Les types morphologiques humains

Dufour , Rigaud , Cabanié , Gouazé . Les types morphologiques humains. In: Bulletins et Mémoires de la Société d'anthropologie de Paris, X° Série. Tome 3 fascicule 3-4, 1952. pp. 174-186

Nomenclature anatomique française /

Inde

Food intake adaptation to dietary fat involves PSA-dependent rewiring of the arcuate melanocortin system in mice.

International audienceHormones such as leptin and ghrelin can rapidly rewire hypothalamic feeding circuits when injected into rodent brains. These experimental manipulations suggest that the hypothalamus might reorganize continually in adulthood to integrate the metabolic status of the whole body. In this study, we examined whether hypothalamic plasticity occurs in naive animals according to their nutritional conditions. For this purpose, we fed mice with a short-term high-fat diet (HFD) and assessed brain remodeling through its molecular and functional signature. We found that HFD for 3 d rewired the hypothalamic arcuate nucleus, increasing the anorexigenic tone due to activated pro-opiomelanocortin (POMC) neurons. We identified the polysialic acid molecule (PSA) as a mediator of the diet-induced rewiring of arcuate POMC. Moreover, local pharmacological inhibition and genetic disruption of the PSA signaling limits the behavioral and metabolic adaptation to HFD, as treated mice failed to normalize energy intake and showed increased body weight gain after the HFD challenge. Altogether, these findings reveal the existence of physiological hypothalamic rewiring involved in the homeostatic response to dietary fat. Furthermore, defects in the hypothalamic plasticity-driven adaptive response to HFD are obesogenic and could be involved in the development of metabolic diseases

Dietary switch to Western diet induces hypothalamic adaptation associated with gut microbiota dysbiosis in rats

International audienceBackground: Early hyperphagia and hypothalamic inflammation encountered after Western diet (WD) are linked to rodent propensity to obesity. Inflammation in several brain structures has been associated with gut dysbiosis. Since gut microbiota is highly sensitive to dietary changes, we hypothesised that immediate gut microbiota adaptation to WD in rats is involved in inflammation-related hypothalamic modifications. Methods: We evaluated short-term impact of WD consumption (2 h, 1, 2 and 4 days) on hypothalamic metabolome and caecal microbiota composition and metabolome. Data integration analyses were performed to uncover potential relationships among these three datasets. Finally, changes in hypothalamic gene expression in absence of gut microbiota were evaluated in germ-free rats fed WD for 2 days. Results: WD quickly and profoundly affected the levels of several hypothalamic metabolites, especially oxidative stress markers. In parallel, WD consumption reduced caecal microbiota diversity, modified its composition towards pro-inflammatory profile and changed caecal metabolome. Data integration identified strong correlations between gut microbiota sub-networks, unidentified caecal metabolites and hypothalamic oxidative stress metabolites. Germ-free rats displayed reduced energy intake and no changes in redox homoeostasis machinery expression or pro-inflammatory cytokines after 2 days of WD, in contrast to conventional rats, which exhibited increased SOD2, GLRX and IL-6 mRNA levels. Conclusion: A potentially pro-inflammatory gut microbiota and an early hypothalamic oxidative stress appear shortly after WD introduction. Tripartite data integration highlighted putative links between gut microbiota sub-networks and hypothalamic oxidative stress. Together with the absence of hypothalamic modifications in germ-free rats, this strongly suggests the involvement of the microbiota-hypothalamus axis in rat adaptation to WD introduction and in energy homoeostasis regulation