraction and territory defense. Successful mate attraction or territorial defense requires that a bird be able to recognize individuals based on their vocal performance and identify these songs in a noisy background. In order to learn more about how birds are able to solve this problem, we investigated, with a two-alternative choice procedure, the ability of adult male canaries to discriminate between conspecific song segments from two different birds and to maintain this discrimination when conspecific songs are superimposed with a variety of distractors. The results indicate that male canaries have the ability to discriminate, with a high level of accuracy song segments produced by two different conspecific birds. Song discrimination was partially maintained when the stimuli were masked by auditory distractors, but the accuracy of the discrimination progressively declined as a function of the number of masking distractors. The type of distractor used in the experiments (other conspecific songs or different types of artificial white noise) did not markedly affect the rate of deterioration of the song discrimination. These data indicate that adult male canaries have the perceptual abilities to discriminate and selectively attend to one ongoing sound that occurs simultaneously with one or more other sounds. The administration of a noradrenergic neurotoxin did not impair markedly the discrimination learning abilities although the number of subjects tested was too small to allow any firm conclusion. In these conditions, however, the noradrenergic lesion significantly increased the number failures to respond in the discrimination learning task suggesting a role, in canaries, of the noradrenergic system in some attentional processes underlying song learning and processing. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailTestosterone-induced singing is regulated by social status in male canaries (serinus canaria)
Carere, C.; Boseret, Géraldine ULg; Ball, G. F. et al

in Hormones & Behavior (2005, June), 48(1), 92

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See detailDistribution of Reelin and its cytoplasmic signaling protein, DAB-1 in the forebrain of male canaries
Boseret, Géraldine ULg; Ball, G. F.; Balthazart, Jacques ULg

in Hormones & Behavior (2005, June), 48(1), 90

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See detailDifferences in neural activation following expression of appetitive and consummatory male sexual behavior in the quail brain
Taziaux, Mélanie ULg; Cornil, Charlotte ULg; Dejace, C. et al

in Hormones & Behavior (2005, June), 48(1), 130

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See detailDaily changes in the expression of the steroid receptor coactivator SRC-1
Charlier, T. D.; Ball, G. F.; Balthazart, Jacques ULg

in Hormones & Behavior (2005, June), 48(1), 93

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See detailAlpha-fetoprotein (AFP) knock out mice demonstrate the protective role of AFP during brain sexual differentiation
Bakker, Julie ULg; de Mees, C.; Balthazart, Jacques ULg et al

in Hormones & Behavior (2005, June), 48(1), 87

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See detailSpatiotemporal properties of the BOLD response in the songbirds' auditory circuit during a variety of listening tasks
Van Meir, V.; Boumans, T.; De Groof, G. et al

in Neuroimage (2005), 25(4), 1242-1255

Auditory fMRI in humans has recently received increasing attention from cognitive neuroscientists as a tool to understand mental processing of learned acoustic sequences and analyzing speech recognition ... [more ▼]

Auditory fMRI in humans has recently received increasing attention from cognitive neuroscientists as a tool to understand mental processing of learned acoustic sequences and analyzing speech recognition and development of musical skills. The present study introduces this tool in a well-documented animal model for vocal learning, the songbird, and provides fundamental insight in the main technical issues associated with auditory fMRI in these songbirds. Stimulation protocols with various listening tasks lead to appropriate activation of successive relays in the songbirds' auditory pathway. The elicited BOLD response is also region and stimulus specific, and its temporal aspects provide accurate measures of the changes in brain physiology induced by the acoustic stimuli. Extensive repetition of an identical stimulus does not lead to habituation of the response in the primary or secondary telencephalic auditory regions of anesthetized subjects. The BOLD signal intensity changes during a stimulation and subsequent rest period have a very specific time course which shows a remarkable resemblance to auditory evoked BOLD responses commonly observed in human subjects. This observation indicates that auditory fMRI in the songbird may establish a link between auditory related neuro-imaging studies done in humans and the large body of neuro-ethological research on song learning and neuro-plasticity performed in songbirds. © 2005 Elsevier Inc. All rights reserved. [less ▲]

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See detailCoordinated and dissociated effects of testosterone on singing behavior and song control nuclei in canaries (Serinus canaria)
Sartor, Jennifer J.; Balthazart, Jacques ULg; Ball, Gregory F.

in Hormones & Behavior (2005), 47(4), 467-476

Temperate zone songbirds that breed seasonally exhibit pronounced differences in reproductive behaviors including song inside and outside the breeding season. Springlike long daylengths are associated ... [more ▼]

Temperate zone songbirds that breed seasonally exhibit pronounced differences in reproductive behaviors including song inside and outside the breeding season. Springlike long daylengths are associated with increases in plasma testosterone (T) concentrations, as well as with increases in singing and in the volume of several brain nuclei known to control this behavior. The mechanisms whereby T can induce changes in behavior and brain, and whether or not these effects are differentially regulated, have recently begun to be examined, as has the question of the relative contributions of T and its androgenic and estrogenic metabolites to the regulation of this seasonal behavioral and neural plasticity. In this experiment, we examined the effects of T, 5 alpha-dihydrotestosterone, or 17 beta-estradiol treatment on castrated male canaries housed on short days and compared neural and behavioral effects in these males to similarly-housed males given only blank implants. We observed that only T treatment was effective in eliciting significant increases in singing behavior after 11 days of hormone exposure. In addition, T alone was effective in increasing the volume of a key song production nucleus, HVC. However, at this time, none of the steroids had any effects on the volumes of two other song control nuclei, Area X of the medial striatum and the robust nucleus of the arcopallium (RA), that are efferent targets of HVC, known to be regulated by androgen in canaries and also to play a role in the control of adult song. T can thus enhance singing well before concomitant androgen-induced changes in the song control system are complete. (c) 2004 Elsevier Inc. All rights reserved. [less ▲]

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See detailAndrogen mediation of conditioned rhythmic cloacal sphincter movements in Japanese quail (Coturnix Japonica)
Holloway, Kevin S.; Balthazart, Jacques ULg; Cornil, Charlotte ULg

in Journal of Comparative Psychology (2005), 119(1), 49-57

Demonstrations of increased reproductive success due to sexual conditioning in Japanese quail (Coturnix japonica) have been reported, although the mechanisms that underlie these effects have remained ... [more ▼]

Demonstrations of increased reproductive success due to sexual conditioning in Japanese quail (Coturnix japonica) have been reported, although the mechanisms that underlie these effects have remained elusive. One possible mechanism is conditioned rhythmic cloacal sphincter movements (RCSM). Two experiments were conducted with male quail to determine whether associations between a conditioned stimulus (CS) and a hen would result in the ability of the CS to elicit RCSM, and to explore the androgen mediation of conditioned RCSM. The results suggest that a focal CS paired with visual access to a female will elicit RCSM via a representation of the hen activated by the CS. Further, the available evidence indicates that conditioned RCSM is androgen mediated and that this learning may transfer across breeding seasons. [less ▲]

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See detailEndocrine correlates of the breeding asynchrony between two corsican populations of blue tits (Parus caeruleus)
Caro, S. P.; Balthazart, Jacques ULg; Thomas, D. W. et al

in General and Comparative Endocrinology (2005), 140(1), 52-60

Analyses of the development of the reproductive system in seasonally breeding birds in the framework of long-term ecological studies are rare. Here, we present the first results of such a study in two ... [more ▼]

Analyses of the development of the reproductive system in seasonally breeding birds in the framework of long-term ecological studies are rare. Here, we present the first results of such a study in two Corsican populations of a European passerine bird, the blue tit (Parus caeruleus). The two study populations occupy different oak habitats and are separated by only 25 km. Despite their close proximity, they show a one-month difference in onset of egg laying, even after controlling for altitude. This micro-geographic difference in breeding date appears adaptive because both study populations raise chicks when food is most plentiful. In our study, males reached their maximum song activity during the egg-laying stage while maximal testosterone levels and testes sizes were reached 2-3 weeks before egg laying. The rate of development of the reproductive system in males was much faster in the earlier population, in spite of a similar onset of gonad development and song activity for the two study populations. No change in the volume of the song-control nuclei (HVC and RA) could be detected during the study period. Development of brain nuclei was completed 2-3 months before the beginning of intense sexual activity. (C) 2004 Elsevier Inc. All rights reserved. [less ▲]

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See detailRapid changes in production and behavioral action of estrogens
Balthazart, Jacques ULg; Baillien, Michelle; Charlier, Thierry ULg et al

in Trabajos del Instituto Cajal (2005), 80

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See detailEffects of calmodulin on aromatase activity in the preoptic area.
Balthazart, Jacques ULg; Baillien, M.; Charlier, Thierry ULg et al

in Journal of Neuroendocrinology (2005), 17(10), 664-71

Oestrogens derived from the neural aromatisation of testosterone play a key role in the activation of male sexual behaviour in many vertebrates. Besides their slow action on gene transcription mediated by ... [more ▼]

Oestrogens derived from the neural aromatisation of testosterone play a key role in the activation of male sexual behaviour in many vertebrates. Besides their slow action on gene transcription mediated by the binding to nuclear receptors, oestrogens have now been recognised to have more rapid membrane-based effects on brain function. Rapid changes in aromatase activity, and hence in local oestrogen concentrations, could thus rapidly modulate behavioural responses. We previously demonstrated that calcium-dependent kinases are able to down-regulate aromatase activity after incubations of 10-15 min in phosphorylating conditions. In the present study, in quail hypothalamic homogenates, we show that Ca2+ or calmodulin alone can very rapidly change aromatase activity. Preincubation with 1 mM EGTA or with a monoclonal antibody raised against calmodulin immediately increased aromatase activity. The presence of calmodulin on aromatase purified by immunoprecipitation and electrophoresis was previously identified by western blot and two consensus binding sites for Ca2+-calmodulin are identified here on the deduced amino acid sequence of the quail brain aromatase. The rapid control of brain aromatase activity thus appears to include two mechanisms: (i) an immediate regulatory process that involves the Ca2+-calmodulin binding site and (ii) a somewhat slower phosphorylation by several protein kinases (PKC, PKA but also possibly Ca2+-calmodulin kinases) of the aromatase molecule. [less ▲]

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See detailSexual behavior activates the expression of the immediate early genes c-fos and Zenk (egr-1) in catecholaminergic neurons of male Japanese quail.
Charlier, Thierry ULg; Ball, G. F.; Balthazart, Jacques ULg

in Neuroscience (2005), 131(1), 13-30

We analyzed the expression of the immediate early genes c-fos and Zenk (egr-1) in the brain of male quail that were gonadally intact (I) or castrated and treated (CX+T) or not (CX) with testosterone and ... [more ▼]

We analyzed the expression of the immediate early genes c-fos and Zenk (egr-1) in the brain of male quail that were gonadally intact (I) or castrated and treated (CX+T) or not (CX) with testosterone and had been exposed for 60 min either to a sexually mature female (F), or to an empty arena (EA) or were left in their home cage (HC). Alternate sections in the brains collected 90 min after the start of behavioral interactions were stained by immunocytochemistry for the proteins FOS or ZENK alone or in association with tyrosine hydroxylase (TH), a marker of catecholaminergic neurons. C-fos and Zenk expression was statistically increased in six brain areas of sexually active birds (I+F, CX+T+F) compared with controls (CX+F, CX+T+EA, CX+T+HC), i.e. the preoptic area, bed nucleus striae terminalis, arcopallium, nucleus intercollicularis, periaqueductal gray and the ventral tegmental area. Interestingly, c-fos and Zenk expression was high in the nucleus intercollicularis, a midbrain vocal control nucleus, of I+F and CX+T+F birds that displayed copulatory behavior but emitted few crows but not in the nucleus intercollicularis of CX+T+EA birds that crowed frequently. Increases in c-fos expression were observed in TH-immunoreactive cells in the periaqueductal gray and ventral tegmental area, but not in the substantia nigra, of I+F and CX+T+F birds indicating the activation of dopaminergic neurons during sexual behavior. Together, these data confirm the implication of the steroid-sensitive preoptic area and bed nucleus striae terminalis in the control of copulation and support the notion that dopamine is involved in its control. [less ▲]

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See detailInhibition of steroid receptor coactivator-1 blocks estrogen and androgen action on male sex behavior and associated brain plasticity.
Charlier, Thierry ULg; Ball, Gregory F; Balthazart, Jacques ULg

in Journal of Neuroscience (2005), 25(4), 906-13

Studies of eukaryotic gene expression demonstrate the importance of nuclear steroid receptor coactivators in mediating efficient gene transcription. However, little is known about the physiological role ... [more ▼]

Studies of eukaryotic gene expression demonstrate the importance of nuclear steroid receptor coactivators in mediating efficient gene transcription. However, little is known about the physiological role of these coactivators in vivo. In Japanese quail, the steroid receptor coactivator-1 (SRC-1) is broadly expressed in steroid-sensitive brain areas that control the expression of male copulatory behavior, and we investigated the role of this coactivator by antisense technology. Daily intracerebroventricular injections of locked nucleic acid (LNA) antisense (AS) oligonucleotides targeting SRC-1 significantly reduced the expression of androgen- and estrogen-dependent male-typical sexual behaviors compared with control animals that received the vehicle alone or scrambled oligonucleotides. Sexual behavior was restored and even enhanced within 48 h after interruption of LNA injections. Western blot analysis confirmed the decrease of SRC-1 expression in AS animals and suggested an overexpression 48 h after the end of injections. The effects of SRC-1 knock-down on behavior correlated with a reduction in volume of the preoptic medial nucleus (POM) when its borders were defined by Nissl staining or by aromatase immunohistochemistry. The amount of aromatase-immunoreactive material in POM was also reduced in the AS compared with the control group. Previous work on SRC-1 knock-out mice raised questions about the importance of this specific coactivator in the regulation of reproductive behavior and development of sexually dimorphic structures in the CNS. Together, the present findings indicate that SRC-1 modulates steroid-dependent gene transcription and behavior and highlight the rapid time course of steroid-induced brain plasticity in adult quail. [less ▲]

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See detailDaily changes in the expression of the steroid receptor coactivator SRC-1.
Charlier, Thierry ULg; Ball, Gregory F.; Balthazart, Jacques ULg

in Hormones & Behavior (2005), 48

Steroid receptor coactivators such as SRC-1 significantly modulate the expression of steroid-dependent physiological and behavioral characteristics in birds and mammals. Changes in coactivator protein ... [more ▼]

Steroid receptor coactivators such as SRC-1 significantly modulate the expression of steroid-dependent physiological and behavioral characteristics in birds and mammals. Changes in coactivator protein expression are therefore likely to affect receptor-mediated transcriptional activity. We previously reported a tissue-dependent regulation of SRC-1 mRNA and protein levels by sex, stress and testosterone in the quail brain. In addition, SRC-1 expression has been shown to vary in mammals during development or in adulthood as a function of seasonal variation in photoperiod. We describe here tissue-specific changes of SRC-1 expression over the course of the day in quail. SRC-1 protein quantified by Western blots in the hindbrain gradually increased in the morning, reached a peak around midday and declined significantly in the afternoon. In contrast, SRC-1 protein levels in the optic lobes progressively decreased in the morning to reach their lowest values around midday before rising in the afternoon. The coactivator concentration in the hippocampus exhibited a progressive increase throughout the day. No change in the SRC-1 protein was detected during the day in the preoptic area and in the cerebellum. The functional significance and the mechanisms of regulation underlying such changes remain to be understood. An important unresolved question is whether this diurnal variation in SRC-1 expression is circadian in nature and if so if SRC-1 is an active player linked to clock genes in the generation of circadian rhythms or if the observed changes in SRC-1 expression are a consequence of the rhythms generated by these genes. [less ▲]

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