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See detailLocalization and Controls of Aromatase in the Quail Spinal Cord
Evrard, H.; Baillien, M.; Foidart, Agnès ULg et al

in Journal of Comparative Neurology (The) (2000), 423(4), 552-64

In adult male and female Japanese quail, aromatase-immunoreactive cells were identified in the spinal dorsal horns from the upper cervical segments to the lower caudal area. These immunoreactive cells are ... [more ▼]

In adult male and female Japanese quail, aromatase-immunoreactive cells were identified in the spinal dorsal horns from the upper cervical segments to the lower caudal area. These immunoreactive cells are located mostly in laminae I-III, with additional sparse cells being present in the medial part of lamina V and, at the cervical level exclusively, in lamina X around the central canal. Radioenzyme assays based on the measurement of tritiated water release confirmed the presence of substantial levels of aromatase activity throughout the rostrocaudal extent of the spinal cord. Contrary to what is observed in the brain, this enzyme activity and the number of aromatase-immunoreactive cells in five representative segments of the spinal cord are not different in sexually mature males or females and are not influenced in males by castration with or without testosterone treatment. The aromatase activity and the numbers of aromatase-immunoreactive cells per section are higher at the brachial and thoracic levels than in the cervical and lumbar segments. These experiments demonstrate for the first time the presence of local estrogen production in the spinal cord of a higher vertebrate. This production was localized in the sensory fields of the dorsal horn, where estrogen receptors have been identified previously in several avian and mammalian species, suggesting an implication of aromatase in the modulation of sensory (particularly nociceptive) processes. [less ▲]

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See detailFos Induction in the Japanese Quail Brain after Expression of Appetitive and Consummatory Aspects of Male Sexual Behavior
Tlemcani, O.; Ball, G. F.; D'Hondt, E. et al

in Brain Research Bulletin (2000), 52(4), 249-62

We investigated the expression of Fos, the protein product of the immediate early gene c-fos in the brain of male Japanese quail after they engaged in either appetitive or consummatory sexual behavior (i ... [more ▼]

We investigated the expression of Fos, the protein product of the immediate early gene c-fos in the brain of male Japanese quail after they engaged in either appetitive or consummatory sexual behavior (i. e., copulation). For 1 h, castrated males treated with testosterone were either allowed to copulate with a female or to exhibit a learned social proximity response indicative of appetitive sexual behavior. Control birds were either left in their home cage or placed in the experimental chamber but did not exhibit the appetitive sexual behavior because they had never learned it. Fos expression was studied with an immunocytochemical procedure in two sets of adjacent sections through the entire forebrain. These sections were immunolabelled with 2 different antibodies raised against a synthetic fragment corresponding to the 21 carboxy-terminal residues of the chicken Fos sequence. Contrary to the results of a previous study in which gonadally intact birds were used, Fos induction was observed neither in the medial preoptic nucleus nor in the nucleus intercollicularis in birds that had interacted for 1 h with a female. This may be related to a lower frequency of copulation in the testosterone-implanted birds than in intact birds, or to differences in the time the brains were collected after the birds engaged in sexual behavior between the two studies (60 min in this study, 120 min in the previous study). The performance of copulation and/or appetitive sexual behavior increased the number of Fos-immunoreactive cells in the ventral hyperstriatum, medial archistriatum, and nucleus striae terminalis. These increases were observed using both antibodies, although each antibody produced minor differences in the number of Fos-immunoreactive cells observed. Using one of the antibodies, but not the other, increases in Fos immunoreactivity were also observed in the nucleus accumbens and hyperstriatum after either copulation or appetitive sexual behavior. These differences illustrate how minor technical variations in the Fos immunocytochemical procedure influence the results obtained. These differences also show that Fos induction in a number of brain regions is observed after performance of consummatory (copulation) as well as appetitive (looking at the female) sexual behavior. This induction is, therefore, not related solely to the control of copulatory acts but, presumably, also to the processing in a variety of telencephalic association areas of stimuli originating from the female. The observation that increased Fos immunoreactivity is present in birds that had learned the response indicative of appetitive sexual behavior, and not in those that had not learned the behavior, further indicates that it is not simply the sight of the female that results in this Fos induction, but the analysis of the relevant stimuli in a sexually explicit context. Conditioned neural activity resulting from a learned association between the stimulus female and the performance of copulatory behavior may also explain some aspects of the brain activation observed in birds viewing, but not allowed to interact with, the female. [less ▲]

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See detailIdentification of the Origin of Catecholaminergic Inputs to Hvc in Canaries by Retrograde Tract Tracing Combined with Tyrosine Hydroxylase Immunocytochemistry
Appeltants, D.; Absil, Philippe ULg; Balthazart, Jacques ULg et al

in Journal of Chemical Neuroanatomy (2000), 18(3), 117-33

The telencephalic nucleus HVc (sometimes referred to as the high vocal center) plays a key role in the production and perception of birdsong. Although many afferent and efferent connections to this ... [more ▼]

The telencephalic nucleus HVc (sometimes referred to as the high vocal center) plays a key role in the production and perception of birdsong. Although many afferent and efferent connections to this nucleus have been described, it has been clear for many years, based on chemical neuroanatomical criteria, that there are projections to this nucleus that remain undescribed. A variety of methods including high performance liquid chromatography, immunohistochemistry and receptor autoradiography have identified high levels of catecholamine transmitters, the presence of enzymes involved in the synthesis of catecholamines such as tyrosine hydroxylase and a variety of catecholamine receptor sub-types in the HVc of several songbird species. However, no definitive projections to HVc have been described from cells groups known to synthesize catecholamines. These projections were analyzed in the present study by retrograde tract tracing combined with immunocytochemistry for tyrosine hydroxylase. The origin of the catecholaminergic inputs to HVc were determined based exclusively on birds in which injections of the retrograde tracer (latex fluospheres) were confined within the cytoarchitectonic boundaries of the nucleus. Retrogradely transported latex fluospheres were found mainly in cells of two dopaminergic nuclei, the mesencephalic central gray (A11) and, to a lesser extend, the area ventralis of Tsai (A10; homologous to the ventral tegmental area of mammals). A few retrogradely-labelled cells were also found in the noradrenergic nucleus subceruleus (A6). Most of these retrogradely-labelled cells were also tyrosine hydroxylase-positive. Other catecholaminergic nuclei were devoid of retrograde label. These data converge with others studies to indicate that HVc receives discrete dopaminergic and noradrenergic inputs. These inputs may influence the steroid regulation of HVc, attentional processes related to song and modulate sensory inputs to the song system. [less ▲]

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See detailImmunocytochemical localization of ionotropic glutamate receptors subunits in the adult quail forebrain
Cornil, Charlotte ULg; Foidart, Agnès ULg; Minet, Arlette ULg et al

in Journal of Comparative Neurology (The) (2000), 428

The excitatory amino acid glutamate is implicated in the central control of many neuroendocrine and behavioral processes. The ionotropic glutamate receptors are usually divided into the N-methyl-D ... [more ▼]

The excitatory amino acid glutamate is implicated in the central control of many neuroendocrine and behavioral processes. The ionotropic glutamate receptors are usually divided into the N-methyl-D-aspartate (NMDA) and non-NMDA (kainate and AMPA) subtypes. Subunits of these receptors have been cloned in a few mammalian species. Information available in birds is more limited. In quail, we recently demonstrated that glutamate agonists (kainate, AMPA, and NMDA) rapidly (within minutes) and reversibly decrease in vitro aromatase activity like several other manipulations affecting intracellular HCa21 pools. Aromatase catalyzes the conversion of androgens into estrogens which is a limiting step in the control by testosterone of many behavioral and physiologic processes. Therefore, glutamate could control estrogen production in the brain, but the anatomic substrate supporting this effect is poorly understood. In quail, aromatase is mainly localized in the preoptic-hypothalamic-limbic system. We visualized here the distribution of the major ionotropic glutamate receptors in quail by immunocytochemical methods by using commercial primary antibodies raised against rat glutamate receptor 1 and receptors 2-3 (GluR1, GluR2/3: AMPA subtype, Chemicon, CA), rat glutamate receptors 5-7 (GluR5-7: kainate subtype, Pharmingen, CA), and rat NMDA receptors (NMDAR1, Pharmingen, CA). Dense and specific signals were obtained with all antibodies. The four types of receptors are broadly distributed in the brain, and, in particular, immunoreactive cells are identified within the major aromatase cell groups located in the medial preoptic nucleus, ventromedial hypothalamus, nucleus striae terminalis, and nucleus taeniae. Dense specific populations of glutamate receptor immunoreactive cells are also present with a receptor subtype-specific distribution in broad areas of the telencephalon. The distribution of glutamate receptors, therefore, is consistent with the idea that these receptors could be located at the surface of aromatase-containing cells and mediate the rapid regulation of aromatase activity in a direct manner. [less ▲]

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See detailEstrogen Receptor-Beta in Quail: Cloning, Tissue Expression and Neuroanatomical Distribution
Foidart, Agnès ULg; Lakaye, Bernard ULg; Grisar, Thierry ULg et al

in Journal of Neurobiology (1999), 40(3), 327-42

A partial estrogen receptor-beta (ERbeta) cDNA had been previously cloned and sequenced in Japanese quail. The 3'- and 5'-rapid amplification of cDNA ends techniques were used here to identify a cDNA ... [more ▼]

A partial estrogen receptor-beta (ERbeta) cDNA had been previously cloned and sequenced in Japanese quail. The 3'- and 5'-rapid amplification of cDNA ends techniques were used here to identify a cDNA sequence of the quail ERbeta that contains a complete open reading frame. For the first time in an avian species, this cDNA sequence and the corresponding amino acid sequence are described. They are compared with the known ERbeta sequences previously described in mammals and with the ERalpha sequences identified in a selection of mammalian and avian species. The analysis by Northern blotting of the ERbeta mRNA expression in the brain and kidneys revealed the presence of several transcripts. The presence of ERbeta identified by reverse transcriptase-polymerase chain reaction demonstrated a widespread distribution quite different from the distribution of ERalpha. The complete neuroanatomical distribution of ERbeta mRNA as determined by in situ hybridization with 35S- and 33P-labeled oligoprobes is also presented. Transcripts are present in many nuclei implicated in the control of reproduction such as the medial preoptic nucleus, the nucleus striae terminalis, and the nucleus taeniae, the avian homologue of the amygdala. These data demonstrate the presence of ERbeta in a nonmammalian species and indicate that the (neuro)-anatomical distribution of this receptor type has been conserved in these two classes of vertebrates. The role of this receptor in the control of reproduction and other physiological processes should now be investigated. [less ▲]

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See detailMating-Induced Fos and Aromatase Are Not Co-Localized in the Preoptic Area
Foidart, Agnès ULg; Meddle, S. L.; Balthazart, Jacques ULg

in Neuroreport (1999), 10(5), 907-12

Male sexual behavior is determined by the interaction of endocrine and environmental stimuli originating from the female, yet it is unknown how and where these stimuli are integrated within the brain ... [more ▼]

Male sexual behavior is determined by the interaction of endocrine and environmental stimuli originating from the female, yet it is unknown how and where these stimuli are integrated within the brain. Activation of copulatory behavior by testosterone is limited by its central aromatization into an estrogen in the preoptic area. We investigated whether mating-induced neuronal activation as identified by the expression of the immediate early gene Fos occurs in aromatase-immunoreactive (ARO-ir) cells of the male quail preoptic area. Fos-immunoreactive (ir) cells were observed within and lateral to these ARO-ir cells groups but few ARO-ir cells contained Fos-ir indicating that mating-related stimuli do not directly affect estrogen-synthesizing cells. [less ▲]

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See detailRegional Distribution and Control of Tyrosine Hydroxylase Activity in the Quail Brain
Baillien, M.; Foidart, Agnès ULg; Balthazart, Jacques ULg

in Brain Research Bulletin (1999), 48(1), 3-17

Tyrosine hydroxylase (TH) activity, the rate-limiting step in the synthesis of catecholamines, was quantified in the preoptic area-hypothalamus of adult male Japanese quail by a new assay measuring the ... [more ▼]

Tyrosine hydroxylase (TH) activity, the rate-limiting step in the synthesis of catecholamines, was quantified in the preoptic area-hypothalamus of adult male Japanese quail by a new assay measuring the tritiated water production from 3,5-[3H]-L-tyrosine. Maximal levels of activity were observed at a 20-25 microM concentration of substrate, with more than 50% inhibition of the activity being recorded at a 100 microM concentration. TH activity was linear as a function of the incubation time during the first 20 min and maximal at a pH of 6.0. TH was heterogeneously distributed in the quail brain with highest levels of activity being found (in decreasing order) in the mesencephalon, diencephalon, and telencephalon. Given the large size of the telencephalon, this is the brain area that contains, as a whole, the highest level of enzyme activity. TH inhibitors that have been well-characterized in mammals, such as 3-iodo-L-tyrosine and L-alpha-methyl-p-tyrosine (AMPT) completely inhibited the enzyme activity at a 100 microM concentration. In mammals, the accumulation of catecholamines exerts a negative feedback control on TH activity. Similar controls were observed in the quail brain. Two inhibitors of the DOPA decarboxylase that should lead to accumulation of DOPA depressed TH activity by 60% or more, and the inhibitor of the dopamine beta-hydroxylase, fusaric acid that should cause an accumulation of dopamine, suppressed 90% of the TH activity. The addition of exogenous DOPA, dopamine, or norepinephrine to the brain homogenates also strongly inhibited TH activity, independently confirming the feedback effects of the enzyme products on the enzyme activity. These data demonstrate that TH activity in the quail brain is heterogeneously distributed and acutely regulated, as it is in mammals, by the accumulation of its products and of the derived catecholamines. [less ▲]

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See detailSteroid sensitive sites in the avian brain: does the distribution of the estrogen receptor alpha and beta types provide insight into their function?
Ball, G. F.; Bernard, D. J.; Foidart, Agnès ULg et al

in Brain, Behavior & Evolution (1999), 54

Studies in avian species have often been useful in elucidating basic concepts relevant to the regulation of reproductive behaviors by sex steroid hormones. Once a link between a steroid hormone and a ... [more ▼]

Studies in avian species have often been useful in elucidating basic concepts relevant to the regulation of reproductive behaviors by sex steroid hormones. Once a link between a steroid hormone and a behavioral response has been established, one can use the localization of steroid hormone receptors in the brain to facilitate the identification of neural circuits that control behavior. The recent identification of a second type of estrogen receptor called estrogen receptor beta or ERbeta has raised new issues about the action of steroid hormones in the brain. A hypothesis has been proposed by Kuiper et al. [1998] based on studies in mammalian species suggesting that ERalpha (the name given to the ER that was previously described) is important for reproduction while ERbeta is more important for non-reproductive functions. In this paper we apply this hypothesis more generally by examining possible functions of ERbeta in avian species. We have initiated studies of the ERbeta in the brain of two avian species, the Japanese quail (Coturnix japonica) and the European starling (Sturnus vulgaris). ERbeta was cloned in both species and the mRNA for this receptor type was localized in the brain employing in situ hybridization histochemistry methods. In both species ERbeta was found to be diffusely present in telencephalic areas consistent with a role for this receptor subtype in cognitive functions. However, ERbeta mRNA was also found in many brain areas that are traditionally thought to be important in the regulation of reproductive functions such as the preoptic region, the bed nucleus of the stria terminalis and the nucleus taeniae. Of the two receptor types, only mRNA for ERalpha was observed in the telencephalic vocal control nucleus HVc of male starlings. Steroid receptors in this nucleus are thought to be an example of an evolutionary specialization that has evolved to coordinate the production of courtship vocalizations with other aspects of reproduction. The lack of ERbeta mRNA expression in HVc is consistent with the hypothesis that ERalpha is preferentially involved in reproductive behaviors while ERbeta is involved in the steroid regulation of other neural functions. However, the widespread occurrence of ERbeta in other nuclei involved in reproductive function suggests that one must be cautious about the general applicability of the above hypothesis until more is known about ERbeta function in these other nuclei [less ▲]

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See detailEffects of Brain Testosterone Implants on Appetitive and Consummatory Components of Male Sexual Behavior in Japanese Quail
Riters, L. V.; Absil, Philippe ULg; Balthazart, Jacques ULg

in Brain Research Bulletin (1998), 47(1), 69-79

Aromatization of testosterone (T) into an estrogen is necessary for the activation of consummatory and appetitive sexual behavior in male Japanese quail. T action within the medial preoptic nucleus (POM ... [more ▼]

Aromatization of testosterone (T) into an estrogen is necessary for the activation of consummatory and appetitive sexual behavior in male Japanese quail. T action within the medial preoptic nucleus (POM) is necessary and sufficient to activate consummatory behavior, and some evidence suggests that POM might be involved in the control of appetitive behavior, but other brain regions, such as the bed nucleus of the stria terminalis (BST), an area that contains a dense population of aromatase-immunoreactive neurons, are also likely to be involved. This study was performed to assess the effects of stereotaxic T implants targeting either the POM or the BST on the activation of both components of sexual behavior in castrated male quail. Appetitive sexual behavior was measured by an acquired social proximity response in which a male will approach a window providing visual access to a female after the window has been repeatedly paired with physical access to a female and the possibility to freely interact with her. Rhythmic cloacal sphincter movements that are produced by the male when given visual access to a female were used as another measure of appetitive sexual behavior that does not appear to depend on sexual learning. The experiments confirmed that copulation is necessary for males to develop the social proximity response that is used to measure the appetitive sexual behavior. T implants in the POM activated both components of sexual behavior, suggesting that these components cannot be completely dissociated. In contrast, T implants located within the BST did not affect either component, but because implants in the BST did not activate copulatory behavior, these results do not preclude a role for BST in the expression of a previously acquired appetitive sexual behavior. [less ▲]

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See detailPartial Cloning and Distribution of Estrogen Receptor Beta in the Avian Brain
Lakaye, Bernard ULg; Foidart, Agnès ULg; Grisar, Thierry ULg et al

in Neuroreport (1998), 9(12), 2743-8

A partial estrogen receptor beta (ER-beta) cDNA was isolated from testicular quail RNA by RT-PCR with degenerate primers specific to the rat ER-beta sequence. A high expression of ER-beta was demonstrated ... [more ▼]

A partial estrogen receptor beta (ER-beta) cDNA was isolated from testicular quail RNA by RT-PCR with degenerate primers specific to the rat ER-beta sequence. A high expression of ER-beta was demonstrated by RT-PCR in the telencephalon, diencephalon, pituitary, testis and kidneys of male quail but little or no expression was detected in the cerebellum, pectoral muscle and adrenal gland. In situ hybridization with a 35S-labelled oligoprobe in sections through the preoptic area-rostral hypothalamus identified high expression in the medial preoptic nucleus, bed nucleus striae terminalis and nucleus taeniae. These data demonstrate the presence of an ER-beta in brain areas implicated in the control of reproduction in a non-mammalian species. [less ▲]

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See detailAppetitive and consummatory male sexual behavior in Japanese quail are differentially regulated by subregions of the preoptic medial nucleus
Balthazart, Jacques ULg; Absil, Philippe ULg; Gérard, Marie-Paule ULg et al

in Journal of Neuroscience (1998), 18(16), 6512-6527

Central testosterone aromatization is required for the activation of both appetitive (ASB) and consummatory (CSB) male sexual behavior in Japanese quail. There are two major clusters of aromatase ... [more ▼]

Central testosterone aromatization is required for the activation of both appetitive (ASB) and consummatory (CSB) male sexual behavior in Japanese quail. There are two major clusters of aromatase immunoreactive (ARO-ir) cells in the rostral forebrain; these outline the nucleus preopticus medialis (POM) and the nucleus striae terminalis (BST). We investigated the role of these nuclei in the regulation of ASB and CSB. Appetitive male sexual behavior was measured with the use of a learned social proximity procedure that quantified the time spent by a male in front of a window with a view of a female who was subsequently released into the cage, providing an opportunity for CSB. Males first acquired the response and then received bilateral electrolytic lesions aimed at the POM or BST, followed by retesting for ASB and CSB. Brain sections were stained for ARO-ir, and lesions to the two ARO-ir cell groups were quantitatively characterized. Lesions damaging the POM completely abolished CSB and also significantly decreased ASB. Lesions of the rostral BST had no effect on ASB, but moderately decreased CSB. Detailed anatomical analysis revealed that lesions of a subdivision of the POM just rostral to the anterior commissure specifically impair CSB, whereas lesions that are more rostral to this subdivision induce a severe deficit in ASB. These data indicate that different subregions of the POM regulate ASB and CSB in a somewhat independent manner, whereas the BST is only important in the regulation of CSB. [less ▲]

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See detailDistribution of Androgen Receptor-Immunoreactive Cells in the Quail Forebrain and Their Relationship with Aromatase Immunoreactivity
Balthazart, Jacques ULg; Foidart, Agnès ULg; Houbart, M. et al

in Journal of Neurobiology (1998), 35(3), 323-40

The distribution of androgen receptor-like immunoreactive (AR-ir) cells in the quail brain was analyzed by immunocytochemistry with the use of the affinity-purified antibody PG-21-19A raised against a ... [more ▼]

The distribution of androgen receptor-like immunoreactive (AR-ir) cells in the quail brain was analyzed by immunocytochemistry with the use of the affinity-purified antibody PG-21-19A raised against a synthetic peptide representing the first 21 N-terminal amino acids of the rat and human AR. This antibody is known to bind to the receptor in the absence as well as in the presence of endogenous ligands, and it was therefore expected that a more complete and accurate characterization of AR-ir cells would be obtained in comparison with previous studies using an antibody that preferentially recognizes the occupied receptor. Selected sections were double labeled for aromatase (ARO) by a technique that uses alkaline phosphatase as the reporter enzyme and Fast blue as the chromogen. AR-ir material was detected in the nucleus of cells located in a variety of brain areas in the preoptic region and the hypothalamus including the medial preoptic (POM), the supraoptic, the paraventricular (PVN), and the ventromedial (VMN) nuclei, but also in the tuberculum olfactorium, the nucleus accumbens/ventral striatum, the nucleus taeniae, the tuberal hypothalamus, the substantia grisea centralis (GCt), and the locus ceruleus. Cells exhibiting a dense AR-ir label were also detected in the nucleus intercollicularis. Preincubation of the primary antibody with an excess of the synthetic peptide used for immunization completely eliminated this nuclear staining. A significant number of AR-ir cells in the POM, VMN, PVN, and tuberal hypothalamus also contained ARO-ir material in their cytoplasm. These data confirm and extend previous studies localizing AR in the avian brain, and raise questions about the possible regulation by androgens of the metabolizing enzyme aromatase. [less ▲]

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See detailNew Insights into the Regulation and Function of Brain Estrogen Synthase (Aromatase)
Balthazart, Jacques ULg; Ball, G. F.

in Trends in Neurosciences (1998), 21(6), 243-9

In the brain, conversion of androgens into estrogens by the enzyme aromatase (estrogen synthase) is a key mechanism by which testosterone regulates many physiological and behavioral processes, including ... [more ▼]

In the brain, conversion of androgens into estrogens by the enzyme aromatase (estrogen synthase) is a key mechanism by which testosterone regulates many physiological and behavioral processes, including the activation of male sexual behavior, brain sexual differentiation and negative feedback effects of steroid hormones on gonadotropin secretion. Studies on the distribution and regulation of brain aromatase have led to a new perspective on the control and function of this enzyme. A growing body of evidence indicates that the estrogen regulation of aromatase is, at least in part, trans-synaptic. Afferent catecholamine pathways appear to regulate aromatase activity in some brain areas and thereby provide a way for environmental cues to modulate this enzyme.The localization of aromatase in pre-synaptic boutons suggests possible roles for estrogens at the synapse. [less ▲]

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See detailNeuroanatomical Distribution and Variations across the Reproductive Cycle of Aromatase Activity and Aromatase-Immunoreactive Cells in the Pied Flycatcher (Ficedula Hypoleuca)
Foidart, Agnès ULg; Silverin, B.; Baillien, M. et al

in Hormones & Behavior (1998), 33(3), 180-96

The anatomical distribution and seasonal variations in aromatase activity and in the number of aromatase-immunoreactive cells were studied in the brain of free-living male pied flycatchers (Ficedula ... [more ▼]

The anatomical distribution and seasonal variations in aromatase activity and in the number of aromatase-immunoreactive cells were studied in the brain of free-living male pied flycatchers (Ficedula hypoleuca). A high aromatase activity was detected in the telencephalon and diencephalon but low to negligible levels were present in the optic lobes, cerebellum, and brain stem. In the diencephalon, most aromatase-immunoreactive cells were confined to three nuclei implicated in the control of reproductive behaviors: the medial preoptic nucleus, the nucleus of the stria terminalis, and the ventromedial nucleus of the hypothalamus. In the telencephalon, the immunopositive cells were clustered in the medial part of the neostriatum and in the hippocampus as previously described in another songbird species, the zebra finch. No immunoreactive cells could be observed in the song control nuclei. A marked drop in aromatase activity was detected in the anterior and posterior diencephalon in the early summer when the behavior of the birds had switched from defending a territory to helping the female in feeding the nestlings. This enzymatic change is presumably controlled by the drop in plasma testosterone levels observed at that stage of the reproductive cycle. No change in enzyme activity, however, was seen at that time in other brain areas. The number of aromatase-immunoreactive cells also decreased at that time in the caudal part of the medial preoptic nucleus but not in the ventromedial nucleus of the hypothalamus (an increase was even observed), suggesting that differential mechanisms control the enzyme concentration and enzyme activity in the hypothalamus. Taken together, these data suggest that changes in diencephalic aromatase activity contribute to the control of seasonal variations in reproductive behavior of male pied flycatchers but the role of the telencephalic aromatase in the control of behavior remains unclear at present. [less ▲]

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See detailAnatomical Relationships between Aromatase and Tyrosine Hydroxylase in the Quail Brain: Double-Label Immunocytochemical Studies
Balthazart, Jacques ULg; Foidart, Agnès ULg; Baillien, M. et al

in Journal of Comparative Neurology (The) (1998), 391(2), 214-26

The activation of male sexual behavior in Japanese quail (Coturnix japonica) requires the transformation of testosterone to 17beta-estradiol by the enzyme aromatase (estrogen synthetase). There are ... [more ▼]

The activation of male sexual behavior in Japanese quail (Coturnix japonica) requires the transformation of testosterone to 17beta-estradiol by the enzyme aromatase (estrogen synthetase). There are prominent sex differences in aromatase activity that may be regulated in part by sex differences in catecholaminergic activity. In this study, we investigate, with double-label immunocytochemistry methods, the anatomical relationship between the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH) and aromatase (ARO) in the quail brain. The immunoreactivity observed for each antigen generally matched the previously described distribution. One exception is the observation that cells weakly labeled for aromatase were found widely distributed throughout the telencephalon. The presence of telencephalic aromatase was confirmed independently by radioenzymatic assays. There was an extensive overlap between the distribution of the two antigens in many brain areas. In all densely labeled aromatase-immunoreactive (ARO-ir) cell groups, including the preoptic medial nucleus, nucleus of the stria terminalis, mediobasal hypothalamus, and paleostriatum ventrale, ARO-ir cells were found in close association with TH-ir fibers. These TH-ir fibers often converged on an ARO-ir cell, and one or more TH-ir punctate structure(s) were found in close contact with nearly every densely labeled ARO-ir cell. In the telencephalon (mostly the neostriatum), all TH-ir fibers were found to be part of fiber groups that surrounded weakly immunoreactive aromatase cells. The few cells exhibiting an intracellular colocalization were detected in the anteroventral periventricular nucleus. These results are consistent with the hypothesis that catecholaminergic inputs regulate brain aromatase. [less ▲]

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See detailSystemic and Intracerebroventricular Injections of Vasotocin Inhibit Appetitive and Consummatory Components of Male Sexual Behavior in Japanese Quail
Castagna, C.; Absil, Philippe ULg; Foidart, Agnès ULg et al

in Behavioral Neuroscience (1998), 112(1), 233-50

The authors investigated the behavioral actions of vasotocin (VT) in castrated testosterone-treated male Japanese quail. The appetitive and consummatory components of sexual behavior as well as the ... [more ▼]

The authors investigated the behavioral actions of vasotocin (VT) in castrated testosterone-treated male Japanese quail. The appetitive and consummatory components of sexual behavior as well as the occurrence frequency of crows were inhibited, in a dose-dependent manner, by injections of VT. The authors observed opposite effects after injection of the V1 receptor antagonist, dPTyr(Me)AVP. Lower doses of VT were more active after central than after systemic injection, and effects of systemic injections of VT were blocked by a central injection of dPTyr(Me)AVP. The behavioral inhibition was associated with a modified diuresis after systemic but not central injection. These results provide direct evidence that VT affects male sexual behavior in quail by a direct action on the brain independent of its peripheral action on diuresis. [less ▲]

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See detailEffects of Dopamine Agonists on Appetitive and Consummatory Male Sexual Behavior in Japanese Quail
Castagna, C.; Ball, G. F.; Balthazart, Jacques ULg

in Pharmacology, Biochemistry & Behavior (1997), 58(2), 403-14

The effects of pharmacological manipulations of dopaminergic transmission on appetitive and consummatory aspects of male sexual behavior were investigated in castrated male Japanese quail treated with ... [more ▼]

The effects of pharmacological manipulations of dopaminergic transmission on appetitive and consummatory aspects of male sexual behavior were investigated in castrated male Japanese quail treated with exogenous testosterone. Appetitive male sexual behavior was assessed by measuring a learned social proximity response and consummatory behavior was assessed by measuring copulatory behavior per se. The nonselective dopamine receptor agonist, apomorphine, inhibited in a dose-dependent manner both components of male sexual behavior. Two indirect dopamine agonists were also tested. Nomifensine, a dopamine re-uptake inhibitor, decreased appetitive sexual behavior but increased the frequency of mount attempts, a measure of consummatory sexual behavior. Amfonelic acid, a compound that enhances dopaminergic tone by a complex mechanism, increased aspects of both appetitive and consummatory behaviors. These data suggest that, in quail, as in rodents, increases in dopaminergic tone facilitate both appetitive and consummatory aspects of male sexual behavior. Apomorphine may be inhibitory in quail because it acts primarily on D2-like receptors, unlike in rats, where it stimulates sexual behavior and acts primarily on D1-like receptors at low doses but interacts with D2-like receptors at higher doses. This is supported by the observation that stereotyped pecking, a behavior stimulated selectively in quail by D2 agonists, was increased by apomorphine but not by the two indirect agonists. The observed partial dissociation between the effects of these dopaminergic agonists on appetitive and consummatory sexual behaviors suggests that these two components of male sexual behavior may be controlled by the action of dopamine through different neuronal systems. [less ▲]

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See detailDifferential Effects of D1 and D2 Dopamine-Receptor Agonists and Antagonists on Appetitive and Consummatory Aspects of Male Sexual Behavior in Japanese Quail
Balthazart, Jacques ULg; Castagna, C.; Ball, G. F.

in Physiology & Behavior (1997), 62(3), 571-80

Pharmacological studies in Japanese quail based on behavioral tests with a variety of dopaminergic compounds suggest that the activation of D2 dopamine receptors inhibits, and the activation of D1 ... [more ▼]

Pharmacological studies in Japanese quail based on behavioral tests with a variety of dopaminergic compounds suggest that the activation of D2 dopamine receptors inhibits, and the activation of D1 dopamine receptors enhances, appetitive and consummatory components of male sexual behavior. This hypothesis was tested by studying the behavioral effects of specific D1 and D2 dopaminergic-receptor agonists and antagonists in castrated male Japanese quail chronically treated with exogenous testosterone (subcutaneous Silastic implants). The effects of 5 compounds were tested: 1 D1 (SKF38393) and 2 D2 (PPHT and quinpirole) agonists, and 1 D1 (SCH23390) and 1 D2 (Spiperone) antagonist. All compounds were tested at a low and a high dose (0.1 and 1 mg/kg, respectively, for all drugs, except spiperone where the doses were 2 and 10 mg/kg). A consistent effect of all drugs on consummatory sexual behavior was observed: it was stimulated by the D1 agonist and the D2 antagonist, but inhibited by the D1 antagonist and the D2 agonists. Far fewer effects of the treatments were detected on the measures of appetitive behavior. Measures of appetitive behavior were decreased by the 2 D2 agonists, but not affected by the other treatments. These data suggest that male copulatory behavior in quail is stimulated by dopamine acting on D1 receptors, but inhibited by activation of the D2 receptor subtype. The partial dissociation observed between the effects of the same treatments on appetitive and consummatory aspects of sexual behavior also suggests that these 2 behavioral systems may be controlled by the action of dopamine on different neuronal systems. [less ▲]

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