Document Detail

Cold exposure and food restriction facilitate physiological responses to short photoperiod in Djungarian hamsters (Phodopus sungorus).
MedLine Citation:
PMID:  8409896     Owner:  NLM     Status:  MEDLINE    
We investigated the influence of ambient temperature (Ta) and food availability on seasonal timing and extent of physiological responses to short photoperiod (SP), in particular daily torpor, in Djungarian hamsters (Phodopus sungorus). Exposure of hamsters to cold temperature (Ta = 5 degrees C), relative to warm Ta (23 degrees C), resulted in: 1) a significant advance (P < 0.05) of the first occurrence of torpor among cold-exposed hamsters (days 52-97 vs. days 83-99 in SP); 2) a higher (P < 0.01) incidence of torpor (48% vs. 20% torpid animals/day); 3) a higher (P < 0.05) degree of molt into the winter pelt; and 4) an accelerated reduction of body weights (P < 0.001). However, within SP/cold-Ta exposed groups, individual hamsters clearly showed different tendencies for torpor (torpor on 0-95% of days observed). Therefore, we evaluated the effects of small changes in Ta on torpor frequency and extension by subjecting the same SP-adapted individuals to varying temperatures. Lowering of Ta from 15 degrees C to 10 degrees C and 5 degrees C caused significant (P < 0.05) increases in the incidence of torpor (20%, 33%, and 40%, respectively) and lower minimal body temperatures during hypothermia (P < 0.05). When the same animals were subjected to 24-48 h lasting periods of food restriction (60% of the ad libitum intake), torpor frequency further increased 1.8- to 2.6-fold at all Tas. These results show that Ta and food availability are effective in modifying both seasonal timing and extent of photoperiodically controlled adaptations. This integration of multiple environmental cues, combined with a pronounced within-species variability of winter adjustments, indicates that Djungarian hamsters are capable of flexible physiological responses towards unpredictable climatic changes in the environment.
T Ruf; A Stieglitz; S Steinlechner; J L Blank; G Heldmaier
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of experimental zoology     Volume:  267     ISSN:  0022-104X     ISO Abbreviation:  J. Exp. Zool.     Publication Date:  1993 Oct 
Date Detail:
Created Date:  1993-11-02     Completed Date:  1993-11-02     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0375365     Medline TA:  J Exp Zool     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  104-12     Citation Subset:  IM; S    
Department of Biology/Zoology, Philipps University, Marburg, Germany.
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MeSH Terms
Body Temperature
Body Weight
Cold Temperature*
Food Deprivation*
Hair Color
Motor Activity

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