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Stress, axe corticotrope et caracteristiques nutritionnelles et metaboliques

Diane Abdoulaye
Abstract : Interactions between stress and food intake are well recognized as being complex and multiple. The usually actnowledged link between stress and body weight gain involves feeding behavior alterations consisting in either a reduction or an increase of food intake according to subjects. The first part of this work studied the influence of a stress on body weight gain and on macronutrient selection. Studies were carried out on Wistar rats submitted to two different food situations (experiment 1 : rats received food ad-lib ; experiment 2 : rats were submitted to food restriction (2 feeding periods per day). The results of these two experimental protocols showed that an acute stress (15-min of swimming/day for 3 consecutive days), applied at the onset of the dark phase, just before the usual feeding time, induced a significant reduction in daily body weight gain in male and female Wistar rats. Moreover stress induced increased plasma corticosterone levels and decreased of insulinemia. Sexual dimorphism was observed regarding the macronutrient selection in response to stress. Thus we concluded that, stress induced not only a quantitative but also a qualitative effect on food intake. In the 2nd part of this work we focused on the genetic variability of HPA axis in relation to the regulation of energy metabolism between two inbred strains of rats : Fischer F344, prone to obesity and Lou, obesity resistant. The neuroendocrinological, nutritional and metabolic comparisons showed that F344 strain presents (i) disturbances of its HPA axis resulting in a higher secretion of corticosterone and (ii) a strong vulnerability to develop obesity by increasing adiposity and reducing the basal metabolism compared with the Lou strain. In the last part of this work, we used a « nutraceutic approach » : testing the influence of a functional food (yeast extract) on stress. From our stress model developped at the point in the first part of this thesis, this work showed the protective properties of yeast extract on stress induced behavioral and eating disorders. These results open a new prospect on relationships between stress and feeding behavior but also provide new elements for understanding obesity resistance in Lou rat implying the HPA axis.
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https://pastel.archives-ouvertes.fr/pastel-00003109
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Submitted on : Tuesday, November 20, 2007 - 8:00:00 AM
Last modification on : Tuesday, November 20, 2007 - 8:00:00 AM
Long-term archiving on: : Thursday, September 30, 2010 - 8:06:15 PM

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Diane Abdoulaye. Stress, axe corticotrope et caracteristiques nutritionnelles et metaboliques. Life Sciences [q-bio]. INAPG (AgroParisTech), 2006. English. ⟨NNT : 2006INAP0033⟩. ⟨pastel-00003109⟩

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