Format

Send to

Choose Destination
See comment in PubMed Commons below
J Exp Biol. 2009 Sep 15;212(18):2885-91. doi: 10.1242/jeb.024430.

Responses to temperature variation: integration of thermoregulation and metabolism in vertebrates.

Author information

1
Integrative Physiology, School of Biological Sciences A08, University of Sydney, NSW 2006, Australia.

Abstract

Many vertebrates regulate their body temperature in response to thermal variability of the environment. Endotherms maintain relatively stable body temperatures by adjusting metabolic heat production in response to varying environmental heat loads. Although most ectotherms do not display adaptive thermogenesis, they do acclimate cellular metabolism to compensate for environmental temperature variation. The components of the thermoregulatory systems in endotherms and ectotherms are evolutionarily conserved, and I suggest that metabolic acclimation in ectotherms relies on the same regulatory pathways as adaptive thermogenesis in endotherms. Both groups rely on transient receptor potential ion channels to sense environmental temperatures. Thermosensory (afferent) information is relayed to the hypothalamus, which initiates a sympathetic efferent response. Cardiovascular responses to heat are similar in ectothermic crocodiles and in mammals, and are mediated by the autonomic nervous system in both cases. The sympathetic nervous system also modulates cellular metabolism by inducing expression of the transcriptional regulator peroxisome proliferator activated receptor gamma coactivator 1alpha (PGC-1alpha), which interacts with a range of transcription factors that control glycolysis, fatty acid oxidation, gluconeogenesis, mitochondrial biogenesis and bioenergetics, and metabolic rate. PGC-1alpha is best known from mammalian model species but there is increasing evidence that it is also instrumental in non-mammalian vertebrates. Hence, endothermic adaptive thermogenesis may result from the same regulatory pathways as ectothermic metabolic acclimation, and both could be considered as adaptive metabolic responses to temperature variation.

PMID:
19717669
DOI:
10.1242/jeb.024430
[Indexed for MEDLINE]
Free full text
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire
    Loading ...
    Support Center