Pheromones in birds: myth or reality?
; Balthazart, Jacques
in Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural and Behavioral Physiology (2010), 196(10), 751-66
Birds are anosmic or at best microsmatic... This misbelief persisted until very recently and has strongly influenced the outcome of communication studies in birds, with olfaction remaining neglected as ... [more ▼]
Birds are anosmic or at best microsmatic... This misbelief persisted until very recently and has strongly influenced the outcome of communication studies in birds, with olfaction remaining neglected as compared to acoustic and visual channels. However, there is now clear empirical evidence showing that olfaction is perfectly functional in birds and birds use olfactory information in a variety of ethological contexts. Although the existence of pheromones has never been formally demonstrated in this vertebrate class, different groups of birds, such as petrels, auklets and ducks have been shown to produce specific scents that could play a significant role in within-species social interactions. Behavioral experiments have indeed demonstrated that these odors influence the behavior of conspecifics. Additionally, in quail, deprivation of olfactory inputs decreases neuronal activation induced by sexual interactions with a female. It seems therefore well established that birds enjoy a functional sense of smell and a fast growing body of experimental evidence suggests that they use this channel of olfactory communication to control their social life. The unequivocal identification of an avian pheromone is, however, still ahead of us but there are now many exciting opportunities to unravel the behavioral and physiological particularities of chemical communication in birds. [less ▲]Detailed reference viewed: 27 (1 ULg)
Effects of estrogen receptors alpha and beta agonists on the sexual behavior and the neuroplasticity in male Japanese quail.
Seredynski, Aurore ; Charlier, Thierry ; Balthazart, Jacques
Poster (2010)Detailed reference viewed: 7 (1 ULg)
Neuroplasticity and steroid-dependent male sexual behavior modulated by steroid receptor coactivator 2 (SRC2) in Japanese quail (Coturnix japonica).
Niessen, Neville-Andrew ; Balthazart, Jacques ; et al
Poster (2010)Detailed reference viewed: 10 (3 ULg)
Own song selectivity in the songbird auditory pathway: suppression by norepinephrine
; ; et al
Poster (2010)Detailed reference viewed: 2 (0 ULg)
Expression of the steroid receptor coactivators SRC-1 and CARM1 is modulated during different phases of neurogenesis in the dentate gyrus of adult female rats
Charlier, Thierry ; ; Balthazart, Jacques et al
Poster (2010)Detailed reference viewed: 6 (1 ULg)
Steroid receptor coactivator 2 (SRC-2) mediates steroid-dependent male sexual behavior and neuroplasticity in Japanese quail (Coturnix japonica).
Niessen, Neville-Andrew ; Balthazart, Jacques ; et al
Poster (2010)Detailed reference viewed: 5 (3 ULg)
Sex steroid-induced neuroplasticity and behavioral activation in birds
Balthazart, Jacques ; Charlier, Thierry ; Barker, Jennifer et al
in European Journal of Neuroscience (2010), 32Detailed reference viewed: 15 (6 ULg)
Rapid regulation of aromatase activity and the role of stress
; Charlier, Thierry ; Cornil, Charlotte et al
Poster (2010)Detailed reference viewed: 12 (0 ULg)
Sex difference and steroid control of corticosteroid-binding globulin concentration in Japanese quail
Charlier, Thierry ; Seredynski, Aurore ; Balthazart, Jacques
Poster (2010)Detailed reference viewed: 10 (1 ULg)
Behavioral implications of rapid changes in steroid production action in the brain [Commentary on Pradhan D.S., Newman A.E.M., Wacker D.W., Wingfield J.C., Schlinger B.A. and Soma K.K.: Aggressive interactions rapidly increase androgen synthesis in the brain during the non-breeding season. Hormones and Behavior, this issue].
in Hormones & Behavior (2010), 57Detailed reference viewed: 22 (6 ULg)
Seasonal and hormonal modulation of neurotransmitter systems in the song control circuit.
; Balthazart, Jacques
in Journal of Chemical Neuroanatomy (2010), 39(2), 82-95
In the years following the discovery of the song system, it was realized that this specialized circuit controlling learned vocalizations in songbirds (a) constitutes a specific target for sex steroid ... [more ▼]
In the years following the discovery of the song system, it was realized that this specialized circuit controlling learned vocalizations in songbirds (a) constitutes a specific target for sex steroid hormone action and expresses androgen and (for some nuclei) estrogen receptors, (b) exhibits a chemical neuroanatomical pattern consisting in a differential expression of various neuropeptides and neurotransmitters receptors as compared to surrounding structures and (c) shows pronounced seasonal variations in volume and physiology based, at least in the case of HVC, on a seasonal change in neuron recruitment and survival. During the past 30 years numerous studies have investigated how seasonal changes, transduced largely but not exclusively through changes in sex steroid concentrations, affect singing frequency and quality by modulating the structure and activity of the song control circuit. These studies showed that testosterone or its metabolite estradiol, control seasonal variation in singing quality by a direct action on song control nuclei. These studies also gave rise to the hypothesis that the probability of song production in response to a given stimulus (i.e. its motivation) is controlled through effects on the medial preoptic area and on catecholaminergic cell groups that project to song control nuclei. Selective pharmacological manipulations confirmed that the noradrenergic system indeed plays a role in the control of singing behavior. More experimental work is, however, needed to identify specific genes related to neurotransmission that are regulated by steroids in functionally defined brain areas to enhance different aspects of song behavior. [less ▲]Detailed reference viewed: 15 (2 ULg)
Introduction to the chemical neuroanatomy of birdsong.
; Balthazart, Jacques
in Journal of Chemical Neuroanatomy (2010), 39(2), 67-71Detailed reference viewed: 30 (0 ULg)
Testosterone recruits new aromatase-imunoreactive cells in neonatal quail brain.
; Cornil, Charlotte ; Balthazart, Jacques
in Neuroreport (2010), 21(5), 376-80
It was shown earlier that, in Japanese quail the mechanism controlling the induction by testosterone of aromatase activity develops between embryonic days 10 and 14. The cellular processes underlying this ... [more ▼]
It was shown earlier that, in Japanese quail the mechanism controlling the induction by testosterone of aromatase activity develops between embryonic days 10 and 14. The cellular processes underlying this activation have, however, not been investigated in detail. Here, we demonstrate that the increase in aromatase activity observed in neonates treated with testosterone propionate between postnatal days 1 and 3 results from the recruitment of additional populations of aromatase-immunoreactive cells that were not expressing the enzyme at detectable levels before. This recruitment concerns all brain nuclei normally expressing the enzyme even if it is more prominent in the ventromedial hypothalamus than in other nuclei. [less ▲]Detailed reference viewed: 19 (1 ULg)
Presence of aromatase and estrogen receptor alpha in the inner ear of zebra finches.
Noirot, Isabelle ; ; Cornil, Charlotte et al
in Hearing Research (2009)
Sex differences in song behavior and in the neural system controlling song in songbirds are well documented but relatively little is known about sex differences in hearing. We recently demonstrated the ... [more ▼]
Sex differences in song behavior and in the neural system controlling song in songbirds are well documented but relatively little is known about sex differences in hearing. We recently demonstrated the existence of sex differences in auditory brainstem responses in a songbird species, the zebra finch (Taeniopygia guttata). Many sex differences are regulated by sex steroid hormone action either during ontogeny or in adulthood. As a first step to test the possible implication of sex steroids in the control of sex differences in the zebra finch auditory system, we evaluated via immunocytochemistry whether estrogens are produced and act in the zebra finch inner ear. Specifically we examined the distribution of aromatase, the enzyme converting testosterone into an estrogen, and of estrogen receptors of the alpha subtype (ERalpha) in adult zebra finch inner ears. The anatomy of the basilar papillae was visualized by fluorescein-phalloidin, which delineated the actin structure of hair cells and supporting cells at their apical surface. Whole mount preparations of basilar papillae stained by immunocytochemistry revealed in both males and females an abundant aromatase distribution in the cytoplasm of hair cells, while ERalpha was identified in the nuclei of hair cells and of underlying supporting cells. Double labeled preparations confirmed the extensive co-localization of aromatase and ERalpha in the vast majority of the hair cells. These results are consistent with studies on non-avian species, suggesting a role for estrogens in auditory function. These findings are also consistent with the notion that estrogens may contribute to a sex difference in hearing. To our knowledge, this is the first demonstration of the presence of aromatase and of the co-localization of aromatase and ERalpha in the sensory epithelium of the inner ear in any animal model. [less ▲]Detailed reference viewed: 72 (10 ULg)
Cloning of the steroid receptor coactivator SRC-2 and distribution in the brain of Japanese quail
Niessen, Neville-Andrew ; Charlier, Thierry ; Balthazart, Jacques
Poster (2009)Detailed reference viewed: 11 (2 ULg)
The fast regulation of aromatase activity by phosphorylations is species and tissue-independent.
Charlier, Thierry ; ; et al
Poster (2009)Detailed reference viewed: 10 (1 ULg)
Species and tissue-independent rapid regulation of aromatase activity by phosphorylations.
Charlier, Thierry ; ; et al
in Acta Neurologica Belgica (2009)
Aromatase activity (AA) is rapidly inhibited in male quail brains, following expression of sexual behavior, activation of glutamatergic receptors or exposure to phosphorylating conditions. Questions ... [more ▼]
Aromatase activity (AA) is rapidly inhibited in male quail brains, following expression of sexual behavior, activation of glutamatergic receptors or exposure to phosphorylating conditions. Questions remain as to whether direct aromatase phosphorylation is the common key regulatory mechanism and whether these inhibitions are specific to quail hypothalamus. We now showed that AA is rapidly downregulated in quail ovary homogenates incubated in phosphorylating conditions, similarly to what is observed in hypothalamic homogenates. To understand the processes underlying this control, we expressed human aromatase in the human cell line HEK293 and 1) researched whether human aromatase can also be rapidly modulated by phosphorylations and 2) investigated more precisely the processes involved in this rapid control of activity. AA in HEK293 was rapidly inhibited following depolarization of intact cells with 100 mM KCl or in cell lysates exposed to phosphorylating conditions. Thus inhibition of AA in phosphorylating conditions is not unique to the quail hypothalamus neural environment but seems to be a general process. We are now defining the contribution of single residues of the aromatase protein to this enzymatic control. [less ▲]Detailed reference viewed: 15 (4 ULg)
Estradiol, a key endocrine signal in the sexual differentiation and activation of reproductive behavior in quail.
Balthazart, Jacques ; Cornil, Charlotte ; Charlier, Thierry et al
in Journal of Experimental Zoology. Part A, Ecological Genetics and Physiology (2009), 311(5), 323-45
In Japanese quail, estrogen's effects on sexual behavior can be divided into three classes based on the underlying mechanisms and time-course of action and release. During embryonic life, the embryonic ... [more ▼]
In Japanese quail, estrogen's effects on sexual behavior can be divided into three classes based on the underlying mechanisms and time-course of action and release. During embryonic life, the embryonic ovary secretes large amounts of estrogens. In contrast to what is observed in mammals where sexual differentiation essentially proceeds via masculinization of the males, in quail, females are demasculinized by their endogenous ovarian estrogens, an effect that can be blocked by injection of an aromatase inhibitor and mimicked in male embryos by an injection of estradiol. In adulthood, testosterone secreted by the testes is converted into estrogens by the preoptic aromatase. Locally produced estrogens activate male sexual behavior largely through the activation of estrogen receptors resulting in the transcription of a variety of genes, including brain aromatase (genomic effect). Both changes in estrogen production and action are observed within latencies ranging from a few hours to a few days, and are completely reversible. Additionally, brain aromatase activity can be modulated within minutes by calcium-dependent phosphorylations, triggered by variations in glutamatergic neurotransmission. These rapid changes in aromatase activity affect with relatively short latencies (10-15 min) the expression of male sexual behavior in quail and also in mice. Overall, the effects of estrogens on sexual behavior can thus be categorized into three classes: organizational (irreversible genomic action during ontogeny), activational (reversible genomic action during adulthood) and rapid nongenomic effects. Rapid and slower changes in brain aromatase activity match well with the two modes of estrogen action on behavior and provide temporal variations in the estrogens' bioavailability that should be able to support the entire range of established effects for this steroid. [less ▲]Detailed reference viewed: 18 (8 ULg)
Steroids and neuroprotection: New advances.
; Balthazart, Jacques
in Frontiers in Neuroendocrinology (2009), 30(2), -
Gonadal hormones exert neuroprotective actions. In addition, it has become evident that the local synthesis of these molecules in the central nervous system may prevent or reduce neurodegeneration.The ... [more ▼]
Gonadal hormones exert neuroprotective actions. In addition, it has become evident that the local synthesis of these molecules in the central nervous system may prevent or reduce neurodegeneration.The neuroprotective actions of steroids involve neurons, glial cells and blood vessels, are exerted via steroid receptor signaling initiated at the nuclear or membrane level and steroid receptor independent mechanisms. They include the regulation of phosphatases and kinases and the regulation of the expression of molecules controlling inflammation and apoptosis. In addition, mitochondria have emerged as new central targets for neuroprotective actions of steroids. These neuroprotective actions have been documented in different experimental models of neurological alterations, including motoneuron injury, Parkinson's disease, traumatic brain injury, multiple sclerosis, stroke and Alzheimer's disease. In addition, steroids promote serotonergic neuronal function and protect against affective disorders. This special issue of Frontiers in Neuroendocrinology contains a collection of reviews of the most recent ideas and findings on these various aspects of sex steroid-dependent neuroprotection [less ▲]Detailed reference viewed: 65 (0 ULg)