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Selected Publication:

Type of publication: Journal Article
Type of document: Review

Year: 2008

Authors: Ruf, T; Arnold, W

Title: Effects of polyunsaturated fatty acids on hibernation and torpor: a review and hypothesis.

Source: Am J Physiol Regul Integr Comp Physiol. 2008; 294(3):R1044-R1052



Authors Vetmeduni Vienna:

Arnold Walter
Ruf Thomas

Vetmed Research Units
Research Institute of Wildlife Ecology


Abstract:
Polyunsaturated fatty acids (PUFAs) can have strong effects on hibernation and daily torpor in mammals. High dietary PUFA contents were found to increase proneness for torpor, decrease body temperatures, prolong torpor bout duration, and attenuate hibernation mass loss. The mechanism by which PUFAs enhance torpor and hibernation is unknown, however. On the basis of a review of the literature, and on reexamining our own data on alpine marmots, we propose that effects on hibernation are not due to PUFAs in general, but to shifts in the ratio of n-6 PUFAs to n-3 PUFAs in membrane phospholipids. Specifically, high ratios of n-6 to n-3 PUFAs increase the activity of the Ca2+-Mg2+ pump in the sarcoplasmic reticulum of the heart (SERCA) and counteract Q10 effects on SERCA activity at low tissue temperatures. Therefore, high n-6 to n-3 PUFA ratios in cardiac myocyte membranes appear to protect the hibernating heart from arrhythmia, which in hypothermic nonhibernators is caused by massive increases in cytosolic Ca2+. The resulting reduced risk of cardiac arrest during hypothermia may explain why increased dietary uptake of n-6 PUFAs, but not of n-3 PUFAs, can strongly enhance the propensity for hibernation, and allows heterotherms to reach lower body temperatures, with associated increased energy savings. Therefore, at least for herbivorous hibernators, such as marmots, linoleic acid (C18:2 n-6)--the dietary source of all n-6 PUFAs--appears to represent a crucial and limited resource in natural environments.

Keywords Pubmed: Animals
Body Temperature
Fatty Acids, Omega-3/pharmacology
Fatty Acids, Omega-6/pharmacology
Fatty Acids, Unsaturated/pharmacology*
Heart/physiology
Hibernation/drug effects*
Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism


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