Effects of food store quality on hibernation performance in common hamsters.

Carina Siutz,Ruth Quint,Matthias Nemeth,Thomas Ruf,Eva Millesi,Karl-Heinz Wagner,De-Hua Wang

doi:10.1371/journal.pone.0185913

Carina Siutz, Ruth Quint + Show 5 more

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https://doi.org/10.1371/journal.pone.0185913

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Abstract

Hibernating animals can adjust torpor expression according to available energy reserves. Besides the quantity, the quality of energy reserves could play an important role for overwintering strategies. Common hamsters are food-storing hibernators and show high individual variation in hibernation performance, which might be related to the quality of food hoards in the hibernacula. In this study, we tested the effects of food stores high in fat content, particularly polyunsaturated fatty acids (PUFAs), on hibernation patterns under laboratory conditions. Control animals received standard rodent pellets only, while in the other group pellets were supplemented with sunflower seeds. We recorded body temperature during winter using subcutaneously implanted data loggers, documented total food consumption during winter, and analysed PUFA proportions in white adipose tissue (WAT) before and after the winter period. About half of the individuals in both groups hibernated and torpor expression did not differ between these animals. Among the high-fat group, however, individuals with high sunflower seeds intake strongly reduced the time spent in deep torpor. PUFA proportions in WAT decreased during winter in both groups and this decline was positively related to the time an individual spent in deep torpor. Sunflower seeds intake dampened the PUFA decline resulting in higher PUFA levels in animals of the high-fat group after winter. In conclusion, our results showed that common hamsters adjusted torpor expression and food intake in relation to the total energy of food reserves, underlining the importance of food hoard quality on hibernation performance.

Highlights

Animals can overcome periods of unfavourable environmental conditions by hibernation, characterized by strongly reduced metabolic rate and body temperature (Tb) during multiday torpor bouts [1,2,3,4,5]
We provided two groups of hamsters with the same amount of food, but one group exclusively received standard laboratory food while in the other group 25% of pellets were replaced by sunflower seeds, resulting in increased energy and polyunsaturated fatty acids (PUFAs), linoleic acid (LA), content
As we focused on PUFAs due to our experimental design of providing sunflower seeds, we restricted the analyses to total PUFA proportions, as n-6 fatty acids accounted for 97.3% (n = 43) of total PUFAs found in white adipose tissue (WAT) samples according to the gas chromatography analyses

Summary

Introduction

Animals can overcome periods of unfavourable environmental conditions by hibernation, characterized by strongly reduced metabolic rate and body temperature (Tb) during multiday torpor bouts [1,2,3,4,5]. It has been shown that individuals intensified torpor expression with increasing internal energy reserves [15, 16]. This overwintering strategy, might implicate costs on an individual as torpor was found to be associated with oxidative stress [17], ischemia [18], shortening of telomeres [19], immune depression [20, 21], reduced synaptic efficacy [22], or impaired memory retention [23]. Torpor adjustment might be more pronounced in food-storing hibernators due to their greater energy-storing capacity [8], similar patterns were found in fat-storing hibernators as individuals with higher body mass prior to hibernation reduced the depth of torpor expression or showed longer euthermic periods [27, 28]

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