Papers by Karine Rousseau
Journal of Neuroendocrinology, Sep 1, 2002
Frontiers in Endocrinology, Dec 16, 2022
In vertebrates, the tachykinin system includes tachykinin genes, which encode one or two peptides... more In vertebrates, the tachykinin system includes tachykinin genes, which encode one or two peptides each, and tachykinin receptors. The complexity of this system is reinforced by the massive conservation of gene duplicates after the whole-genome duplication events that occurred in vertebrates and furthermore in teleosts. Added to this, the expression of the tachykinin system is more widespread than first thought, being found beyond the brain and gut. The discovery of the co-expression of neurokinin B, encoded by the tachykinin 3 gene, and kisspeptin/dynorphin in neurons involved in the generation of GnRH pulse, in mammals, put a spotlight on the tachykinin system in vertebrate reproductive physiology. As food intake and reproduction are linked processes, and considering that hypothalamic hormones classically involved in the control of reproduction are reported to regulate also appetite and energy homeostasis, it is of interest to look at the potential involvement of tachykinins in these two major physiological functions. The purpose of this review is thus to provide first a general overview of the tachykinin system in mammals and teleosts, before giving a state of the art on the different levels of action of tachykinins in the control of reproduction and food intake. This work has been conducted with a comparative point of view, highlighting the major similarities and differences of tachykinin systems and actions between mammals and teleosts.
CRC Press eBooks, Sep 7, 2020
Frontiers in Endocrinology
In vertebrates, the tachykinin system includes tachykinin genes, which encode one or two peptides... more In vertebrates, the tachykinin system includes tachykinin genes, which encode one or two peptides each, and tachykinin receptors. The complexity of this system is reinforced by the massive conservation of gene duplicates after the whole-genome duplication events that occurred in vertebrates and furthermore in teleosts. Added to this, the expression of the tachykinin system is more widespread than first thought, being found beyond the brain and gut. The discovery of the co-expression of neurokinin B, encoded by the tachykinin 3 gene, and kisspeptin/dynorphin in neurons involved in the generation of GnRH pulse, in mammals, put a spotlight on the tachykinin system in vertebrate reproductive physiology. As food intake and reproduction are linked processes, and considering that hypothalamic hormones classically involved in the control of reproduction are reported to regulate also appetite and energy homeostasis, it is of interest to look at the potential involvement of tachykinins in the...
Journal of Molecular Endocrinology, 2014
General and Comparative Endocrinology, 2019
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires Gonadotropin-inhibitory hormone in teleosts: new insights from a basal representative, the eel
Metamorphosis in Fish, 2012
Metamorphosis in Fish, 2012
Endocrinology, 2002
Seasonal Siberian hamsters lose fat reserves, decrease body weight and leptin concentrations, and... more Seasonal Siberian hamsters lose fat reserves, decrease body weight and leptin concentrations, and suppress reproduction on short-day photoperiod (SD). Chronic leptin infusion at physiological doses caused body weight and fat loss in SD animals but was ineffective in long-day (LD) hamsters. Using ovariectomized estrogen-treated females, we tested the hypothesis that responsiveness to leptin is regulated by photoperiod. On SD, hypothalamic neuropeptide Y, agouti-related peptide, and cocaine-and amphetamine-regulated transcript gene expression in the arcuate nucleus did not exhibit significant changes, and despite SD-induced fat loss, the catabolic peptide proopiomelanocortin was down-regulated. Food restriction of LD-housed animals caused significant reduction of fat reserves and serum leptin concentrations to SD levels, suppressed serum gonadotropins, and induced increased anabolic (neuropeptide Y, agouti-related peptide) and decreased catabolic (proopiomelanocortin, cocaine-and amphetamineregulated transcript) gene expression in the arcuate nucleus. Leptin infusion in food-restricted animals had no effect on fat reserves or gonadotropins and did not modulate neuropeptide gene expression. Also, leptin treatment did not blunt the refeeding responses or weight and fat gain in LD-housed foodrestricted animals. In conclusion, our results strongly suggest that hypothalamic responses to leptin are regulated primarily by photoperiod, rather than seasonal changes in fat reserves, sex steroids, or leptin concentrations.
Physiological Reviews, 2019
In humans, as in the other mammals, the neuroendocrine control of reproduction is ensured by the ... more In humans, as in the other mammals, the neuroendocrine control of reproduction is ensured by the brain-pituitary gonadotropic axis. Multiple internal and environmental cues are integrated via brain neuronal networks, ultimately leading to the modulation of the activity of gonadotropin-releasing hormone (GnRH) neurons. The decapeptide GnRH is released into the hypothalamic-hypophysial portal blood system and stimulates the production of pituitary glycoprotein hormones, the two gonadotropins luteinizing hormone and follicle-stimulating hormone. A novel actor, the neuropeptide kisspeptin, acting upstream of GnRH, has attracted increasing attention in recent years. Other neuropeptides, such as gonadotropin-inhibiting hormone/RF-amide related peptide, and other members of the RF-amide peptide superfamily, as well as various nonpeptidic neuromediators such as dopamine and serotonin also provide a large panel of stimulatory or inhibitory regulators. This paper addresses the origin and evol...
Journal of Fish Biology, 2010
While gonadotropin-releasing hormone (GnRH) is considered as the major hypothalamic factor contro... more While gonadotropin-releasing hormone (GnRH) is considered as the major hypothalamic factor controlling pituitary gonadotrophins in mammals and most other vertebrates, its stimulatory actions may be opposed by the potent inhibitory actions of dopamine (DA) in teleosts. This dual neuroendocrine control of reproduction by GnRH and DA has been demonstrated in various, but not all, adult teleosts, where DA participates in an inhibitory role in the neuroendocrine regulation of the last steps of gametogenesis (final oocyte maturation and ovulation in females and spermiation in males). This has major implications for inducing spawning in aquaculture. In addition, DA may also play an inhibitory role during the early steps of gametogenesis in some teleost species, and thus interact with GnRH in the control of puberty. Various neuroanatomical investigations have shown that DA neurones responsible for the inhibitory control of reproduction originate in a specific nucleus of the preoptic area (NPOav) and project directly to the region of the pituitary where gonadotrophic cells are located. Pharmacological studies showed that the inhibitory effects of DA on pituitary gonadotrophin production are mediated by DA-D2 type receptors. DA-D2 receptors have now been sequenced in several teleosts, and the coexistence of several DA-D2 subtypes has been demonstrated in a few species. Hypophysiotropic DA activity varies with development and reproductive cycle and probably is controlled by environmental cues as well as endogenous signals. Sex steroids have been shown to regulate dopaminergic systems in several teleost species, affecting both DA synthesis and DA-D2 receptor expression. This demonstrates that sex steroid feedbacks target DA hypophysiotropic system, as well as the other components of the brain-pituitary gonadotrophic axis, GnRH and gonadotrophins. Recent studies have revealed that melatonin modulates the activity of DA systems in some teleosts, making the melatonin-DA pathway a prominent relay between environmental cues and control of reproduction. The recruitment of DA neurons for the neuroendocrine control of reproduction provides an additional brain pathway for the integration of various internal and environmental cues. The plasticity of the DA neuroendocrine role observed in teleosts may have contributed to their large diversity of reproductive cycles.
General and Comparative Endocrinology
Frontiers in Endocrinology
We recently characterized two paralogs of the thyrotropin (TSH) beta subunit in Atlantic salmon,t... more We recently characterized two paralogs of the thyrotropin (TSH) beta subunit in Atlantic salmon,tshβaandtshβb, issued from teleost-specific whole genome duplication. The transcript expression oftshβb, but not oftshβa, peaks at the time of smoltification, which revealed a specific involvement oftshβbparalog in this metamorphic event.Tshβaandtshβbare expressed by distinct pituitary cells in salmon, likely related to TSH cells from thepars distalisandpars tuberalis, respectively, in mammals and birds. The present study aimed at investigating the neuroendocrine and endocrine factors potentially involved in the differential regulation oftshβaandtshβbparalogs, using primary cultures of Atlantic salmon pituitary cells. The effects of various neurohormones and endocrine factors potentially involved in the control of development, growth, and metabolism were tested. Transcript levels oftshβaandtshβbwere measured by qPCR, as well as those of growth hormone (gh), for comparison and validation. ...
Frontiers in Endocrinology
Prediction of the Three-Dimensional Peptide structure of eel Tac3 Peptides Secondary structures o... more Prediction of the Three-Dimensional Peptide structure of eel Tac3 Peptides Secondary structures of eel TAC3 peptides were modeled using the I-TASSER server, an automated protein-modeling server (48). Only models with the C-score between 2 and −5 were considered. The visualization of the predicted three-dimensional structures 8 http://www.genomicus.biologie.ens.fr/genomicus-91.01/cgi-bin/search.pl.
Frontiers in endocrinology, 2017
The European eel () presents a blockade of sexual maturation at a prepubertal stage due to a defi... more The European eel () presents a blockade of sexual maturation at a prepubertal stage due to a deficient production of gonadotropins. We previously initiated, in the eel, the investigation of the kisspeptin system, one of the major gatekeepers of puberty in mammals, and we predicted the sequence of two genes. In the present study, we cloned and sequenced and cDNAs from the eel brain. The tissue distributions of and transcripts, as investigated by quantitative real-time PCR, showed that both genes are primarily expressed in the eel brain and pituitary. The two 10-residue long sequences characteristic of kisspeptin, eel Kp1(10) and Kp2(10), as well as two longer sequences, predicted as mature peptides, eel Kp1(15) and Kp2(12), were synthesized and functionally analyzed. Using rat Kiss1 receptor-transfected Chinese hamster ovary cells, we found that the four synthesized eel peptides were able to induce [Ca] responses, indicating their ability to bind mammalian KissR-1 and to activate sec...
Cybium, 2004
Growth hormone (GH) is involved in many physiological functions such as growth, metabolism, repro... more Growth hormone (GH) is involved in many physiological functions such as growth, metabolism, reproduction and immunity. In mammals, it is well established that GH release is under a dual hypothalamic control, stimulatory by somatoliberin (GHRH) and inhibitory by somatostatin (sRIH). Peripheral hormones such as the insulin-like growth factors (IGfs) and the thyroid hormones (TH) can also regulate GH release. In non-mammalian vertebrates, a great variability of hypothalamic neuropeptides involved in GH stimulation seems to occur. This review underlines the important contribution of teleost models in the phylogenetic study of GH control. Teleost somatotrophs show a high autonomous activity of synthesis and release in vitro in a serum-free medium and without any secretagogues. This strong autonomous activity in vitro suggests that these cells are under a dominant inhibitory control in vivo. sRIH and IGf1 have strong inhibitory effects on the release and synthesis of GH in teleosts. Concerning the stimulatory control of GH in teleosts, a great diversity of factors involved exists. Thus, depending on species or physiological stage, thyreoliberin, gonadoliberin, corticoliberin and dopamine are able to stimulate GH release. Contrary to mammals, in teleosts, PaCaP, which is encoded by the same gene as GHRH, stimulates GH release, whereas GHRH has lower or no effect. Variable actions of TH in GH control are found among teleosts as well as among other vertebrates. In conclusion, the inhibitory control exerted by sRIH and IGf1, which shows a strong molecular and functional conservation, could represent the basic neuroendocrine control of GH, established early during evolution, at least in a common ancestor of the actinopterygians and the sarcopterygians. In contrast, a great variability is seen among the hypothalamic neuropeptides involved in the stimulatory control of GH release. PaCaP may represent the ancestral GH-releasing factor, whereas GHRH would have acquired a major role during tetrapod and especially mammalian evolution. résumé.-Évolution phylogénétique du contrôle neuroendocrinien de l'hormone de croissance : apport des modèles téléostéens. L'hormone de croissance (GH) est impliquée dans de nombreuses fonctions physiologiques, telles que la croissance, le métabolisme, la reproduction et l'immunité. Chez les mammifères, il est bien établi que la libération de GH est sous un double contrôle hypothalamique, stimulateur par la somatolibérine (GHRH) et inhibiteur par la somatostatine (sRIH). Des hormones périphériques comme les facteurs de croissance de type insulinique (IGfs) et les hormones thyroïdiennes (HT) peuvent également agir sur la libération de GH. Chez les vertébrés non-mammaliens, il semble exister une grande diversité quant aux neuropeptides hypothalamiques impliqués dans la stimulation de GH. Cette revue souligne l'importante contribution des modèles téléostéens dans l'étude phylogénétique du contrôle de GH. Les cellules somatotropes de téléostéens possèdent une forte activité autonome de synthèse et de libération in vitro en milieu sans sérum et en absence de tout secrétagogue. Cette importante activité autonome in vitro suggère que ces cellules sont soumises in vivo à un contrôle inhibiteur dominant. sRIH et IGf1 possèdent des effets inhibiteurs puissants sur la libération et la synthèse de GH chez tous les téléostéens. en ce qui concerne le contrôle stimulateur de GH chez les téléostéens, une grande diversité de facteurs pouvant intervenir existe. ainsi, suivant l'espèce ou le stade physiologique, la thyréolibérine, la gonadolibérine, la corticolibérine et la dopamine sont capables de stimuler la libération de GH. À l'inverse de chez les mammifères, chez les téléostéens, PaCaP, qui est codé par le même gène que GHRH, stimule la libération de GH, alors que GHRH n'a pas ou moins d'effet. Des rôles variables des HT dans le contrôle de GH sont trouvés au sein des téléostéens comme des autres vertébrés. en conclusion, le contrôle inhibiteur exercé par sRIH et IGf1, qui montre une forte conservation moléculaire et fonctionnelle, peut représenter le contrôle neuroendocrine de base de la GH, mis en place tôt au cours de l'évolution des vertébrés, au moins chez un ancêtre commun aux actinoptérygiens et sarcoptérygiens. au contraire, il existe une forte variabilité des neuropeptides hypothalamiques impliqués dans le contrôle stimulateur de la libération de GH. PaCaP pourrait avoir joué un rôle ancestral de facteur de libération de GH, tandis que GHRH n'aurait acquis un rôle majeur qu'au cours de l'évolution des tétrapodes et en particulier chez les mammifères.
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Papers by Karine Rousseau