Effects of chronic exposure to insulin on lipid synthesis in 3T3-L1 fatty fibroblasts.

The acute effects of insulin on 3H incorporation into lipid from glucose was measured in 3T3-L1 fatty fibroblasts cultured with and without insulin at 10 microgram/ml for 7 days. Basal lipid synthesis did not differ between control cells and cells treated chronically with insulin. There was no insulin stimulation in treated cells while 3H incorporation into lipid in control cells increased from a basal level of 1.39 to 3.85 nmol/dish/90 min with a maximally-stimulating concentration of insulin. This is the first study of 3T3-L1 fatty fibroblasts which describes a lack of acute insulin responsiveness in cells exposed chronically to insulin as compared to control cells.