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Horm Metab Res 1989; 21(10): 542-545
DOI: 10.1055/s-2007-1009283
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© Georg Thieme Verlag, Stuttgart · New York

Flight Effects on Plasma Levels of Lipid, Glucagon and Thyroid Hormones in Homing Pigeons

J. C. George1 , T. M. John1 , M. A. Mitchell2
  • 1Department of Zoology, University of Guelph, Guelph, Ontario, Canada
  • 2AFRC Institute for Grassland and Animal Production, Poultry Department, Roslin, Midlothian, Scotland, United Kingdom
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Publication History

1988

1989

Publication Date:
14 March 2008 (online)

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Summary

Significant increases in the concentration of plasma glucagon-like immunoreactivity (GLI) and plasma levels of free fatty acids (FFA) and triglycerides (TG) concomitant with decreases in circulating levels of thyroxine (T4) and triiodothyronine (T3) and T3/T4 ratio were observed in homing pigeons, untrained for 3 months, after a flight of 48 km lasting 90-160 min. The increased level of FFA is attributed to glucagon stimulated lipolysis. The elevation of TG levels may be due to altered partitioning and utilization of lipoprotein in adipose tissue and muscle. Reductions in plasma T4, T3 and T3/T4 ratio are probably due to inhibition of T4 secretion and 5'-monodeiodination with possible conversion of T4 to reverse T3 (rT3). These processes may represent a mechanism for regulation of thyroid hormone metabolism during strenuous and extended night.

Key-Words

Homing Flight - Blood Values - Glucagon - Thyroxine - Triiodothyronine - Triglycerides - Free Fatty Acids

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