Endocrine responses of ducks (Anas platyrhynchos) to treadmill exercise

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

“…A study in which ducks ran on a treadmill, Harvey et al (1982) demonstrated a significant reduction in plasma level of T4 whereas T3 was markedly increased. The metabolically active iodohormone T3 is known to be derived from T4 as a result of peripheral monodeiodination (Astierarvd Newcomer 1978) and it has been found that the rate of conversion of T4 to T3 is faster in chickens than in mammals (Rudas and Pethes 1984a).…”

“…1982). It was also suggested that the effect of exercise on thyroid activity in birds may differ from that in mammals in which blood levels of T4 and T3 were unaffected by non-exhaustive exercise (Harvey et al 1982). Harvey et al (1982) attributed the increase in plasma T3 in their treadmillrun ducks to the possibility of increased sympathetic activity enhancing deiodinating activity in the liver.…”

“…It was also suggested that the effect of exercise on thyroid activity in birds may differ from that in mammals in which blood levels of T4 and T3 were unaffected by non-exhaustive exercise (Harvey et al 1982). Harvey et al (1982) attributed the increase in plasma T3 in their treadmillrun ducks to the possibility of increased sympathetic activity enhancing deiodinating activity in the liver. John et al (1988) however, observed no flight-induced changes in plasma levels of T4 and T3 in homing pigeons even though plasma levels of adrenaline and noradrenaline were shown to be significantly increased in the flown pigeons (Viswanathan et al 1987).…”

Flight Effects on Plasma Glucose, Lactate, Catecholamines and Corticosterone in Homing Pigeons

“…These results indicate that in sustained free flight the bird maintains its high blood sugar level with the help of its active liver which has a high capacity for gluconeogenesis (Pearce 1983) and also because glucagon as a glucogenic hormone is more powerful in birds than in mammals. Indeed, plasma glucagon concentration has been found to be increased during 90 min of treadmill exercise in the domestic duck (Harvey, Klandorf, Foltzer, Strosser and Phillips 1982). This calls for the measurement of preand post-flight levels of plasma glucagon in future studies with homing pigeons.…”

Avian Adjustments to Cold

“…We are not aware of any measurements of the effects of acute cold exposure on glucagon levels in birds, although cited unpublished findings that glucagon is higher during chronic cold exposure in ducklings. Harvey et al (1985) found increases in glucagon levels in exercising mallard ducks, suggesting a physiological role of glucagon under conditions of accelerated energy demand. Other hormones, or putative hormones that have lipolytic activity in birds and could potentially contribute to physiological regulation of lipolysis, include growth hormone (LeClerq 1984) and two intestinal peptides (Krug and Mialhe 1975;Krug 1978).…”