The effect of hyperglycemic-glycogenolytic factor and epinephrine on fatty acid synthesis.

It is well known that the synthesis of fat by mammalian tissues is influenced by hormones. For example Stetten and Boxer (1) showed that the synthesis of fat is markedly impaired in the alloxan-diabetic rat. Stetten and Klein (2) found that insulin increased the conversion of carbohydrate to fat in the normal rabbit. It was first demonstrated by Bloch and Kramer (3) that insulin stimulates fatty acid synthesis in vitro. They found that insulin increases the incorporation of isotopic acetat,e into fatty acids of rat liver slices in the presence of non-isotopic pyruvate. Later Brady and Gurin (4) reported that insulin stimulates fatty acid synthesis from acetate in the absence of added pyruvate. Liver slices from alloxan-diabetic rats (5, 6) and depancreatized cats (7) have almost completely lost the ability to synt,hesize fatty acids and synthesis is not restored by insulin in vitro. Normal fatty acid synthesis is restored after insulin injection in the alloxan-diabetic rat (8). Evidence has been obtained recently that t’he ant’erior pituitary (probably growth hormone) and adrenal cortical hormones influence the synthesis of fatty acids from acetate by liver slices (7). The present investigation is concerned with the effects of insulin, hyperglycemic factor, and epinephrine on the incorporation of radioactive acetate into fatty acids by rat liver slices.