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

J. C. George; T. M. John; M. A. Mitchell

doi:10.1055/s-2007-1009283

Hormone and Metabolic Research, Table of Contents

Horm Metab Res 1989; 21(10): 542-545
DOI: 10.1055/s-2007-1009283

Originals Basic

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

Abstract

PDF Download

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

PDF (420 kb)