The mechanisms by which melatonin controls seasonal reproduction are poorly understood. The use of a large animal model, namely the sheep, has allowed progress in the understanding of these ...mechanisms, and is the subject of this review. Firstly, the contribution made by large animal models to demonstrating that melatonin acts in the hypothalamus and the identification of this hypothalamic target is reviewed. Secondly, the way in which large animal models have facilitated the demonstration of a specific mechanism of release of melatonin in the cerebrospinal fluid and, thus, raised the question of the route used by melatonin to reach its central targets is discussed. Finally, the human and agricultural relevance of the data presented is considered.
Bulletin bibliographique Airiau, Paul; Allouche-Benayoun, Joëlle; Asad, Talal ...
Archives de sciences sociales des religions,
2017
180
Journal Article
Odprti dostop
Ce nouveau Bulletin bibliographique s’ouvre sur l’évocation de deux pertes pour la revue, Françoise Aubin et André Padoux. Deux savants qui mêlaient heureusement compétence érudite et curiosité du ...monde oriental ; également collaborateurs au long cours de notre Bulletin bibliographique. L’« Atelier des sciences sociales du religieux » qui suit se compose de sept contributions (dont une traduction) avec pour objets principaux quelques éléments de trajectoire des sociologies du protestantisme et des anthropologies de l’islam. Parcours qui entremêlent histoire des concepts et vies savantes. Sept « notes critiques » abordent ensuite sous un jour actuel les questions classiques du blasphème, du pèlerinage, de l’art sacré et de l’utopie. Ces notes portent notamment attention aux querelles disciplinaires et débats scientifiques qui jalonnent l’approche de ces phénomènes sur longue période. Le temps des moines, dernier livre de Danièle Hervieu-Léger, fait ici l’objet d’une « lecture croisée » mettant en jeu les perspectives de la sociologie et de l’histoire sur une survivance qui nous en apprend encore beaucoup sur notre temps présent. La centaine de comptes rendus de cette livraison traite d’une multitude irréductible de sujets, allant de Satan à Esther, de Luther à Mauss.
Mathias Ledroit et Sarah Pech-Pelletier - ÉditorialStanis Perez Charles Quint, empereur « grand public » ? (XIXe XXIe siècle) Carlos Quinto, un Emperador para un “amplio público”? (ss. XIX y ...XX)Marie-Blanche Requejo Carrio La Balada del Norte de Alfonso Zapico : l’histoire d’une révolution entre texte et images, (Asturies-octobre 1934) La Balada del Norte de Alfonso Zapico: relatos e imágenes de una revolución (Asturias-1934)Roberta Previtera Goya entre dos guerras: biopic y reconstrucción histórica Goya entre deux guerres : biopic et reconstruction historiqueAnaïs Fabriol Prismes de l’Histoire de l’Espagne El Ministerio del Tiempo ou la constante reconstruction du passé Los prismas de la Historia de España: El Ministerio del tiempo (RTVE) u otra lectura del pasadoFrançoise Prioul Tango en Histoire majeure : l’écriture de l’Histoire dans les paroles du tango, des origines à Perón Tango en historia mayor: escritura de la historia en las letras de tango, de los orígenes a PerónPierre Civil Marie-Hélène Maux et Marc Zuili (dir.), Les traductions de la littérature espagnole (XVIe XVIIe siècle) / Las traducciones de la literatura española (siglos XVI-XVIII), Paris, L’Harmattan, 2021 Claudie Terrasson Albert Chartier, Une famille française dans l’Empire ottoman. Vie et pérégrinations (1858-1921).
We wanted to determine if changes in the expression of serotonin 2A receptor (5HT2A receptor) gene in the premammillary hypothalamus are associated with changes in reproductive neuroendocrine status. ...Thus, we compared 2 groups of ovariectomized-estradiol-treated ewes that expressed high vs low LH pulsatility in two different paradigms (2 groups per paradigm): (a) refractoriness (low LH secretion) or not (high LH secretion) to short days in pineal-intact Ile-de-France ewes (RSD) and (b) endogenous circannual rhythm (ECR) in free-running pinealectomized Suffolk ewes in the active or inactive stage of their reproductive rhythm.
In RSD ewes, density of 5HT2A receptor mRNA (by in situ hybridization) was significantly higher in the high LH group (25.3 +/- 1.4 vs 21.4 +/- 1.5 grains/neuron, P < 0.05) and 3H-Ketanserin binding (a specific radioligand) of the median part of the premammillary hypothalamus tended to be higher in the high group (29.1 +/- 4.0 vs 24.6 +/- 4.2 fmol/mg tissu-equivalent; P < 0.10). In ECR ewes, density of 5HT2A receptor mRNA and 3H-Ketanserin binding were both significantly higher in the high LH group (20.8 +/- 1.6 vs 17.0 +/- 1.5 grains/neuron, P < 0.01, and 19.7 +/- 5.0 vs 7.4 +/- 3.4 fmol/mg tissu-equivalent; P < 0.05, respectively).
We conclude that these higher 5HT2A receptor gene expression and binding activity of 5HT2A receptor in the premammillary hypothalamus are associated with stimulation of LH pulsatility expressed before the development of refractoriness to short days and prior to the decline of reproductive neuroendocrine activity during expression of the endogenous circannual rhythm.
Serotonin and serotonin receptors of class II (5HT2-R) are thought to be involved in the neural mechanisms which regulate the LH release associated with photoperiodic changes in sheep. A specific ...premammillary hypothalamic area displaying a significant binding of 3H-ketanserin, a potent 5HT2-R antagonist, was previously identified. The aim of the present study was to ascertain by in situ hybridization (ISH) that 5HT2-R mRNA-containing cells were also present in this specific hypothalamic area. Total RNA was prepared from sheep pars tuberalis/median eminence, and a cDNA fragment of 546 bp was amplified by reverse transcriptase polymerase chain reaction (RT-PCR) using degenerated primers deduced from the human and rat 5HT2A-R sequences. After cloning and sequencing, the sheep nucleotide sequence had the highest homology (85.1-92.3%) with the other known mammalian 5HT2-R or 5HT2A-R sequences. Homology with other 5HT-R subtypes or other monoamine receptors was much lower, 60% at maximum. After ISH using sense and antisense 35S-riboprobes, specific labelling was found in different parts of the hypothalamus, especially in the mammillary bodies where the binding was higher. Within the hypothalamus, the density of labelled cells, mainly neurons, varied considerably. It was maximal in the mammillary bodies and also in a restricted ventral region of the premammillary hypothalamus located from about 500/700 micrometer to 1200/1400 micrometer in front of the mammillary recess, where 3H-ketanserin binding was previously reported.
(1) the structural study of the sequence indicated that the new cloned cDNA corresponds to the sheep 5HT2-R class and, probably, to the 5HT2A-R subtype and (2) the ISH studies revealed that a restricted area of the premammillary hypothalamus shows a large number of 5HT2-R mRNA-containing neurons.
This study was undertaken to assess the influence of photoperiod on growth hormone (GH) secretion in rams and its possible influence on body weight. Twenty young adult rams were divided into two ...groups. One was subjected to an annual (AR) and the other to a semestral (SR) light regime during the same 18-month period. In both groups, daylength (DL) varied gradually between 8 to 17 hr. Plasma prolactin (PRL) and GH profiles consisting of 6 hr samples were determined and animals were weighed throughout the course of the experiment. Maximal PRL secretion was observed with largest DL. In contrast, GH secretion increased during increasing DL but it began to decrease before maximal DL was reached in both light regimes. Mean GH secretion was maximal when the DL was about 11 hr in SR and between 8 to 12 hr in AR. Similarly, body weight increased when DL increased and plateaued during decreasing DL in both AR and SR animal groups. Significant (P less than 0.05) differences were observed throughout the course of the experiment according to the effects of decreasing or increasing DL in each group. Analysis of variance showed that the effect of DL on plasma PRL and GH levels and weight velocity (WV) was significant (P less than 0.05) in both light regimes. This suggests that in SR, plasma PRL and GH levels and WV vary according to a six month period.
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