Lipid metabolism in marine animals.

and insulin in birds. Insulin potentiates the glucagon stimulation of lipolysis (Langslow & Hales, 1969), whereas in rat adipose tissue insulin has an antilipolytic effect on glucagon-stimulated lipolysis. In the rat, insulin stimulates lipogenesis in the adipose tissue, whereas avian adipose tissue is either poorly sensitive or insensitive to the lipogenic action of insulin (Kompiang & Gibson, 1976). This may be related to the fact that avian adipose tissue is not important in lipogenesis. In mammals hepatic lipogenesis is also stimulated by insulin and it has been reported that insulin stimulates hepatic lipogenesis (Goodridge, 1973) and liver lipogenic enzyme activity in the fowl (Kompiang & Gibson, 1976); these effects in birds were only seen with relatively large doses of insulin. It is clear that further studies of the effects of hormones and in particular, insulin, on lipid metabolism in avian species are necessary.