Gastric inhibitory polypeptide enhancement of the insulin effect on fatty acid incorporation into adipose tissue in the rat.

The influence of gastric inhibitory polypeptide (GIP) on fatty acid incorporation into adipose tissue (FIAT) was studied in the rat on epididymal fat pads at concentrations amounting to 1, 2 and 4 ng/ml. Without insulin in the incubation medium, GIP induced a slight though significant FIAT decrease with a maximum of 9% for 2 ng/ml concentration. In the presence of rat insulin (100 microU/ml), it significantly enhanced the insulin-induced FIAT increase, that progressed from 106.4% of the basal value to 110.5% for 1 ng/ml concentration (P less than 0.025) and to 118.2% for 4 ng/ml concentration (P less than 0.0025). The existence of such a phenomenon as well as that of an hyperactive enteroinsular axis in obese subjects could represent two important factors in the development of obesity.