Dietary lipid saturation influences environmental temperature preference but not resting metabolic rate in the Djungarian Hamster (Phodopus sungorus).
Heterothermic rodents increase self-selection of diets rich in polyunsaturated fatty acids (PUFAs) when exposed to cold, short days, or short-day melatonin profiles, and Djungarian hamsters (Phodopus sungorus) do so in long days in response to cold exposure alone. To determine whether Djungarian hamsters are also capable of selecting a thermal environment in response to dietary lipid composition, continuously normothermic hamsters were fed either a PUFA-rich diet or a diet rich in saturated fatty acids (SFAs) for 6-10 wk and given a choice of thermal environments. As predicted, SFA-fed hamsters were more likely than PUFA-fed hamsters to occupy the single heated corner of their cage ([Formula: see text]) and were most likely to show this diet-related difference in behavior when T(a) fell within the thermal neutral zone. Respirometry revealed no effect of diet on whole-animal or mass-specific resting metabolic rate or on lower critical temperature. The results are more consistent with the homeoviscous adaptation hypothesis, which predicts that organisms should make physiological and/or behavioral adjustments that preserve membrane fluidity within a relatively small range, than with the membrane pacemaker hypothesis, which predicts that high PUFA content in membrane phospholipids should increase basal metabolic rate.
Department of Biology, Swarthmore College, Swarthmore, Pennsylvania 19081, USA.
Ryan
R
Pannorfi
Barry M
BM
Zee
Itzick
I
Vatnick
Nancy
N
Berner
Sara M
SM
Hiebert
D000064:Acclimatization; D000818:Animals; D001481:Basal Metabolism; D006224:Cricetinae; D004041:Dietary Fats / Q000008:administration & dosage*; D005227:Fatty Acids / Q000008:administration & dosage*; D005231:Fatty Acids, Unsaturated / Q000008:administration & dosage*; D008834:Microclimate; D010101:Oxygen Consumption; D017111:Phodopus / Q000502:physiology*; D011897:Random Allocation; D012621:Seasons; D013696:Temperature
D004041:Dietary Fats; D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated