Effects of adrenal corticoids on fatty acid synthesis in mammary gland slices in vitro

Abstract

The effect of cortisone, cortisol, corticosterone and deoxycorticosterone, alone and in conjunction with insulin, on the incorporation of glucose and acetate labeled with C14 or H3 into the fatty acids of lactating mammary gland slices from rats and sheep was studied. In rat tissue cortisone at a concentration of 100 [mu]g/ml medium was found to reduce fatty acid synthesis from glucose to about 70% of the control value and from acetate to about 60% of the control; the stimulating effect of insulin (0.045 [mu]g/mg) was largely antagonized by the cortisone addition. With sheep tissue, 100 [mu]g/ml and even 250 [mu]g/ml cortisone failed to reduce fatty acid synthesis from acetate. Cortisol at 100 [mu]g/ml had no significant effect on incorporation of either acetate or glucose C into fatty acids in rat tissue, nor did it antagonize the stimulation produced by 1.0 [mu]g/ml insulin: in sheep tissue there was some evidence that it could inhibit synthesis of fatty acids from acetate. Corticosterone at 100 [mu]g/ml markedly inhibited fatty acid synthesis from glucose in rat tissue and reduced the stimulating effect of 1.0 [mu]g/ml insulin. In sheep tissue, 50 [mu]g/ml slightly inhibited fatty acid synthesis from acetate, 100 [mu]g caused pronounced inhibition and at 200 [mu]g/ml fatty acid synthesis was almost suppressed. Deoxycorticosterone behaved very similarly to corticosterone, but was slightly more inhibitory in sheep at 100 [mu]g/ml than corticosterone.