title: The effects of poly-unsaturated fatty acids on the physiology of hibernation in a South American marsupial, Dromiciops gliroides.
abstract: Many mammals hibernate, which is a profound lethargic state of several weeks or months during winter, that represents a transitory episode of hetherothermy. As with other cases of dormancy, the main benefit of hibernation seems to be energy saving. However, the depth and duration of torpor can be experimentally modified by the composition of food, especially by fattyacid composition. In eutherians, diets rich in unsaturated fatty acids (i.e., fatty acids with at least one double bond) lengthen torpor, reduce metabolism and permit hibernation at lower temperatures. Here we studied whether diets varying in fatty acid composition have an effect on the physiology of hibernation in a South American marsupial, Dromiciops gliroides. We designed a factorial experiment where thermal acclimation (two levels: natural versus constant temperature) was combined with diet acclimation: saturated (i.e., diets with high concentration of saturated fatty acids) versus unsaturated (i.e., diets with high concentration of unsaturated fatty acids). We measured energy metabolism in active and torpid individuals, as well as torpor duration, and a suite of 12 blood biochemical parameters. After a cafeteria test, we found that D. gliroides did not show any preference for a given diet. Also, we did not find effects of diet on body temperature during torpor, or its duration. However, saturated diets, combined with high temperatures provoked a disproportionate increase in fat utilization, leading to body mass reduction. Those animals were more active, and metabolized more fats than those fed with a high proportion of unsaturated fatty acids (="unsaturated diets"). These results contrast with previous studies, which showed a significant effect of fatty acid composition of diets on food preferences and torpor patterns in mammals.
authors.affiliation: Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Casilla 567, Campus Isla Teja, Valdivia 5090000, Chile.
authors.forename: Carolina
authors.initials: C
authors.lastname: Contreras
authors.affiliation: Facultad de Ciencias Naturales y Matemáticas, Universidad de Ibagué, Carrera 22 Calle 67 Barrio Ambalá, Ibagué, Tolima, Colombia.
authors.forename: Marcela
authors.initials: M
authors.lastname: Franco
authors.affiliation: Department of Population Medicine & Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Ned J
authors.initials: NJ
authors.lastname: Place
authors.affiliation: Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Casilla 567, Campus Isla Teja, Valdivia 5090000, Chile; Center of Applied Ecology and Sustainability (CAPES). Electronic address: robertonespolorossi@gmail.com.
authors.forename: Roberto F
authors.initials: RF
authors.lastname: Nespolo
mesh_terms: D000818:Animals; D015992:Body Mass Index; D004042:Dietary Fats, Unsaturated / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D006605:Hibernation / Q000502:physiology*; D008394:Marsupialia / Q000378:metabolism* / Q000502:physiology*; D012621:Seasons; D013696:Temperature; D064348:Torpor / Q000502:physiology
chemical_list: D004042:Dietary Fats, Unsaturated; D005231:Fatty Acids, Unsaturated
keywords: Dromiciops; Hibernation; Poly-unsaturated fatty acids; South American marsupial