Effects of somatostatin on gastrointestinal hormone-induced glycogenolysis and gluconeogenesis in cultured liver cells.

When isolated rat liver cells were incubated for 15 min in the presence of vasoactive intestinal peptide, gastric inhibitory polypeptide, secretin or glucagon at a concentration of 2.0 micrograms/ml, glycogenolysis was stimulated by 30%-67% above the control. Slight but significant increase on gluconeogenesis was also observed by the addition vasoactive intestinal peptide, gastric inhibitory polypeptide or secretin. Somatostatin inhibited both glycogenolysis and gluconeogenesis induced by these hormones, but the degrees of inhibition are clearly much higher in the hormone-induced gluconeogenesis than glycogenolysis, and no significant inhibition of glycogenolysis was observed in case of glucagon and VIP. These results suggest the possibility that the so-called enterohepatic axis may play a part of roles in the regulation of serum glucose levels through gastrointestinal hormones belonging to the secretin family, and that it may be further regulated by somatostatin through gluconeogenesis.