Fasting-induced daily torpor in desert hamsters ('Phodopus roborovskii')

Title
Fasting-induced daily torpor in desert hamsters ('Phodopus roborovskii')
Publication Date
2016
Author(s)
Chi, Qing-Sheng
Wan, Xin-Rong
Geiser, Fritz
( author )
OrcID: https://orcid.org/0000-0001-7621-5049
Email: fgeiser@une.edu.au
UNE Id une-id:fgeiser
Wang, De-Hua
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
Elsevier Inc
Place of publication
United States of America
DOI
10.1016/j.cbpa.2016.05.019
UNE publication id
une:20248
Abstract
Daily torpor is frequently expressed in small rodents when facing energetically unfavorable ambient conditions. Desert hamsters ('Phodopus roborovskii', ~20 g) appear to be an exception as they have been described as homeothermic. However, we hypothesized that they can use torpor because we observed reversible decreases of body temperature (Tb) in fasted hamsters. To test this hypothesis we (i) randomly exposed fasted summer-acclimated hamsters to ambient temperatures (Tₐs) ranging from 5 to 30 °C or (ii) supplied them with different rations of food at Tₐ 23 °C. All desert hamsters showed heterothermy with the lowest mean Tb of 31.4±1.9 °C (minimum, 29.0 °C) and 31.8±2.0 °C (minimum, 29.0 °C) when fasted at Tₐ of 23 °C and 19 °C, respectively. Below Ta 19 °C, the lowest Tb and metabolic rate increased and the proportion of hamsters using heterothermy declined. At Ta 5 °C, nearly all hamsters remained normothermic by increasing heat production, suggesting that the heterothermy only occurs in moderately cold conditions, perhaps to avoid freezing at extremely low Tₐs. During heterothermy, Tbs below 31 °C with metabolic rates below 25% of those during normothermia were detected in four individuals at Tₐ of 19 °C and 23 °C. Consequently, by definition, our observations confirm that fasted desert hamsters are capable of shallow daily torpor. The negative correlation between the lowest Tbs and amount of food supply shows that heterothermy was mainly triggered by food shortage. Our data indicate that summer-acclimated desert hamsters can express fasting-induced shallow daily torpor, which may be of significance for energy conservation and survival in the wild.
Link
Citation
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, v.199, p. 71-77
ISSN
1531-4332
1095-6433
Start page
71
End page
77

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