The effect of insulin, glucagon and prolactin on lipid synthesis and related metabolic activity in migratory and non-migratory finches

Abstract

1. The effects of insulin, glucagon and prolactin on lipid synthesis were investigated in house sparrows (Passer domesticus) and white-crowned sparrows (Zonotrichia leucophrys gambelii).2. The incorporation of glucose-U-C 14 and acetate-l-C 14 into abdominal fat pad lipid was measured in in vitro and in vivo experiments.3. None of these hormones accelerated lipid synthesis, even though lipogenesis is sensitive to changes in carbohydrate metabolism (i.e. glucose uptake) in this tissue.4. Insulin, a potent stimulator of lipid synthesis in mammalian adipose tissue, had no effect on the metabolism of finch fat pads.5. Glucagon and prolactin inhibited the synthesis of fatty acids from acetate. Only glucagon has the necessary potency to be of physiological significance.6. It is hypothesized that a relatively high glucagon output inhibits lipid synthesis during non-migratory periods. During migratory periods the output of glucagon falls, allowing lipid synthesis to proceed at a more rapid rate.

Effect of Hypophysectomy and Insulin on Lipogenesis in Cockerels

“…OUf observations on adipose tissue are consistent with earlier reports (Goodridge 1964, Goodridge and Ball 1966, O'Hea and Leveille 1968 that avian adipose tissue (cf mammals -Goldman and Cahill 1964) is probably not important in fatty acid synthesis and that it is not stimulated by insulin. However the adipose tissue of younger chickens is capable of responding to insulin (Goodridge 1968).…”

Response of Blood Plasma Glucose, Free Fatty Acids, Triglycerides, Insulin and Food Intake to Bovine Insulin in Geese and Cockerels

“…The effects of bovine insulin injection observed in the cockerels and geese were similar to those described earlier in chickens (Goodridge, 1964;Heald et al, 1965;Junod et al, 1967;Lepkovsky et al, 1967;Grande, 1969;Langslow et al, 1970) i.e. decreased glucose and increased FFA concentration.…”

Fatty-acid synthesis in the echinoderms:Asterias rubens, Echinus esculentusandHolothuria forskali

“…This fact is the more remarkable in the face of evidence that two of the major food organisms of P. ochraceus possess fatty-acid mixtures containing upwards of 30% of polyenoic acids (Rodegker & Nevenzel, 1964). There is abundant evidence from vertebrate studies to show that the rates of such processes are strongly dependent upon diet (Masoro, 1962) and phase of reproductive cycle (Goodridge, 1964). to the gonads) of dietary polyenes or net de novo synthesis of monoenes and saturates from dietary glycolytic substrates.…”