The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Endotoxin injection attenuates rest-phase hypothermia in wintering great tits through the onset of fever

Author

Summary, in English

Endothermic animals in the boreal region experience considerable thermoregulatory costs in winter, especially during inactive periods when high demands cannot be met by increased food intake. This might necessitate a trade-off between resting thermoregulation and other energetically expensive processes, such as immune function, but this has rarely been investigated. We evaluated how immune activation affected rest-phase hypothermia (an important energy conservation mechanism in small animals), in wild great tits (Parus major L.) wintering under semi-natural conditions in southern Sweden. The acute phase response was triggered immediately prior to sunset through intramuscular lipopolysaccharide (LPS, an endotoxin) administration in two contrasting, naturally occurring, thermal regimes (cold, mild). We then noninvasively measured the thermoregulatory response throughout the night using subcutaneously implanted temperature-sensitive transmitters. Despite the energetic benefits of hypothermia, immunized great tits displayed an attenuated hypothermic response manifested through the onset of fever, possibly at the expense of a higher sustained metabolic rate. In line with this, these birds lost more body mass overnight (but only in mild conditions) and consequently were in worse condition the subsequent morning. Fever expression was remarkably similar in cold and mild conditions, despite substantial variation in the energetic cost for thermoregulation. This suggest that the degree of fever is flexible, and represents a trade-off between the minimum body temperature required to mount an adequate acute phase response and the energy expenditure needed to maintain it. We suggest that while energy conservation and immune function may not always be exclusive activities, costs of immune defences probably constitute an important additive energetic cost during northern winter conditions, sometimes calling for trade-offs with other important physiological processes to survive the night.

Publishing year

2013

Language

English

Pages

236-244

Publication/Series

Functional Ecology

Issue

online: 9 NOV 2012

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Biological Sciences

Keywords

  • acute phase response
  • body temperature
  • ecological immunology
  • heterothermy
  • LPS
  • metabolism
  • Parus major
  • thermoregulation

Status

Published

Project

  • Immunoecology

Research group

  • Molecular Ecology and Evolution Lab
  • Life History and Functional Ecology

ISBN/ISSN/Other

  • ISSN: 1365-2435