Metabolic adaptations and diet influence in a food-storing hibernator

Cette thèse présente les adaptations spécifiques des hibernants ‘food-storing’ qui s’alimentent au cours de l’hibernation, et les conséquences de la qualité du régime alimentaire sur leur cycle annuel. Tandis que les espèces ‘fat-storing’ jeûnent pendant toute l’hibernation, les ‘food-storing’ alternent jeûnes courts et réalimentations. L’adiponectine stimulerait la lipolyse pendant l’hibernation contribuant ainsi à la cétogenèse. Le maintien d’un système digestif fonctionnel conduisant à la sécrétion d’incrétines, permet l’absorption optimale de nutriments lors des courtes euthermies inter-torpeurs. Une absorption accrue de glucose en particulier permettrait de restaurer la glycémie et les réserves de glycogène. Par ailleurs, un régime appauvri en protéines et enrichi en lipides induit un engraissement augmenté en période pré-hibernatoire provoquant une moindre utilisation de la torpeur donc une perte de masse accrue lors de l’hibernation, et une baisse du succès reproducteur.This thesis presents the specific adaptations of food-storing hibernators that feed during hibernation, and the impact of diet quality on their annual cycle. In contrast to the fat-Storing species which fast during hibernation, the food-storing presents metabolic responses to an alternation of short fasting phases and hyperphagia. These responses involve one hand use of fat reserves during hibernation contributing to ketogenesis, which would be induced by adiponectin. On the other hand, maintaining a functional digestive system leading to the secretion of incretins, permits optimal nutrient absorption in the short inter-torpor euthermia. Increased glucose uptake in particular would restore body reserves to spare. Moreover, a lean protein diet enriched in fat and induces increased in body mass in pre-hibernation period causing reduced use of torpor thus an increased loss of mass during hibernation, and decreased reproductive success

Adaptations métaboliques et influence du régime alimentaire chez un hibernant food-storing

This thesis presents the specific adaptations of food-storing hibernators that feed during hibernation, and the impact of diet quality on their annual cycle. In contrast to the fat-Storing species which fast during hibernation, the food-storing presents metabolic responses to an alternation of short fasting phases and hyperphagia. These responses involve one hand use of fat reserves during hibernation contributing to ketogenesis, which would be induced by adiponectin. On the other hand, maintaining a functional digestive system leading to the secretion of incretins, permits optimal nutrient absorption in the short inter-torpor euthermia. Increased glucose uptake in particular would restore body reserves to spare. Moreover, a lean protein diet enriched in fat and induces increased in body mass in pre-hibernation period causing reduced use of torpor thus an increased loss of mass during hibernation, and decreased reproductive success.Cette thèse présente les adaptations spécifiques des hibernants ‘food-storing’ qui s’alimentent au cours de l’hibernation, et les conséquences de la qualité du régime alimentaire sur leur cycle annuel. Tandis que les espèces ‘fat-storing’ jeûnent pendant toute l’hibernation, les ‘food-storing’ alternent jeûnes courts et réalimentations. L’adiponectine stimulerait la lipolyse pendant l’hibernation contribuant ainsi à la cétogenèse. Le maintien d’un système digestif fonctionnel conduisant à la sécrétion d’incrétines, permet l’absorption optimale de nutriments lors des courtes euthermies inter-torpeurs. Une absorption accrue de glucose en particulier permettrait de restaurer la glycémie et les réserves de glycogène. Par ailleurs, un régime appauvri en protéines et enrichi en lipides induit un engraissement augmenté en période pré-hibernatoire provoquant une moindre utilisation de la torpeur donc une perte de masse accrue lors de l’hibernation, et une baisse du succès reproducteur

Metabolic adaptations and diet influence in a food-storing hibernator

Cette thèse présente les adaptations spécifiques des hibernants ‘food-storing’ qui s’alimentent au cours de l’hibernation, et les conséquences de la qualité du régime alimentaire sur leur cycle annuel. Tandis que les espèces ‘fat-storing’ jeûnent pendant toute l’hibernation, les ‘food-storing’ alternent jeûnes courts et réalimentations. L’adiponectine stimulerait la lipolyse pendant l’hibernation contribuant ainsi à la cétogenèse. Le maintien d’un système digestif fonctionnel conduisant à la sécrétion d’incrétines, permet l’absorption optimale de nutriments lors des courtes euthermies inter-torpeurs. Une absorption accrue de glucose en particulier permettrait de restaurer la glycémie et les réserves de glycogène. Par ailleurs, un régime appauvri en protéines et enrichi en lipides induit un engraissement augmenté en période pré-hibernatoire provoquant une moindre utilisation de la torpeur donc une perte de masse accrue lors de l’hibernation, et une baisse du succès reproducteur.This thesis presents the specific adaptations of food-storing hibernators that feed during hibernation, and the impact of diet quality on their annual cycle. In contrast to the fat-Storing species which fast during hibernation, the food-storing presents metabolic responses to an alternation of short fasting phases and hyperphagia. These responses involve one hand use of fat reserves during hibernation contributing to ketogenesis, which would be induced by adiponectin. On the other hand, maintaining a functional digestive system leading to the secretion of incretins, permits optimal nutrient absorption in the short inter-torpor euthermia. Increased glucose uptake in particular would restore body reserves to spare. Moreover, a lean protein diet enriched in fat and induces increased in body mass in pre-hibernation period causing reduced use of torpor thus an increased loss of mass during hibernation, and decreased reproductive success

Les agranulocytoses aux antithyroidiens de synthèse (une étude retrospective de 203 cas et analyse critique de la littérature)

STRASBOURG-Medecine (674822101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Nanoparticle emissions from a fleet of CNG buses in transient and steady state operation

Particle emission measurements from a fleet of 14 CNG and 5 Diesel buses were measured both for transient and steady state mode s on a chassis dynamometer with a CVS dilution system. Several transient DT80 cycles and 4 steady sate modes (0, 25, 50 100% of maximum load) were measured for each bus tested. Particle number concentration data was collected by three CPC’s (TSI 3022, 3010 3782WCPC) having D50 cut-offs set to 5, 10 and 20nm respectively. The size distributions were measured with a TSI 3080 SMPS with a 3025 CPC during the steady state modes. Particle mass emissions were measured with a TSI Dustrak. Particle mass emissions for Diesel buses were upto 2 orders of magnitude higher than for CNG buses. Particle number emissions during steady state modes for Diesel busses were 2 to 5 times higher than for CNG busses for all of the tested loads. On the other hand for the DT80 transient cycle particle number emissions were up to 3 times higher for the CNG buses. More detailed analysis of the transient cycles revealed that the reason for this was due to high particle number emissions from CNG busses during the acceleration parts of the cycles. Particles emitted by the CNG busses during acceleration were in the nucleation mode with the majority being smaller than 10nm. Volatility measurements have also shown that they were highly volatile

Les interruptions volontaires de grossesse répétées au centre hospitalier de Mulhouse et leur prévention

STRASBOURG-Medecine (674822101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Maintenance of a fully functional digestive system during hibernation in the European hamster, a food-storing hibernator

International audienceSome small mammals limit energy expenditure during winter conditions through torpor bouts, which are characterizedby a decrease in body temperature and metabolic rate. Individuals arise periodically from torpor to restorecritical functions requiring euthermia. Althoughmost of the species involved do not feed during hibernationand rely on body reserves to fulfil energy requirements (fat-storing species), others hoard food in a burrow(food-storing species) and can feed during interbout euthermy. Whereas fat-storing species undergo a markedatrophy of the digestive tract, food-storing species have to maintain a functional digestive system during hibernation.Our study aimed to evaluate the absorption capacities of a food-storing species, the European hamster,throughout the annual cycle. In vivo intestinal perfusions were conducted in different groups of hamsters(n = 5) during the different life periods, namely before hibernation, in torpor, during interbout euthermy, andduring summer rest. The triglyceride, non-esterified free fatty acid, starch, glucose and protein composition ofthe perfusate was evaluated before and after the 1 h perfusion of a closed intestinal loop. Triglyceride, starchand protein hydrolysis rates were similar in hibernating (torpid and euthermic) and non-hibernating hamsters.Intestinal absorption of free fatty acid was also similar in all groups. However, glucose uptake rate was higherduring hibernation than during the summer. In contrastwith fat-storing species, the intestinal absorption capacitiesof food-storing species are fully maintained during hibernation to optimize nutrient assimilation duringshort interbout euthermy. In particular, glucose uptake rate is increased during hibernation to restore glycaemiaand ensure glucose-dependent pathways

Dietary proteins improve hibernation and subsequent reproduction in the European hamster, Cricetus cricetus

International audienc

Hormonal changes and energy substrate availability during the hibernation cycle of Syrian hamsters

International audienceAnimals have to adapt to seasonal variations in food resources and temperature. Hibernation is one of the most efficient means used by animals to cope with harsh winter conditions, where survival is achieved through a significant decrease in energy expenditure. The hibernation period is constituted by a succession of torpor bouts (hypometabolism and decrease in body temperature) and periodic arousals (eumetabolism and euthermia). Some species feed during these periodic arousals, and thus show different metabolic adaptations to fat-storing species that fast throughout the hibernation period. Our study aims to define these metabolic adaptations, including hormone (insulin, glucagon, leptin, adiponectin, GLP-1, GiP) and metabolite (glucose, free fatty acids, triglycerides, urea) profiles together with body composition adjustments. Syrian hamsters were exposed to varied photoperiod and temperature conditions mimicking different phases of the hibernation cycle: a long photoperiod at 20°C (LP20 group), a short photoperiod at 20°C (SP20 group), and a short photoperiod at 8°C (SP8). SP8 animals were sampled either at the beginning of a torpor bout (Torpor group) or at the beginning of a periodic arousal (Arousal group). We show that fat store mobilization in hamsters during torpor bouts is associated with decreased circulating levels of glucagon, insulin, leptin, and an increase in adiponectin. Refeeding during periodic arousals results in a decreased free fatty acid plasma concentration and an increase in glycaemia and plasma incretin concentrations. Reduced incretin and increased adiponectin levels are therefore in accordance with the changes in nutrient availability and feeding behavior observed during the hibernation cycle of Syrian hamsters