A Comparative Analysis Shows Morphofunctional Differences between the Rat and Mouse Melanin-Concentrating Hormone Systems

Sub-populations of neurons producing melanin-concentrating hormone (MCH) are characterized by distinct projection patterns, birthdates and CART/NK3 expression in rat. Evidence for such sub-populations has not been reported in other species. However, given that genetically engineered mouse lines are now commonly used as experimental models, a better characterization of the anatomy and morphofunctionnal organization of MCH system in this species is then necessary. Combining multiple immunohistochemistry experiments with in situ hybridization, tract tracing or BrdU injections, evidence supporting the hypothesis that rat and mouse MCH systems are not identical was obtained: sub-populations of MCH neurons also exist in mouse, but their relative abundance is different. Furthermore, divergences in the distribution of MCH axons were observed, in particular in the ventromedial hypothalamus. These differences suggest that rat and mouse MCH neurons are differentially involved in anatomical networks that control feeding and the sleep/wake cycle

MCH and feeding behavior-interaction with peptidic network.

International audienceNumerous works associate the MCH peptide, and the hypothalamic neurons that produce it, to the feeding behavior and energy homeostasis. It is commonly admitted that MCH is an orexigenic peptide, and MCH neurons could be under the control of arcuate NPY and POMC neurons. However, the literature data is not always concordant. In particular questions about the intrahypothalamic circuit involving other neuropeptides and about the mechanisms through which MCH could act are not yet clearly answered. For example, which receptors mediate a MCH response to NPY or alpha-MSH, does MCH act alone, is there any local anatomical organization within the tuberal LHA? A review of the current literature is then needed to help focus attention on these unresolved and often neglected issues

Distribution of αCDCP-immunoreactive neurons in the central nervous system of the snail Helix aspersa

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Étude de l'action des ganglions cérébroïdes et des corps dorsaux sur la synthèse d'ADN induite par la chaleur dans l'ovotestis d'Helix aspersa en hibernation

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Permanence des grandes échelles en turbulence homogène avec densité variable

The principle of permanence of large eddies is one of the central pillars onto which our understanding of decaying homogeneous turbulence is built. The validity conditions of this principle have been thoroughly discussed for constant density flows, but not for variable-density ones. In this work, we show that density non-uniformities modify the remote action of the pressure field. It results into distant velocity correlations being submitted to a stronger non-linear transfer of energy. A simple example is proposed to illustrate this property and a spectral analysis of non-linear transfer terms is undertook to further characterize it. From there, we derive that large eddies in variable density flows remain permanent for a smaller set of initial conditions than when density is constant. Permanence strictly applies to initial spectra having an infrared exponent smaller than 2 instead of 4. Implicit large-eddy simulations are performed to verify the main predictions of this work